go.mod: update golang.org/x dependencies

Update golang.org/x dependencies to their latest tagged versions.

Change-Id: Icf986acf9290649488777328f470200bf9e11442
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/710098
Reviewed-by: David Chase <drchase@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@google.com>

acme/autocert/autocert_test.go

@@ -561,9 +561,9 @@ func TestHTTPHandlerDefaultFallback(t *testing.T) {
 		{"GET", "http://example.org/foo?a=b", 302, "https://example.org/foo?a=b"},
 		{"GET", "http://example.org:80/foo?a=b", 302, "https://example.org:443/foo?a=b"},
 		{"GET", "http://example.org:80/foo%20bar", 302, "https://example.org:443/foo%20bar"},
-		{"GET", "http://[2602:d1:xxxx::c60a]:1234", 302, "https://[2602:d1:xxxx::c60a]:443/"},
-		{"GET", "http://[2602:d1:xxxx::c60a]", 302, "https://[2602:d1:xxxx::c60a]/"},
-		{"GET", "http://[2602:d1:xxxx::c60a]/foo?a=b", 302, "https://[2602:d1:xxxx::c60a]/foo?a=b"},
+		{"GET", "http://[2602:d1:abcd::c60a]:1234", 302, "https://[2602:d1:abcd::c60a]:443/"},
+		{"GET", "http://[2602:d1:abcd::c60a]", 302, "https://[2602:d1:abcd::c60a]/"},
+		{"GET", "http://[2602:d1:abcd::c60a]/foo?a=b", 302, "https://[2602:d1:abcd::c60a]/foo?a=b"},
 		{"HEAD", "http://example.org", 302, "https://example.org/"},
 		{"HEAD", "http://example.org/foo", 302, "https://example.org/foo"},
 		{"HEAD", "http://example.org/foo/bar/", 302, "https://example.org/foo/bar/"},

curve25519/curve25519.go

@@ -3,11 +3,14 @@
 // license that can be found in the LICENSE file.
 
 // Package curve25519 provides an implementation of the X25519 function, which
-// performs scalar multiplication on the elliptic curve known as Curve25519.
-// See RFC 7748.
+// performs scalar multiplication on the elliptic curve known as Curve25519
+// according to [RFC 7748].
 //
-// This package is a wrapper for the X25519 implementation
-// in the crypto/ecdh package.
+// The curve25519 package is a wrapper for the X25519 implementation in the
+// crypto/ecdh package. It is [frozen] and is not accepting new features.
+//
+// [RFC 7748]: https://datatracker.ietf.org/doc/html/rfc7748
+// [frozen]: https://go.dev/wiki/Frozen
 package curve25519
 
 import "crypto/ecdh"

ed25519/ed25519.go

@@ -2,16 +2,19 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Package ed25519 implements the Ed25519 signature algorithm. See
-// https://ed25519.cr.yp.to/.
+// Package ed25519 implements the Ed25519 signature algorithm.
 //
 // These functions are also compatible with the “Ed25519” function defined in
-// RFC 8032. However, unlike RFC 8032's formulation, this package's private key
+// [RFC 8032]. However, unlike RFC 8032's formulation, this package's private key
 // representation includes a public key suffix to make multiple signing
 // operations with the same key more efficient. This package refers to the RFC
 // 8032 private key as the “seed”.
 //
-// This package is a wrapper around the standard library crypto/ed25519 package.
+// The ed25519 package is a wrapper for the Ed25519 implementation in the
+// crypto/ed25519 package. It is [frozen] and is not accepting new features.
+//
+// [RFC 8032]: https://datatracker.ietf.org/doc/html/rfc8032
+// [frozen]: https://go.dev/wiki/Frozen
 package ed25519
 
 import (

go.mod

@@ -3,9 +3,9 @@ module golang.org/x/crypto
 go 1.24.0
 
 require (
-	golang.org/x/net v0.43.0 // tagx:ignore
-	golang.org/x/sys v0.36.0
-	golang.org/x/term v0.35.0
+	golang.org/x/net v0.45.0 // tagx:ignore
+	golang.org/x/sys v0.37.0
+	golang.org/x/term v0.36.0
 )
 
-require golang.org/x/text v0.29.0 // indirect
+require golang.org/x/text v0.30.0 // indirect

go.sum

@@ -1,8 +1,8 @@
-golang.org/x/net v0.43.0 h1:lat02VYK2j4aLzMzecihNvTlJNQUq316m2Mr9rnM6YE=
-golang.org/x/net v0.43.0/go.mod h1:vhO1fvI4dGsIjh73sWfUVjj3N7CA9WkKJNQm2svM6Jg=
-golang.org/x/sys v0.36.0 h1:KVRy2GtZBrk1cBYA7MKu5bEZFxQk4NIDV6RLVcC8o0k=
-golang.org/x/sys v0.36.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
-golang.org/x/term v0.35.0 h1:bZBVKBudEyhRcajGcNc3jIfWPqV4y/Kt2XcoigOWtDQ=
-golang.org/x/term v0.35.0/go.mod h1:TPGtkTLesOwf2DE8CgVYiZinHAOuy5AYUYT1lENIZnA=
-golang.org/x/text v0.29.0 h1:1neNs90w9YzJ9BocxfsQNHKuAT4pkghyXc4nhZ6sJvk=
-golang.org/x/text v0.29.0/go.mod h1:7MhJOA9CD2qZyOKYazxdYMF85OwPdEr9jTtBpO7ydH4=
+golang.org/x/net v0.45.0 h1:RLBg5JKixCy82FtLJpeNlVM0nrSqpCRYzVU1n8kj0tM=
+golang.org/x/net v0.45.0/go.mod h1:ECOoLqd5U3Lhyeyo/QDCEVQ4sNgYsqvCZ722XogGieY=
+golang.org/x/sys v0.37.0 h1:fdNQudmxPjkdUTPnLn5mdQv7Zwvbvpaxqs831goi9kQ=
+golang.org/x/sys v0.37.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
+golang.org/x/term v0.36.0 h1:zMPR+aF8gfksFprF/Nc/rd1wRS1EI6nDBGyWAvDzx2Q=
+golang.org/x/term v0.36.0/go.mod h1:Qu394IJq6V6dCBRgwqshf3mPF85AqzYEzofzRdZkWss=
+golang.org/x/text v0.30.0 h1:yznKA/E9zq54KzlzBEAWn1NXSQ8DIp/NYMy88xJjl4k=
+golang.org/x/text v0.30.0/go.mod h1:yDdHFIX9t+tORqspjENWgzaCVXgk0yYnYuSZ8UzzBVM=

nacl/auth/auth.go

@@ -2,25 +2,16 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-/*
-Package auth authenticates a message using a secret key.
-
-The Sum function, viewed as a function of the message for a uniform random
-key, is designed to meet the standard notion of unforgeability. This means
-that an attacker cannot find authenticators for any messages not authenticated
-by the sender, even if the attacker has adaptively influenced the messages
-authenticated by the sender. For a formal definition see, e.g., Section 2.4
-of Bellare, Kilian, and Rogaway, "The security of the cipher block chaining
-message authentication code," Journal of Computer and System Sciences 61 (2000),
-362–399; http://www-cse.ucsd.edu/~mihir/papers/cbc.html.
-
-auth does not make any promises regarding "strong" unforgeability; perhaps
-one valid authenticator can be converted into another valid authenticator for
-the same message. NaCl also does not make any promises regarding "truncated
-unforgeability."
-
-This package is interoperable with NaCl: https://nacl.cr.yp.to/auth.html.
-*/
+// Package auth authenticates a message using a secret key.
+//
+// This package is interoperable with [NaCl].
+//
+// The auth package is essentially a wrapper for HMAC-SHA-512 (implemented by
+// crypto/hmac and crypto/sha512), truncated to 32 bytes. It is [frozen] and is
+// not accepting new features.
+//
+// [NaCl]: https://nacl.cr.yp.to/auth.html
+// [frozen]: https://go.dev/wiki/Frozen
 package auth
 
 import (

nacl/sign/sign.go

@@ -4,20 +4,15 @@
 
 // Package sign signs small messages using public-key cryptography.
 //
-// Sign uses Ed25519 to sign messages. The length of messages is not hidden.
-// Messages should be small because:
-// 1. The whole message needs to be held in memory to be processed.
-// 2. Using large messages pressures implementations on small machines to process
-// plaintext without verifying the signature. This is very dangerous, and this API
-// discourages it, but a protocol that uses excessive message sizes might present
-// some implementations with no other choice.
-// 3. Performance may be improved by working with messages that fit into data caches.
-// Thus large amounts of data should be chunked so that each message is small.
+// This package is interoperable with [libsodium], as well as [TweetNaCl].
 //
-// This package is not interoperable with the current release of NaCl
-// (https://nacl.cr.yp.to/sign.html), which does not support Ed25519 yet. However,
-// it is compatible with the NaCl fork libsodium (https://www.libsodium.org), as well
-// as TweetNaCl (https://tweetnacl.cr.yp.to/).
+// The sign package is essentially a wrapper for the Ed25519 signature
+// algorithm (implemented by crypto/ed25519). It is [frozen] and is not accepting
+// new features.
+//
+// [libsodium]: https://libsodium.gitbook.io/doc/public-key_cryptography/public-key_signatures
+// [TweetNaCl]: https://tweetnacl.cr.yp.to/
+// [frozen]: https://go.dev/wiki/Frozen
 package sign
 
 import (

otr/otr.go

@@ -8,6 +8,10 @@
 // The version of OTR implemented by this package has been deprecated
 // (https://bugs.otr.im/lib/libotr/issues/140). An implementation of OTRv3 is
 // available at https://github.com/coyim/otr3.
+//
+// The otr package is [frozen] and is not accepting new features.
+//
+// [frozen]: https://go.dev/wiki/Frozen
 package otr
 
 import (

pkcs12/pkcs12.go

@@ -4,12 +4,16 @@
 
 // Package pkcs12 implements some of PKCS#12.
 //
-// This implementation is distilled from https://tools.ietf.org/html/rfc7292
-// and referenced documents. It is intended for decoding P12/PFX-stored
-// certificates and keys for use with the crypto/tls package.
+// This implementation is distilled from [RFC 7292] and referenced documents.
+// It is intended for decoding P12/PFX-stored certificates and keys for use
+// with the crypto/tls package.
 //
-// This package is frozen. If it's missing functionality you need, consider
-// an alternative like software.sslmate.com/src/go-pkcs12.
+// The pkcs12 package is [frozen] and is not accepting new features.
+// If it's missing functionality you need, consider an alternative like
+// software.sslmate.com/src/go-pkcs12.
+//
+// [RFC 7292]: https://datatracker.ietf.org/doc/html/rfc7292
+// [frozen]: https://go.dev/wiki/Frozen
 package pkcs12
 
 import (

salsa20/salsa/hsalsa20.go

@@ -3,6 +3,10 @@
 // license that can be found in the LICENSE file.
 
