From 964142eb526efd9ad5b909a094a5f7f139252c60 Mon Sep 17 00:00:00 2001 From: Casey Marshall Date: Tue, 3 Sep 2013 10:36:04 -0400 Subject: [PATCH] openpgp/packet: Add support for V3 public keys and signatures. My goal here is to allow read-only access to legacy key material without allowing new V3 keys or signatures. R=agl CC=golang-dev https://golang.org/cl/12746046 --- openpgp/packet/opaque_test.go | 32 ++-- openpgp/packet/packet.go | 38 +++- openpgp/packet/public_key.go | 79 +++++++- openpgp/packet/public_key_v3.go | 274 +++++++++++++++++++++++++++ openpgp/packet/public_key_v3_test.go | 82 ++++++++ openpgp/packet/signature.go | 4 +- openpgp/packet/signature_v3.go | 146 ++++++++++++++ openpgp/packet/signature_v3_test.go | 92 +++++++++ 8 files changed, 711 insertions(+), 36 deletions(-) create mode 100644 openpgp/packet/public_key_v3.go create mode 100644 openpgp/packet/public_key_v3_test.go create mode 100644 openpgp/packet/signature_v3.go create mode 100644 openpgp/packet/signature_v3_test.go diff --git a/openpgp/packet/opaque_test.go b/openpgp/packet/opaque_test.go index dc275ef..f27bbfe 100644 --- a/openpgp/packet/opaque_test.go +++ b/openpgp/packet/opaque_test.go @@ -6,36 +6,20 @@ package packet import ( "bytes" - "code.google.com/p/go.crypto/openpgp/armor" + "encoding/hex" "io" "testing" ) -// This key contains version 2 public key and signature packets. -// If these are ever supported, this test will need to be updated -// with bad packets that won't parse. -const UnsupportedKeyArmor = `-----BEGIN PGP PUBLIC KEY BLOCK----- -Version: SKS 1.0.10 - -mI0CLnoYogAAAQQA1qwA2SuJwfQ5bCQ6u5t20ulnOtY0gykf7YjiK4LiVeRBwHjGq7v30tGV -5Qti7qqRW4Ww7CDCJc4sZMFnystucR2vLkXaSoNWoFm4Fg47NiisDdhDezHwbVPW6OpCFNSi -ZAamtj4QAUBu8j4LswafrJqZqR9336/V3g8Yil2l48kABRG0J0FybWluIE0uIFdhcmRhIDx3 -YXJkYUBuZXBoaWxpbS5ydWhyLmRlPoiVAgUQLok2xwXR6zmeWEiZAQE/DgP/WgxPQh40/Po4 -gSkWZCDAjNdph7zexvAb0CcUWahcwiBIgg3U5ErCx9I5CNVA9U+s8bNrDZwgSIeBzp3KhWUx -524uhGgm6ZUTOAIKA6CbV6pfqoLpJnRYvXYQU5mIWsNa99wcu2qu18OeEDnztb7aLA6Ra9OF -YFCbq4EjXRoOrYM= -=LPjs ------END PGP PUBLIC KEY BLOCK-----` - // Test packet.Read error handling in OpaquePacket.Parse, // which attempts to re-read an OpaquePacket as a supported // Packet type. func TestOpaqueParseReason(t *testing.T) { - armorBlock, err := armor.Decode(bytes.NewBufferString(UnsupportedKeyArmor)) + buf, err := hex.DecodeString(UnsupportedKeyHex) if err != nil { - t.Fatalf("armor Decode failed: %v", err) + t.Fatal(err) } - or := NewOpaqueReader(armorBlock.Body) + or := NewOpaqueReader(bytes.NewBuffer(buf)) count := 0 badPackets := 0 var uid *UserId @@ -64,7 +48,7 @@ func TestOpaqueParseReason(t *testing.T) { count++ } - const expectedBad = 2 + const expectedBad = 3 // Test post-conditions, make sure we actually parsed packets as expected. if badPackets != expectedBad { t.Errorf("unexpected # unparseable packets: %d (want %d)", badPackets, expectedBad) @@ -75,3 +59,9 @@ func TestOpaqueParseReason(t *testing.T) { t.Errorf("unexpected UID: %v", uid.Id) } } + +// This key material has public key and signature packet versions modified to +// an unsupported value (1), so that trying to parse the OpaquePacket to +// a typed packet will get an error. It also contains a GnuPG trust packet. +// (Created with: od -An -t x1 pubring.gpg | xargs | sed 's/ //g') +const UnsupportedKeyHex = `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` diff --git a/openpgp/packet/packet.go b/openpgp/packet/packet.go index d9c80ad..832b33f 100644 --- a/openpgp/packet/packet.go +++ b/openpgp/packet/packet.go @@ -7,6 +7,7 @@ package packet import ( + "bufio" "code.google.com/p/go.crypto/cast5" "code.google.com/p/go.crypto/openpgp/errors" "crypto/aes" @@ -297,6 +298,19 @@ const ( packetTypeSymmetricallyEncryptedMDC packetType = 18 ) +// peekVersion detects the version of a public key packet about to +// be read. A bufio.Reader at the original position of the io.Reader +// is returned. +func peekVersion(r io.Reader) (bufr *bufio.Reader, ver byte, err error) { + bufr = bufio.NewReader(r) + var verBuf []byte + if verBuf, err = bufr.Peek(1); err != nil { + return + } + ver = verBuf[0] + return +} + // Read reads a single OpenPGP packet from the given io.Reader. If there is an // error parsing a packet, the whole packet is consumed from the input. func Read(r io.Reader) (p Packet, err error) { @@ -309,7 +323,16 @@ func Read(r io.Reader) (p Packet, err error) { case packetTypeEncryptedKey: p = new(EncryptedKey) case packetTypeSignature: - p = new(Signature) + var version byte + // Detect signature version + if contents, version, err = peekVersion(contents); err != nil { + return + } + if version < 4 { + p = new(SignatureV3) + } else { + p = new(Signature) + } case packetTypeSymmetricKeyEncrypted: p = new(SymmetricKeyEncrypted) case packetTypeOnePassSignature: @@ -321,11 +344,16 @@ func Read(r io.Reader) (p Packet, err error) { } p = pk case packetTypePublicKey, packetTypePublicSubkey: - pk := new(PublicKey) - if tag == packetTypePublicSubkey { - pk.IsSubkey = true + var version byte + if contents, version, err = peekVersion(contents); err != nil { + return + } + isSubkey := tag == packetTypePublicSubkey + if version < 4 { + p = &PublicKeyV3{IsSubkey: isSubkey} + } else { + p = &PublicKey{IsSubkey: isSubkey} } - p = pk case packetTypeCompressed: p = new(Compressed) case packetTypeSymmetricallyEncrypted: diff --git a/openpgp/packet/public_key.go b/openpgp/packet/public_key.go index 3a1b5db..0fe312f 100644 --- a/openpgp/packet/public_key.go +++ b/openpgp/packet/public_key.go @@ -8,6 +8,7 @@ import ( "bytes" "code.google.com/p/go.crypto/openpgp/elgamal" "code.google.com/p/go.crypto/openpgp/errors" + "crypto" "crypto/dsa" "crypto/ecdsa" "crypto/elliptic" @@ -163,6 +164,13 @@ type PublicKey struct { ecdh *ecdhKdf } +// signingKey provides a convenient abstraction over signature verification +// for v3 and v4 public keys. +type signingKey interface { + SerializeSignaturePrefix(io.Writer) + serializeWithoutHeaders(io.Writer) error +} + func fromBig(n *big.Int) parsedMPI { return parsedMPI{ bytes: n.Bytes(), @@ -493,13 +501,58 @@ func (pk *PublicKey) VerifySignature(signed hash.Hash, sig *Signature) (err erro panic("unreachable") } +// VerifySignatureV3 returns nil iff sig is a valid signature, made by this +// public key, of the data hashed into signed. signed is mutated by this call. +func (pk *PublicKey) VerifySignatureV3(signed hash.Hash, sig *SignatureV3) (err error) { + if !pk.CanSign() { + return errors.InvalidArgumentError("public key cannot generate signatures") + } + + suffix := make([]byte, 5) + suffix[0] = byte(sig.SigType) + binary.BigEndian.PutUint32(suffix[1:], uint32(sig.CreationTime.Unix())) + signed.Write(suffix) + hashBytes := signed.Sum(nil) + + if hashBytes[0] != sig.HashTag[0] || hashBytes[1] != sig.HashTag[1] { + return errors.SignatureError("hash tag doesn't match") + } + + if pk.PubKeyAlgo != sig.PubKeyAlgo { + return errors.InvalidArgumentError("public key and signature use different algorithms") + } + + switch pk.PubKeyAlgo { + case PubKeyAlgoRSA, PubKeyAlgoRSASignOnly: + rsaPublicKey := pk.PublicKey.(*rsa.PublicKey) + if err = rsa.VerifyPKCS1v15(rsaPublicKey, sig.Hash, hashBytes, sig.RSASignature.bytes); err != nil { + return errors.SignatureError("RSA verification failure") + } + return + case PubKeyAlgoDSA: + dsaPublicKey := pk.PublicKey.