ssh: allow to configure public key auth algorithms on the server side

Fixes golang/go#61244

Change-Id: I29b43e379cf0cdb07b0d6935666491b997157e73
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/510775
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
Commit-Queue: Nicola Murino <nicola.murino@gmail.com>
Run-TryBot: Nicola Murino <nicola.murino@gmail.com>
Auto-Submit: Nicola Murino <nicola.murino@gmail.com>
Reviewed-by: Han-Wen Nienhuys <hanwen@google.com>

acme/acme_test.go

@@ -354,11 +354,12 @@ func TestWaitAuthorization(t *testing.T) {
 		})
 	}
 	t.Run("context cancel", func(t *testing.T) {
-		ctx, cancel := context.WithTimeout(context.Background(), 200*time.Millisecond)
+		ctx, cancel := context.WithCancel(context.Background())
 		defer cancel()
 		_, err := runWaitAuthorization(ctx, t, func(w http.ResponseWriter, r *http.Request) {
 			w.Header().Set("Retry-After", "60")
 			fmt.Fprintf(w, `{"status":"pending"}`)
+			time.AfterFunc(1*time.Millisecond, cancel)
 		})
 		if err == nil {
 			t.Error("err is nil")
@@ -373,28 +374,14 @@ func runWaitAuthorization(ctx context.Context, t *testing.T, h http.HandlerFunc)
 		h(w, r)
 	}))
 	defer ts.Close()
-	type res struct {
-		authz *Authorization
-		err   error
+
+	client := &Client{
+		Key:          testKey,
+		DirectoryURL: ts.URL,
+		dir:          &Directory{},
+		KID:          "some-key-id", // set to avoid lookup attempt
 	}
-	ch := make(chan res, 1)
-	go func() {
-		client := &Client{
-			Key:          testKey,
-			DirectoryURL: ts.URL,
-			dir:          &Directory{},
-			KID:          "some-key-id", // set to avoid lookup attempt
-		}
-		a, err := client.WaitAuthorization(ctx, ts.URL)
-		ch <- res{a, err}
-	}()
-	select {
-	case <-time.After(3 * time.Second):
-		t.Fatal("WaitAuthorization took too long to return")
-	case v := <-ch:
-		return v.authz, v.err
-	}
-	panic("runWaitAuthorization: out of select")
+	return client.WaitAuthorization(ctx, ts.URL)
 }
 
 func TestRevokeAuthorization(t *testing.T) {

acme/autocert/autocert_test.go

@@ -427,18 +427,7 @@ func TestGetCertificate(t *testing.T) {
 
 			man.Client = &acme.Client{DirectoryURL: s.URL()}
 
-			var tlscert *tls.Certificate
-			var err error
-			done := make(chan struct{})
-			go func() {
-				tlscert, err = man.GetCertificate(tt.hello)
-				close(done)
-			}()
-			select {
-			case <-time.After(time.Minute):
-				t.Fatal("man.GetCertificate took too long to return")
-			case <-done:
-			}
+			tlscert, err := man.GetCertificate(tt.hello)
 			if tt.expectError != "" {
 				if err == nil {
 					t.Fatal("expected error, got certificate")
@@ -515,15 +504,12 @@ func TestGetCertificate_failedAttempt(t *testing.T) {
 	if _, err := man.GetCertificate(hello); err == nil {
 		t.Error("GetCertificate: err is nil")
 	}
-	select {
-	case <-time.After(5 * time.Second):
-		t.Errorf("took too long to remove the %q state", exampleCertKey)
-	case <-done:
-		man.stateMu.Lock()
-		defer man.stateMu.Unlock()
-		if v, exist := man.state[exampleCertKey]; exist {
-			t.Errorf("state exists for %v: %+v", exampleCertKey, v)
-		}
+
+	<-done
+	man.stateMu.Lock()
+	defer man.stateMu.Unlock()
+	if v, exist := man.state[exampleCertKey]; exist {
+		t.Errorf("state exists for %v: %+v", exampleCertKey, v)
 	}
 }
 
@@ -542,8 +528,9 @@ func TestRevokeFailedAuthz(t *testing.T) {
 		t.Fatal("expected GetCertificate to fail")
 	}
 
-	start := time.Now()
-	for time.Since(start) < 3*time.Second {
+	logTicker := time.NewTicker(3 * time.Second)
+	defer logTicker.Stop()
+	for {
 		authz, err := m.Client.GetAuthorization(context.Background(), ca.URL()+"/authz/0")
 		if err != nil {
 			t.Fatal(err)
@@ -551,10 +538,14 @@ func TestRevokeFailedAuthz(t *testing.T) {
 		if authz.Status == acme.StatusDeactivated {
 			return
 		}
+
+		select {
+		case <-logTicker.C:
+			t.Logf("still waiting on revocations")
+		default:
+		}
 		time.Sleep(50 * time.Millisecond)
 	}
-	t.Error("revocations took too long")
-
 }
 
 func TestHTTPHandlerDefaultFallback(t *testing.T) {

acme/rfc8555.go

@@ -117,7 +117,7 @@ func (c *Client) updateRegRFC(ctx context.Context, a *Account) (*Account, error)
 	return responseAccount(res)
 }
 
-// getGegRFC is equivalent to c.GetReg but for CAs implementing RFC 8555.
+// getRegRFC is equivalent to c.GetReg but for CAs implementing RFC 8555.
 // It expects c.Discover to have already been called.
 func (c *Client) getRegRFC(ctx context.Context) (*Account, error) {
 	req := json.RawMessage(`{"onlyReturnExisting": true}`)

acme/rfc8555_test.go

@@ -177,8 +177,7 @@ func TestRFC_postKID(t *testing.T) {
 	}))
 	defer ts.Close()
 
-	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
-	defer cancel()
+	ctx := context.Background()
 	cl := &Client{
 		Key:          testKey,
 		DirectoryURL: ts.URL,
@@ -316,8 +315,7 @@ func TestRFC_Register(t *testing.T) {
 	s.start()
 	defer s.close()
 
-	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
-	defer cancel()
+	ctx := context.Background()
 	cl := &Client{
 		Key:          testKeyEC,
 		DirectoryURL: s.url("/"),
@@ -454,8 +452,7 @@ func TestRFC_RegisterExternalAccountBinding(t *testing.T) {
 	s.start()
 	defer s.close()
 
-	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
-	defer cancel()
+	ctx := context.Background()
 	cl := &Client{
 		Key:          testKeyEC,
 		DirectoryURL: s.url("/"),
@@ -867,24 +864,13 @@ func testWaitOrderStatus(t *testing.T, okStatus string) {
 	s.start()
 	defer s.close()
 
-	var order *Order
-	var err error
-	done := make(chan struct{})
-	go func() {
-		cl := &Client{Key: testKeyEC, DirectoryURL: s.url("/")}
-		order, err = cl.WaitOrder(context.Background(), s.url("/orders/1"))
-		close(done)
-	}()
-	select {
-	case <-time.After(3 * time.Second):
-		t.Fatal("WaitOrder took too long to return")
-	case <-done:
-		if err != nil {
-			t.Fatalf("WaitOrder: %v", err)
-		}
-		if order.Status != okStatus {
-			t.Errorf("order.Status = %q; want %q", order.Status, okStatus)
-		}
+	cl := &Client{Key: testKeyEC, DirectoryURL: s.url("/")}
+	order, err := cl.WaitOrder(context.Background(), s.url("/orders/1"))
+	if err != nil {
+		t.Fatalf("WaitOrder: %v", err)
+	}
+	if order.Status != okStatus {
+		t.Errorf("order.Status = %q; want %q", order.Status, okStatus)
 	}
 }
 
@@ -909,30 +895,20 @@ func TestRFC_WaitOrderError(t *testing.T) {
 	s.start()
 	defer s.close()
 
-	var err error
-	done := make(chan struct{})
-	go func() {
-		cl := &Client{Key: testKeyEC, DirectoryURL: s.url("/")}
-		_, err = cl.WaitOrder(context.Background(), s.url("/orders/1"))
-		close(done)
-	}()
-	select {
-	case <-time.After(3 * time.Second):
-		t.Fatal("WaitOrder took too long to return")
-	case <-done:
-		if err == nil {
-			t.Fatal("WaitOrder returned nil error")
-		}
-		e, ok := err.(*OrderError)
-		if !ok {
-			t.Fatalf("err = %v (%T); want OrderError", err, err)
-		}
-		if e.OrderURL != s.url("/orders/1") {
-			t.Errorf("e.OrderURL = %q; want %q", e.OrderURL, s.url("/orders/1"))
-		}
-		if e.Status != StatusInvalid {
-			t.Errorf("e.Status = %q; want %q", e.Status, StatusInvalid)
-		}
+	cl := &Client{Key: testKeyEC, DirectoryURL: s.url("/")}
+	_, err := cl.WaitOrder(context.Background(), s.url("/orders/1"))
+	if err == nil {
+		t.Fatal("WaitOrder returned nil error")
+	}
+	e, ok := err.(*OrderError)
+	if !ok {
+		t.Fatalf("err = %v (%T); want OrderError", err, err)
+	}
+	if e.OrderURL != s.url("/orders/1") {
+		t.Errorf("e.OrderURL = %q; want %q", e.OrderURL, s.url("/orders/1"))
+	}
+	if e.Status != StatusInvalid {
+		t.Errorf("e.Status = %q; want %q", e.Status, StatusInvalid)
 	}
 }
 
@@ -972,8 +948,7 @@ func TestRFC_CreateOrderCert(t *testing.T) {
 	})
 	s.start()
 	defer s.close()
-	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
-	defer cancel()
+	ctx := context.Background()
 
 	cl := &Client{Key: testKeyEC, DirectoryURL: s.url("/")}
 	cert, curl, err := cl.CreateOrderCert(ctx, s.url("/pleaseissue"), csr, true)

acme/version_go112.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build go1.12
-// +build go1.12
 
 package acme
 

argon2/blamka_amd64.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build amd64 && gc && !purego
-// +build amd64,gc,!purego
 
 package argon2
 

argon2/blamka_amd64.s

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build amd64 && gc && !purego
-// +build amd64,gc,!purego
 