 // Package salsa provides low-level access to functions in the Salsa family.
+//
+// Deprecated: this package exposes unsafe low-level operations. New applications
+// should consider using the AEAD construction in golang.org/x/crypto/chacha20poly1305
+// instead. Existing users should migrate to golang.org/x/crypto/salsa20.
 package salsa
 
 import "math/bits"

ssh/agent/client.go

@@ -430,8 +430,9 @@ func (c *client) List() ([]*Key, error) {
 		return keys, nil
 	case *failureAgentMsg:
 		return nil, errors.New("agent: failed to list keys")
+	default:
+		return nil, fmt.Errorf("agent: failed to list keys, unexpected message type %T", msg)
 	}
-	panic("unreachable")
 }
 
 // Sign has the agent sign the data using a protocol 2 key as defined
@@ -462,8 +463,9 @@ func (c *client) SignWithFlags(key ssh.PublicKey, data []byte, flags SignatureFl
 		return &sig, nil
 	case *failureAgentMsg:
 		return nil, errors.New("agent: failed to sign challenge")
+	default:
+		return nil, fmt.Errorf("agent: failed to sign challenge, unexpected message type %T", msg)
 	}
-	panic("unreachable")
 }
 
 // unmarshal parses an agent message in packet, returning the parsed

ssh/agent/client_test.go

@@ -7,6 +7,7 @@ package agent
 import (
 	"bytes"
 	"crypto/rand"
+	"encoding/binary"
 	"errors"
 	"io"
 	"net"
@@ -347,6 +348,53 @@ func TestServerResponseTooLarge(t *testing.T) {
 	}
 }
 
+func TestInvalidResponses(t *testing.T) {
+	a, b, err := netPipe()
+	if err != nil {
+		t.Fatalf("netPipe: %v", err)
+	}
+	done := make(chan struct{})
+	defer func() { <-done }()
+
+	defer a.Close()
+	defer b.Close()
+
+	agent := NewClient(a)
+	go func() {
+		defer close(done)
+
+		resp := []byte{agentSuccess}
+		msg := make([]byte, 4+len(resp))
+		binary.BigEndian.PutUint32(msg[:4], uint32(len(resp)))
+		copy(msg[4:], resp)
+
+		if _, err := b.Write(msg); err != nil {
+			t.Errorf("unexpected error sending agent reply: %v", err)
+			b.Close()
+			return
+		}
+
+		if _, err := b.Write(msg); err != nil {
+			t.Errorf("unexpected error sending agent reply: %v", err)
+			b.Close()
+		}
+	}()
+	_, err = agent.List()
+	if err == nil {
+		t.Fatal("error expected")
+	}
+	if !strings.Contains(err.Error(), "failed to list keys, unexpected message type") {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	_, err = agent.Sign(testPublicKeys["rsa"], []byte("message"))
+	if err == nil {
+		t.Fatal("error expected")
+	}
+	if !strings.Contains(err.Error(), "failed to sign challenge, unexpected message type") {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
 func TestAuth(t *testing.T) {
 	agent, _, cleanup := startOpenSSHAgent(t)
 	defer cleanup()

ssh/certs_test.go

@@ -338,7 +338,9 @@ func TestCertTypes(t *testing.T) {
 				CertType: UserCert,
 				Key:      priv.PublicKey(),
 			}
-			cert.SignCert(rand.Reader, priv)
+			if err := cert.SignCert(rand.Reader, priv); err != nil {
+				t.Fatalf("error signing certificate: %v", err)
+			}
 
 			certSigner, err := NewCertSigner(cert, priv)
 			if err != nil {

ssh/cipher.go

@@ -8,6 +8,7 @@ import (
 	"crypto/aes"
 	"crypto/cipher"
 	"crypto/des"
+	"crypto/fips140"
 	"crypto/rc4"
 	"crypto/subtle"
 	"encoding/binary"
@@ -15,6 +16,7 @@ import (
 	"fmt"
 	"hash"
 	"io"
+	"slices"
 
 	"golang.org/x/crypto/chacha20"
 	"golang.org/x/crypto/internal/poly1305"
@@ -93,41 +95,41 @@ func streamCipherMode(skip int, createFunc func(key, iv []byte) (cipher.Stream,
 }
 
 // cipherModes documents properties of supported ciphers. Ciphers not included
-// are not supported and will not be negotiated, even if explicitly requested in
-// ClientConfig.Crypto.Ciphers.
-var cipherModes = map[string]*cipherMode{
-	// Ciphers from RFC 4344, which introduced many CTR-based ciphers. Algorithms
-	// are defined in the order specified in the RFC.
-	CipherAES128CTR: {16, aes.BlockSize, streamCipherMode(0, newAESCTR)},
-	CipherAES192CTR: {24, aes.BlockSize, streamCipherMode(0, newAESCTR)},
-	CipherAES256CTR: {32, aes.BlockSize, streamCipherMode(0, newAESCTR)},
+// are not supported and will not be negotiated, even if explicitly configured.
+// When FIPS mode is enabled, only FIPS-approved algorithms are included.
+var cipherModes = map[string]*cipherMode{}
 
-	// Ciphers from RFC 4345, which introduces security-improved arcfour ciphers.
-	// They are defined in the order specified in the RFC.
-	InsecureCipherRC4128: {16, 0, streamCipherMode(1536, newRC4)},
-	InsecureCipherRC4256: {32, 0, streamCipherMode(1536, newRC4)},
+func init() {
+	cipherModes[CipherAES128CTR] = &cipherMode{16, aes.BlockSize, streamCipherMode(0, newAESCTR)}
+	cipherModes[CipherAES192CTR] = &cipherMode{24, aes.BlockSize, streamCipherMode(0, newAESCTR)}
+	cipherModes[CipherAES256CTR] = &cipherMode{32, aes.BlockSize, streamCipherMode(0, newAESCTR)}
+	//  Use of GCM with arbitrary IVs is not allowed in FIPS 140-only mode,
+	// we'll wire it up to NewGCMForSSH in Go 1.26.
+	//
+	// For now it means we'll work with fips140=on but not fips140=only.
+	cipherModes[CipherAES128GCM] = &cipherMode{16, 12, newGCMCipher}
+	cipherModes[CipherAES256GCM] = &cipherMode{32, 12, newGCMCipher}
 
-	// Cipher defined in RFC 4253, which describes SSH Transport Layer Protocol.
-	// Note that this cipher is not safe, as stated in RFC 4253: "Arcfour (and
-	// RC4) has problems with weak keys, and should be used with caution."
-	// RFC 4345 introduces improved versions of Arcfour.
-	InsecureCipherRC4: {16, 0, streamCipherMode(0, newRC4)},
-
-	// AEAD ciphers
-	CipherAES128GCM:        {16, 12, newGCMCipher},
-	CipherAES256GCM:        {32, 12, newGCMCipher},
-	CipherChaCha20Poly1305: {64, 0, newChaCha20Cipher},
+	if fips140.Enabled() {
+		defaultCiphers = slices.DeleteFunc(defaultCiphers, func(algo string) bool {
+			_, ok := cipherModes[algo]
+			return !ok
+		})
+		return
+	}
 
+	cipherModes[CipherChaCha20Poly1305] = &cipherMode{64, 0, newChaCha20Cipher}
+	// Insecure ciphers not included in the default configuration.
+	cipherModes[InsecureCipherRC4128] = &cipherMode{16, 0, streamCipherMode(1536, newRC4)}
+	cipherModes[InsecureCipherRC4256] = &cipherMode{32, 0, streamCipherMode(1536, newRC4)}
+	cipherModes[InsecureCipherRC4] = &cipherMode{16, 0, streamCipherMode(0, newRC4)}
 	// CBC mode is insecure and so is not included in the default config.
 	// (See https://www.ieee-security.org/TC/SP2013/papers/4977a526.pdf). If absolutely
 	// needed, it's possible to specify a custom Config to enable it.
 	// You should expect that an active attacker can recover plaintext if
 	// you do.
-	InsecureCipherAES128CBC: {16, aes.BlockSize, newAESCBCCipher},
-
-	// 3des-cbc is insecure and is not included in the default
-	// config.
-	InsecureCipherTripleDESCBC: {24, des.BlockSize, newTripleDESCBCCipher},
+	cipherModes[InsecureCipherAES128CBC] = &cipherMode{16, aes.BlockSize, newAESCBCCipher}
+	cipherModes[InsecureCipherTripleDESCBC] = &cipherMode{24, des.BlockSize, newTripleDESCBCCipher}
 }
 
 // prefixLen is the length of the packet prefix that contains the packet length

ssh/client_auth.go

@@ -9,6 +9,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"slices"
 	"strings"
 )
 
@@ -83,7 +84,7 @@ func (c *connection) clientAuthenticate(config *ClientConfig) error {
 			// success
 			return nil
 		} else if ok == authFailure {
-			if m := auth.method(); !contains(tried, m) {
+			if m := auth.method(); !slices.Contains(tried, m) {
 				tried = append(tried, m)
 			}
 		}
@@ -97,7 +98,7 @@ func (c *connection) clientAuthenticate(config *ClientConfig) error {
 	findNext:
 		for _, a := range config.Auth {
 			candidateMethod := a.method()
-			if contains(tried, candidateMethod) {
+			if slices.Contains(tried, candidateMethod) {
 				continue
 			}
 			for _, meth := range methods {
@@ -117,15 +118,6 @@ func (c *connection) clientAuthenticate(config *ClientConfig) error {
 	return fmt.Errorf("ssh: unable to authenticate, attempted methods %v, no supported methods remain", tried)
 }
 
-func contains(list []string, e string) bool {
-	for _, s := range list {
-		if s == e {
-			return true
-		}
-	}
-	return false
-}
-
 // An AuthMethod represents an instance of an RFC 4252 authentication method.
 type AuthMethod interface {
 	// auth authenticates user over transport t.
@@ -255,7 +247,7 @@ func pickSignatureAlgorithm(signer Signer, extensions map[string][]byte) (MultiA
 		// Fallback to use if there is no "server-sig-algs" extension or a
 		// common algorithm cannot be found. We use the public key format if the
 		// MultiAlgorithmSigner supports it, otherwise we return an error.
-		if !contains(as.Algorithms(), underlyingAlgo(keyFormat)) {
+		if !slices.Contains(as.Algorithms(), underlyingAlgo(keyFormat)) {
 			return "", fmt.Errorf("ssh: no common public key signature algorithm, server only supports %q for key type %q, signer only supports %v",
 				underlyingAlgo(keyFormat), keyFormat, as.Algorithms())
 		}
@@ -284,7 +276,7 @@ func pickSignatureAlgorithm(signer Signer, extensions map[string][]byte) (MultiA
 	// Filter algorithms based on those supported by MultiAlgorithmSigner.
 	var keyAlgos []string
 	for _, algo := range algorithmsForKeyFormat(keyFormat) {
-		if contains(as.Algorithms(), underlyingAlgo(algo)) {
+		if slices.Contains(as.Algorithms(), underlyingAlgo(algo)) {
 			keyAlgos = append(keyAlgos, algo)
 		}
 	}
@@ -334,7 +326,7 @@ func (cb publicKeyCallback) auth(session []byte, user string, c packetConn, rand
 		// the key try to use the obtained algorithm as if "server-sig-algs" had
 		// not been implemented if supported from the algorithm signer.
 		if !ok && idx < origSignersLen && isRSACert(algo) && algo != CertAlgoRSAv01 {
-			if contains(as.Algorithms(), KeyAlgoRSA) {
+			if slices.Contains(as.Algorithms(), KeyAlgoRSA) {
 				// We retry using the compat algorithm after all signers have
 				// been tried normally.
 				signers = append(signers, &multiAlgorithmSigner{
@@ -385,7 +377,7 @@ func (cb publicKeyCallback) auth(session []byte, user string, c packetConn, rand
 		// contain the "publickey" method, do not attempt to authenticate with any
 		// other keys.  According to RFC 4252 Section 7, the latter can occur when
 		// additional authentication methods are required.
-		if success == authSuccess || !contains(methods, cb.method()) {
+		if success == authSuccess || !slices.Contains(methods, cb.method()) {
 			return success, methods, err
 		}
 	}
@@ -434,7 +426,7 @@ func confirmKeyAck(key PublicKey, c packetConn) (bool, error) {
 			// servers send the key type instead. OpenSSH allows any algorithm
 			// that matches the public key, so we do the same.
 			// https://github.com/openssh/openssh-portable/blob/86bdd385/sshconnect2.c#L709
-			if !contains(algorithmsForKeyFormat(key.Type()), msg.Algo) {
+			if !slices.Contains(algorithmsForKeyFormat(key.Type()), msg.Algo) {
 				return false, nil
 			}
 			if !bytes.Equal(msg.PubKey, pubKey) {

ssh/client_auth_test.go

@@ -14,6 +14,7 @@ import (
 	"net"
 	"os"
 	"runtime"
+	"slices"
 	"strings"
 	"testing"
 )
@@ -1214,7 +1215,7 @@ func (cb configurablePublicKeyCallback) auth(session []byte, user string, c pack
 	if err != nil {
 		return authFailure, nil, err
 	}
-	if success == authSuccess || !contains(methods, cb.method()) {
+	if success == authSuccess || !slices.Contains(methods, cb.method()) {
 		return success, methods, err
 	}
 

ssh/common.go

@@ -6,6 +6,7 @@ package ssh
 
 import (
 	"crypto"
+	"crypto/fips140"
 	"crypto/rand"
 	"fmt"
 	"io"
@@ -256,6 +257,40 @@ type Algorithms struct {
 	PublicKeyAuths []string
 }
 