(*dsa.PublicKey) + // Need to truncate hashBytes to match FIPS 186-3 section 4.6. + subgroupSize := (dsaPublicKey.Q.BitLen() + 7) / 8 + if len(hashBytes) > subgroupSize { + hashBytes = hashBytes[:subgroupSize] + } + if !dsa.Verify(dsaPublicKey, hashBytes, new(big.Int).SetBytes(sig.DSASigR.bytes), new(big.Int).SetBytes(sig.DSASigS.bytes)) { + return errors.SignatureError("DSA verification failure") + } + return nil + default: + panic("shouldn't happen") + } + panic("unreachable") +} + // keySignatureHash returns a Hash of the message that needs to be signed for // pk to assert a subkey relationship to signed. -func keySignatureHash(pk, signed *PublicKey, sig *Signature) (h hash.Hash, err error) { - h = sig.Hash.New() - if h == nil { +func keySignatureHash(pk, signed signingKey, hashFunc crypto.Hash) (h hash.Hash, err error) { + if !hashFunc.Available() { return nil, errors.UnsupportedError("hash function") } + h = hashFunc.New() // RFC 4880, section 5.2.4 pk.SerializeSignaturePrefix(h) @@ -512,7 +565,7 @@ func keySignatureHash(pk, signed *PublicKey, sig *Signature) (h hash.Hash, err e // VerifyKeySignature returns nil iff sig is a valid signature, made by this // public key, of signed. func (pk *PublicKey) VerifyKeySignature(signed *PublicKey, sig *Signature) (err error) { - h, err := keySignatureHash(pk, signed, sig) + h, err := keySignatureHash(pk, signed, sig.Hash) if err != nil { return err } @@ -521,11 +574,11 @@ func (pk *PublicKey) VerifyKeySignature(signed *PublicKey, sig *Signature) (err // userIdSignatureHash returns a Hash of the message that needs to be signed // to assert that pk is a valid key for id. -func userIdSignatureHash(id string, pk *PublicKey, sig *Signature) (h hash.Hash, err error) { - h = sig.Hash.New() - if h == nil { +func userIdSignatureHash(id string, pk *PublicKey, hashFunc crypto.Hash) (h hash.Hash, err error) { + if !hashFunc.Available() { return nil, errors.UnsupportedError("hash function") } + h = hashFunc.New() // RFC 4880, section 5.2.4 pk.SerializeSignaturePrefix(h) @@ -546,13 +599,23 @@ func userIdSignatureHash(id string, pk *PublicKey, sig *Signature) (h hash.Hash, // VerifyUserIdSignature returns nil iff sig is a valid signature, made by this // public key, of id. func (pk *PublicKey) VerifyUserIdSignature(id string, sig *Signature) (err error) { - h, err := userIdSignatureHash(id, pk, sig) + h, err := userIdSignatureHash(id, pk, sig.Hash) if err != nil { return err } return pk.VerifySignature(h, sig) } +// VerifyUserIdSignatureV3 returns nil iff sig is a valid signature, made by this +// public key, of id. +func (pk *PublicKey) VerifyUserIdSignatureV3(id string, sig *SignatureV3) (err error) { + h, err := userIdSignatureV3Hash(id, pk, sig.Hash) + if err != nil { + return err + } + return pk.VerifySignatureV3(h, sig) +} + // KeyIdString returns the public key's fingerprint in capital hex // (e.g. "6C7EE1B8621CC013"). func (pk *PublicKey) KeyIdString() string { diff --git a/openpgp/packet/public_key_v3.go b/openpgp/packet/public_key_v3.go new file mode 100644 index 0000000..c6adf75 --- /dev/null +++ b/openpgp/packet/public_key_v3.go @@ -0,0 +1,274 @@ +// Copyright 2013 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 packet + +import ( + "crypto" + "crypto/md5" + "crypto/rsa" + "encoding/binary" + "fmt" + "hash" + "io" + "math/big" + "strconv" + "time" + + "code.google.com/p/go.crypto/openpgp/errors" +) + +// PublicKeyV3 represents older, version 3 public keys. These keys are less secure and +// should not be used for signing or encrypting. They