 #include "textflag.h"
 

argon2/blamka_ref.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build !amd64 || purego || !gc
-// +build !amd64 purego !gc
 
 package argon2
 

bcrypt/bcrypt.go

@@ -50,7 +50,7 @@ func (ih InvalidHashPrefixError) Error() string {
 type InvalidCostError int
 
 func (ic InvalidCostError) Error() string {
-	return fmt.Sprintf("crypto/bcrypt: cost %d is outside allowed range (%d,%d)", int(ic), int(MinCost), int(MaxCost))
+	return fmt.Sprintf("crypto/bcrypt: cost %d is outside allowed range (%d,%d)", int(ic), MinCost, MaxCost)
 }
 
 const (
@@ -82,11 +82,20 @@ type hashed struct {
 	minor byte
 }
 
+// ErrPasswordTooLong is returned when the password passed to
+// GenerateFromPassword is too long (i.e. > 72 bytes).
+var ErrPasswordTooLong = errors.New("bcrypt: password length exceeds 72 bytes")
+
 // GenerateFromPassword returns the bcrypt hash of the password at the given
 // cost. If the cost given is less than MinCost, the cost will be set to
 // DefaultCost, instead. Use CompareHashAndPassword, as defined in this package,
 // to compare the returned hashed password with its cleartext version.
+// GenerateFromPassword does not accept passwords longer than 72 bytes, which
+// is the longest password bcrypt will operate on.
 func GenerateFromPassword(password []byte, cost int) ([]byte, error) {
+	if len(password) > 72 {
+		return nil, ErrPasswordTooLong
+	}
 	p, err := newFromPassword(password, cost)
 	if err != nil {
 		return nil, err

bcrypt/bcrypt_test.go

@@ -241,3 +241,10 @@ func TestNoSideEffectsFromCompare(t *testing.T) {
 		t.Errorf("got=%q want=%q", got, want)
 	}
 }
+
+func TestPasswordTooLong(t *testing.T) {
+	_, err := GenerateFromPassword(make([]byte, 73), 1)
+	if err != ErrPasswordTooLong {
+		t.Errorf("unexpected error: got %q, want %q", err, ErrPasswordTooLong)
+	}
+}

blake2b/blake2bAVX2_amd64.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build go1.7 && amd64 && gc && !purego
-// +build go1.7,amd64,gc,!purego
 
 package blake2b
 

blake2b/blake2bAVX2_amd64.s

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build go1.7 && amd64 && gc && !purego
-// +build go1.7,amd64,gc,!purego
 
 #include "textflag.h"
 

blake2b/blake2b_amd64.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build !go1.7 && amd64 && gc && !purego
-// +build !go1.7,amd64,gc,!purego
 
 package blake2b
 

blake2b/blake2b_amd64.s

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build amd64 && gc && !purego
-// +build amd64,gc,!purego
 
 #include "textflag.h"
 

blake2b/blake2b_ref.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build !amd64 || purego || !gc
-// +build !amd64 purego !gc
 
 package blake2b
 

blake2b/register.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build go1.9
-// +build go1.9
 
 package blake2b
 

blake2s/blake2s_386.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build 386 && gc && !purego
-// +build 386,gc,!purego
 
 package blake2s
 

blake2s/blake2s_386.s

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build 386 && gc && !purego
-// +build 386,gc,!purego
 
 #include "textflag.h"
 

blake2s/blake2s_amd64.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build amd64 && gc && !purego
-// +build amd64,gc,!purego
 
 package blake2s
 

blake2s/blake2s_amd64.s

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build amd64 && gc && !purego
-// +build amd64,gc,!purego
 
 #include "textflag.h"
 

blake2s/blake2s_ref.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build (!amd64 && !386) || !gc || purego
-// +build !amd64,!386 !gc purego
 
 package blake2s
 

blake2s/register.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build go1.9
-// +build go1.9
 
 package blake2s
 

chacha20/chacha_arm64.go

@@ -2,8 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build go1.11 && gc && !purego
-// +build go1.11,gc,!purego
+//go:build gc && !purego
 
 package chacha20
 

chacha20/chacha_arm64.s

@@ -2,8 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build go1.11 && gc && !purego
-// +build go1.11,gc,!purego
+//go:build gc && !purego
 
 #include "textflag.h"
 

chacha20/chacha_noasm.go

@@ -2,8 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build (!arm64 && !s390x && !ppc64le) || (arm64 && !go1.11) || !gc || purego
-// +build !arm64,!s390x,!ppc64le arm64,!go1.11 !gc purego
+//go:build (!arm64 && !s390x && !ppc64le) || !gc || purego
 
 package chacha20
 

chacha20/chacha_ppc64le.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build gc && !purego
-// +build gc,!purego
 
 package chacha20
 

chacha20/chacha_ppc64le.s

@@ -20,7 +20,6 @@
 // due to the calling conventions and initialization of constants.
 
 //go:build gc && !purego
-// +build gc,!purego
 
 #include "textflag.h"
 

chacha20/chacha_s390x.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build gc && !purego
-// +build gc,!purego
 
 package chacha20
 

chacha20/chacha_s390x.s

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build gc && !purego
-// +build gc,!purego
 
 #include "go_asm.h"
 #include "textflag.h"

chacha20poly1305/chacha20poly1305_amd64.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build gc && !purego
-// +build gc,!purego
 
 package chacha20poly1305
 

chacha20poly1305/chacha20poly1305_amd64.s

@@ -5,7 +5,6 @@
 // This file was originally from https://golang.org/cl/24717 by Vlad Krasnov of CloudFlare.
 
 //go:build gc && !purego
-// +build gc,!purego
 
 #include "textflag.h"
 // General register allocation
@@ -184,11 +183,31 @@ GLOBL ·andMask<>(SB), (NOPTR+RODATA), $240
 #define shiftD1Right BYTE $0x66; BYTE $0x45; BYTE $0x0f; BYTE $0x3a; BYTE $0x0f; BYTE $0xd2; BYTE $0x04 // PALIGNR $4, X10, X10
 #define shiftD2Right BYTE $0x66; BYTE $0x45; BYTE $0x0f; BYTE $0x3a; BYTE $0x0f; BYTE $0xdb; BYTE $0x04 // PALIGNR $4, X11, X11
 #define shiftD3Right BYTE $0x66; BYTE $0x45; BYTE $0x0f; BYTE $0x3a; BYTE $0x0f; BYTE $0xff; BYTE $0x04 // PALIGNR $4, X15, X15
+
 // Some macros
+
+// ROL rotates the uint32s in register R left by N bits, using temporary T.
+#define ROL(N, R, T) \
+	MOVO R, T; PSLLL $(N), T; PSRLL $(32-(N)), R; PXOR T, R
+
+// ROL16 rotates the uint32s in register R left by 16, using temporary T if needed.
+#ifdef GOAMD64_v2
+#define ROL16(R, T) PSHUFB ·rol16<>(SB), R
+#else
+#define ROL16(R, T) ROL(16, R, T)
+#endif
+
+// ROL8 rotates the uint32s in register R left by 8, using temporary T if needed.
+#ifdef GOAMD64_v2
+#define ROL8(R, T) PSHUFB ·rol8<>(SB), R
+#else
+#define ROL8(R, T) ROL(8, R, T)
+#endif
+
 #define chachaQR(A, B, C, D, T) \
-	PADDD B, A; PXOR A, D; PSHUFB ·rol16<>(SB), D                            \
+	PADDD B, A; PXOR A, D; ROL16(D, T) \
 	PADDD D, C; PXOR C, B; MOVO B, T; PSLLL $12, T; PSRLL $20, B; PXOR T, B \
-	PADDD B, A; PXOR A, D; PSHUFB ·rol8<>(SB), D                             \
+	PADDD B, A; PXOR A, D; ROL8(D, T) \
 	PADDD D, C; PXOR C, B; MOVO B, T; PSLLL $7, T; PSRLL $25, B; PXOR T, B
 
 #define chachaQR_AVX2(A, B, C, D, T) \

chacha20poly1305/chacha20poly1305_noasm.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build !amd64 || !gc || purego
-// +build !amd64 !gc purego
 
 package chacha20poly1305
 

cryptobyte/asn1.go

@@ -264,36 +264,35 @@ func (s *String) ReadASN1Boolean(out *bool) bool {
 	return true
 }
 
-var bigIntType = reflect.TypeOf((*big.Int)(nil)).Elem()
-
 // ReadASN1Integer decodes an ASN.1 INTEGER into out and advances. If out does
-// not point to an integer or to a big.Int, it panics. It reports whether the
-// read was successful.
+// not point to an integer, to a big.Int, or to a []byte it panics. Only
+// positive and zero values can be decoded into []byte, and they are returned as
+// big-endian binary values that share memory with s. Positive values will have
+// no leading zeroes, and zero will be returned as a single zero byte.
+// ReadASN1Integer reports whether the read was successful.
 func (s *String) ReadASN1Integer(out interface{}) bool {
-	if reflect.TypeOf(out).Kind() != reflect.Ptr {
-		panic("out is not a pointer")
-	}
-	switch reflect.ValueOf(out).Elem().Kind() {
-	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+	switch out := out.(type) {
+	case *int, *int8, *int16, *int32, *int64:
 		var i int64
 		if !s.readASN1Int64(&i) || reflect.ValueOf(out).Elem().OverflowInt(i) {
 			return false
 		}
 		reflect.ValueOf(out).Elem().SetInt(i)
 		return true
-	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+	case *uint, *uint8, *uint16, *uint32, *uint64:
 		var u uint64
 		if !s.readASN1Uint64(&u) || reflect.ValueOf(out).Elem().OverflowUint(u) {
 			return false
 		}
 		reflect.ValueOf(out).Elem().SetUint(u)
 		return true
-	case reflect.Struct:
-		if reflect.TypeOf(out).Elem() == bigIntType {
-			return s.readASN1BigInt(out.(*big.Int))
-		}
+	case *big.Int:
+		return s.readASN1BigInt(out)
+	case *[]byte:
+		return s.readASN1Bytes(out)
+	default:
+		panic("out does not point to an integer type")
 	}
-	panic("out does not point to an integer type")
 }
 
 func checkASN1Integer(bytes []byte) bool {
@@ -333,6 +332,21 @@ func (s *String) readASN1BigInt(out *big.Int) bool {
 	return true
 }
 
+func (s *String) readASN1Bytes(out *[]byte) bool {
+	var bytes String
+	if !s.ReadASN1(&bytes, asn1.INTEGER) || !checkASN1Integer(bytes) {
+		return false
+	}
+	if bytes[0]&0x80 == 0x80 {
+		return false
+	}
+	for len(bytes) > 1 && bytes[0] == 0 {
+		bytes = bytes[1:]
+	}
+	*out = bytes
+	return true
+}
+
 func (s *String) readASN1Int64(out *int64) bool {
 	var bytes String
 	if !s.ReadASN1(&bytes, asn1.INTEGER) || !checkASN1Integer(bytes) || !asn1Signed(out, bytes) {
@@ -417,6 +431,14 @@ func (s *String) readBase128Int(out *int) bool {
 		}
 		ret <<= 7
 		b := s.read(1)[0]
+
+		// ITU-T X.690, section 8.19.2:
+		// The subidentifier shall be encoded in the fewest possible octets,
+		// that is, the leading octet of the subidentifier shall not have the value 0x80.
+		if i == 0 && b == 0x80 {
+			return false
+		}
+
 		ret |= int(b & 0x7f)
 		if b&0x80 == 0 {
 			*out = ret
@@ -532,7 +554,7 @@ func (s *String) ReadASN1BitString(out *encoding_asn1.BitString) bool {
 		return false
 	}
 