+func init() {
+	if fips140.Enabled() {
+		defaultHostKeyAlgos = slices.DeleteFunc(defaultHostKeyAlgos, func(algo string) bool {
+			_, err := hashFunc(underlyingAlgo(algo))
+			return err != nil
+		})
+		defaultPubKeyAuthAlgos = slices.DeleteFunc(defaultPubKeyAuthAlgos, func(algo string) bool {
+			_, err := hashFunc(underlyingAlgo(algo))
+			return err != nil
+		})
+	}
+}
+
+func hashFunc(format string) (crypto.Hash, error) {
+	switch format {
+	case KeyAlgoRSASHA256, KeyAlgoECDSA256, KeyAlgoSKED25519, KeyAlgoSKECDSA256:
+		return crypto.SHA256, nil
+	case KeyAlgoECDSA384:
+		return crypto.SHA384, nil
+	case KeyAlgoRSASHA512, KeyAlgoECDSA521:
+		return crypto.SHA512, nil
+	case KeyAlgoED25519:
+		// KeyAlgoED25519 doesn't pre-hash.
+		return 0, nil
+	case KeyAlgoRSA, InsecureKeyAlgoDSA:
+		if fips140.Enabled() {
+			return 0, fmt.Errorf("ssh: hash algorithm for format %q not allowed in FIPS 140 mode", format)
+		}
+		return crypto.SHA1, nil
+	default:
+		return 0, fmt.Errorf("ssh: hash algorithm for format %q not mapped", format)
+	}
+}
+
 // SupportedAlgorithms returns algorithms currently implemented by this package,
 // excluding those with security issues, which are returned by
 // InsecureAlgorithms. The algorithms listed here are in preference order.
@@ -283,21 +318,6 @@ func InsecureAlgorithms() Algorithms {
 
 var supportedCompressions = []string{compressionNone}
 
-// hashFuncs keeps the mapping of supported signature algorithms to their
-// respective hashes needed for signing and verification.
-var hashFuncs = map[string]crypto.Hash{
-	KeyAlgoRSA:         crypto.SHA1,
-	KeyAlgoRSASHA256:   crypto.SHA256,
-	KeyAlgoRSASHA512:   crypto.SHA512,
-	InsecureKeyAlgoDSA: crypto.SHA1,
-	KeyAlgoECDSA256:    crypto.SHA256,
-	KeyAlgoECDSA384:    crypto.SHA384,
-	KeyAlgoECDSA521:    crypto.SHA512,
-	// KeyAlgoED25519 doesn't pre-hash.
-	KeyAlgoSKECDSA256: crypto.SHA256,
-	KeyAlgoSKED25519:  crypto.SHA256,
-}
-
 // algorithmsForKeyFormat returns the supported signature algorithms for a given
 // public key format (PublicKey.Type), in order of preference. See RFC 8332,
 // Section 2. See also the note in sendKexInit on backwards compatibility.
@@ -312,11 +332,40 @@ func algorithmsForKeyFormat(keyFormat string) []string {
 	}
 }
 
+// keyFormatForAlgorithm returns the key format corresponding to the given
+// signature algorithm. It returns an empty string if the signature algorithm is
+// invalid or unsupported.
+func keyFormatForAlgorithm(sigAlgo string) string {
+	switch sigAlgo {
+	case KeyAlgoRSA, KeyAlgoRSASHA256, KeyAlgoRSASHA512:
+		return KeyAlgoRSA
+	case CertAlgoRSAv01, CertAlgoRSASHA256v01, CertAlgoRSASHA512v01:
+		return CertAlgoRSAv01
+	case KeyAlgoED25519,
+		KeyAlgoSKED25519,
+		KeyAlgoSKECDSA256,
+		KeyAlgoECDSA256,
+		KeyAlgoECDSA384,
+		KeyAlgoECDSA521,
+		InsecureKeyAlgoDSA,
+		InsecureCertAlgoDSAv01,
+		CertAlgoECDSA256v01,
+		CertAlgoECDSA384v01,
+		CertAlgoECDSA521v01,
+		CertAlgoSKECDSA256v01,
+		CertAlgoED25519v01,
+		CertAlgoSKED25519v01:
+		return sigAlgo
+	default:
+		return ""
+	}
+}
+
 // isRSA returns whether algo is a supported RSA algorithm, including certificate
 // algorithms.
 func isRSA(algo string) bool {
 	algos := algorithmsForKeyFormat(KeyAlgoRSA)
-	return contains(algos, underlyingAlgo(algo))
+	return slices.Contains(algos, underlyingAlgo(algo))
 }
 
 func isRSACert(algo string) bool {
@@ -515,7 +564,7 @@ func (c *Config) SetDefaults() {
 		if kexAlgoMap[k] != nil {
 			// Ignore the KEX if we have no kexAlgoMap definition.
 			kexs = append(kexs, k)
-			if k == KeyExchangeCurve25519 && !contains(c.KeyExchanges, keyExchangeCurve25519LibSSH) {
+			if k == KeyExchangeCurve25519 && !slices.Contains(c.KeyExchanges, keyExchangeCurve25519LibSSH) {
 				kexs = append(kexs, keyExchangeCurve25519LibSSH)
 			}
 		}

ssh/common_test.go

@@ -5,7 +5,9 @@
 package ssh
 
 import (
+	"maps"
 	"reflect"
+	"slices"
 	"testing"
 )
 
@@ -174,3 +176,21 @@ func TestFindAgreedAlgorithms(t *testing.T) {
 		})
 	}
 }
+
+func TestKeyFormatAlgorithms(t *testing.T) {
+	supportedAlgos := SupportedAlgorithms()
+	insecureAlgos := InsecureAlgorithms()
+	algoritms := append(supportedAlgos.PublicKeyAuths, insecureAlgos.PublicKeyAuths...)
+	algoritms = append(algoritms, slices.Collect(maps.Keys(certKeyAlgoNames))...)
+
+	for _, algo := range algoritms {
+		keyFormat := keyFormatForAlgorithm(algo)
+		if keyFormat == "" {
+			t.Errorf("got empty key format for algorithm %q", algo)
+		}
+		if !slices.Contains(algorithmsForKeyFormat(keyFormat), algo) {
+			t.Errorf("algorithms for key format %q, does not contain %q", keyFormat, algo)
+		}
+
+	}
+}

ssh/doc.go

@@ -17,8 +17,18 @@ References:
 	[PROTOCOL.certkeys]: http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/PROTOCOL.certkeys?rev=HEAD
 	[SSH-PARAMETERS]:    http://www.iana.org/assignments/ssh-parameters/ssh-parameters.xml#ssh-parameters-1
 	[SSH-CERTS]:	https://datatracker.ietf.org/doc/html/draft-miller-ssh-cert-01
+	[FIPS 140-3 mode]: https://go.dev/doc/security/fips140
 
 This package does not fall under the stability promise of the Go language itself,
 so its API may be changed when pressing needs arise.
+
+# FIPS 140-3 mode
+
+When the program is in [FIPS 140-3 mode], this package behaves as if only SP
+800-140C and SP 800-140D approved cipher suites, signature algorithms,
+certificate public key types and sizes, and key exchange and derivation
+algorithms were implemented. Others are silently ignored and not negotiated, or
+rejected. This set may depend on the algorithms supported by the FIPS 140-3 Go
+Cryptographic Module selected with GOFIPS140, and may change across Go versions.
 */
 package ssh

ssh/handshake.go

@@ -10,6 +10,7 @@ import (
 	"io"
 	"log"
 	"net"
+	"slices"
 	"strings"
 	"sync"
 )
@@ -527,7 +528,7 @@ func (t *handshakeTransport) sendKexInit() error {
 			switch s := k.(type) {
 			case MultiAlgorithmSigner:
 				for _, algo := range algorithmsForKeyFormat(keyFormat) {
-					if contains(s.Algorithms(), underlyingAlgo(algo)) {
+					if slices.Contains(s.Algorithms(), underlyingAlgo(algo)) {
 						msg.ServerHostKeyAlgos = append(msg.ServerHostKeyAlgos, algo)
 					}
 				}
@@ -679,7 +680,7 @@ func (t *handshakeTransport) enterKeyExchange(otherInitPacket []byte) error {
 		return err
 	}
 
-	if t.sessionID == nil && ((isClient && contains(serverInit.KexAlgos, kexStrictServer)) || (!isClient && contains(clientInit.KexAlgos, kexStrictClient))) {
+	if t.sessionID == nil && ((isClient && slices.Contains(serverInit.KexAlgos, kexStrictServer)) || (!isClient && slices.Contains(clientInit.KexAlgos, kexStrictClient))) {
 		t.strictMode = true
 		if err := t.conn.setStrictMode(); err != nil {
 			return err
@@ -736,7 +737,7 @@ func (t *handshakeTransport) enterKeyExchange(otherInitPacket []byte) error {
 	// On the server side, after the first SSH_MSG_NEWKEYS, send a SSH_MSG_EXT_INFO
 	// message with the server-sig-algs extension if the client supports it. See
 	// RFC 8308, Sections 2.4 and 3.1, and [PROTOCOL], Section 1.9.
-	if !isClient && firstKeyExchange && contains(clientInit.KexAlgos, "ext-info-c") {
+	if !isClient && firstKeyExchange && slices.Contains(clientInit.KexAlgos, "ext-info-c") {
 		supportedPubKeyAuthAlgosList := strings.Join(t.publicKeyAuthAlgorithms, ",")
 		extInfo := &extInfoMsg{
 			NumExtensions: 2,
@@ -790,7 +791,7 @@ func (a algorithmSignerWrapper) SignWithAlgorithm(rand io.Reader, data []byte, a
 func pickHostKey(hostKeys []Signer, algo string) AlgorithmSigner {
 	for _, k := range hostKeys {
 		if s, ok := k.(MultiAlgorithmSigner); ok {
-			if !contains(s.Algorithms(), underlyingAlgo(algo)) {
+			if !slices.Contains(s.Algorithms(), underlyingAlgo(algo)) {
 				continue
 			}
 		}

ssh/kex.go

@@ -8,12 +8,14 @@ import (
 	"crypto"
 	"crypto/ecdsa"
 	"crypto/elliptic"
+	"crypto/fips140"
 	"crypto/rand"
 	"encoding/binary"
 	"errors"
 	"fmt"
 	"io"
 	"math/big"
+	"slices"
 
 	"golang.org/x/crypto/curve25519"
 )
@@ -395,9 +397,27 @@ func ecHash(curve elliptic.Curve) crypto.Hash {
 	return crypto.SHA512
 }
 
+// kexAlgoMap defines the supported KEXs. KEXs not included are not supported
+// and will not be negotiated, even if explicitly configured. When FIPS mode is
+// enabled, only FIPS-approved algorithms are included.
 var kexAlgoMap = map[string]kexAlgorithm{}
 
 func init() {
+	// mlkem768x25519-sha256 we'll work with fips140=on but not fips140=only
+	// until Go 1.26.
+	kexAlgoMap[KeyExchangeMLKEM768X25519] = &mlkem768WithCurve25519sha256{}
+	kexAlgoMap[KeyExchangeECDHP521] = &ecdh{elliptic.P521()}
+	kexAlgoMap[KeyExchangeECDHP384] = &ecdh{elliptic.P384()}
+	kexAlgoMap[KeyExchangeECDHP256] = &ecdh{elliptic.P256()}
+
+	if fips140.Enabled() {
+		defaultKexAlgos = slices.DeleteFunc(defaultKexAlgos, func(algo string) bool {
+			_, ok := kexAlgoMap[algo]
+			return !ok
+		})
+		return
+	}
+
 	p, _ := new(big.Int).SetString(oakleyGroup2, 16)
 	kexAlgoMap[InsecureKeyExchangeDH1SHA1] = &dhGroup{
 		g:        new(big.Int).SetInt64(2),
@@ -431,14 +451,10 @@ func init() {
 		hashFunc: crypto.SHA512,
 	}
 
-	kexAlgoMap[KeyExchangeECDHP521] = &ecdh{elliptic.P521()}
-	kexAlgoMap[KeyExchangeECDHP384] = &ecdh{elliptic.P384()}
-	kexAlgoMap[KeyExchangeECDHP256] = &ecdh{elliptic.P256()}
 	kexAlgoMap[KeyExchangeCurve25519] = &curve25519sha256{}
 	kexAlgoMap[keyExchangeCurve25519LibSSH] = &curve25519sha256{}
 	kexAlgoMap[InsecureKeyExchangeDHGEXSHA1] = &dhGEXSHA{hashFunc: crypto.SHA1}
 	kexAlgoMap[KeyExchangeDHGEXSHA256] = &dhGEXSHA{hashFunc: crypto.SHA256}
-	kexAlgoMap[KeyExchangeMLKEM768X25519] = &mlkem768WithCurve25519sha256{}
 }
 
