From da934910d6e43ac46c41a3415580bf42f867157a Mon Sep 17 00:00:00 2001 From: Casey Marshall Date: Thu, 29 Aug 2013 17:10:08 -0400 Subject: [PATCH] openpgp/packet: Parse and serialize ECC key material (RFC 6637). Support ECDSA signature verification. R=agl CC=golang-dev https://golang.org/cl/13141044 --- openpgp/packet/packet.go | 3 + openpgp/packet/public_key.go | 176 +++++++++++++++++++++++++++++- openpgp/packet/public_key_test.go | 103 +++++++++++++++++ openpgp/packet/signature.go | 19 +++- 4 files changed, 295 insertions(+), 6 deletions(-) diff --git a/openpgp/packet/packet.go b/openpgp/packet/packet.go index 8056a48..d9c80ad 100644 --- a/openpgp/packet/packet.go +++ b/openpgp/packet/packet.go @@ -377,6 +377,9 @@ const ( PubKeyAlgoRSASignOnly PublicKeyAlgorithm = 3 PubKeyAlgoElGamal PublicKeyAlgorithm = 16 PubKeyAlgoDSA PublicKeyAlgorithm = 17 + // RFC 6637, Section 5. + PubKeyAlgoECDH PublicKeyAlgorithm = 18 + PubKeyAlgoECDSA PublicKeyAlgorithm = 19 ) // CanEncrypt returns true if it's possible to encrypt a message to a public diff --git a/openpgp/packet/public_key.go b/openpgp/packet/public_key.go index fc9012d..45d944e 100644 --- a/openpgp/packet/public_key.go +++ b/openpgp/packet/public_key.go @@ -5,11 +5,16 @@ package packet import ( + "bytes" "code.google.com/p/go.crypto/openpgp/elgamal" "code.google.com/p/go.crypto/openpgp/errors" "crypto/dsa" + "crypto/ecdsa" + "crypto/elliptic" "crypto/rsa" "crypto/sha1" + _ "crypto/sha256" + _ "crypto/sha512" "encoding/binary" "fmt" "hash" @@ -19,16 +24,143 @@ import ( "time" ) +var ( + // NIST curve P-256 + oidCurveP256 []byte = []byte{0x2A, 0x86, 0x48, 0xCE, 0x3D, 0x03, 0x01, 0x07} + // NIST curve P-384 + oidCurveP384 []byte = []byte{0x2B, 0x81, 0x04, 0x00, 0x22} + // NIST curve P-521 + oidCurveP521 []byte = []byte{0x2B, 0x81, 0x04, 0x00, 0x23} +) + +const maxOIDLength = 8 + +// ecdsaKey stores the algorithm-specific fields for ECDSA keys. +// as defined in RFC 6637, Section 9. +type ecdsaKey struct { + // oid contains the OID byte sequence identifying the elliptic curve used + oid []byte + // p contains the elliptic curve point that represents the public key + p parsedMPI +} + +// parseOID reads the OID for the curve as defined in RFC 6637, Section 9. +func parseOID(r io.Reader) (oid []byte, err error) { + buf := make([]byte, maxOIDLength) + if _, err = readFull(r, buf[:1]); err != nil { + return + } + oidLen := buf[0] + if int(oidLen) > len(buf) { + err = errors.UnsupportedError("invalid oid length: " + strconv.Itoa(int(oidLen))) + return + } + oid = buf[:oidLen] + _, err = readFull(r, oid) + return +} + +func (f *ecdsaKey) parse(r io.Reader) (err error) { + if f.oid, err = parseOID(r); err != nil { + return err + } + f.p.bytes, f.p.bitLength, err = readMPI(r) + return +} + +func (f *ecdsaKey) serialize(w io.Writer) (err error) { + buf := make([]byte, maxOIDLength+1) + buf[0] = byte(len(f.oid)) + copy(buf[1:], f.oid) + if _, err = w.Write(buf[:len(f.oid)+1]); err != nil { + return + } + return writeMPIs(w, f.p) +} + +func (f *ecdsaKey) newECDSA() (*ecdsa.PublicKey, error) { + var c elliptic.Curve + if bytes.Equal(f.oid, oidCurveP256) { + c = elliptic.P256() + } else if bytes.Equal(f.oid, oidCurveP384) { + c = elliptic.P384() + } else if bytes.Equal(f.oid, oidCurveP521) { + c = elliptic.P521() + } else { + return nil, errors.UnsupportedError(fmt.Sprintf("unsupported oid: %x", f.oid)) + } + x, y := elliptic.Unmarshal(c, f.p.bytes) + if x == nil { + return nil, errors.UnsupportedError("failed to parse EC point") + } + return &ecdsa.PublicKey{Curve: c, X: x, Y: y}, nil +} + +func (f *ecdsaKey) byteLen() int { + return 1 + len(f.oid) + 2 + len(f.p.bytes) +} + +type kdfHashFunction byte +type kdfAlgorithm byte + +// ecdhKdf stores key derivation function parameters +// used for ECDH encryption. See RFC 6637, Section 9. +type ecdhKdf struct { + KdfHash kdfHashFunction + KdfAlgo kdfAlgorithm +} + +func (f *ecdhKdf) parse(r io.Reader) (err error) { + buf := make([]byte, 1) + if _, err = readFull(r, buf); err != nil { + return + } + kdfLen := int(buf[0]) + if kdfLen < 3 { + return errors.UnsupportedError("Unsupported ECDH KDF length: " + strconv.Itoa(kdfLen)) + } + buf = make([]byte, kdfLen) + if _, err = readFull(r, buf); err != nil { + return + } + reserved := int(buf[0]) + f.KdfHash = kdfHashFunction(buf[1]) + f.KdfAlgo = kdfAlgorithm(buf[2]) + if reserved != 0x01 { + return errors.UnsupportedError("Unsupported KDF reserved field: " + strconv.Itoa(reserved)) + } + return +} + +func (f *ecdhKdf) serialize(w io.Writer) (err error) { + buf := make([]byte, 4) + // See RFC 6637, Section 9, Algorithm-Specific Fields for ECDH keys. + buf[0] = byte(0x03) // Length of the following fields + buf[1] = byte(0x01) // Reserved for future extensions, must be 1 for now + buf[2] = byte(f.KdfHash) + buf[3] = byte(f.KdfAlgo) + _, err = w.Write(buf[:]) + return +} + +func (f *ecdhKdf) byteLen() int { + return 4 +} + // PublicKey represents an OpenPGP public key. See RFC 4880, section 5.5.2. type PublicKey struct { CreationTime time.Time PubKeyAlgo PublicKeyAlgorithm - PublicKey interface{} // Either a *rsa.PublicKey or *dsa.PublicKey + PublicKey interface{} // *rsa.PublicKey, *dsa.PublicKey or *ecdsa.PublicKey Fingerprint [20]byte KeyId uint64 IsSubkey bool n, e, p, q, g, y parsedMPI + + // RFC 6637 fields + ec *ecdsaKey + ecdh *ecdhKdf } func fromBig(n *big.Int) parsedMPI { @@ -87,6 +219,23 @@ func (pk *PublicKey) parse(r io.Reader) (err error) { err = pk.parseDSA(r) case PubKeyAlgoElGamal: err = pk.parseElGamal(r) + case PubKeyAlgoECDSA: + pk.ec = new(ecdsaKey) + if err = pk.ec.parse(r); err != nil { + return err + } + pk.PublicKey, err = pk.ec.newECDSA() + case PubKeyAlgoECDH: + pk.ec = new(ecdsaKey) + if err = pk.ec.parse(r); err != nil { + return + } + pk.ecdh = new(ecdhKdf) + if err = pk.ecdh.parse(r); err != nil { + return + } + // The ECDH key is stored in an ecdsa.PublicKey for convenience. + pk.PublicKey, err = pk.ec.newECDSA() default: err = errors.UnsupportedError("public key type: " + strconv.Itoa(int(pk.PubKeyAlgo))) } @@ -206,6 +355,11 @@ func (pk *PublicKey) SerializeSignaturePrefix(h hash.Hash) { pLength += 2 + uint16(len(pk.p.bytes)) pLength += 2 + uint16(len(pk.g.bytes)) pLength += 2 + uint16(len(pk.y.bytes)) + case PubKeyAlgoECDSA: + pLength += uint16(pk.ec.byteLen()) + case PubKeyAlgoECDH: + pLength += uint16(pk.ec.byteLen()) + pLength += uint16(pk.ecdh.byteLen()) default: panic("unknown public key algorithm") } @@ -230,6 +384,11 @@ func (pk *PublicKey) Serialize(w io.Writer) (err error) { length += 2 + len(pk.p.bytes) length += 2 + len(pk.g.bytes) length += 2 + len(pk.y.bytes) + case PubKeyAlgoECDSA: + length += pk.ec.byteLen() + case PubKeyAlgoECDH: + length += pk.ec.byteLen() + length += pk.ecdh.byteLen() default: panic("unknown public key algorithm") } @@ -269,6 +428,13 @@ func (pk *PublicKey) serializeWithoutHeaders(w io.Writer) (err error) { return writeMPIs(w, pk.p, pk.q, pk.g, pk.y) case PubKeyAlgoElGamal: return writeMPIs(w, pk.p, pk.g, pk.y) + case PubKeyAlgoECDSA: + return pk.ec.serialize(w) + case PubKeyAlgoECDH: + if err = pk.ec.serialize(w); err != nil { + return + } + return pk.ecdh.serialize(w) } return errors.InvalidArgumentError("bad public-key algorithm") } @@ -315,8 +481,14 @@ func (pk *PublicKey) VerifySignature(signed hash.Hash, sig *Signature) (err erro return errors.SignatureError("DSA verification failure") } return nil + case PubKeyAlgoECDSA: + ecdsaPublicKey := pk.PublicKey.(*ecdsa.PublicKey) + if !ecdsa.Verify(ecdsaPublicKey, hashBytes, new(big.Int).SetBytes(sig.ECDSASigR.bytes), new(big.Int).SetBytes(sig.ECDSASigS.bytes)) { + return errors.SignatureError("ECDSA verification failure") + } + return nil default: - panic("shouldn't happen") + return errors.SignatureError("Unsupported public key algorithm used in signature") } panic("unreachable") } diff --git a/openpgp/packet/public_key_test.go b/openpgp/packet/public_key_test.go index 72f459f..47168a4 100644 --- a/openpgp/packet/public_key_test.go +++ b/openpgp/packet/public_key_test.go @@ -22,6 +22,7 @@ var pubKeyTests = []struct { }{ {rsaPkDataHex, rsaFingerprintHex, time.Unix(0x4d3c5c10, 0), PubKeyAlgoRSA, 0xa34d7e18c20c31bb, "A34D7E18C20C31BB", "C20C31BB"}, {dsaPkDataHex, dsaFingerprintHex, time.Unix(0x4d432f89, 0), PubKeyAlgoDSA, 0x8e8fbe54062f19ed, "8E8FBE54062F19ED", "062F19ED"}, + {ecdsaPkDataHex, ecdsaFingerprintHex, time.Unix(0x5071c294, 0), PubKeyAlgoECDSA, 0x43fe956c542ca00b, "43FE956C542CA00B", "542CA00B"}, } func TestPublicKeyRead(t *testing.T) { @@ -90,6 +91,101 @@ func TestPublicKeySerialize(t *testing.T) { } } +func TestEcc384Serialize(t *testing.T) { + r := readerFromHex(ecc384PubHex) + var w bytes.Buffer + for i := 0; i < 2; i++ { + // Public key + p, err := Read(r) + if err != nil { + t.Error(err) + } + pubkey := p.(*PublicKey) + if !bytes.Equal(pubkey.ec.oid, []byte{0x2b, 0x81, 0x04, 0x00, 0x22}) { + t.Errorf("Unexpected pubkey OID: %x", pubkey.ec.oid) + } + if !bytes.Equal(pubkey.ec.p.bytes[:5], []byte{0x04, 0xf6, 0xb8, 0xc5, 0xac}) { + t.Errorf("Unexpected pubkey P[:5]: %x", pubkey.ec.p.bytes) + } + if pubkey.KeyId != 0x098033880F54719F { + t.Errorf("Unexpected pubkey ID: %x", pubkey.KeyId) + } + err = pubkey.Serialize(&w) + if err != nil { + t.Error(err) + } + // User ID + p, err = Read(r) + if err != nil { + t.Error(err) + } + uid := p.