-	paddingBits := uint8(bytes[0])
+	paddingBits := bytes[0]
 	bytes = bytes[1:]
 	if paddingBits > 7 ||
 		len(bytes) == 0 && paddingBits != 0 ||
@@ -545,7 +567,7 @@ func (s *String) ReadASN1BitString(out *encoding_asn1.BitString) bool {
 	return true
 }
 
-// ReadASN1BitString decodes an ASN.1 BIT STRING into out and advances. It is
+// ReadASN1BitStringAsBytes decodes an ASN.1 BIT STRING into out and advances. It is
 // an error if the BIT STRING is not a whole number of bytes. It reports
 // whether the read was successful.
 func (s *String) ReadASN1BitStringAsBytes(out *[]byte) bool {
@@ -554,7 +576,7 @@ func (s *String) ReadASN1BitStringAsBytes(out *[]byte) bool {
 		return false
 	}
 
-	paddingBits := uint8(bytes[0])
+	paddingBits := bytes[0]
 	if paddingBits != 0 {
 		return false
 	}
@@ -654,34 +676,27 @@ func (s *String) SkipOptionalASN1(tag asn1.Tag) bool {
 	return s.ReadASN1(&unused, tag)
 }
 
-// ReadOptionalASN1Integer attempts to read an optional ASN.1 INTEGER
-// explicitly tagged with tag into out and advances. If no element with a
-// matching tag is present, it writes defaultValue into out instead. If out
-// does not point to an integer or to a big.Int, it panics. It reports
-// whether the read was successful.
+// ReadOptionalASN1Integer attempts to read an optional ASN.1 INTEGER explicitly
+// tagged with tag into out and advances. If no element with a matching tag is
+// present, it writes defaultValue into out instead. Otherwise, it behaves like
+// ReadASN1Integer.
 func (s *String) ReadOptionalASN1Integer(out interface{}, tag asn1.Tag, defaultValue interface{}) bool {
-	if reflect.TypeOf(out).Kind() != reflect.Ptr {
-		panic("out is not a pointer")
-	}
 	var present bool
 	var i String
 	if !s.ReadOptionalASN1(&i, &present, tag) {
 		return false
 	}
 	if !present {
-		switch reflect.ValueOf(out).Elem().Kind() {
-		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
-			reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		switch out.(type) {
+		case *int, *int8, *int16, *int32, *int64,
+			*uint, *uint8, *uint16, *uint32, *uint64, *[]byte:
 			reflect.ValueOf(out).Elem().Set(reflect.ValueOf(defaultValue))
-		case reflect.Struct:
-			if reflect.TypeOf(out).Elem() != bigIntType {
-				panic("invalid integer type")
-			}
-			if reflect.TypeOf(defaultValue).Kind() != reflect.Ptr ||
-				reflect.TypeOf(defaultValue).Elem() != bigIntType {
+		case *big.Int:
+			if defaultValue, ok := defaultValue.(*big.Int); ok {
+				out.(*big.Int).Set(defaultValue)
+			} else {
 				panic("out points to big.Int, but defaultValue does not")
 			}
-			out.(*big.Int).Set(defaultValue.(*big.Int))
 		default:
 			panic("invalid integer type")
 		}

cryptobyte/asn1_test.go

@@ -154,6 +154,32 @@ func TestReadASN1IntegerSigned(t *testing.T) {
 		}
 	})
 
+	// Repeat the same cases, reading into a []byte.
+	t.Run("bytes", func(t *testing.T) {
+		for i, test := range testData64 {
+			in := String(test.in)
+			var out []byte
+			ok := in.ReadASN1Integer(&out)
+			if test.out < 0 {
+				if ok {
+					t.Errorf("#%d: in.ReadASN1Integer(%d) = %v, want false", i, test.out, ok)
+				}
+				continue
+			}
+			if !ok {
+				t.Errorf("#%d: in.ReadASN1Integer() = %v, want true", i, ok)
+				continue
+			}
+			n := new(big.Int).SetBytes(out).Int64()
+			if n != test.out {
+				t.Errorf("#%d: in.ReadASN1Integer() = %v, want true; out = %x, want %d", i, ok, out, test.out)
+			}
+			if out[0] == 0 && len(out) > 1 {
+				t.Errorf("#%d: in.ReadASN1Integer() = %v; out = %x, has leading zeroes", i, ok, out)
+			}
+		}
+	})
+
 	// Repeat with the implicit-tagging functions
 	t.Run("WithTag", func(t *testing.T) {
 		for i, test := range testData64 {
@@ -250,6 +276,7 @@ func TestASN1ObjectIdentifier(t *testing.T) {
 		{[]byte{6, 7, 85, 0x02, 0x85, 0xc7, 0xcc, 0xfb, 0x01}, true, []int{2, 5, 2, 1492336001}},
 		{[]byte{6, 7, 0x55, 0x02, 0x87, 0xff, 0xff, 0xff, 0x7f}, true, []int{2, 5, 2, 2147483647}}, // 2**31-1
 		{[]byte{6, 7, 0x55, 0x02, 0x88, 0x80, 0x80, 0x80, 0x00}, false, []int{}},                   // 2**31
+		{[]byte{6, 3, 85, 0x80, 0x02}, false, []int{}},                                             // leading 0x80 octet
 	}
 
 	for i, test := range testData {

cryptobyte/builder.go

@@ -95,6 +95,11 @@ func (b *Builder) AddUint32(v uint32) {
 	b.add(byte(v>>24), byte(v>>16), byte(v>>8), byte(v))
 }
 
+// AddUint48 appends a big-endian, 48-bit value to the byte string.
+func (b *Builder) AddUint48(v uint64) {
+	b.add(byte(v>>40), byte(v>>32), byte(v>>24), byte(v>>16), byte(v>>8), byte(v))
+}
+
 // AddUint64 appends a big-endian, 64-bit value to the byte string.
 func (b *Builder) AddUint64(v uint64) {
 	b.add(byte(v>>56), byte(v>>48), byte(v>>40), byte(v>>32), byte(v>>24), byte(v>>16), byte(v>>8), byte(v))
@@ -303,9 +308,9 @@ func (b *Builder) add(bytes ...byte) {
 	b.result = append(b.result, bytes...)
 }
 
-// Unwrite rolls back n bytes written directly to the Builder. An attempt by a
-// child builder passed to a continuation to unwrite bytes from its parent will
-// panic.
+// Unwrite rolls back non-negative n bytes written directly to the Builder.
+// An attempt by a child builder passed to a continuation to unwrite bytes
+// from its parent will panic.
 func (b *Builder) Unwrite(n int) {
 	if b.err != nil {
 		return
@@ -317,6 +322,9 @@ func (b *Builder) Unwrite(n int) {
 	if length < 0 {
 		panic("cryptobyte: internal error")
 	}
+	if n < 0 {
+		panic("cryptobyte: attempted to unwrite negative number of bytes")
+	}
 	if n > length {
 		panic("cryptobyte: attempted to unwrite more than was written")
 	}

cryptobyte/cryptobyte_test.go

@@ -179,6 +179,27 @@ func TestUint32(t *testing.T) {
 	}
 }
 
+func TestUint48(t *testing.T) {
+	var b Builder
+	var u uint64 = 0xfefcff3cfdfc
+	b.AddUint48(u)
+	if err := builderBytesEq(&b, 254, 252, 255, 60, 253, 252); err != nil {
+		t.Error(err)
+	}
+
+	var s String = b.BytesOrPanic()
+	var v uint64
+	if !s.ReadUint48(&v) {
+		t.Error("ReadUint48() = false, want true")
+	}
+	if v != u {
+		t.Errorf("v = %x, want %x", v, u)
+	}
+	if len(s) != 0 {
+		t.Errorf("len(s) = %d, want 0", len(s))
+	}
+}
+
 func TestUint64(t *testing.T) {
 	var b Builder
 	b.AddUint64(0xf2fefefcff3cfdfc)

cryptobyte/string.go

@@ -81,6 +81,17 @@ func (s *String) ReadUint32(out *uint32) bool {
 	return true
 }
 
+// ReadUint48 decodes a big-endian, 48-bit value into out and advances over it.
+// It reports whether the read was successful.
+func (s *String) ReadUint48(out *uint64) bool {
+	v := s.read(6)
+	if v == nil {
+		return false
+	}
+	*out = uint64(v[0])<<40 | uint64(v[1])<<32 | uint64(v[2])<<24 | uint64(v[3])<<16 | uint64(v[4])<<8 | uint64(v[5])
+	return true
+}
+
 // ReadUint64 decodes a big-endian, 64-bit value into out and advances over it.
 // It reports whether the read was successful.
 func (s *String) ReadUint64(out *uint64) bool {

curve25519/curve25519.go

@@ -5,71 +5,18 @@
 // Package curve25519 provides an implementation of the X25519 function, which
 // performs scalar multiplication on the elliptic curve known as Curve25519.
 // See RFC 7748.
+//
+// Starting in Go 1.20, this package is a wrapper for the X25519 implementation
+// in the crypto/ecdh package.
 package curve25519 // import "golang.org/x/crypto/curve25519"
 
-import (
-	"crypto/subtle"
-	"errors"
-	"strconv"
-
-	"golang.org/x/crypto/curve25519/internal/field"
-)
-
 // ScalarMult sets dst to the product scalar * point.
 //
 // Deprecated: when provided a low-order point, ScalarMult will set dst to all
 // zeroes, irrespective of the scalar. Instead, use the X25519 function, which
 // will return an error.
 func ScalarMult(dst, scalar, point *[32]byte) {
-	var e [32]byte
-
-	copy(e[:], scalar[:])
-	e[0] &= 248
-	e[31] &= 127
-	e[31] |= 64
-
-	var x1, x2, z2, x3, z3, tmp0, tmp1 field.Element
-	x1.SetBytes(point[:])
-	x2.One()
-	x3.Set(&x1)
-	z3.One()
-
-	swap := 0
-	for pos := 254; pos >= 0; pos-- {
-		b := e[pos/8] >> uint(pos&7)
-		b &= 1
-		swap ^= int(b)
-		x2.Swap(&x3, swap)
-		z2.Swap(&z3, swap)
-		swap = int(b)
-
-		tmp0.Subtract(&x3, &z3)
-		tmp1.Subtract(&x2, &z2)
-		x2.Add(&x2, &z2)
-		z2.Add(&x3, &z3)
-		z3.Multiply(&tmp0, &x2)
-		z2.Multiply(&z2, &tmp1)
-		tmp0.Square(&tmp1)
-		tmp1.Square(&x2)
-		x3.Add(&z3, &z2)
-		z2.Subtract(&z3, &z2)
-		x2.Multiply(&tmp1, &tmp0)
-		tmp1.Subtract(&tmp1, &tmp0)
-		z2.Square(&z2)
-
-		z3.Mult32(&tmp1, 121666)
-		x3.Square(&x3)
-		tmp0.Add(&tmp0, &z3)
-		z3.Multiply(&x1, &z2)
-		z2.Multiply(&tmp1, &tmp0)
-	}
-
-	x2.Swap(&x3, swap)
-	z2.Swap(&z3, swap)
-
-	z2.Invert(&z2)
-	x2.Multiply(&x2, &z2)
-	copy(dst[:], x2.Bytes())
+	scalarMult(dst, scalar, point)
 }
 