are supported here only for +// parsing version 3 key material and validating signatures. +// See RFC 4880, section 5.5.2. +type PublicKeyV3 struct { + CreationTime time.Time + DaysToExpire uint16 + PubKeyAlgo PublicKeyAlgorithm + PublicKey *rsa.PublicKey + Fingerprint [16]byte + KeyId uint64 + IsSubkey bool + + n, e parsedMPI +} + +// newRSAPublicKeyV3 returns a PublicKey that wraps the given rsa.PublicKey. +// Included here for testing purposes only. RFC 4880, section 5.5.2: +// "an implementation MUST NOT generate a V3 key, but MAY accept it." +func newRSAPublicKeyV3(creationTime time.Time, pub *rsa.PublicKey) *PublicKeyV3 { + pk := &PublicKeyV3{ + CreationTime: creationTime, + PublicKey: pub, + n: fromBig(pub.N), + e: fromBig(big.NewInt(int64(pub.E))), + } + + pk.setFingerPrintAndKeyId() + return pk +} + +func (pk *PublicKeyV3) parse(r io.Reader) (err error) { + // RFC 4880, section 5.5.2 + var buf [8]byte + if _, err = readFull(r, buf[:]); err != nil { + return + } + if buf[0] < 2 || buf[0] > 3 { + return errors.UnsupportedError("public key version") + } + pk.CreationTime = time.Unix(int64(uint32(buf[1])<<24|uint32(buf[2])<<16|uint32(buf[3])<<8|uint32(buf[4])), 0) + pk.DaysToExpire = binary.BigEndian.Uint16(buf[5:7]) + pk.PubKeyAlgo = PublicKeyAlgorithm(buf[7]) + switch pk.PubKeyAlgo { + case PubKeyAlgoRSA, PubKeyAlgoRSAEncryptOnly, PubKeyAlgoRSASignOnly: + err = pk.parseRSA(r) + default: + err = errors.UnsupportedError("public key type: " + strconv.Itoa(int(pk.PubKeyAlgo))) + } + if err != nil { + return + } + + pk.setFingerPrintAndKeyId() + return +} + +func (pk *PublicKeyV3) setFingerPrintAndKeyId() { + // RFC 4880, section 12.2 + fingerPrint := md5.New() + fingerPrint.Write(pk.n.bytes) + fingerPrint.Write(pk.e.bytes) + fingerPrint.Sum(pk.Fingerprint[:0]) + pk.KeyId = binary.BigEndian.Uint64(pk.n.bytes[len(pk.n.bytes)-8:]) +} + +// parseRSA parses RSA public key material from the given Reader. See RFC 4880, +// section 5.5.2. +func (pk *PublicKeyV3) parseRSA(r io.Reader) (err error) { + if pk.n.bytes, pk.n.bitLength, err = readMPI(r); err != nil { + return + } + if pk.e.bytes, pk.e.bitLength, err = readMPI(r); err != nil { + return + } + + if len(pk.e.bytes) > 3 { + err = errors.UnsupportedError("large public exponent") + return + } + rsa := &rsa.PublicKey{N: new(big.Int).SetBytes(pk.n.bytes)} + for i := 0; i < len(pk.e.bytes); i++ { + rsa.E <<= 8 + rsa.E |= int(pk.e.bytes[i]) + } + pk.PublicKey = rsa + return +} + +// SerializeSignaturePrefix writes the prefix for this public key to the given Writer. +// The prefix is used when calculating a signature over this public key. See +// RFC 4880, section 5.2.4. +func (pk *PublicKeyV3) SerializeSignaturePrefix(w io.Writer) { + var pLength uint16 + switch pk.PubKeyAlgo { + case PubKeyAlgoRSA, PubKeyAlgoRSAEncryptOnly, PubKeyAlgoRSASignOnly: + pLength += 2 + uint16(len(pk.n.bytes)) + pLength += 2 + uint16(len(pk.e.bytes)) + default: + panic("unknown public key algorithm") + } + pLength += 6 + w.Write([]byte{0x99, byte(pLength >> 8), byte(pLength)}) + return +} + +func (pk *PublicKeyV3) Serialize(w io.Writer) (err error) { + length := 8 // 8 byte header + + switch pk.PubKeyAlgo { + case PubKeyAlgoRSA, PubKeyAlgoRSAEncryptOnly, PubKeyAlgoRSASignOnly: + length += 2 + len(pk.n.bytes) + length += 2 + len(pk.e.bytes) + default: + panic("unknown public key algorithm") + } + + packetType := packetTypePublicKey + if pk.IsSubkey { + packetType = packetTypePublicSubkey + } + if err = serializeHeader(w, packetType, length); err != nil { + return + } + return pk.serializeWithoutHeaders(w) +} + +// serializeWithoutHeaders marshals the