 // curve25519sha256 implements the curve25519-sha256 (formerly known as

ssh/keys.go

@@ -27,6 +27,7 @@ import (
 	"fmt"
 	"io"
 	"math/big"
+	"slices"
 	"strings"
 
 	"golang.org/x/crypto/ssh/internal/bcrypt_pbkdf"
@@ -89,6 +90,11 @@ func parsePubKey(in []byte, algo string) (pubKey PublicKey, rest []byte, err err
 		}
 		return cert, nil, nil
 	}
+	if keyFormat := keyFormatForAlgorithm(algo); keyFormat != "" {
+		return nil, nil, fmt.Errorf("ssh: signature algorithm %q isn't a key format; key is malformed and should be re-encoded with type %q",
+			algo, keyFormat)
+	}
+
 	return nil, nil, fmt.Errorf("ssh: unknown key algorithm: %v", algo)
 }
 
@@ -191,9 +197,10 @@ func ParseKnownHosts(in []byte) (marker string, hosts []string, pubKey PublicKey
 	return "", nil, nil, "", nil, io.EOF
 }
 
-// ParseAuthorizedKey parses a public key from an authorized_keys
-// file used in OpenSSH according to the sshd(8) manual page.
+// ParseAuthorizedKey parses a public key from an authorized_keys file used in
+// OpenSSH according to the sshd(8) manual page. Invalid lines are ignored.
 func ParseAuthorizedKey(in []byte) (out PublicKey, comment string, options []string, rest []byte, err error) {
+	var lastErr error
 	for len(in) > 0 {
 		end := bytes.IndexByte(in, '\n')
 		if end != -1 {
@@ -222,6 +229,8 @@ func ParseAuthorizedKey(in []byte) (out PublicKey, comment string, options []str
 
 		if out, comment, err = parseAuthorizedKey(in[i:]); err == nil {
 			return out, comment, options, rest, nil
+		} else {
+			lastErr = err
 		}
 
 		// No key type recognised. Maybe there's an options field at
@@ -264,12 +273,18 @@ func ParseAuthorizedKey(in []byte) (out PublicKey, comment string, options []str
 		if out, comment, err = parseAuthorizedKey(in[i:]); err == nil {
 			options = candidateOptions
 			return out, comment, options, rest, nil
+		} else {
+			lastErr = err
 		}
 
 		in = rest
 		continue
 	}
 
+	if lastErr != nil {
+		return nil, "", nil, nil, fmt.Errorf("ssh: no key found; last parsing error for ignored line: %w", lastErr)
+	}
+
 	return nil, "", nil, nil, errors.New("ssh: no key found")
 }
 
@@ -395,11 +410,11 @@ func NewSignerWithAlgorithms(signer AlgorithmSigner, algorithms []string) (Multi
 	}
 
 	for _, algo := range algorithms {
-		if !contains(supportedAlgos, algo) {
+		if !slices.Contains(supportedAlgos, algo) {
 			return nil, fmt.Errorf("ssh: algorithm %q is not supported for key type %q",
 				algo, signer.PublicKey().Type())
 		}
-		if !contains(signerAlgos, algo) {
+		if !slices.Contains(signerAlgos, algo) {
 			return nil, fmt.Errorf("ssh: algorithm %q is restricted for the provided signer", algo)
 		}
 	}
@@ -486,10 +501,13 @@ func (r *rsaPublicKey) Marshal() []byte {
 
 func (r *rsaPublicKey) Verify(data []byte, sig *Signature) error {
 	supportedAlgos := algorithmsForKeyFormat(r.Type())
-	if !contains(supportedAlgos, sig.Format) {
+	if !slices.Contains(supportedAlgos, sig.Format) {
 		return fmt.Errorf("ssh: signature type %s for key type %s", sig.Format, r.Type())
 	}
-	hash := hashFuncs[sig.Format]
+	hash, err := hashFunc(sig.Format)
+	if err != nil {
+		return err
+	}
 	h := hash.New()
 	h.Write(data)
 	digest := h.Sum(nil)
@@ -606,7 +624,11 @@ func (k *dsaPublicKey) Verify(data []byte, sig *Signature) error {
 	if sig.Format != k.Type() {
 		return fmt.Errorf("ssh: signature type %s for key type %s", sig.Format, k.Type())
 	}
-	h := hashFuncs[sig.Format].New()
+	hash, err := hashFunc(sig.Format)
+	if err != nil {
+		return err
+	}
+	h := hash.New()
 	h.Write(data)
 	digest := h.Sum(nil)
 
@@ -651,7 +673,11 @@ func (k *dsaPrivateKey) SignWithAlgorithm(rand io.Reader, data []byte, algorithm
 		return nil, fmt.Errorf("ssh: unsupported signature algorithm %s", algorithm)
 	}
 
-	h := hashFuncs[k.PublicKey().Type()].New()
+	hash, err := hashFunc(k.PublicKey().Type())
+	if err != nil {
+		return nil, err
+	}
+	h := hash.New()
 	h.Write(data)
 	digest := h.Sum(nil)
 	r, s, err := dsa.Sign(rand, k.PrivateKey, digest)
@@ -801,8 +827,11 @@ func (k *ecdsaPublicKey) Verify(data []byte, sig *Signature) error {
 	if sig.Format != k.Type() {
 		return fmt.Errorf("ssh: signature type %s for key type %s", sig.Format, k.Type())
 	}
-
-	h := hashFuncs[sig.Format].New()
+	hash, err := hashFunc(sig.Format)
+	if err != nil {
+		return err
+	}
+	h := hash.New()
 	h.Write(data)
 	digest := h.Sum(nil)
 
@@ -905,8 +934,11 @@ func (k *skECDSAPublicKey) Verify(data []byte, sig *Signature) error {
 	if sig.Format != k.Type() {
 		return fmt.Errorf("ssh: signature type %s for key type %s", sig.Format, k.Type())
 	}
-
-	h := hashFuncs[sig.Format].New()
+	hash, err := hashFunc(sig.Format)
+	if err != nil {
+		return err
+	}
+	h := hash.New()
 	h.Write([]byte(k.application))
 	appDigest := h.Sum(nil)
 
@@ -1009,7 +1041,11 @@ func (k *skEd25519PublicKey) Verify(data []byte, sig *Signature) error {
 		return fmt.Errorf("invalid size %d for Ed25519 public key", l)
 	}
 
-	h := hashFuncs[sig.Format].New()
+	hash, err := hashFunc(sig.Format)
+	if err != nil {
+		return err
+	}
+	h := hash.New()
 	h.Write([]byte(k.application))
 	appDigest := h.Sum(nil)
 
@@ -1112,11 +1148,14 @@ func (s *wrappedSigner) SignWithAlgorithm(rand io.Reader, data []byte, algorithm
 		algorithm = s.pubKey.Type()
 	}
 
-	if !contains(s.Algorithms(), algorithm) {
+	if !slices.Contains(s.Algorithms(), algorithm) {
 		return nil, fmt.Errorf("ssh: unsupported signature algorithm %q for key format %q", algorithm, s.pubKey.Type())
 	}
 
-	hashFunc := hashFuncs[algorithm]
+	hashFunc, err := hashFunc(algorithm)
+	if err != nil {
+		return nil, err
+	}
 	var digest []byte
 	if hashFunc != 0 {
 		h := hashFunc.New()

ssh/keys_test.go

@@ -59,6 +59,17 @@ func TestKeyMarshalParse(t *testing.T) {
 	}
 }
 
+func TestParsePublicKeyWithSigningAlgoAsKeyFormat(t *testing.T) {
+	key := []byte(`rsa-sha2-256 AAAADHJzYS1zaGEyLTI1NgAAAAMBAAEAAAEBAJ7qMyjLXEJCCJmRknuCLo0uPi5GrPY5pQYr84lhlN8Gor5KVL2LKYCW4e70r5xzj7SrHHSCft1FMlYg1KDO9xrprJh733kQqAPWETmSuH0EfRtGtcH6EarKyVxk6As076/yNiiMKVBtG0RPa1L7FviTfcYK4vnCCVrbv3RmA5CCzuG5BSMbRLxzVb4Ri3p8jhxYT8N4QGe/2yqvJLys5vQ9szpZR3tcFp3DJIVZhBRfR6LnoY23XZniAAMQaUVBX86dXQ++dNwAwZSXSt9Og+AniOCiBYqhNVa5n3DID/H7YtEtG+CbZr3r2KD3fv8AfSLRar4XOp8rsRdD31h/kr8=`)
+	_, _, _, _, err := ParseAuthorizedKey(key)
+	if err == nil {
+		t.Fatal("parsing a public key using a signature algorithm as the key format succeeded unexpectedly")
+	}
+	if !strings.Contains(err.Error(), `signature algorithm "rsa-sha2-256" isn't a key format`) {
+		t.Errorf(`got %v, expected 'signature algorithm "rsa-sha2-256" isn't a key format'`, err)
+	}
+}
+
 func TestUnsupportedCurves(t *testing.T) {
 	raw, err := ecdsa.GenerateKey(elliptic.P224(), rand.Reader)
 	if err != nil {

ssh/mac.go

@@ -7,11 +7,13 @@ package ssh
 // Message authentication support
 
 import (
+	"crypto/fips140"
 	"crypto/hmac"
 	"crypto/sha1"
 	"crypto/sha256"
 	"crypto/sha512"
 	"hash"
+	"slices"
 )
 
 type macMode struct {
@@ -46,23 +48,37 @@ func (t truncatingMAC) Size() int {
 
 func (t truncatingMAC) BlockSize() int { return t.hmac.BlockSize() }
 
-var macModes = map[string]*macMode{
-	HMACSHA512ETM: {64, true, func(key []byte) hash.Hash {
+// macModes defines the supported MACs. MACs not included are not supported
+// and will not be negotiated, even if explicitly configured. When FIPS mode is
+// enabled, only FIPS-approved algorithms are included.
+var macModes = map[string]*macMode{}
+
+func init() {
+	macModes[HMACSHA512ETM] = &macMode{64, true, func(key []byte) hash.Hash {
 		return hmac.New(sha512.New, key)
-	}},
-	HMACSHA256ETM: {32, true, func(key []byte) hash.Hash {
+	}}
+	macModes[HMACSHA256ETM] = &macMode{32, true, func(key []byte) hash.Hash {
 		return hmac.New(sha256.New, key)
-	}},
-	HMACSHA512: {64, false, func(key []byte) hash.Hash {
+	}}
+	macModes[HMACSHA512] = &macMode{64, false, func(key []byte) hash.Hash {
 		return hmac.New(sha512.New, key)
-	}},
-	HMACSHA256: {32, false, func(key []byte) hash.Hash {
+	}}
+	macModes[HMACSHA256] = &macMode{32, false, func(key []byte) hash.Hash {
 		return hmac.New(sha256.New, key)
-	}},
-	HMACSHA1: {20, false, func(key []byte) hash.Hash {
+	}}
+
+	if fips140.Enabled() {
+		defaultMACs = slices.DeleteFunc(defaultMACs, func(algo string) bool {
+			_, ok := macModes[algo]
+			return !ok
+		})
+		return
+	}
+
+	macModes[HMACSHA1] = &macMode{20, false, func(key []byte) hash.Hash {
 		return hmac.New(sha1.New, key)
-	}},
-	InsecureHMACSHA196: {20, false, func(key []byte) hash.Hash {
+	}}
+	macModes[InsecureHMACSHA196] = &macMode{20, false, func(key []byte) hash.Hash {
 		return truncatingMAC{12, hmac.New(sha1.New, key)}
-	}},
+	}}
 }

ssh/server.go

@@ -10,6 +10,7 @@ import (
 	"fmt"
 	"io"
 	"net"
+	"slices"
 	"strings"
 )
 
@@ -43,6 +44,9 @@ type Permissions struct {
 	// pass data from the authentication callbacks to the server
 	// application layer.
 	Extensions map[string]string
+
+	// ExtraData allows to store user defined data.
+	ExtraData map[any]any
 }
 
 type GSSAPIWithMICConfig struct {
@@ -126,6 +130,21 @@ type ServerConfig struct {
 	// Permissions.Extensions entry.
 	PublicKeyCallback func(conn ConnMetadata, key PublicKey) (*Permissions, error)
 