 // ScalarBaseMult sets dst to the product scalar * base where base is the
@@ -78,7 +25,7 @@ func ScalarMult(dst, scalar, point *[32]byte) {
 // It is recommended to use the X25519 function with Basepoint instead, as
 // copying into fixed size arrays can lead to unexpected bugs.
 func ScalarBaseMult(dst, scalar *[32]byte) {
-	ScalarMult(dst, scalar, &basePoint)
+	scalarBaseMult(dst, scalar)
 }
 
 const (
@@ -91,21 +38,10 @@ const (
 // Basepoint is the canonical Curve25519 generator.
 var Basepoint []byte
 
-var basePoint = [32]byte{9, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
+var basePoint = [32]byte{9}
 
 func init() { Basepoint = basePoint[:] }
 
-func checkBasepoint() {
-	if subtle.ConstantTimeCompare(Basepoint, []byte{
-		0x09, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-	}) != 1 {
-		panic("curve25519: global Basepoint value was modified")
-	}
-}
-
 // X25519 returns the result of the scalar multiplication (scalar * point),
 // according to RFC 7748, Section 5. scalar, point and the return value are
 // slices of 32 bytes.
@@ -121,26 +57,3 @@ func X25519(scalar, point []byte) ([]byte, error) {
 	var dst [32]byte
 	return x25519(&dst, scalar, point)
 }
-
-func x25519(dst *[32]byte, scalar, point []byte) ([]byte, error) {
-	var in [32]byte
-	if l := len(scalar); l != 32 {
-		return nil, errors.New("bad scalar length: " + strconv.Itoa(l) + ", expected 32")
-	}
-	if l := len(point); l != 32 {
-		return nil, errors.New("bad point length: " + strconv.Itoa(l) + ", expected 32")
-	}
-	copy(in[:], scalar)
-	if &point[0] == &Basepoint[0] {
-		checkBasepoint()
-		ScalarBaseMult(dst, &in)
-	} else {
-		var base, zero [32]byte
-		copy(base[:], point)
-		ScalarMult(dst, &in, &base)
-		if subtle.ConstantTimeCompare(dst[:], zero[:]) == 1 {
-			return nil, errors.New("bad input point: low order point")
-		}
-	}
-	return dst[:], nil
-}

curve25519/curve25519_compat.go

@@ -0,0 +1,105 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !go1.20
+
+package curve25519
+
+import (
+	"crypto/subtle"
+	"errors"
+	"strconv"
+
+	"golang.org/x/crypto/curve25519/internal/field"
+)
+
+func scalarMult(dst, scalar, point *[32]byte) {
+	var e [32]byte
+
+	copy(e[:], scalar[:])
+	e[0] &= 248
+	e[31] &= 127
+	e[31] |= 64
+
+	var x1, x2, z2, x3, z3, tmp0, tmp1 field.Element
+	x1.SetBytes(point[:])
+	x2.One()
+	x3.Set(&x1)
+	z3.One()
+
+	swap := 0
+	for pos := 254; pos >= 0; pos-- {
+		b := e[pos/8] >> uint(pos&7)
+		b &= 1
+		swap ^= int(b)
+		x2.Swap(&x3, swap)
+		z2.Swap(&z3, swap)
+		swap = int(b)
+
+		tmp0.Subtract(&x3, &z3)
+		tmp1.Subtract(&x2, &z2)
+		x2.Add(&x2, &z2)
+		z2.Add(&x3, &z3)
+		z3.Multiply(&tmp0, &x2)
+		z2.Multiply(&z2, &tmp1)
+		tmp0.Square(&tmp1)
+		tmp1.Square(&x2)
+		x3.Add(&z3, &z2)
+		z2.Subtract(&z3, &z2)
+		x2.Multiply(&tmp1, &tmp0)
+		tmp1.Subtract(&tmp1, &tmp0)
+		z2.Square(&z2)
+
+		z3.Mult32(&tmp1, 121666)
+		x3.Square(&x3)
+		tmp0.Add(&tmp0, &z3)
+		z3.Multiply(&x1, &z2)
+		z2.Multiply(&tmp1, &tmp0)
+	}
+
+	x2.Swap(&x3, swap)
+	z2.Swap(&z3, swap)
+
+	z2.Invert(&z2)
+	x2.Multiply(&x2, &z2)
+	copy(dst[:], x2.Bytes())
+}
+
+func scalarBaseMult(dst, scalar *[32]byte) {
+	checkBasepoint()
+	scalarMult(dst, scalar, &basePoint)
+}
+
+func x25519(dst *[32]byte, scalar, point []byte) ([]byte, error) {
+	var in [32]byte
+	if l := len(scalar); l != 32 {
+		return nil, errors.New("bad scalar length: " + strconv.Itoa(l) + ", expected 32")
+	}
+	if l := len(point); l != 32 {
+		return nil, errors.New("bad point length: " + strconv.Itoa(l) + ", expected 32")
+	}
+	copy(in[:], scalar)
+	if &point[0] == &Basepoint[0] {
+		scalarBaseMult(dst, &in)
+	} else {
+		var base, zero [32]byte
+		copy(base[:], point)
+		scalarMult(dst, &in, &base)
+		if subtle.ConstantTimeCompare(dst[:], zero[:]) == 1 {
+			return nil, errors.New("bad input point: low order point")
+		}
+	}
+	return dst[:], nil
+}
+
+func checkBasepoint() {
+	if subtle.ConstantTimeCompare(Basepoint, []byte{
+		0x09, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	}) != 1 {
+		panic("curve25519: global Basepoint value was modified")
+	}
+}

curve25519/curve25519_go120.go

@@ -0,0 +1,46 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build go1.20
+
+package curve25519
+
+import "crypto/ecdh"
+
+func x25519(dst *[32]byte, scalar, point []byte) ([]byte, error) {
+	curve := ecdh.X25519()
+	pub, err := curve.NewPublicKey(point)
+	if err != nil {
+		return nil, err
+	}
+	priv, err := curve.NewPrivateKey(scalar)
+	if err != nil {
+		return nil, err
+	}
+	out, err := priv.ECDH(pub)
+	if err != nil {
+		return nil, err
+	}
+	copy(dst[:], out)
+	return dst[:], nil
+}
+
+func scalarMult(dst, scalar, point *[32]byte) {
+	if _, err := x25519(dst, scalar[:], point[:]); err != nil {
+		// The only error condition for x25519 when the inputs are 32 bytes long
+		// is if the output would have been the all-zero value.
+		for i := range dst {
+			dst[i] = 0
+		}
+	}
+}
+
+func scalarBaseMult(dst, scalar *[32]byte) {
+	curve := ecdh.X25519()
+	priv, err := curve.NewPrivateKey(scalar[:])
+	if err != nil {
+		panic("curve25519: internal error: scalarBaseMult was not 32 bytes")
+	}
+	copy(dst[:], priv.PublicKey().Bytes())
+}

curve25519/curve25519_test.go

@@ -2,13 +2,15 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package curve25519
+package curve25519_test
 
 import (
 	"bytes"
 	"crypto/rand"
 	"encoding/hex"
 	"testing"
+
+	"golang.org/x/crypto/curve25519"
 )
 
 const expectedHex = "89161fde887b2b53de549af483940106ecc114d6982daa98256de23bdf77661a"
@@ -19,7 +21,7 @@ func TestX25519Basepoint(t *testing.T) {
 
 	for i := 0; i < 200; i++ {
 		var err error
-		x, err = X25519(x, Basepoint)
+		x, err = curve25519.X25519(x, curve25519.Basepoint)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -32,12 +34,12 @@ func TestX25519Basepoint(t *testing.T) {
 }
 
 func TestLowOrderPoints(t *testing.T) {
-	scalar := make([]byte, ScalarSize)
+	scalar := make([]byte, curve25519.ScalarSize)
 	if _, err := rand.Read(scalar); err != nil {
 		t.Fatal(err)
 	}
 	for i, p := range lowOrderPoints {
-		out, err := X25519(scalar, p)
+		out, err := curve25519.X25519(scalar, p)
 		if err == nil {
 			t.Errorf("%d: expected error, got nil", i)
 		}
@@ -48,10 +50,10 @@ func TestLowOrderPoints(t *testing.T) {
 }
 
 func TestTestVectors(t *testing.T) {
-	t.Run("Legacy", func(t *testing.T) { testTestVectors(t, ScalarMult) })
+	t.Run("Legacy", func(t *testing.T) { testTestVectors(t, curve25519.ScalarMult) })
 	t.Run("X25519", func(t *testing.T) {
 		testTestVectors(t, func(dst, scalar, point *[32]byte) {
-			out, err := X25519(scalar[:], point[:])
+			out, err := curve25519.X25519(scalar[:], point[:])
 			if err != nil {
 				t.Fatal(err)
 			}
@@ -88,10 +90,10 @@ func TestHighBitIgnored(t *testing.T) {
 	var hi0, hi1 [32]byte
 
 	u[31] &= 0x7f
-	ScalarMult(&hi0, &s, &u)
+	curve25519.ScalarMult(&hi0, &s, &u)
 
 	u[31] |= 0x80
-	ScalarMult(&hi1, &s, &u)
+	curve25519.ScalarMult(&hi1, &s, &u)
 
 	if !bytes.Equal(hi0[:], hi1[:]) {
 		t.Errorf("high bit of group point should not affect result")
@@ -101,14 +103,14 @@ func TestHighBitIgnored(t *testing.T) {
 var benchmarkSink byte
 
 func BenchmarkX25519Basepoint(b *testing.B) {
-	scalar := make([]byte, ScalarSize)
+	scalar := make([]byte, curve25519.ScalarSize)
 	if _, err := rand.Read(scalar); err != nil {
 		b.Fatal(err)
 	}
 
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
-		out, err := X25519(scalar, Basepoint)
+		out, err := curve25519.X25519(scalar, curve25519.Basepoint)
 		if err != nil {
 			b.Fatal(err)
 		}
@@ -117,11 +119,11 @@ func BenchmarkX25519Basepoint(b *testing.B) {
 }
 
 func BenchmarkX25519(b *testing.B) {
-	scalar := make([]byte, ScalarSize)
+	scalar := make([]byte, curve25519.ScalarSize)
 	if _, err := rand.Read(scalar); err != nil {
 		b.Fatal(err)
 	}
-	point, err := X25519(scalar, Basepoint)
+	point, err := curve25519.X25519(scalar, curve25519.Basepoint)
 	if err != nil {
 		b.Fatal(err)
 	}
@@ -131,7 +133,7 @@ func BenchmarkX25519(b *testing.B) {
 