PublicKey to w in the form of an +// OpenPGP public key packet, not including the packet header. +func (pk *PublicKeyV3) serializeWithoutHeaders(w io.Writer) (err error) { + var buf [8]byte + // Version 3 + buf[0] = 3 + // Creation time + t := uint32(pk.CreationTime.Unix()) + buf[1] = byte(t >> 24) + buf[2] = byte(t >> 16) + buf[3] = byte(t >> 8) + buf[4] = byte(t) + // Days to expire + buf[5] = byte(pk.DaysToExpire >> 8) + buf[6] = byte(pk.DaysToExpire) + // Public key algorithm + buf[7] = byte(pk.PubKeyAlgo) + + if _, err = w.Write(buf[:]); err != nil { + return + } + + switch pk.PubKeyAlgo { + case PubKeyAlgoRSA, PubKeyAlgoRSAEncryptOnly, PubKeyAlgoRSASignOnly: + return writeMPIs(w, pk.n, pk.e) + } + return errors.InvalidArgumentError("bad public-key algorithm") +} + +// CanSign returns true iff this public key can generate signatures +func (pk *PublicKeyV3) CanSign() bool { + return pk.PubKeyAlgo != PubKeyAlgoRSAEncryptOnly +} + +// VerifySignatureV3 returns nil iff sig is a valid signature, made by this +// public key, of the data hashed into signed. signed is mutated by this call. +func (pk *PublicKeyV3) VerifySignatureV3(signed hash.Hash, sig *SignatureV3) (err error) { + if !pk.CanSign() { + return errors.InvalidArgumentError("public key cannot generate signatures") + } + + suffix := make([]byte, 5) + suffix[0] = byte(sig.SigType) + binary.BigEndian.PutUint32(suffix[1:], uint32(sig.CreationTime.Unix())) + signed.Write(suffix) + hashBytes := signed.Sum(nil) + + if hashBytes[0] != sig.HashTag[0] || hashBytes[1] != sig.HashTag[1] { + return errors.SignatureError("hash tag doesn't match") + } + + if pk.PubKeyAlgo != sig.PubKeyAlgo { + return errors.InvalidArgumentError("public key and signature use different algorithms") + } + + switch pk.PubKeyAlgo { + case PubKeyAlgoRSA, PubKeyAlgoRSASignOnly: + if err = rsa.VerifyPKCS1v15(pk.PublicKey, sig.Hash, hashBytes, sig.RSASignature.bytes); err != nil { + return errors.SignatureError("RSA verification failure") + } + return + default: + // V3 public keys only support RSA. + panic("shouldn't happen") + } + panic("unreachable") +} + +// VerifyUserIdSignatureV3 returns nil iff sig is a valid signature, made by this +// public key, of id. +func (pk *PublicKeyV3) VerifyUserIdSignatureV3(id string, sig *SignatureV3) (err error) { + h, err := userIdSignatureV3Hash(id, pk, sig.Hash) + if err != nil { + return err + } + return pk.VerifySignatureV3(h, sig) +} + +// VerifyKeySignatureV3 returns nil iff sig is a valid signature, made by this +// public key, of signed. +func (pk *PublicKeyV3) VerifyKeySignatureV3(signed *PublicKeyV3, sig *SignatureV3) (err error) { + h, err := keySignatureHash(pk, signed, sig.Hash) + if err != nil { + return err + } + return pk.VerifySignatureV3(h, sig) +} + +// userIdSignatureV3Hash returns a Hash of the message that needs to be signed +// to assert that pk is a valid key for id. +func userIdSignatureV3Hash(id string, pk signingKey, hfn crypto.Hash) (h hash.Hash, err error) { + if h = hfn.New(); h == nil { + return nil, errors.UnsupportedError("hash function") + } + + // RFC 4880, section 5.2.4 + pk.SerializeSignaturePrefix(h) + pk.serializeWithoutHeaders(h) + + h.Write([]byte(id)) + + return +} + +// KeyIdString returns the public key's fingerprint in capital hex +// (e.g. "6C7EE1B8621CC013"). +func (pk *PublicKeyV3) KeyIdString() string { + return fmt.Sprintf("%X", pk.KeyId) +} + +// KeyIdShortString returns the short form of public key's fingerprint +// in capital hex, as shown by gpg --list-keys (e.g. "621CC013"). +func (pk *PublicKeyV3) KeyIdShortString() string { + return