+	// VerifiedPublicKeyCallback, if non-nil, is called after a client
+	// successfully confirms having control over a key that was previously
+	// approved by PublicKeyCallback. The permissions object passed to the
+	// callback is the one returned by PublicKeyCallback for the given public
+	// key and its ownership is transferred to the callback. The returned
+	// Permissions object can be the same object, optionally modified, or a
+	// completely new object. If VerifiedPublicKeyCallback is non-nil,
+	// PublicKeyCallback is not allowed to return a PartialSuccessError, which
+	// can instead be returned by VerifiedPublicKeyCallback.
+	//
+	// VerifiedPublicKeyCallback does not affect which authentication methods
+	// are included in the list of methods that can be attempted by the client.
+	VerifiedPublicKeyCallback func(conn ConnMetadata, key PublicKey, permissions *Permissions,
+		signatureAlgorithm string) (*Permissions, error)
+
 	// KeyboardInteractiveCallback, if non-nil, is called when
 	// keyboard-interactive authentication is selected (RFC
 	// 4256). The client object's Challenge function should be
@@ -246,7 +265,7 @@ func NewServerConn(c net.Conn, config *ServerConfig) (*ServerConn, <-chan NewCha
 		fullConf.PublicKeyAuthAlgorithms = defaultPubKeyAuthAlgos
 	} else {
 		for _, algo := range fullConf.PublicKeyAuthAlgorithms {
-			if !contains(SupportedAlgorithms().PublicKeyAuths, algo) && !contains(InsecureAlgorithms().PublicKeyAuths, algo) {
+			if !slices.Contains(SupportedAlgorithms().PublicKeyAuths, algo) && !slices.Contains(InsecureAlgorithms().PublicKeyAuths, algo) {
 				c.Close()
 				return nil, nil, nil, fmt.Errorf("ssh: unsupported public key authentication algorithm %s", algo)
 			}
@@ -631,7 +650,7 @@ userAuthLoop:
 				return nil, parseError(msgUserAuthRequest)
 			}
 			algo := string(algoBytes)
-			if !contains(config.PublicKeyAuthAlgorithms, underlyingAlgo(algo)) {
+			if !slices.Contains(config.PublicKeyAuthAlgorithms, underlyingAlgo(algo)) {
 				authErr = fmt.Errorf("ssh: algorithm %q not accepted", algo)
 				break
 			}
@@ -652,6 +671,9 @@ userAuthLoop:
 				candidate.pubKeyData = pubKeyData
 				candidate.perms, candidate.result = authConfig.PublicKeyCallback(s, pubKey)
 				_, isPartialSuccessError := candidate.result.(*PartialSuccessError)
+				if isPartialSuccessError && config.VerifiedPublicKeyCallback != nil {
+					return nil, errors.New("ssh: invalid library usage: PublicKeyCallback must not return partial success when VerifiedPublicKeyCallback is defined")
+				}
 
 				if (candidate.result == nil || isPartialSuccessError) &&
 					candidate.perms != nil &&
@@ -695,7 +717,7 @@ userAuthLoop:
 				// ssh-rsa-cert-v01@openssh.com algorithm with ssh-rsa public
 				// key type. The algorithm and public key type must be
 				// consistent: both must be certificate algorithms, or neither.
-				if !contains(algorithmsForKeyFormat(pubKey.Type()), algo) {
+				if !slices.Contains(algorithmsForKeyFormat(pubKey.Type()), algo) {
 					authErr = fmt.Errorf("ssh: public key type %q not compatible with selected algorithm %q",
 						pubKey.Type(), algo)
 					break
@@ -705,7 +727,7 @@ userAuthLoop:
 				// algorithm name that corresponds to algo with
 				// sig.Format.  This is usually the same, but
 				// for certs, the names differ.
-				if !contains(config.PublicKeyAuthAlgorithms, sig.Format) {
+				if !slices.Contains(config.PublicKeyAuthAlgorithms, sig.Format) {
 					authErr = fmt.Errorf("ssh: algorithm %q not accepted", sig.Format)
 					break
 				}
@@ -722,6 +744,12 @@ userAuthLoop:
 
 				authErr = candidate.result
 				perms = candidate.perms
+				if authErr == nil && config.VerifiedPublicKeyCallback != nil {
+					// Only call VerifiedPublicKeyCallback after the key has been accepted
+					// and successfully verified. If authErr is non-nil, the key is not
+					// considered verified and the callback must not run.
+					perms, authErr = config.VerifiedPublicKeyCallback(s, pubKey, perms, algo)
+				}
 			}
 		case "gssapi-with-mic":
 			if authConfig.GSSAPIWithMICConfig == nil {

ssh/server_test.go

@@ -434,6 +434,380 @@ func TestPreAuthConnAndBanners(t *testing.T) {
 	}
 }
 
+func TestVerifiedPublicKeyCallback(t *testing.T) {
+	c1, c2, err := netPipe()
+	if err != nil {
+		t.Fatalf("netPipe: %v", err)
+	}
+	defer c1.Close()
+	defer c2.Close()
+
+	extraKey := "extra"
+	extraDataString := "just a string"
+
+	serverConf := &ServerConfig{
+		VerifiedPublicKeyCallback: func(conn ConnMetadata, key PublicKey, permissions *Permissions, signatureAlgorithm string) (*Permissions, error) {
+			if permissions != nil && permissions.ExtraData != nil {
+				if !reflect.DeepEqual(map[any]any{extraKey: extraDataString}, permissions.ExtraData) {
+					t.Errorf("expected extra data: %v; got: %v", extraDataString, permissions.ExtraData)
+				}
+			} else {
+				t.Error("expected extra data is missing")
+			}
+			if signatureAlgorithm != KeyAlgoRSASHA256 {
+				t.Errorf("expected signature algorithm: %q; got: %q", KeyAlgoRSASHA256, signatureAlgorithm)
+			}
+			return permissions, nil
+		},
+		PublicKeyCallback: func(conn ConnMetadata, key PublicKey) (*Permissions, error) {
+			return &Permissions{ExtraData: map[any]any{extraKey: extraDataString}}, nil
+		},
+	}
+	serverConf.AddHostKey(testSigners["rsa"])
+
+	done := make(chan struct{})
+	go func() {
+		defer close(done)
+		conn, _, _, err := NewServerConn(c1, serverConf)
+		if err != nil {
+			t.Errorf("unexpected server error: %v", err)
+		}
+		if !reflect.DeepEqual(map[any]any{extraKey: extraDataString}, conn.Permissions.ExtraData) {
+			t.Errorf("expected extra data: %v; got: %v", extraDataString, conn.Permissions.ExtraData)
+		}
+	}()
+
+	clientConf := ClientConfig{
+		User: "user",
+		Auth: []AuthMethod{
+			PublicKeys(testSigners["rsa"]),
+		},
+		HostKeyCallback: InsecureIgnoreHostKey(),
+	}
+
+	_, _, _, err = NewClientConn(c2, "", &clientConf)
+	if err != nil {
+		t.Fatal(err)
+	}
+	<-done
+}
+
+func TestVerifiedPublicCallbackPartialSuccess(t *testing.T) {
+	c1, c2, err := netPipe()
+	if err != nil {
+		t.Fatalf("netPipe: %v", err)
+	}
+	defer c1.Close()
+	defer c2.Close()
+
+	serverConf := &ServerConfig{
+		PublicKeyCallback: func(conn ConnMetadata, key PublicKey) (*Permissions, error) {
+			if bytes.Equal(key.Marshal(), testPublicKeys["rsa"].Marshal()) {
+				return nil, nil
+			}
+			return nil, errors.New("invalid credentials")
+		},
+		VerifiedPublicKeyCallback: func(conn ConnMetadata, key PublicKey, permissions *Permissions, signatureAlgorithm string) (*Permissions, error) {
+			if bytes.Equal(key.Marshal(), testPublicKeys["rsa"].Marshal()) {
+				return nil, &PartialSuccessError{
+					Next: ServerAuthCallbacks{
+						PasswordCallback: func(conn ConnMetadata, password []byte) (*Permissions, error) {
+							if string(password) == clientPassword {
+								return nil, nil
+							}
+							return nil, nil
+						},
+					},
+				}
+			}
+			return nil, errors.New("invalid credentials")
+		},
+	}
+	serverConf.AddHostKey(testSigners["rsa"])
+
+	clientConf := ClientConfig{
+		User: "user",
+		Auth: []AuthMethod{
+			PublicKeys(testSigners["rsa"]),
+			Password(clientPassword),
+		},
+		HostKeyCallback: InsecureIgnoreHostKey(),
+	}
+
+	go NewServerConn(c1, serverConf)
+
+	_, _, _, err = NewClientConn(c2, "", &clientConf)
+	if err != nil {
+		t.Fatalf("client login error: %s", err)
+	}
+}
+
+func TestVerifiedPublicKeyCallbackPwdAndKey(t *testing.T) {
+	c1, c2, err := netPipe()
+	if err != nil {
+		t.Fatalf("netPipe: %v", err)
+	}
+	defer c1.Close()
+	defer c2.Close()
+
+	serverConf := &ServerConfig{
+		PasswordCallback: func(conn ConnMetadata, password []byte) (*Permissions, error) {
+			if string(password) == clientPassword {
+				return nil, &PartialSuccessError{
+					Next: ServerAuthCallbacks{
+						PublicKeyCallback: func(conn ConnMetadata, key PublicKey) (*Permissions, error) {
+							if bytes.Equal(key.Marshal(), testPublicKeys["rsa"].Marshal()) {
+								return nil, nil
+							}
+							return nil, errors.New("invalid credentials")
+						},
+					},
+				}
+			}
+			return nil, errors.New("invalid credentials")
+
+		},
+		VerifiedPublicKeyCallback: func(conn ConnMetadata, key PublicKey, permissions *Permissions, signatureAlgorithm string) (*Permissions, error) {
+			if bytes.Equal(key.Marshal(), testPublicKeys["rsa"].Marshal()) {
+				return nil, nil
+			}
+			return nil, errors.New("invalid credentials")
+		},
+	}
+	serverConf.AddHostKey(testSigners["rsa"])
+
+	clientConf := ClientConfig{
+		User: "user",
+		Auth: []AuthMethod{
+			Password(clientPassword),
+			PublicKeys(testSigners["rsa"]),
+		},
+		HostKeyCallback: InsecureIgnoreHostKey(),
+	}
+
+	go NewServerConn(c1, serverConf)
+
+	_, _, _, err = NewClientConn(c2, "", &clientConf)
+	if err != nil {
+		t.Fatalf("client login error: %s", err)
+	}
+}
+
+func TestVerifiedPubKeyCallbackAuthMethods(t *testing.T) {
+	c1, c2, err := netPipe()
+	if err != nil {
+		t.Fatalf("netPipe: %v", err)
+	}
+	defer c1.Close()
+	defer c2.Close()
+
+	serverConf := &ServerConfig{
+		PasswordCallback: func(conn ConnMetadata, password []byte) (*Permissions, error) {
+			return nil, nil
+		},
+		VerifiedPublicKeyCallback: func(conn ConnMetadata, key PublicKey, permissions *Permissions, signatureAlgorithm string) (*Permissions, error) {
+			if bytes.Equal(key.Marshal(), testPublicKeys["rsa"].Marshal()) {
+				return nil, nil
+			}
+			return nil, errors.New("invalid credentials")
+		},
+	}
+	serverConf.AddHostKey(testSigners["rsa"])
+
+	clientConf := ClientConfig{
+		User: "user",
+		Auth: []AuthMethod{
+			PublicKeys(testSigners["rsa"]),
+		},
+		HostKeyCallback: InsecureIgnoreHostKey(),
+	}
+
+	go NewServerConn(c1, serverConf)
+
+	_, _, _, err = NewClientConn(c2, "", &clientConf)
+	if err == nil {
+		t.Fatal("client login succeed with only VerifiedPublicKeyCallback defined")
+	}
+}
+
+func TestVerifiedPubKeyCallbackError(t *testing.T) {
+	c1, c2, err := netPipe()
+	if err != nil {
+		t.Fatalf("netPipe: %v", err)
+	}
+	defer c1.Close()
+	defer c2.Close()
+
+	serverConf := &ServerConfig{
+		PublicKeyCallback: func(conn ConnMetadata, key PublicKey) (*Permissions, error) {
+			return nil, nil
+		},
+		VerifiedPublicKeyCallback: func(conn ConnMetadata, key PublicKey, permissions *Permissions, signatureAlgorithm string) (*Permissions, error) {
+			return nil, errors.New("invalid credentials")
+		},
+	}
+	serverConf.AddHostKey(testSigners["rsa"])
+
+	clientConf := ClientConfig{
+		User: "user",
+		Auth: []AuthMethod{
+			PublicKeys(testSigners["rsa"]),
+		},
+		HostKeyCallback: InsecureIgnoreHostKey(),
+	}
+
+	go NewServerConn(c1, serverConf)
+
+	_, _, _, err = NewClientConn(c2, "", &clientConf)
+	if err == nil {
+		t.Fatal("client login succeed with VerifiedPublicKeyCallback returning an error")
+	}
+}
+
+func TestVerifiedPublicCallbackPartialSuccessBadUsage(t *testing.T) {
+	c1, c2, err := netPipe()
+	if err != nil {
+		t.Fatalf("netPipe: %v", err)
+	}
+	defer c1.Close()
+	defer c2.Close()
+
+	serverConf := &ServerConfig{
+		PublicKeyCallback: func(conn ConnMetadata, key PublicKey) (*Permissions, error) {
+			if bytes.Equal(key.Marshal(), testPublicKeys["rsa"].Marshal()) {
+				// Returning PartialSuccessError is not permitted when
+				// VerifiedPublicKeyCallback is defined. This callback is
+				// invoked for both query requests and real authentications,
+				// while VerifiedPublicKeyCallback is only triggered if the
+				// client has proven control of the key.
+				return nil, &PartialSuccessError{
+					Next: ServerAuthCallbacks{
+						PasswordCallback: func(conn ConnMetadata, password []byte) (*Permissions, error) {
+							if string(password) == clientPassword {
+								return nil, nil
+							}
+							return nil, nil
+						},
+					},
+				}
+			}
+			return nil, errors.New("invalid credentials")
+		},
+		VerifiedPublicKeyCallback: func(conn ConnMetadata, key PublicKey, permissions *Permissions, signatureAlgorithm string) (*Permissions, error) {
+			if bytes.Equal(key.Marshal(), testPublicKeys["rsa"].Marshal()) {
+				return nil, &PartialSuccessError{
+					Next: ServerAuthCallbacks{
+						PasswordCallback: func(conn ConnMetadata, password []byte) (*Permissions, error) {
+							if string(password) == clientPassword {
+								return nil, nil
+							}
+							return nil, nil
+						},
+					},
+				}
+			}
+			return nil, errors.New("invalid credentials")
+		},
+	}
+	serverConf.AddHostKey(testSigners["rsa"])
+
+	clientConf := ClientConfig{
+		User: "user",
+		Auth: []AuthMethod{
+			PublicKeys(testSigners["rsa"]),
+			Password(clientPassword),
+		},
+		HostKeyCallback: InsecureIgnoreHostKey(),
+	}
+
+	go NewServerConn(c1, serverConf)
+
+	_, _, _, err = NewClientConn(c2, "", &clientConf)
+	if err == nil {
+		t.Fatal("authentication suceeded with PartialSuccess returned from PublicKeyCallback and  VerifiedPublicKeyCallback defined")
+	}
+}
+
+func TestVerifiedPublicKeyCallbackOnError(t *testing.T) {
+	c1, c2, err := netPipe()
+	if err != nil {
+		t.Fatalf("netPipe: %v", err)
+	}
+	defer c1.Close()
+	defer c2.Close()
+
+	var verifiedCallbackCalled bool
+
+	serverConf := &ServerConfig{
+		VerifiedPublicKeyCallback: func(conn ConnMetadata, key PublicKey, permissions *Permissions, signatureAlgorithm string) (*Permissions, error) {
+			verifiedCallbackCalled = true
+			return nil, nil
+		},
+		PublicKeyCallback: func(conn ConnMetadata, key PublicKey) (*Permissions, error) {
+			return nil, errors.New("invalid key")
+		},
+	}
+	serverConf.AddHostKey(testSigners["rsa"])
+
+	done := make(chan struct{})
+	go func() {
+		defer close(done)
+		NewServerConn(c1, serverConf)
+	}()
+
+	clientConf := ClientConfig{
+		User: "user",
+		Auth: []AuthMethod{
+			PublicKeys(testSigners["rsa"]),
+		},
+		HostKeyCallback: InsecureIgnoreHostKey(),
+	}
+
+	_, _, _, err = NewClientConn(c2, "", &clientConf)
+	if err == nil {
+		t.Fatal("authentication should fail")
+	}
+	<-done
+	if verifiedCallbackCalled {
+		t.Error("VerifiedPublicKeyCallback called after PublicKeyCallback returned an error")
+	}
+}
+
+func TestVerifiedPublicKeyCallbackOnly(t *testing.T) {
+	c1, c2, err := netPipe()
+	if err != nil {
+		t.Fatalf("netPipe: %v", err)
+	}
+	defer c1.Close()
+	defer c2.Close()
+
+	serverConf := &ServerConfig{
+		VerifiedPublicKeyCallback: func(conn ConnMetadata, key PublicKey, permissions *Permissions, signatureAlgorithm string) (*Permissions, error) {
+			return nil, nil
+		},
+	}
+	serverConf.AddHostKey(testSigners["rsa"])
+	done := make(chan struct{})
+	go func() {
+		defer close(done)
+		NewServerConn(c1, serverConf)
+	}()
+
+	clientConf := ClientConfig{
+		User: "user",
+		Auth: []AuthMethod{
+			PublicKeys(testSigners["rsa"]),
+		},
+		HostKeyCallback: InsecureIgnoreHostKey(),
+	}
+
+	_, _, _, err = NewClientConn(c2, "", &clientConf)
+	if err == nil {
+		t.Fatal("authentication suceeded with only VerifiedPublicKeyCallback defined")
+	}
+	<-done
+}
+
 type markerConn struct {
 	closed uint32
 	used   uint32