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
-		out, err := X25519(scalar, point)
+		out, err := curve25519.X25519(scalar, point)
 		if err != nil {
 			b.Fatal(err)
 		}

curve25519/internal/field/_asm/go.mod

@@ -1,10 +1,16 @@
 module asm
 
-go 1.16
+go 1.18
 
 require (
-	github.com/mmcloughlin/avo v0.4.0
-	golang.org/x/crypto v0.0.0
+	github.com/mmcloughlin/avo v0.5.0
+	golang.org/x/crypto v0.1.0
 )
 
-replace golang.org/x/crypto v0.0.0 => ../../../..
+require (
+	golang.org/x/mod v0.8.0 // indirect
+	golang.org/x/sys v0.13.0 // indirect
+	golang.org/x/tools v0.6.0 // indirect
+)
+
+replace golang.org/x/crypto v0.1.0 => ../../../..

curve25519/internal/field/_asm/go.sum

@@ -1,34 +1,51 @@
-github.com/mmcloughlin/avo v0.4.0 h1:jeHDRktVD+578ULxWpQHkilor6pkdLF7u7EiTzDbfcU=
-github.com/mmcloughlin/avo v0.4.0/go.mod h1:RW9BfYA3TgO9uCdNrKU2h6J8cPD8ZLznvfgHAeszb1s=
-github.com/yuin/goldmark v1.4.0/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
-golang.org/x/arch v0.0.0-20210923205945-b76863e36670/go.mod h1:5om86z9Hs0C8fWVUuoMHwpExlXzs5Tkyp9hOrfG7pp8=
+github.com/mmcloughlin/avo v0.5.0 h1:nAco9/aI9Lg2kiuROBY6BhCI/z0t5jEvJfjWbL8qXLU=
+github.com/mmcloughlin/avo v0.5.0/go.mod h1:ChHFdoV7ql95Wi7vuq2YT1bwCJqiWdZrQ1im3VujLYM=
+github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
+golang.org/x/arch v0.1.0/go.mod h1:5om86z9Hs0C8fWVUuoMHwpExlXzs5Tkyp9hOrfG7pp8=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
-golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
-golang.org/x/mod v0.4.2 h1:Gz96sIWK3OalVv/I/qNygP42zyoKp3xptRVCWRFEBvo=
-golang.org/x/mod v0.4.2/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
-golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
+golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
+golang.org/x/mod v0.6.0/go.mod h1:4mET923SAdbXp2ki8ey+zGs1SLqsuM2Y0uvdZR/fUNI=
+golang.org/x/mod v0.8.0 h1:LUYupSeNrTNCGzR/hVBk2NHZO4hXcVaW1k4Qx7rjPx8=
+golang.org/x/mod v0.8.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
-golang.org/x/net v0.0.0-20210805182204-aaa1db679c0d/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
-golang.org/x/net v0.0.0-20211112202133-69e39bad7dc2/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
+golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
+golang.org/x/net v0.0.0-20220722155237-a158d28d115b/go.mod h1:XRhObCWvk6IyKnWLug+ECip1KBveYUHfp+8e9klMJ9c=
+golang.org/x/net v0.1.0/go.mod h1:Cx3nUiGt4eDBEyega/BKRp+/AlGL8hYe7U9odMt2Cco=
+golang.org/x/net v0.6.0/go.mod h1:2Tu9+aMcznHK/AK1HMvgo6xiTLG5rD5rZLDS+rp2Bjs=
+golang.org/x/net v0.10.0/go.mod h1:0qNGK6F8kojg2nk9dLZ2mShWaEBan6FAoqfSigmmuDg=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.1.0 h1:wsuoTGHzEhffawBOhz5CYhcrV4IdKZbEyZjBMuTp12o=
+golang.org/x/sync v0.1.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
-golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.0.0-20210809222454-d867a43fc93e/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.0.0-20211030160813-b3129d9d1021 h1:giLT+HuUP/gXYrG2Plg9WTjj4qhfgaW424ZIFog3rlk=
-golang.org/x/sys v0.0.0-20211030160813-b3129d9d1021/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.1.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.5.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.8.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.13.0 h1:Af8nKPmuFypiUBjVoU9V20FiaFXOcuZI21p0ycVYYGE=
+golang.org/x/sys v0.13.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
+golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
+golang.org/x/term v0.1.0/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
+golang.org/x/term v0.5.0/go.mod h1:jMB1sMXY+tzblOD4FWmEbocvup2/aLOaQEp7JmGp78k=
+golang.org/x/term v0.8.0/go.mod h1:xPskH00ivmX89bAKVGSKKtLOWNx2+17Eiy94tnKShWo=
+golang.org/x/term v0.13.0/go.mod h1:LTmsnFJwVN6bCy1rVCoS+qHT1HhALEFxKncY3WNNh4U=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
-golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
+golang.org/x/text v0.4.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
+golang.org/x/text v0.7.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
+golang.org/x/text v0.9.0/go.mod h1:e1OnstbJyHTd6l/uOt8jFFHp6TRDWZR/bV3emEE/zU8=
+golang.org/x/text v0.13.0/go.mod h1:TvPlkZtksWOMsz7fbANvkp4WM8x/WCo/om8BMLbz+aE=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
-golang.org/x/tools v0.1.7 h1:6j8CgantCy3yc8JGBqkDLMKWqZ0RDU2g1HVgacojGWQ=
-golang.org/x/tools v0.1.7/go.mod h1:LGqMHiF4EqQNHR1JncWGqT5BVaXmza+X+BDGol+dOxo=
+golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=
+golang.org/x/tools v0.2.0/go.mod h1:y4OqIKeOV/fWJetJ8bXPU1sEVniLMIyDAZWeHdV+NTA=
+golang.org/x/tools v0.6.0 h1:BOw41kyTf3PuCW1pVQf8+Cyg8pMlkYB1oo9iJ6D/lKM=
+golang.org/x/tools v0.6.0/go.mod h1:Xwgl3UAJ/d3gWutnCtw505GrjyAbvKui8lOU390QaIU=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
-golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
-golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 h1:go1bK/D/BFZV2I8cIQd1NKEZ+0owSTG1fDTci4IqFcE=
-golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 rsc.io/pdf v0.1.1/go.mod h1:n8OzWcQ6Sp37PL01nO98y4iUCRdTGarVfzxY20ICaU4=

curve25519/internal/field/fe_amd64.go

@@ -1,7 +1,6 @@
 // Code generated by command: go run fe_amd64_asm.go -out ../fe_amd64.s -stubs ../fe_amd64.go -pkg field. DO NOT EDIT.
 
 //go:build amd64 && gc && !purego
-// +build amd64,gc,!purego
 
 package field
 

curve25519/internal/field/fe_amd64.s

@@ -1,7 +1,6 @@
 // Code generated by command: go run fe_amd64_asm.go -out ../fe_amd64.s -stubs ../fe_amd64.go -pkg field. DO NOT EDIT.
 
 //go:build amd64 && gc && !purego
-// +build amd64,gc,!purego
 
 #include "textflag.h"
 

curve25519/internal/field/fe_amd64_noasm.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build !amd64 || !gc || purego
-// +build !amd64 !gc purego
 
 package field
 

curve25519/internal/field/fe_arm64.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build arm64 && gc && !purego
-// +build arm64,gc,!purego
 
 package field
 

curve25519/internal/field/fe_arm64.s

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build arm64 && gc && !purego
-// +build arm64,gc,!purego
 
 #include "textflag.h"
 

curve25519/internal/field/fe_arm64_noasm.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build !arm64 || !gc || purego
-// +build !arm64 !gc purego
 
 package field
 

curve25519/internal/field/fe_generic.go

@@ -245,7 +245,7 @@ func feSquareGeneric(v, a *Element) {
 	v.carryPropagate()
 }
 
-// carryPropagate brings the limbs below 52 bits by applying the reduction
+// carryPropagateGeneric brings the limbs below 52 bits by applying the reduction
 // identity (a * 2²⁵⁵ + b = a * 19 + b) to the l4 carry. TODO inline
 func (v *Element) carryPropagateGeneric() *Element {
 	c0 := v.l0 >> 51

curve25519/vectors_test.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package curve25519
+package curve25519_test
 
 // lowOrderPoints from libsodium.
 // https://github.com/jedisct1/libsodium/blob/65621a1059a37d/src/libsodium/crypto_scalarmult/curve25519/ref10/x25519_ref10.c#L11-L70

go.mod

@@ -1,11 +1,11 @@
 module golang.org/x/crypto
 
-go 1.17
+go 1.18
 
 require (
-	golang.org/x/net v0.2.0
-	golang.org/x/sys v0.2.0
-	golang.org/x/term v0.2.0
+	golang.org/x/net v0.10.0 // tagx:ignore
+	golang.org/x/sys v0.14.0
+	golang.org/x/term v0.14.0
 )
 
-require golang.org/x/text v0.4.0 // indirect
+require golang.org/x/text v0.14.0 // indirect

go.sum

@@ -1,31 +1,8 @@
-github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
-golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
-golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
-golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
-golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
-golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
-golang.org/x/net v0.0.0-20220722155237-a158d28d115b/go.mod h1:XRhObCWvk6IyKnWLug+ECip1KBveYUHfp+8e9klMJ9c=
-golang.org/x/net v0.2.0 h1:sZfSu1wtKLGlWI4ZZayP0ck9Y73K1ynO6gqzTdBVdPU=
-golang.org/x/net v0.2.0/go.mod h1:KqCZLdyyvdV855qA2rE3GC2aiw5xGR5TEjj8smXukLY=
-golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
-golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.2.0 h1:ljd4t30dBnAvMZaQCevtY0xLLD0A+bRZXbgLMLU1F/A=
-golang.org/x/sys v0.2.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
-golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
-golang.org/x/term v0.2.0 h1:z85xZCsEl7bi/KwbNADeBYoOP0++7W1ipu+aGnpwzRM=
-golang.org/x/term v0.2.0/go.mod h1:TVmDHMZPmdnySmBfhjOoOdhjzdE1h4u1VwSiw2l1Nuc=
-golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
-golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
-golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
-golang.org/x/text v0.4.0 h1:BrVqGRd7+k1DiOgtnFvAkoQEWQvBc25ouMJM6429SFg=
-golang.org/x/text v0.4.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
-golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
-golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
-golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=
-golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/net v0.10.0 h1:X2//UzNDwYmtCLn7To6G58Wr6f5ahEAQgKNzv9Y951M=
+golang.org/x/net v0.10.0/go.mod h1:0qNGK6F8kojg2nk9dLZ2mShWaEBan6FAoqfSigmmuDg=
+golang.org/x/sys v0.14.0 h1:Vz7Qs629MkJkGyHxUlRHizWJRG2j8fbQKjELVSNhy7Q=
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+golang.org/x/term v0.14.0 h1:LGK9IlZ8T9jvdy6cTdfKUCltatMFOehAQo9SRC46UQ8=
+golang.org/x/term v0.14.0/go.mod h1:TySc+nGkYR6qt8km8wUhuFRTVSMIX3XPR58y2lC8vww=
+golang.org/x/text v0.14.0 h1:ScX5w1eTa3QqT8oi6+ziP7dTV1S2+ALU0bI+0zXKWiQ=
+golang.org/x/text v0.14.0/go.mod h1:18ZOQIKpY8NJVqYksKHtTdi31H5itFRjB5/qKTNYzSU=

hkdf/hkdf.go

@@ -56,7 +56,9 @@ func (f *hkdf) Read(p []byte) (int, error) {
 
 	// Fill the rest of the buffer
 	for len(p) > 0 {
-		f.expander.Reset()
+		if f.counter > 1 {
+			f.expander.Reset()
+		}
 		f.expander.Write(f.prev)
 		f.expander.Write(f.info)
 		f.expander.Write([]byte{f.counter})

internal/alias/alias.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build !purego
-// +build !purego
 