fmt.Sprintf("%X", pk.KeyId&0xFFFFFFFF) +} + +// BitLength returns the bit length for the given public key. +func (pk *PublicKeyV3) BitLength() (bitLength uint16, err error) { + switch pk.PubKeyAlgo { + case PubKeyAlgoRSA, PubKeyAlgoRSAEncryptOnly, PubKeyAlgoRSASignOnly: + bitLength = pk.n.bitLength + default: + err = errors.InvalidArgumentError("bad public-key algorithm") + } + return +} diff --git a/openpgp/packet/public_key_v3_test.go b/openpgp/packet/public_key_v3_test.go new file mode 100644 index 0000000..e064059 --- /dev/null +++ b/openpgp/packet/public_key_v3_test.go @@ -0,0 +1,82 @@ +// Copyright 2013 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 packet + +import ( + "bytes" + "encoding/hex" + "testing" + "time" +) + +var pubKeyV3Test = struct { + hexFingerprint string + creationTime time.Time + pubKeyAlgo PublicKeyAlgorithm + keyId uint64 + keyIdString string + keyIdShort string +}{ + "103BECF5BD1E837C89D19E98487767F7", + time.Unix(779753634, 0), + PubKeyAlgoRSA, + 0xDE0F188A5DA5E3C9, + "DE0F188A5DA5E3C9", + "5DA5E3C9"} + +func TestPublicKeyV3Read(t *testing.T) { + i, test := 0, pubKeyV3Test + packet, err := Read(v3KeyReader(t)) + if err != nil { + t.Fatalf("#%d: Read error: %s", i, err) + } + pk, ok := packet.(*PublicKeyV3) + if !ok { + t.Fatalf("#%d: failed to parse, got: %#v", i, packet) + } + if pk.PubKeyAlgo != test.pubKeyAlgo { + t.Errorf("#%d: bad public key algorithm got:%x want:%x", i, pk.PubKeyAlgo, test.pubKeyAlgo) + } + if !pk.CreationTime.Equal(test.creationTime) { + t.Errorf("#%d: bad creation time got:%v want:%v", i, pk.CreationTime, test.creationTime) + } + expectedFingerprint, _ := hex.DecodeString(test.hexFingerprint) + if !bytes.Equal(expectedFingerprint, pk.Fingerprint[:]) { + t.Errorf("#%d: bad fingerprint got:%x want:%x", i, pk.Fingerprint[:], expectedFingerprint) + } + if pk.KeyId != test.keyId { + t.Errorf("#%d: bad keyid got:%x want:%x", i, pk.KeyId, test.keyId) + } + if g, e := pk.KeyIdString(), test.keyIdString; g != e { + t.Errorf("#%d: bad KeyIdString got:%q want:%q", i, g, e) + } + if g, e := pk.KeyIdShortString(), test.keyIdShort; g != e { + t.Errorf("#%d: bad KeyIdShortString got:%q want:%q", i, g, e) + } +} + +func TestPublicKeyV3Serialize(t *testing.T) { + //for i, test := range pubKeyV3Tests { + i := 0 + packet, err := Read(v3KeyReader(t)) + if err != nil { + t.Fatalf("#%d: Read error: %s", i, err) + } + pk, ok := packet.(*PublicKeyV3) + if !ok { + t.Fatalf("#%d: failed to parse, got: %#v", i, packet) + } + var serializeBuf bytes.Buffer + if err = pk.Serialize(&serializeBuf); err != nil { + t.Fatalf("#%d: failed to serialize: %s", i, err) + } + + if packet, err = Read(bytes.NewBuffer(serializeBuf.Bytes())); err != nil { + t.Fatalf("#%d: Read error (from serialized data): %s", i, err) + } + if pk, ok = packet.(*PublicKeyV3); !ok { + t.Fatalf("#%d: failed to parse serialized data, got: %#v", i, packet) + } +} diff --git a/openpgp/packet/signature.go b/openpgp/packet/signature.go index e0c9a5e..d0d6890 100644 --- a/openpgp/packet/signature.go +++ b/openpgp/packet/signature.go @@ -481,7 +481,7 @@ func (sig *Signature) Sign(h hash.Hash, priv *PrivateKey, config *Config) (err e // Serialize to write it out. // If config is nil, sensible defaults will be used. func (sig *Signature) SignUserId(id string, pub *PublicKey, priv *PrivateKey, config *Config) error { - h, err := userIdSignatureHash(id, pub, sig) + h, err := userIdSignatureHash(id, pub, sig.Hash) if err != nil { return nil } @@ -492,7 +492,7 @@ func (sig *Signature) SignUserId(id string, pub *PublicKey, priv *PrivateKey, co // success, the signature is stored in sig. Call Serialize to write it