ssh/test/doc.go

@@ -4,4 +4,6 @@
 
 // Package test contains integration tests for the
 // golang.org/x/crypto/ssh package.
+//
+// Deprecated: this package is for internal use only.
 package test

ssh/transport.go

@@ -8,6 +8,7 @@ import (
 	"bufio"
 	"bytes"
 	"errors"
+	"fmt"
 	"io"
 	"log"
 )
@@ -254,6 +255,9 @@ var (
 // (to setup server->client keys) or clientKeys (for client->server keys).
 func newPacketCipher(d direction, algs DirectionAlgorithms, kex *kexResult) (packetCipher, error) {
 	cipherMode := cipherModes[algs.Cipher]
+	if cipherMode == nil {
+		return nil, fmt.Errorf("ssh: unsupported cipher %v", algs.Cipher)
+	}
 
 	iv := make([]byte, cipherMode.ivSize)
 	key := make([]byte, cipherMode.keySize)

x509roots/fallback/bundle/bundle.go

@@ -1,6 +1,6 @@
 // Code generated by gen_fallback_bundle.go; DO NOT EDIT.
 
-package fallback
+package bundle
 
 var unparsedCertificates = []unparsedCertificate{
 	{
@@ -521,365 +521,377 @@ var unparsedCertificates = []unparsedCertificate{
 		certStartOff: 88949,
 		certLength:   1049,
 	},
+	{
+		cn:           "CN=OISTE Server Root ECC G1,O=OISTE Foundation,C=CH",
+		sha256Hash:   "eec997c0c30f216f7e3b8b307d2bae42412d753fc8219dafd1520b2572850f49",
+		certStartOff: 89998,
+		certLength:   569,
+	},
+	{
+		cn:           "CN=OISTE Server Root RSA G1,O=OISTE Foundation,C=CH",
+		sha256Hash:   "9ae36232a5189ffddb353dfd26520c015395d22777dac59db57b98c089a651e6",
+		certStartOff: 90567,
+		certLength:   1415,
+	},
 	{
 		cn:           "CN=OISTE WISeKey Global Root GB CA,OU=OISTE Foundation Endorsed,O=WISeKey,C=CH",
 		sha256Hash:   "6b9c08e86eb0f767cfad65cd98b62149e5494a67f5845e7bd1ed019f27b86bd6",
-		certStartOff: 89998,
+		certStartOff: 91982,
 		certLength:   953,
 	},
 	{
 		cn:           "CN=OISTE WISeKey Global Root GC CA,OU=OISTE Foundation Endorsed,O=WISeKey,C=CH",
 		sha256Hash:   "8560f91c3624daba9570b5fea0dbe36ff11a8323be9486854fb3f34a5571198d",
-		certStartOff: 90951,
+		certStartOff: 92935,
 		certLength:   621,
 	},
 	{
 		cn:           "CN=QuoVadis Root CA 1 G3,O=QuoVadis Limited,C=BM",
 		sha256Hash:   "8a866fd1b276b57e578e921c65828a2bed58e9f2f288054134b7f1f4bfc9cc74",
-		certStartOff: 91572,
+		certStartOff: 93556,
 		certLength:   1380,
 	},
 	{
 		cn:           "CN=QuoVadis Root CA 2 G3,O=QuoVadis Limited,C=BM",
 		sha256Hash:   "8fe4fb0af93a4d0d67db0bebb23e37c71bf325dcbcdd240ea04daf58b47e1840",
-		certStartOff: 92952,
+		certStartOff: 94936,
 		certLength:   1380,
 	},
 	{
 		cn:           "CN=QuoVadis Root CA 2,O=QuoVadis Limited,C=BM",
 		sha256Hash:   "85a0dd7dd720adb7ff05f83d542b209dc7ff4528f7d677b18389fea5e5c49e86",
-		certStartOff: 94332,
+		certStartOff: 96316,
 		certLength:   1467,
 	},
 	{
 		cn:           "CN=QuoVadis Root CA 3 G3,O=QuoVadis Limited,C=BM",
 		sha256Hash:   "88ef81de202eb018452e43f864725cea5fbd1fc2d9d205730709c5d8b8690f46",
-		certStartOff: 95799,
+		certStartOff: 97783,
 		certLength:   1380,
 	},
 	{
 		cn:           "CN=QuoVadis Root CA 3,O=QuoVadis Limited,C=BM",
 		sha256Hash:   "18f1fc7f205df8adddeb7fe007dd57e3af375a9c4d8d73546bf4f1fed1e18d35",
-		certStartOff: 97179,
+		certStartOff: 99163,
 		certLength:   1697,
 	},
 	{
 		cn:           "CN=SSL.com EV Root Certification Authority ECC,O=SSL Corporation,L=Houston,ST=Texas,C=US",
 		sha256Hash:   "22a2c1f7bded704cc1e701b5f408c310880fe956b5de2a4a44f99c873a25a7c8",
-		certStartOff: 98876,
+		certStartOff: 100860,
 		certLength:   664,
 	},
 	{
 		cn:           "CN=SSL.com EV Root Certification Authority RSA R2,O=SSL Corporation,L=Houston,ST=Texas,C=US",
 		sha256Hash:   "2e7bf16cc22485a7bbe2aa8696750761b0ae39be3b2fe9d0cc6d4ef73491425c",
-		certStartOff: 99540,
+		certStartOff: 101524,
 		certLength:   1519,
 	},
 	{
 		cn:           "CN=SSL.com Root Certification Authority ECC,O=SSL Corporation,L=Houston,ST=Texas,C=US",
 		sha256Hash:   "3417bb06cc6007da1b961c920b8ab4ce3fad820e4aa30b9acbc4a74ebdcebc65",
-		certStartOff: 101059,
+		certStartOff: 103043,
 		certLength:   657,
 	},
 	{
 		cn:           "CN=SSL.com Root Certification Authority RSA,O=SSL Corporation,L=Houston,ST=Texas,C=US",
 		sha256Hash:   "85666a562ee0be5ce925c1d8890a6f76a87ec16d4d7d5f29ea7419cf20123b69",
-		certStartOff: 101716,
+		certStartOff: 103700,
 		certLength:   1505,
 	},
 	{
 		cn:           "CN=SSL.com TLS ECC Root CA 2022,O=SSL Corporation,C=US",
 		sha256Hash:   "c32ffd9f46f936d16c3673990959434b9ad60aafbb9e7cf33654f144cc1ba143",
-		certStartOff: 103221,
+		certStartOff: 105205,
 		certLength:   574,
 	},
 	{
 		cn:           "CN=SSL.com TLS RSA Root CA 2022,O=SSL Corporation,C=US",
 		sha256Hash:   "8faf7d2e2cb4709bb8e0b33666bf75a5dd45b5de480f8ea8d4bfe6bebc17f2ed",
-		certStartOff: 103795,
+		certStartOff: 105779,
 		certLength:   1421,
 	},
 	{
 		cn:           "CN=SZAFIR ROOT CA2,O=Krajowa Izba Rozliczeniowa S.A.,C=PL",
 		sha256Hash:   "a1339d33281a0b56e557d3d32b1ce7f9367eb094bd5fa72a7e5004c8ded7cafe",
-		certStartOff: 105216,
+		certStartOff: 107200,
 		certLength:   886,
 	},
 	{
 		cn:           "CN=Sectigo Public Server Authentication Root E46,O=Sectigo Limited,C=GB",
 		sha256Hash:   "c90f26f0fb1b4018b22227519b5ca2b53e2ca5b3be5cf18efe1bef47380c5383",
-		certStartOff: 106102,
+		certStartOff: 108086,
 		certLength:   574,
 	},
 	{
 		cn:           "CN=Sectigo Public Server Authentication Root R46,O=Sectigo Limited,C=GB",
 		sha256Hash:   "7bb647a62aeeac88bf257aa522d01ffea395e0ab45c73f93f65654ec38f25a06",
-		certStartOff: 106676,
+		certStartOff: 108660,
 		certLength:   1422,
 	},
 	{
 		cn:           "CN=Secure Global CA,O=SecureTrust Corporation,C=US",
 		sha256Hash:   "4200f5043ac8590ebb527d209ed1503029fbcbd41ca1b506ec27f15ade7dac69",
-		certStartOff: 108098,
+		certStartOff: 110082,
 		certLength:   960,
 	},
 	{
 		cn:           "CN=SecureSign Root CA12,O=Cybertrust Japan Co.\\, Ltd.,C=JP",
 		sha256Hash:   "3f034bb5704d44b2d08545a02057de93ebf3905fce721acbc730c06ddaee904e",
-		certStartOff: 109058,
+		certStartOff: 111042,
 		certLength:   886,
 	},
 	{
 		cn:           "CN=SecureSign Root CA14,O=Cybertrust Japan Co.\\, Ltd.,C=JP",
 		sha256Hash:   "4b009c1034494f9ab56bba3ba1d62731fc4d20d8955adcec10a925607261e338",
-		certStartOff: 109944,
+		certStartOff: 111928,
 		certLength:   1398,
 	},
 	{
 		cn:           "CN=SecureSign Root CA15,O=Cybertrust Japan Co.\\, Ltd.,C=JP",
 		sha256Hash:   "e778f0f095fe843729cd1a0082179e5314a9c291442805e1fb1d8fb6b8886c3a",
-		certStartOff: 111342,
+		certStartOff: 113326,
 		certLength:   551,
 	},
 	{
 		cn:           "CN=SecureTrust CA,O=SecureTrust Corporation,C=US",
 		sha256Hash:   "f1c1b50ae5a20dd8030ec9f6bc24823dd367b5255759b4e71b61fce9f7375d73",
-		certStartOff: 111893,
+		certStartOff: 113877,
 		certLength:   956,
 	},
 	{
 		cn:           "CN=Security Communication ECC RootCA1,O=SECOM Trust Systems CO.\\,LTD.,C=JP",
 		sha256Hash:   "e74fbda55bd564c473a36b441aa799c8a68e077440e8288b9fa1e50e4bbaca11",
-		certStartOff: 112849,
+		certStartOff: 114833,
 		certLength:   572,
 	},
 	{
 		cn:           "CN=Starfield Root Certificate Authority - G2,O=Starfield Technologies\\, Inc.,L=Scottsdale,ST=Arizona,C=US",
 		sha256Hash:   "2ce1cb0bf9d2f9e102993fbe215152c3b2dd0cabde1c68e5319b839154dbb7f5",
-		certStartOff: 113421,
+		certStartOff: 115405,
 		certLength:   993,
 	},
 	{
 		cn:           "CN=Starfield Services Root Certificate Authority - G2,O=Starfield Technologies\\, Inc.,L=Scottsdale,ST=Arizona,C=US",
 		sha256Hash:   "568d6905a2c88708a4b3025190edcfedb1974a606a13c6e5290fcb2ae63edab5",
-		certStartOff: 114414,
+		certStartOff: 116398,
 		certLength:   1011,
 	},
 	{
 		cn:           "CN=SwissSign Gold CA - G2,O=SwissSign AG,C=CH",
 		sha256Hash:   "62dd0be9b9f50a163ea0f8e75c053b1eca57ea55c8688f647c6881f2c8357b95",
-		certStartOff: 115425,
+		certStartOff: 117409,
 		certLength:   1470,
 	},
 	{
 		cn:           "CN=SwissSign RSA TLS Root CA 2022 - 1,O=SwissSign AG,C=CH",
 		sha256Hash:   "193144f431e0fddb740717d4de926a571133884b4360d30e272913cbe660ce41",
-		certStartOff: 116895,
+		certStartOff: 118879,
 		certLength:   1431,
 	},
 	{
 		cn:           "CN=T-TeleSec GlobalRoot Class 2,OU=T-Systems Trust Center,O=T-Systems Enterprise Services GmbH,C=DE",
 		sha256Hash:   "91e2f5788d5810eba7ba58737de1548a8ecacd014598bc0b143e041b17052552",
-		certStartOff: 118326,
+		certStartOff: 120310,
 		certLength:   967,
 	},
 	{
 		cn:           "CN=T-TeleSec GlobalRoot Class 3,OU=T-Systems Trust Center,O=T-Systems Enterprise Services GmbH,C=DE",