 // Package alias implements memory aliasing tests.
 package alias

internal/alias/alias_purego.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build purego
-// +build purego
 
 // Package alias implements memory aliasing tests.
 package alias

internal/poly1305/bits_compat.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build !go1.13
-// +build !go1.13
 
 package poly1305
 

internal/poly1305/bits_go1.13.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build go1.13
-// +build go1.13
 
 package poly1305
 

internal/poly1305/mac_noasm.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build (!amd64 && !ppc64le && !s390x) || !gc || purego
-// +build !amd64,!ppc64le,!s390x !gc purego
 
 package poly1305
 

internal/poly1305/sum_amd64.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build gc && !purego
-// +build gc,!purego
 
 package poly1305
 

internal/poly1305/sum_amd64.s

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build gc && !purego
-// +build gc,!purego
 
 #include "textflag.h"
 

internal/poly1305/sum_ppc64le.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build gc && !purego
-// +build gc,!purego
 
 package poly1305
 

internal/poly1305/sum_ppc64le.s

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build gc && !purego
-// +build gc,!purego
 
 #include "textflag.h"
 

internal/poly1305/sum_s390x.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build gc && !purego
-// +build gc,!purego
 
 package poly1305
 

internal/poly1305/sum_s390x.s

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build gc && !purego
-// +build gc,!purego
 
 #include "textflag.h"
 

internal/testenv/exec.go

@@ -0,0 +1,120 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package testenv
+
+import (
+	"context"
+	"os"
+	"os/exec"
+	"reflect"
+	"strconv"
+	"testing"
+	"time"
+)
+
+// CommandContext is like exec.CommandContext, but:
+//   - skips t if the platform does not support os/exec,
+//   - sends SIGQUIT (if supported by the platform) instead of SIGKILL
+//     in its Cancel function
+//   - if the test has a deadline, adds a Context timeout and WaitDelay
+//     for an arbitrary grace period before the test's deadline expires,
+//   - fails the test if the command does not complete before the test's deadline, and
+//   - sets a Cleanup function that verifies that the test did not leak a subprocess.
+func CommandContext(t testing.TB, ctx context.Context, name string, args ...string) *exec.Cmd {
+	t.Helper()
+
+	var (
+		cancelCtx   context.CancelFunc
+		gracePeriod time.Duration // unlimited unless the test has a deadline (to allow for interactive debugging)
+	)
+
+	if t, ok := t.(interface {
+		testing.TB
+		Deadline() (time.Time, bool)
+	}); ok {
+		if td, ok := t.Deadline(); ok {
+			// Start with a minimum grace period, just long enough to consume the
+			// output of a reasonable program after it terminates.
+			gracePeriod = 100 * time.Millisecond
+			if s := os.Getenv("GO_TEST_TIMEOUT_SCALE"); s != "" {
+				scale, err := strconv.Atoi(s)
+				if err != nil {
+					t.Fatalf("invalid GO_TEST_TIMEOUT_SCALE: %v", err)
+				}
+				gracePeriod *= time.Duration(scale)
+			}
+
+			// If time allows, increase the termination grace period to 5% of the
+			// test's remaining time.
+			testTimeout := time.Until(td)
+			if gp := testTimeout / 20; gp > gracePeriod {
+				gracePeriod = gp
+			}
+
+			// When we run commands that execute subprocesses, we want to reserve two
+			// grace periods to clean up: one for the delay between the first
+			// termination signal being sent (via the Cancel callback when the Context
+			// expires) and the process being forcibly terminated (via the WaitDelay
+			// field), and a second one for the delay becween the process being
+			// terminated and and the test logging its output for debugging.
+			//
+			// (We want to ensure that the test process itself has enough time to
+			// log the output before it is also terminated.)
+			cmdTimeout := testTimeout - 2*gracePeriod
+
+			if cd, ok := ctx.Deadline(); !ok || time.Until(cd) > cmdTimeout {
+				// Either ctx doesn't have a deadline, or its deadline would expire
+				// after (or too close before) the test has already timed out.
+				// Add a shorter timeout so that the test will produce useful output.
+				ctx, cancelCtx = context.WithTimeout(ctx, cmdTimeout)
+			}
+		}
+	}
+
+	cmd := exec.CommandContext(ctx, name, args...)
+	// Set the Cancel and WaitDelay fields only if present (go 1.20 and later).
+	// TODO: When Go 1.19 is no longer supported, remove this use of reflection
+	// and instead set the fields directly.
+	if cmdCancel := reflect.ValueOf(cmd).Elem().FieldByName("Cancel"); cmdCancel.IsValid() {
+		cmdCancel.Set(reflect.ValueOf(func() error {
+			if cancelCtx != nil && ctx.Err() == context.DeadlineExceeded {
+				// The command timed out due to running too close to the test's deadline.
+				// There is no way the test did that intentionally — it's too close to the
+				// wire! — so mark it as a test failure. That way, if the test expects the
+				// command to fail for some other reason, it doesn't have to distinguish
+				// between that reason and a timeout.
+				t.Errorf("test timed out while running command: %v", cmd)
+			} else {
+				// The command is being terminated due to ctx being canceled, but
+				// apparently not due to an explicit test deadline that we added.
+				// Log that information in case it is useful for diagnosing a failure,
+				// but don't actually fail the test because of it.
+				t.Logf("%v: terminating command: %v", ctx.Err(), cmd)
+			}
+			return cmd.Process.Signal(Sigquit)
+		}))
+	}
+	if cmdWaitDelay := reflect.ValueOf(cmd).Elem().FieldByName("WaitDelay"); cmdWaitDelay.IsValid() {
+		cmdWaitDelay.Set(reflect.ValueOf(gracePeriod))
+	}
+
+	t.Cleanup(func() {
+		if cancelCtx != nil {
+			cancelCtx()
+		}
+		if cmd.Process != nil && cmd.ProcessState == nil {
+			t.Errorf("command was started, but test did not wait for it to complete: %v", cmd)
+		}
+	})
+
+	return cmd
+}
+
+// Command is like exec.Command, but applies the same changes as
+// testenv.CommandContext (with a default Context).
+func Command(t testing.TB, name string, args ...string) *exec.Cmd {
+	t.Helper()
+	return CommandContext(t, context.Background(), name, args...)
+}

internal/testenv/testenv_notunix.go

@@ -0,0 +1,15 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build windows || plan9 || (js && wasm) || wasip1
+
+package testenv
+
+import (
+	"os"
+)
+
+// Sigquit is the signal to send to kill a hanging subprocess.
+// On Unix we send SIGQUIT, but on non-Unix we only have os.Kill.
+var Sigquit = os.Kill

internal/testenv/testenv_unix.go

@@ -0,0 +1,15 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build unix
+
+package testenv
+
+import (
+	"syscall"
+)
+
+// Sigquit is the signal to send to kill a hanging subprocess.
+// Send SIGQUIT to get a stack trace.
+var Sigquit = syscall.SIGQUIT

internal/wycheproof/ecdh_stdlib_test.go

@@ -118,7 +118,7 @@ func TestECDHStdLib(t *testing.T) {
 					}
 
 					shared := decodeHex(tt.Shared)
-					x, err := curve.ECDH(priv, pub)
+					x, err := priv.ECDH(pub)
 					if err != nil {
 						if tg.Curve == "curve25519" && !shouldPass {
 							// ECDH is expected to only return an error when using X25519,

internal/wycheproof/ecdsa_test.go

@@ -6,7 +6,11 @@ package wycheproof
 
 import (
 	"crypto/ecdsa"
+	"math/big"
 	"testing"
+
+	"golang.org/x/crypto/cryptobyte"
+	"golang.org/x/crypto/cryptobyte/asn1"
 )
 
 func TestECDSA(t *testing.T) {
@@ -76,9 +80,25 @@ func TestECDSA(t *testing.T) {
 			h.Reset()
 			h.Write(decodeHex(sig.Msg))
 			hashed := h.Sum(nil)
-			got := ecdsa.VerifyASN1(pub, hashed, decodeHex(sig.Sig))
+			sigBytes := decodeHex(sig.Sig)
+			got := ecdsa.VerifyASN1(pub, hashed, sigBytes)
 			if want := shouldPass(sig.Result, sig.Flags, flagsShouldPass); got != want {
-				t.Errorf("tcid: %d, type: %s, comment: %q, wanted success: %t", sig.TcID, sig.Result, sig.Comment, want)
+				t.Errorf("tcid: %d, type: %s, comment: %q, VerifyASN1 wanted success: %t", sig.TcID, sig.Result, sig.Comment, want)
+			}
+
+			var r, s big.Int
+			var inner cryptobyte.String
+			input := cryptobyte.String(sigBytes)
+			if !input.ReadASN1(&inner, asn1.SEQUENCE) ||
+				!input.Empty() ||
+				!inner.ReadASN1Integer(&r) ||
+				!inner.ReadASN1Integer(&s) ||
+				!inner.Empty() {
+				continue
+			}
+			got = ecdsa.Verify(pub, hashed, &r, &s)
+			if want := shouldPass(sig.Result, sig.Flags, flagsShouldPass); got != want {
+				t.Errorf("tcid: %d, type: %s, comment: %q, Verify wanted success: %t", sig.TcID, sig.Result, sig.Comment, want)
 			}
 		}
 	}

internal/wycheproof/eddsa_test.go

@@ -3,14 +3,12 @@
 // license that can be found in the LICENSE file.
 