out. // If config is nil, sensible defaults will be used. func (sig *Signature) SignKey(pub *PublicKey, priv *PrivateKey, config *Config) error { - h, err := keySignatureHash(&priv.PublicKey, pub, sig) + h, err := keySignatureHash(&priv.PublicKey, pub, sig.Hash) if err != nil { return err } diff --git a/openpgp/packet/signature_v3.go b/openpgp/packet/signature_v3.go new file mode 100644 index 0000000..1bba74d --- /dev/null +++ b/openpgp/packet/signature_v3.go @@ -0,0 +1,146 @@ +// Copyright 2013 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 packet + +import ( + "crypto" + "encoding/binary" + "fmt" + "io" + "strconv" + "time" + + "code.google.com/p/go.crypto/openpgp/errors" + "code.google.com/p/go.crypto/openpgp/s2k" +) + +// SignatureV3 represents older version 3 signatures. These signatures are less secure +// than version 4 and should not be used to create new signatures. They are included +// here for backwards compatibility to read and validate with older key material. +// See RFC 4880, section 5.2.2. +type SignatureV3 struct { + SigType SignatureType + CreationTime time.Time + IssuerKeyId uint64 + PubKeyAlgo PublicKeyAlgorithm + Hash crypto.Hash + HashTag [2]byte + + RSASignature parsedMPI + DSASigR, DSASigS parsedMPI +} + +func (sig *SignatureV3) parse(r io.Reader) (err error) { + // RFC 4880, section 5.2.2 + var buf [8]byte + if _, err = readFull(r, buf[:1]); err != nil { + return + } + if buf[0] < 2 || buf[0] > 3 { + err = errors.UnsupportedError("signature packet version " + strconv.Itoa(int(buf[0]))) + return + } + if _, err = readFull(r, buf[:1]); err != nil { + return + } + if buf[0] != 5 { + err = errors.UnsupportedError( + "invalid hashed material length " + strconv.Itoa(int(buf[0]))) + return + } + + // Read hashed material: signature type + creation time + if _, err = readFull(r, buf[:5]); err != nil { + return + } + sig.SigType = SignatureType(buf[0]) + t := binary.BigEndian.Uint32(buf[1:5]) + sig.CreationTime = time.Unix(int64(t), 0) + + // Eight-octet Key ID of signer. + if _, err = readFull(r, buf[:8]); err != nil { + return + } + sig.IssuerKeyId = binary.BigEndian.Uint64(buf[:]) + + // Public-key and hash algorithm + if _, err = readFull(r, buf[:2]); err != nil { + return + } + sig.PubKeyAlgo = PublicKeyAlgorithm(buf[0]) + switch sig.PubKeyAlgo { + case PubKeyAlgoRSA, PubKeyAlgoRSASignOnly, PubKeyAlgoDSA: + default: + err = errors.UnsupportedError("public key algorithm " + strconv.Itoa(int(sig.PubKeyAlgo))) + return + } + var ok bool + if sig.Hash, ok = s2k.HashIdToHash(buf[1]); !ok { + return errors.UnsupportedError("hash function " + strconv.Itoa(int(buf[2]))) + } + + // Two-octet field holding left 16 bits of signed hash value. + if _, err = readFull(r, sig.HashTag[:2]); err != nil { + return + } + + switch sig.PubKeyAlgo { + case PubKeyAlgoRSA, PubKeyAlgoRSASignOnly: + sig.RSASignature.bytes, sig.RSASignature.bitLength, err = readMPI(r) + case PubKeyAlgoDSA: + if sig.DSASigR.bytes, sig.DSASigR.bitLength, err = readMPI(r); err != nil { + return + } + sig.DSASigS.bytes, sig.DSASigS.bitLength, err = readMPI(r) + default: + panic("unreachable") + } + return +} + +// Serialize marshals sig to w. Sign, SignUserId or SignKey must have been +// called first. +func (sig *SignatureV3) Serialize(w io.Writer) (err error) { + buf := make([]byte, 8) + + // Write the sig type and creation time + buf[0] = byte(sig.SigType) + binary.BigEndian.PutUint32(buf[1:5], uint32(sig.CreationTime.Unix())) + if _, err = w.Write(buf[:5]); err != nil { + return + } + + // Write the issuer long key ID + binary.BigEndian.PutUint64(buf[:8], sig.IssuerKeyId) + if _, err = w.Write(buf[:8]); err != nil { + return + } + + // Write public key algorithm, hash ID, and hash value + buf[0] = byte(sig.PubKeyAlgo) + hashId, ok := s2k.HashToHashId(sig.Hash) + if !ok { + return errors.UnsupportedError(fmt.Sprintf("hash function %v", sig.Hash)) + } + buf[1] = hashId + copy(buf[2:4], sig.HashTag[:]) + if _, err = w.Write(buf[:4]); err != nil { + return + } + + if sig.RSASignature.bytes == nil && sig.DSASigR.bytes == nil { + return errors.InvalidArgumentError("Signature: need to call Sign, SignUserId or SignKey before Serialize") + } + + switch sig.PubKeyAlgo { + case PubKeyAlgoRSA, PubKeyAlgoRSASignOnly: + err = writeMPIs(w, sig.RSASignature) + case PubKeyAlgoDSA: + err = writeMPIs(w, sig.DSASigR, sig.DSASigS) + default: + panic("impossible") + } + return +} diff --git a/openpgp/packet/signature_v3_test.go b/openpgp/packet/signature_v3_test.go new file mode 100644 index 0000000..57f26b5 --- /dev/null +++ b/openpgp/packet/signature_v3_test.go @@ -0,0 +1,92 @@ +// Copyright 2013 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 packet + +import ( + "bytes" + "crypto" + "encoding/hex" + "io" + "io/ioutil" + "testing" + + "code.google.com/p/go.crypto/openpgp/armor" +) + +func TestSignatureV3Read(t *testing.T) { + r := v3KeyReader(t) + Read(r) // Skip public key + Read(r) // Skip uid + packet, err := Read(r) // Signature + if err != nil { + t.Error(err) + return + } + sig, ok := packet.(*SignatureV3) + if !ok || sig.SigType != SigTypeGenericCert || sig.PubKeyAlgo != PubKeyAlgoRSA || sig.Hash != crypto.MD5 { + t.Errorf("failed to parse, got: %#v", packet) + } +} + +func TestSignatureV3Reserialize(t *testing.T) { + r := v3KeyReader(t) + Read(r) // Skip public key + Read(r) // Skip uid + packet, err := Read(r) + if err != nil { + t.Error(err) + return + } + sig := packet.(*SignatureV3) + out := new(bytes.Buffer) + if err = sig.Serialize(out); err != nil { + t.Errorf("error reserializing: %s", err) + return + } + expected, err := ioutil.ReadAll(v3KeyReader(t)) + if err != nil { + t.Error(err) + return + } + expected = expected[4+141+4+39:] // See pgpdump offsets below, this is where the sig starts + if !bytes.Equal(expected, out.Bytes()) { + t.Errorf("output doesn't match input (got vs expected):\n%s\n%s", hex.Dump(out.Bytes()), hex.Dump(expected)) + } +} + +func v3KeyReader(t *testing.T) io.Reader { + armorBlock, err := armor.Decode(bytes.NewBufferString(keySigV3Armor)) + if err != nil { + t.Fatalf("armor Decode failed: %v", err) + } + return armorBlock.Body +} + +// keySigV3Armor is some V3 public key I found in an SKS dump. +// Old: Public Key Packet(tag 6)(141 bytes) +// Ver 4 - new +// Public key creation time - Fri Sep 16 17:13:54 CDT 1994 +// Pub alg - unknown(pub 0) +// Unknown public key(pub 0) +// Old: User ID Packet(tag 13)(39 bytes) +// User ID - Armin M. Warda +// Old: Signature Packet(tag 2)(149 bytes) +// Ver 4 - new +// Sig type - unknown(05) +// Pub alg - ElGamal Encrypt-Only(pub 16) +// Hash alg - unknown(hash 46) +// Hashed Sub: unknown(sub 81, critical)(1988 bytes) +const keySigV3Armor = `-----BEGIN PGP PUBLIC KEY BLOCK----- +Version: SKS 1.0.10 + +mI0CLnoYogAAAQQA1qwA2SuJwfQ5bCQ6u5t20ulnOtY0gykf7YjiK4LiVeRBwHjGq7v30tGV +5Qti7qqRW4Ww7CDCJc4sZMFnystucR2vLkXaSoNWoFm4Fg47NiisDdhDezHwbVPW6OpCFNSi +ZAamtj4QAUBu8j4LswafrJqZqR9336/V3g8Yil2l48kABRG0J0FybWluIE0uIFdhcmRhIDx3 +YXJkYUBuZXBoaWxpbS5ydWhyLmRlPoiVAgUQLok2xwXR6zmeWEiZAQE/DgP/WgxPQh40/Po4 +gSkWZCDAjNdph7zexvAb0CcUWahcwiBIgg3U5ErCx9I5CNVA9U+s8bNrDZwgSIeBzp3KhWUx +524uhGgm6ZUTOAIKA6CbV6pfqoLpJnRYvXYQU5mIWsNa99wcu2qu18OeEDnztb7aLA6Ra9OF +YFCbq4EjXRoOrYM= +=LPjs +-----END PGP PUBLIC KEY BLOCK-----`