 		sha256Hash:   "fd73dad31c644ff1b43bef0ccdda96710b9cd9875eca7e31707af3e96d522bbd",
-		certStartOff: 119293,
+		certStartOff: 121277,
 		certLength:   967,
 	},
 	{
 		cn:           "CN=TWCA CYBER Root CA,OU=Root CA,O=TAIWAN-CA,C=TW",
 		sha256Hash:   "3f63bb2814be174ec8b6439cf08d6d56f0b7c405883a5648a334424d6b3ec558",
-		certStartOff: 120260,
+		certStartOff: 122244,
 		certLength:   1425,
 	},
 	{
 		cn:           "CN=TWCA Global Root CA,OU=Root CA,O=TAIWAN-CA,C=TW",
 		sha256Hash:   "59769007f7685d0fcd50872f9f95d5755a5b2b457d81f3692b610a98672f0e1b",
-		certStartOff: 121685,
+		certStartOff: 123669,
 		certLength:   1349,
 	},
 	{
 		cn:           "CN=TWCA Root Certification Authority,OU=Root CA,O=TAIWAN-CA,C=TW",
 		sha256Hash:   "bfd88fe1101c41ae3e801bf8be56350ee9bad1a6b9bd515edc5c6d5b8711ac44",
-		certStartOff: 123034,
+		certStartOff: 125018,
 		certLength:   895,
 	},
 	{
 		cn:           "CN=Telekom Security TLS ECC Root 2020,O=Deutsche Telekom Security GmbH,C=DE",
 		sha256Hash:   "578af4ded0853f4e5998db4aeaf9cbea8d945f60b620a38d1a3c13b2bc7ba8e1",
-		certStartOff: 123929,
+		certStartOff: 125913,
 		certLength:   582,
 	},
 	{
 		cn:           "CN=Telekom Security TLS RSA Root 2023,O=Deutsche Telekom Security GmbH,C=DE",
 		sha256Hash:   "efc65cadbb59adb6efe84da22311b35624b71b3b1ea0da8b6655174ec8978646",
-		certStartOff: 124511,
+		certStartOff: 126495,
 		certLength:   1463,
 	},
 	{
 		cn:           "CN=Telia Root CA v2,O=Telia Finland Oyj,C=FI",
 		sha256Hash:   "242b69742fcb1e5b2abf98898b94572187544e5b4d9911786573621f6a74b82c",
-		certStartOff: 125974,
+		certStartOff: 127958,
 		certLength:   1400,
 	},
 	{
 		cn:           "CN=TeliaSonera Root CA v1,O=TeliaSonera",
 		sha256Hash:   "dd6936fe21f8f077c123a1a521c12224f72255b73e03a7260693e8a24b0fa389",
-		certStartOff: 127374,
+		certStartOff: 129358,
 		certLength:   1340,
 	},
 	{
 		cn:           "CN=TrustAsia Global Root CA G3,O=TrustAsia Technologies\\, Inc.,C=CN",
 		sha256Hash:   "e0d3226aeb1163c2e48ff9be3b50b4c6431be7bb1eacc5c36b5d5ec509039a08",
-		certStartOff: 128714,
+		certStartOff: 130698,
 		certLength:   1449,
 	},
 	{
 		cn:           "CN=TrustAsia Global Root CA G4,O=TrustAsia Technologies\\, Inc.,C=CN",
 		sha256Hash:   "be4b56cb5056c0136a526df444508daa36a0b54f42e4ac38f72af470e479654c",
-		certStartOff: 130163,
+		certStartOff: 132147,
 		certLength:   601,
 	},
 	{
 		cn:           "CN=TrustAsia TLS ECC Root CA,O=TrustAsia Technologies\\, Inc.,C=CN",
 		sha256Hash:   "c0076b9ef0531fb1a656d67c4ebe97cd5dbaa41ef44598acc2489878c92d8711",
-		certStartOff: 130764,
+		certStartOff: 132748,
 		certLength:   565,
 	},
 	{
 		cn:           "CN=TrustAsia TLS RSA Root CA,O=TrustAsia Technologies\\, Inc.,C=CN",
 		sha256Hash:   "06c08d7dafd876971eb1124fe67f847ec0c7a158d3ea53cbe940e2ea9791f4c3",
-		certStartOff: 131329,
+		certStartOff: 133313,
 		certLength:   1412,
 	},
 	{
 		cn:           "CN=Trustwave Global Certification Authority,O=Trustwave Holdings\\, Inc.,L=Chicago,ST=Illinois,C=US",
 		sha256Hash:   "97552015f5ddfc3c8788c006944555408894450084f100867086bc1a2bb58dc8",
-		certStartOff: 132741,
+		certStartOff: 134725,
 		certLength:   1502,
 	},
 	{
 		cn:           "CN=Trustwave Global ECC P256 Certification Authority,O=Trustwave Holdings\\, Inc.,L=Chicago,ST=Illinois,C=US",
 		sha256Hash:   "945bbc825ea554f489d1fd51a73ddf2ea624ac7019a05205225c22a78ccfa8b4",
-		certStartOff: 134243,
+		certStartOff: 136227,
 		certLength:   612,
 	},
 	{
 		cn:           "CN=Trustwave Global ECC P384 Certification Authority,O=Trustwave Holdings\\, Inc.,L=Chicago,ST=Illinois,C=US",
 		sha256Hash:   "55903859c8c0c3ebb8759ece4e2557225ff5758bbd38ebd48276601e1bd58097",
-		certStartOff: 134855,
+		certStartOff: 136839,
 		certLength:   673,
 	},
 	{
 		cn:           "CN=TunTrust Root CA,O=Agence Nationale de Certification Electronique,C=TN",
 		sha256Hash:   "2e44102ab58cb85419451c8e19d9acf3662cafbc614b6a53960a30f7d0e2eb41",
-		certStartOff: 135528,
+		certStartOff: 137512,
 		certLength:   1463,
 	},
 	{
 		cn:           "CN=UCA Extended Validation Root,O=UniTrust,C=CN",
 		sha256Hash:   "d43af9b35473755c9684fc06d7d8cb70ee5c28e773fb294eb41ee71722924d24",
-		certStartOff: 136991,
+		certStartOff: 138975,
 		certLength:   1374,
 	},
 	{
 		cn:           "CN=UCA Global G2 Root,O=UniTrust,C=CN",
 		sha256Hash:   "9bea11c976fe014764c1be56a6f914b5a560317abd9988393382e5161aa0493c",
-		certStartOff: 138365,
+		certStartOff: 140349,
 		certLength:   1354,
 	},
 	{
 		cn:           "CN=USERTrust ECC Certification Authority,O=The USERTRUST Network,L=Jersey City,ST=New Jersey,C=US",
 		sha256Hash:   "4ff460d54b9c86dabfbcfc5712e0400d2bed3fbc4d4fbdaa86e06adcd2a9ad7a",
-		certStartOff: 139719,
+		certStartOff: 141703,
 		certLength:   659,
 	},
 	{
 		cn:           "CN=USERTrust RSA Certification Authority,O=The USERTRUST Network,L=Jersey City,ST=New Jersey,C=US",
 		sha256Hash:   "e793c9b02fd8aa13e21c31228accb08119643b749c898964b1746d46c3d4cbd2",
-		certStartOff: 140378,
+		certStartOff: 142362,
 		certLength:   1506,
 	},
 	{
 		cn:           "CN=e-Szigno Root CA 2017,O=Microsec Ltd.,L=Budapest,C=HU,2.5.4.97=#130e56415448552d3233353834343937",
 		sha256Hash:   "beb00b30839b9bc32c32e4447905950641f26421b15ed089198b518ae2ea1b99",
-		certStartOff: 141884,
+		certStartOff: 143868,
 		certLength:   580,
 	},
 	{
 		cn:           "CN=emSign ECC Root CA - C3,OU=emSign PKI,O=eMudhra Inc,C=US",
 		sha256Hash:   "bc4d809b15189d78db3e1d8cf4f9726a795da1643ca5f1358e1ddb0edc0d7eb3",
-		certStartOff: 142464,
+		certStartOff: 144448,
 		certLength:   559,
 	},
 	{
 		cn:           "CN=emSign ECC Root CA - G3,OU=emSign PKI,O=eMudhra Technologies Limited,C=IN",
 		sha256Hash:   "86a1ecba089c4a8d3bbe2734c612ba341d813e043cf9e8a862cd5c57a36bbe6b",
-		certStartOff: 143023,
+		certStartOff: 145007,
 		certLength:   594,
 	},
 	{
 		cn:           "CN=emSign Root CA - C1,OU=emSign PKI,O=eMudhra Inc,C=US",
 		sha256Hash:   "125609aa301da0a249b97a8239cb6a34216f44dcac9f3954b14292f2e8c8608f",
-		certStartOff: 143617,
+		certStartOff: 145601,
 		certLength:   887,
 	},
 	{
 		cn:           "CN=emSign Root CA - G1,OU=emSign PKI,O=eMudhra Technologies Limited,C=IN",
 		sha256Hash:   "40f6af0346a99aa1cd1d555a4e9cce62c7f9634603ee406615833dc8c8d00367",
-		certStartOff: 144504,
+		certStartOff: 146488,
 		certLength:   920,
 	},
 	{
 		cn:           "CN=vTrus ECC Root CA,O=iTrusChina Co.\\,Ltd.,C=CN",
 		sha256Hash:   "30fbba2c32238e2a98547af97931e550428b9b3f1c8eeb6633dcfa86c5b27dd3",
-		certStartOff: 145424,
+		certStartOff: 147408,
 		certLength:   531,
 	},
 	{
 		cn:           "CN=vTrus Root CA,O=iTrusChina Co.\\,Ltd.,C=CN",
 		sha256Hash:   "8a71de6559336f426c26e53880d00d88a18da4c6a91f0dcb6194e206c5c96387",
-		certStartOff: 145955,
+		certStartOff: 147939,
 		certLength:   1370,
 	},
 	{
 		cn:           "OU=AC RAIZ FNMT-RCM,O=FNMT-RCM,C=ES",
 		sha256Hash:   "ebc5570c29018c4d67b1aa127baf12f703b4611ebc17b7dab5573894179b93fa",
-		certStartOff: 147325,
+		certStartOff: 149309,
 		certLength:   1415,
 	},
 	{
 		cn:           "OU=Security Communication RootCA2,O=SECOM Trust Systems CO.\\,LTD.,C=JP",
 		sha256Hash:   "513b2cecb810d4cde5dd85391adfc6c2dd60d87bb736d2b521484aa47a0ebef6",
-		certStartOff: 148740,
+		certStartOff: 150724,
 		certLength:   891,
 	},
 	{
 		cn:           "OU=certSIGN ROOT CA G2,O=CERTSIGN SA,C=RO",
 		sha256Hash:   "657cfe2fa73faa38462571f332a2363a46fce7020951710702cdfbb6eeda3305",
-		certStartOff: 149631,
+		certStartOff: 151615,
 		certLength:   1355,
 	},
 	{
 		cn:           "OU=certSIGN ROOT CA,O=certSIGN,C=RO",
 		sha256Hash:   "eaa962c4fa4a6bafebe415196d351ccd888d4f53f3fa8ae6d7c466a94e6042bb",
-		certStartOff: 150986,
+		certStartOff: 152970,
 		certLength:   828,
 	},
 	{
 		cn:            "OU=ePKI Root Certification Authority,O=Chunghwa Telecom Co.\\, Ltd.,C=TW",
 		sha256Hash:    "c0a6f4dc63a24bfdcf54ef2a6a082a0a72de35803e2ff5ff527ae5d87206dfd5",
-		certStartOff:  151814,
+		certStartOff:  153798,
 		certLength:    1460,
 		distrustAfter: "2025-04-15T23:59:59Z",
 	},
 	{
 		cn:           "SERIALNUMBER=G63287510,CN=ANF Secure Server Root CA,OU=ANF CA Raiz,O=ANF Autoridad de Certificacion,C=ES",
 		sha256Hash:   "fb8fec759169b9106b1e511644c618c51304373f6c0643088d8beffd1b997599",
-		certStartOff: 153274,
+		certStartOff: 155258,
 		certLength:   1523,
 	},
 }