 //go:build go1.13
-// +build go1.13
 
 package wycheproof
 
 import (
+	"crypto/ed25519"
 	"testing"
-
-	"golang.org/x/crypto/ed25519"
 )
 
 func TestEddsa(t *testing.T) {

internal/wycheproof/wycheproof_test.go

@@ -11,6 +11,7 @@ import (
 	"crypto/x509"
 	"encoding/hex"
 	"encoding/json"
+	"flag"
 	"fmt"
 	"log"
 	"os"
@@ -28,6 +29,11 @@ const wycheproofModVer = "v0.0.0-20191219022705-2196000605e4"
 var wycheproofTestVectorsDir string
 
 func TestMain(m *testing.M) {
+	flag.Parse()
+	if flag.Lookup("test.short").Value.(flag.Getter).Get().(bool) {
+		log.Println("skipping test that downloads testdata via 'go mod download' in short mode")
+		os.Exit(0)
+	}
 	if _, err := exec.LookPath("go"); err != nil {
 		log.Printf("skipping test because 'go' command is unavailable: %v", err)
 		os.Exit(0)
@@ -42,8 +48,6 @@ func TestMain(m *testing.M) {
 	// can be used in the following tests.
 	path := "github.com/google/wycheproof@" + wycheproofModVer
 	cmd := exec.Command("go", "mod", "download", "-json", path)
-	// TODO: enable the sumdb once the Trybots proxy supports it.
-	cmd.Env = append(os.Environ(), "GONOSUMDB=*")
 	output, err := cmd.Output()
 	if err != nil {
 		log.Fatalf("failed to run `go mod download -json %s`, output: %s", path, output)

nacl/sign/sign.go

@@ -21,9 +21,9 @@
 package sign
 
 import (
+	"crypto/ed25519"
 	"io"
 
-	"golang.org/x/crypto/ed25519"
 	"golang.org/x/crypto/internal/alias"
 )
 

ocsp/ocsp_test.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build go1.7
-// +build go1.7
 
 package ocsp
 

openpgp/armor/armor.go

@@ -156,7 +156,7 @@ func (r *openpgpReader) Read(p []byte) (n int, err error) {
 	n, err = r.b64Reader.Read(p)
 	r.currentCRC = crc24(r.currentCRC, p[:n])
 
-	if err == io.EOF && r.lReader.crcSet && r.lReader.crc != uint32(r.currentCRC&crc24Mask) {
+	if err == io.EOF && r.lReader.crcSet && r.lReader.crc != r.currentCRC&crc24Mask {
 		return 0, ArmorCorrupt
 	}
 

openpgp/keys.go

@@ -61,7 +61,7 @@ type Key struct {
 type KeyRing interface {
 	// KeysById returns the set of keys that have the given key id.
 	KeysById(id uint64) []Key
-	// KeysByIdAndUsage returns the set of keys with the given id
+	// KeysByIdUsage returns the set of keys with the given id
 	// that also meet the key usage given by requiredUsage.
 	// The requiredUsage is expressed as the bitwise-OR of
 	// packet.KeyFlag* values.
@@ -183,7 +183,7 @@ func (el EntityList) KeysById(id uint64) (keys []Key) {
 	return
 }
 
-// KeysByIdAndUsage returns the set of keys with the given id that also meet
+// KeysByIdUsage returns the set of keys with the given id that also meet
 // the key usage given by requiredUsage.  The requiredUsage is expressed as
 // the bitwise-OR of packet.KeyFlag* values.
 func (el EntityList) KeysByIdUsage(id uint64, requiredUsage byte) (keys []Key) {

openpgp/packet/compressed.go

@@ -60,7 +60,7 @@ func (c *Compressed) parse(r io.Reader) error {
 	return err
 }
 
-// compressedWriterCloser represents the serialized compression stream
+// compressedWriteCloser represents the serialized compression stream
 // header and the compressor. Its Close() method ensures that both the
 // compressor and serialized stream header are closed. Its Write()
 // method writes to the compressor.

otr/libotr_test_helper.c

@@ -5,7 +5,7 @@
 // This code can be compiled and used to test the otr package against libotr.
 // See otr_test.go.
 
-// +build ignore
+//go:build ignore
 
 #include <stdio.h>
 #include <stdlib.h>

salsa20/salsa/salsa20_amd64.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build amd64 && !purego && gc
-// +build amd64,!purego,gc
 
 package salsa
 

salsa20/salsa/salsa20_amd64.s

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build amd64 && !purego && gc
-// +build amd64,!purego,gc
 
 // This code was translated into a form compatible with 6a from the public
 // domain sources in SUPERCOP: https://bench.cr.yp.to/supercop.html

salsa20/salsa/salsa20_amd64_test.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build amd64 && !purego && gc
-// +build amd64,!purego,gc
 
 package salsa
 

salsa20/salsa/salsa20_noasm.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build !amd64 || purego || !gc
-// +build !amd64 purego !gc
 
 package salsa
 

sha3/hashes_generic.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build !gc || purego || !s390x
-// +build !gc purego !s390x
 
 package sha3
 

sha3/keccakf.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build !amd64 || purego || !gc
-// +build !amd64 purego !gc
 
 package sha3
 

sha3/keccakf_amd64.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build amd64 && !purego && gc
-// +build amd64,!purego,gc
 
 package sha3
 

sha3/keccakf_amd64.s

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build amd64 && !purego && gc
-// +build amd64,!purego,gc
 
 // This code was translated into a form compatible with 6a from the public
 // domain sources at https://github.com/gvanas/KeccakCodePackage

sha3/register.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build go1.4
-// +build go1.4
 
 package sha3
 

sha3/sha3.go

@@ -121,11 +121,11 @@ func (d *state) padAndPermute(dsbyte byte) {
 	copyOut(d, d.buf)
 }
 
-// Write absorbs more data into the hash's state. It produces an error
-// if more data is written to the ShakeHash after writing
+// Write absorbs more data into the hash's state. It panics if any
+// output has already been read.
 func (d *state) Write(p []byte) (written int, err error) {
 	if d.state != spongeAbsorbing {
-		panic("sha3: write to sponge after read")
+		panic("sha3: Write after Read")
 	}
 	if d.buf == nil {
 		d.buf = d.storage.asBytes()[:0]
@@ -182,12 +182,16 @@ func (d *state) Read(out []byte) (n int, err error) {
 }
 
 // Sum applies padding to the hash state and then squeezes out the desired
-// number of output bytes.
+// number of output bytes. It panics if any output has already been read.
 func (d *state) Sum(in []byte) []byte {
+	if d.state != spongeAbsorbing {
+		panic("sha3: Sum after Read")
+	}
+
 	// Make a copy of the original hash so that caller can keep writing
 	// and summing.
 	dup := d.clone()
-	hash := make([]byte, dup.outputLen)
+	hash := make([]byte, dup.outputLen, 64) // explicit cap to allow stack allocation
 	dup.Read(hash)
 	return append(in, hash...)
 }

sha3/sha3_s390x.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build gc && !purego
-// +build gc,!purego
 
 package sha3
 
@@ -49,7 +48,7 @@ type asmState struct {
 	buf       []byte          // care must be taken to ensure cap(buf) is a multiple of rate
 	rate      int             // equivalent to block size
 	storage   [3072]byte      // underlying storage for buf
-	outputLen int             // output length if fixed, 0 if not
+	outputLen int             // output length for full security
 	function  code            // KIMD/KLMD function code
 	state     spongeDirection // whether the sponge is absorbing or squeezing
 }
@@ -72,8 +71,10 @@ func newAsmState(function code) *asmState {
 		s.outputLen = 64
 	case shake_128:
 		s.rate = 168
+		s.outputLen = 32
 	case shake_256:
 		s.rate = 136
+		s.outputLen = 64
 	default:
 		panic("sha3: unrecognized function code")
 	}
@@ -108,7 +109,7 @@ func (s *asmState) resetBuf() {
 // It never returns an error.
 func (s *asmState) Write(b []byte) (int, error) {
 	if s.state != spongeAbsorbing {
-		panic("sha3: write to sponge after read")
+		panic("sha3: Write after Read")
 	}
 	length := len(b)
 	for len(b) > 0 {
@@ -192,8 +193,8 @@ func (s *asmState) Read(out []byte) (n int, err error) {
 // Sum appends the current hash to b and returns the resulting slice.
 // It does not change the underlying hash state.
 func (s *asmState) Sum(b []byte) []byte {
-	if s.outputLen == 0 {
-		panic("sha3: cannot call Sum on SHAKE functions")
+	if s.state != spongeAbsorbing {
+		panic("sha3: Sum after Read")
 	}
 
 	// Copy the state to preserve the original.

sha3/sha3_s390x.s

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build gc && !purego
-// +build gc,!purego
 
 #include "textflag.h"
 

sha3/shake.go

@@ -17,26 +17,25 @@ package sha3
 
 import (
 	"encoding/binary"
+	"hash"
 	"io"
 )
 
-// ShakeHash defines the interface to hash functions that
-// support arbitrary-length output.
+// ShakeHash defines the interface to hash functions that support
+// arbitrary-length output. When used as a plain [hash.Hash], it
+// produces minimum-length outputs that provide full-strength generic
+// security.
 type ShakeHash interface {
-	// Write absorbs more data into the hash's state. It panics if input is
-	// written to it after output has been read from it.
-	io.Writer
+	hash.Hash
 
 	// Read reads more output from the hash; reading affects the hash's
 	// state. (ShakeHash.Read is thus very different from Hash.Sum)
-	// It never returns an error.
+	// It never returns an error, but subsequent calls to Write or Sum
+	// will panic.
 	io.Reader
 
 	// Clone returns a copy of the ShakeHash in its current state.
 	Clone() ShakeHash
-
-	// Reset resets the ShakeHash to its initial state.
-	Reset()
 }
 
 // cSHAKE specific context
@@ -81,8 +80,8 @@ func leftEncode(value uint64) []byte {
 	return b[i-1:]
 }
 
-func newCShake(N, S []byte, rate int, dsbyte byte) ShakeHash {
-	c := cshakeState{state: &state{rate: rate, dsbyte: dsbyte}}
+func newCShake(N, S []byte, rate, outputLen int, dsbyte byte) ShakeHash {
+	c := cshakeState{state: &state{rate: rate, outputLen: outputLen, dsbyte: dsbyte}}
 
 	// leftEncode returns max 9 bytes
 	c.initBlock = make([]byte, 0, 9*2+len(N)+len(S))
@@ -119,7 +118,7 @@ func NewShake128() ShakeHash {
 	if h := newShake128Asm(); h != nil {
 		return h
 	}
-	return &state{rate: rate128, dsbyte: dsbyteShake}
+	return &state{rate: rate128, outputLen: 32, dsbyte: dsbyteShake}
 }
 
 // NewShake256 creates a new SHAKE256 variable-output-length ShakeHash.
@@ -129,7 +128,7 @@ func NewShake256() ShakeHash {
 	if h := newShake256Asm(); h != nil {
 		return h
 	}
-	return &state{rate: rate256, dsbyte: dsbyteShake}
+	return &state{rate: rate256, outputLen: 64, dsbyte: dsbyteShake}
 }
 
 // NewCShake128 creates a new instance of cSHAKE128 variable-output-length ShakeHash,
@@ -142,7 +141,7 @@ func NewCShake128(N, S []byte) ShakeHash {
 	if len(N) == 0 && len(S) == 0 {
 		return NewShake128()
 	}
-	return newCShake(N, S, rate128, dsbyteCShake)
+	return newCShake(N, S, rate128, 32, dsbyteCShake)
 }
 
 // NewCShake256 creates a new instance of cSHAKE256 variable-output-length ShakeHash,
@@ -155,7 +154,7 @@ func NewCShake256(N, S []byte) ShakeHash {
 	if len(N) == 0 && len(S) == 0 {
 		return NewShake256()
 	}
-	return newCShake(N, S, rate256, dsbyteCShake)
+	return newCShake(N, S, rate256, 64, dsbyteCShake)
 }
 
 // ShakeSum128 writes an arbitrary-length digest of data into hash.

sha3/shake_generic.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build !gc || purego || !s390x
-// +build !gc purego !s390x
 
 package sha3
 

sha3/xor.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build (!amd64 && !386 && !ppc64le) || purego
-// +build !amd64,!386,!ppc64le purego
 
 package sha3
 

sha3/xor_unaligned.go

@@ -3,8 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build (amd64 || 386 || ppc64le) && !purego
-// +build amd64 386 ppc64le
-// +build !purego
 
 package sha3
 

ssh/agent/client.go

@@ -16,6 +16,7 @@ import (
 	"bytes"
 	"crypto/dsa"
 	"crypto/ecdsa"
+	"crypto/ed25519"
 	"crypto/elliptic"
 	"crypto/rsa"
 	"encoding/base64"
@@ -26,7 +27,6 @@ import (
 	"math/big"
 	"sync"
 
-	"golang.org/x/crypto/ed25519"
 	"golang.org/x/crypto/ssh"
 )
 
@@ -141,9 +141,14 @@ const (
 	agentAddSmartcardKeyConstrained = 26
 
 	// 3.7 Key constraint identifiers
-	agentConstrainLifetime  = 1
-	agentConstrainConfirm   = 2
-	agentConstrainExtension = 3
+	agentConstrainLifetime = 1
+	agentConstrainConfirm  = 2
+	// Constraint extension identifier up to version 2 of the protocol. A
+	// backward incompatible change will be required if we want to add support
+	// for SSH_AGENT_CONSTRAIN_MAXSIGN which uses the same ID.
+	agentConstrainExtensionV00 = 3
+	// Constraint extension identifier in version 3 and later of the protocol.
+	agentConstrainExtension = 255
 )
 
 // maxAgentResponseBytes is the maximum agent reply size that is accepted. This
@@ -205,7 +210,7 @@ type constrainLifetimeAgentMsg struct {
 }
 
 type constrainExtensionAgentMsg struct {
-	ExtensionName    string `sshtype:"3"`
+	ExtensionName    string `sshtype:"255|3"`
 	ExtensionDetails []byte
 
 	// Rest is a field used for parsing, not part of message

ssh/agent/client_test.go

@@ -29,6 +29,9 @@ func startOpenSSHAgent(t *testing.T) (client ExtendedAgent, socket string, clean
 		// types supported vary by platform.
 		t.Skip("skipping test due to -short")
 	}
+	if runtime.GOOS == "windows" {
+		t.Skip("skipping on windows, we don't support connecting to the ssh-agent via a named pipe")
+	}
 
 	bin, err := exec.LookPath("ssh-agent")
 	if err != nil {
@@ -366,7 +369,8 @@ func TestAuth(t *testing.T) {
 	go func() {
 		conn, _, _, err := ssh.NewServerConn(a, &serverConf)
 		if err != nil {
-			t.Fatalf("Server: %v", err)
+			t.Errorf("NewServerConn error: %v", err)
+			return
 		}
 		conn.Close()
 	}()

ssh/agent/server.go

@@ -7,6 +7,7 @@ package agent
 import (
 	"crypto/dsa"
 	"crypto/ecdsa"
+	"crypto/ed25519"
 	"crypto/elliptic"
 	"crypto/rsa"
 	"encoding/binary"
@@ -16,11 +17,10 @@ import (
 	"log"
 	"math/big"
 
-	"golang.org/x/crypto/ed25519"
 	"golang.org/x/crypto/ssh"
 )
 
-// Server wraps an Agent and uses it to implement the agent side of
+// server wraps an Agent and uses it to implement the agent side of
 // the SSH-agent, wire protocol.
 type server struct {
 	agent Agent
@@ -208,7 +208,7 @@ func parseConstraints(constraints []byte) (lifetimeSecs uint32, confirmBeforeUse
 		case agentConstrainConfirm:
 			confirmBeforeUse = true
 			constraints = constraints[1:]
-		case agentConstrainExtension:
+		case agentConstrainExtension, agentConstrainExtensionV00:
 			var msg constrainExtensionAgentMsg
 			if err = ssh.Unmarshal(constraints, &msg); err != nil {
 				return 0, false, nil, err

ssh/agent/server_test.go

@@ -53,10 +53,11 @@ func TestSetupForwardAgent(t *testing.T) {
 	incoming := make(chan *ssh.ServerConn, 1)
 	go func() {
 		conn, _, _, err := ssh.NewServerConn(a, &serverConf)
-		if err != nil {
-			t.Fatalf("Server: %v", err)
-		}
 		incoming <- conn
+		if err != nil {
+			t.Errorf("NewServerConn error: %v", err)
+			return
+		}
 	}()
 
 	conf := ssh.ClientConfig{
@@ -71,8 +72,10 @@ func TestSetupForwardAgent(t *testing.T) {
 	if err := ForwardToRemote(client, socket); err != nil {
 		t.Fatalf("SetupForwardAgent: %v", err)
 	}
-
 	server := <-incoming
+	if server == nil {
+		t.Fatal("Unable to get server")
+	}
 	ch, reqs, err := server.OpenChannel(channelType, nil)
 	if err != nil {
 		t.Fatalf("OpenChannel(%q): %v", channelType, err)
@@ -240,7 +243,11 @@ func TestParseConstraints(t *testing.T) {
 			ExtensionDetails: []byte(fmt.Sprintf("details: %d", i)),
 		}
 		expect = append(expect, ext)
-		data = append(data, agentConstrainExtension)
+		if i%2 == 0 {
+			data = append(data, agentConstrainExtension)
+		} else {
+			data = append(data, agentConstrainExtensionV00)
+		}
 		data = append(data, ssh.Marshal(ext)...)
 	}
 	_, _, extensions, err := parseConstraints(data)

ssh/benchmark_test.go

@@ -6,6 +6,7 @@ package ssh
 
 import (
 	"errors"
+	"fmt"
 	"io"
 	"net"
 	"testing"
@@ -90,16 +91,16 @@ func BenchmarkEndToEnd(b *testing.B) {
 	go func() {
 		newCh, err := server.Accept()
 		if err != nil {
-			b.Fatalf("Client: %v", err)
+			panic(fmt.Sprintf("Client: %v", err))
 		}
 		ch, incoming, err := newCh.Accept()
 		if err != nil {
-			b.Fatalf("Accept: %v", err)
+			panic(fmt.Sprintf("Accept: %v", err))
 		}
 		go DiscardRequests(incoming)
 		for i := 0; i < b.N; i++ {
 			if _, err := io.ReadFull(ch, output); err != nil {
-				b.Fatalf("ReadFull: %v", err)
+				panic(fmt.Sprintf("ReadFull: %v", err))
 			}
 		}
 		ch.Close()

ssh/certs.go

@@ -16,8 +16,9 @@ import (
 
 // Certificate algorithm names from [PROTOCOL.certkeys]. These values can appear
 // in Certificate.Type, PublicKey.Type, and ClientConfig.HostKeyAlgorithms.
-// Unlike key algorithm names, these are not passed to AlgorithmSigner and don't
-// appear in the Signature.Format field.
+// Unlike key algorithm names, these are not passed to AlgorithmSigner nor
+// returned by MultiAlgorithmSigner and don't appear in the Signature.Format
+// field.
 const (
 	CertAlgoRSAv01        = "ssh-rsa-cert-v01@openssh.com"
 	CertAlgoDSAv01        = "ssh-dss-cert-v01@openssh.com"
@@ -255,10 +256,17 @@ func NewCertSigner(cert *Certificate, signer Signer) (Signer, error) {
 		return nil, errors.New("ssh: signer and cert have different public key")
 	}
 
-	if algorithmSigner, ok := signer.(AlgorithmSigner); ok {
+	switch s := signer.(type) {
+	case MultiAlgorithmSigner:
+		return &multiAlgorithmSigner{
+			AlgorithmSigner: &algorithmOpenSSHCertSigner{
+				&openSSHCertSigner{cert, signer}, s},
+			supportedAlgorithms: s.Algorithms(),
+		}, nil
+	case AlgorithmSigner:
 		return &algorithmOpenSSHCertSigner{
-			&openSSHCertSigner{cert, signer}, algorithmSigner}, nil
-	} else {
+			&openSSHCertSigner{cert, signer}, s}, nil
+	default:
 		return &openSSHCertSigner{cert, signer}, nil
 	}
 }
@@ -432,7 +440,9 @@ func (c *CertChecker) CheckCert(principal string, cert *Certificate) error {
 }
 
 // SignCert signs the certificate with an authority, setting the Nonce,
-// SignatureKey, and Signature fields.
+// SignatureKey, and Signature fields. If the authority implements the
+// MultiAlgorithmSigner interface the first algorithm in the list is used. This
+// is useful if you want to sign with a specific algorithm.
 func (c *Certificate) SignCert(rand io.Reader, authority Signer) error {
 	c.Nonce = make([]byte, 32)
 	if _, err := io.ReadFull(rand, c.Nonce); err != nil {
@@ -440,8 +450,20 @@ func (c *Certificate) SignCert(rand io.Reader, authority Signer) error {
 	}
 	c.SignatureKey = authority.PublicKey()
 
-	// Default to KeyAlgoRSASHA512 for ssh-rsa signers.
-	if v, ok := authority.(AlgorithmSigner); ok && v.PublicKey().Type() == KeyAlgoRSA {
+	if v, ok := authority.(MultiAlgorithmSigner); ok {
+		if len(v.Algorithms()) == 0 {
+			return errors.New("the provided authority has no signature algorithm")
+		}
+		// Use the first algorithm in the list.
+		sig, err := v.SignWithAlgorithm(rand, c.bytesForSigning(), v.Algorithms()[0])
+		if err != nil {
+			return err
+		}
+		c.Signature = sig
+		return nil
+	} else if v, ok := authority.(AlgorithmSigner); ok && v.PublicKey().Type() == KeyAlgoRSA {
+		// Default to KeyAlgoRSASHA512 for ssh-rsa signers.
+		// TODO: consider using KeyAlgoRSASHA256 as default.
 		sig, err := v.SignWithAlgorithm(rand, c.bytesForSigning(), KeyAlgoRSASHA512)
 		if err != nil {
 			return err