x509roots/fallback/bundle/bundle_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 fallback
+package bundle
 
 import (
 	"crypto/sha256"

x509roots/fallback/bundle/roots.go

@@ -0,0 +1,73 @@
+// Copyright 2025 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 bundle contains the bundle of root certificates parsed from the NSS
+// trust store, using x509roots/nss.
+package bundle
+
+import (
+	"crypto/x509"
+	_ "embed"
+	"fmt"
+	"iter"
+	"time"
+)
+
+//go:embed bundle.der
+var rawCerts []byte
+
+// Root represents a root certificate parsed from the NSS trust store.
+type Root struct {
+	// Certificate is the DER-encoded certificate (read-only; do not modify!).
+	Certificate []byte
+
+	// Constraint is nil if the root is unconstrained. If Constraint is non-nil,
+	// the certificate has additional constraints that cannot be encoded in
+	// X.509, and when building a certificate chain anchored with this root the
+	// chain should be passed to this function to check its validity. If using a
+	// [crypto/x509.CertPool] the root should be added using
+	// [crypto/x509.CertPool.AddCertWithConstraint].
+	Constraint func([]*x509.Certificate) error
+}
+
+// Roots returns the bundle of root certificates from the NSS trust store. The
+// [Root.Certificate] slice must be treated as read-only and should not be
+// modified.
+func Roots() iter.Seq[Root] {
+	return func(yield func(Root) bool) {
+		for _, unparsed := range unparsedCertificates {
+			root := Root{
+				Certificate: rawCerts[unparsed.certStartOff : unparsed.certStartOff+unparsed.certLength],
+			}
+			// parse possible constraints, this should check all fields of unparsedCertificate.
+			if unparsed.distrustAfter != "" {
+				distrustAfter, err := time.Parse(time.RFC3339, unparsed.distrustAfter)
+				if err != nil {
+					panic(fmt.Sprintf("failed to parse distrustAfter %q: %s", unparsed.distrustAfter, err))
+				}
+				root.Constraint = func(chain []*x509.Certificate) error {
+					for _, c := range chain {
+						if c.NotBefore.After(distrustAfter) {
+							return fmt.Errorf("certificate issued after distrust-after date %q", distrustAfter)
+						}
+					}
+					return nil
+				}
+			}
+			if !yield(root) {
+				return
+			}
+		}
+	}
+}
+
+type unparsedCertificate struct {
+	cn           string
+	sha256Hash   string
+	certStartOff int
+	certLength   int
+
+	// possible constraints
+	distrustAfter string
+}

x509roots/fallback/bundle/roots_test.go

@@ -0,0 +1,18 @@
+// Copyright 2025 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 bundle
+
+import (
+	"crypto/x509"
+	"testing"
+)
+
+func TestRootsCanBeParsed(t *testing.T) {
+	for root := range Roots() {
+		if _, err := x509.ParseCertificate(root.Certificate); err != nil {
+			t.Fatalf("Could not parse root certificate: %v", err)
+		}
+	}
+}

x509roots/fallback/fallback.go

@@ -20,13 +20,9 @@ package fallback
 
 import (
 	"crypto/x509"
-	_ "embed"
-	"fmt"
-	"time"
-)
 
-//go:embed bundle.der
-var rawCerts []byte
+	"golang.org/x/crypto/x509roots/fallback/bundle"
+)
 
 func init() {
 	x509.SetFallbackRoots(newFallbackCertPool())
@@ -34,62 +30,16 @@ func init() {
 
 func newFallbackCertPool() *x509.CertPool {
 	p := x509.NewCertPool()
-	for _, c := range mustParse(unparsedCertificates) {
-		if len(c.constraints) == 0 {
-			p.AddCert(c.cert)
+	for c := range bundle.Roots() {
+		cert, err := x509.ParseCertificate(c.Certificate)
+		if err != nil {
+			panic(err)
+		}
+		if c.Constraint == nil {
+			p.AddCert(cert)
 		} else {
-			p.AddCertWithConstraint(c.cert, func(chain []*x509.Certificate) error {
-				for _, constraint := range c.constraints {
-					if err := constraint(chain); err != nil {
-						return err
-					}
-				}
-				return nil
-			})
+			p.AddCertWithConstraint(cert, c.Constraint)
 		}
 	}
 	return p
 }
-
-type unparsedCertificate struct {
-	cn           string
-	sha256Hash   string
-	certStartOff int
-	certLength   int
-
-	// possible constraints
-	distrustAfter string
-}
-
-type parsedCertificate struct {
-	cert        *x509.Certificate
-	constraints []func([]*x509.Certificate) error
-}
-
-func mustParse(unparsedCerts []unparsedCertificate) []parsedCertificate {
-	b := make([]parsedCertificate, 0, len(unparsedCerts))
-	for _, unparsed := range unparsedCerts {
-		cert, err := x509.ParseCertificate(rawCerts[unparsed.certStartOff : unparsed.certStartOff+unparsed.certLength])
-		if err != nil {
-			panic(err)
-		}
-		parsed := parsedCertificate{cert: cert}
-		// parse possible constraints, this should check all fields of unparsedCertificate.
-		if unparsed.distrustAfter != "" {
-			distrustAfter, err := time.Parse(time.RFC3339, unparsed.distrustAfter)
-			if err != nil {
-				panic(fmt.Sprintf("failed to parse distrustAfter %q: %s", unparsed.distrustAfter, err))
-			}
-			parsed.constraints = append(parsed.constraints, func(chain []*x509.Certificate) error {
-				for _, c := range chain {
-					if c.NotBefore.After(distrustAfter) {
-						return fmt.Errorf("certificate issued after distrust-after date %q", distrustAfter)
-					}
-				}
-				return nil
-			})
-		}
-		b = append(b, parsed)
-	}
-	return b
-}

x509roots/gen_fallback_bundle.go

@@ -27,7 +27,7 @@ import (
 
 const tmpl = `// Code generated by gen_fallback_bundle.go; DO NOT EDIT.
 
-package fallback
+package bundle
 
 var unparsedCertificates = []unparsedCertificate{
 `
@@ -35,8 +35,8 @@ var unparsedCertificates = []unparsedCertificate{
 var (
 	certDataURL  = flag.String("certdata-url", "https://hg.mozilla.org/mozilla-central/raw-file/tip/security/nss/lib/ckfw/builtins/certdata.txt", "URL to the raw certdata.txt file to parse (certdata-path overrides this, if provided)")
 	certDataPath = flag.String("certdata-path", "", "Path to the NSS certdata.txt file to parse (this overrides certdata-url, if provided)")
-	output       = flag.String("output", "fallback/bundle.go", "Path to file to write output to")
-	derOutput    = flag.String("deroutput", "fallback/bundle.der", "Path to file to write output to (DER certificate bundle)")
+	output       = flag.String("output", "fallback/bundle/bundle.go", "Path to file to write output to")
+	derOutput    = flag.String("deroutput", "fallback/bundle/bundle.der", "Path to file to write output to (DER certificate bundle)")
 )
 
 func main() {

xts/xts.go

@@ -21,6 +21,10 @@
 //
 // Note that XTS is usually not appropriate for any use besides disk encryption.
 // Most users should use an AEAD mode like GCM (from crypto/cipher.NewGCM) instead.
+//
+// The xts package is [frozen] and is not accepting new features.
+//
+// [frozen]: https://go.dev/wiki/Frozen
 package xts
 
 import (