(*UserId) + if uid.Id != "ec_dsa_dh_384 " { + t.Error("Unexpected UID:", uid.Id) + } + err = uid.Serialize(&w) + if err != nil { + t.Error(err) + } + // User ID Sig + p, err = Read(r) + if err != nil { + t.Error(err) + } + uidSig := p.(*Signature) + err = pubkey.VerifyUserIdSignature(uid.Id, uidSig) + if err != nil { + t.Error(err, ": UID") + } + err = uidSig.Serialize(&w) + if err != nil { + t.Error(err) + } + // Subkey + p, err = Read(r) + if err != nil { + t.Error(err) + } + subkey := p.(*PublicKey) + if !bytes.Equal(subkey.ec.oid, []byte{0x2b, 0x81, 0x04, 0x00, 0x22}) { + t.Errorf("Unexpected subkey OID: %x", subkey.ec.oid) + } + if !bytes.Equal(subkey.ec.p.bytes[:5], []byte{0x04, 0x2f, 0xaa, 0x84, 0x02}) { + t.Errorf("Unexpected subkey P[:5]: %x", subkey.ec.p.bytes) + } + if subkey.ecdh.KdfHash != 0x09 { + t.Error("Expected KDF hash function SHA384 (0x09), got", subkey.ecdh.KdfHash) + } + if subkey.ecdh.KdfAlgo != 0x09 { + t.Error("Expected KDF symmetric alg AES256 (0x09), got", subkey.ecdh.KdfAlgo) + } + if subkey.KeyId != 0xAA8B938F9A201946 { + t.Errorf("Unexpected subkey ID: %x", subkey.KeyId) + } + err = subkey.Serialize(&w) + if err != nil { + t.Error(err) + } + // Subkey Sig + p, err = Read(r) + if err != nil { + t.Error(err) + } + subkeySig := p.(*Signature) + err = pubkey.VerifyKeySignature(subkey, subkeySig) + if err != nil { + t.Error(err) + } + err = subkeySig.Serialize(&w) + if err != nil { + t.Error(err) + } + // Now read back what we've written again + r = bytes.NewBuffer(w.Bytes()) + w.Reset() + } +} + const rsaFingerprintHex = "5fb74b1d03b1e3cb31bc2f8aa34d7e18c20c31bb" const rsaPkDataHex = "988d044d3c5c10010400b1d13382944bd5aba23a4312968b5095d14f947f600eb478e14a6fcb16b0e0cac764884909c020bc495cfcc39a935387c661507bdb236a0612fb582cac3af9b29cc2c8c70090616c41b662f4da4c1201e195472eb7f4ae1ccbcbf9940fe21d985e379a5563dde5b9a23d35f1cfaa5790da3b79db26f23695107bfaca8e7b5bcd0011010001" @@ -97,3 +193,10 @@ const rsaPkDataHex = "988d044d3c5c10010400b1d13382944bd5aba23a4312968b5095d14f94 const dsaFingerprintHex = "eece4c094db002103714c63c8e8fbe54062f19ed" const dsaPkDataHex = "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" + +const ecdsaFingerprintHex = "9892270b38b8980b05c8d56d43fe956c542ca00b" + +const ecdsaPkDataHex = "9893045071c29413052b8104002304230401f4867769cedfa52c325018896245443968e52e51d0c2df8d939949cb5b330f2921711fbee1c9b9dddb95d15cb0255e99badeddda7cc23d9ddcaacbc290969b9f24019375d61c2e4e3b36953a28d8b2bc95f78c3f1d592fb24499be348656a7b17e3963187b4361afe497bc5f9f81213f04069f8e1fb9e6a6290ae295ca1a92b894396cb4" + +// Source: https://sites.google.com/site/brainhub/pgpecckeys#TOC-ECC-NIST-P-384-key +const ecc384PubHex = `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` diff --git a/openpgp/packet/signature.go b/openpgp/packet/signature.go index 1689f21..e0c9a5e 100644 --- a/openpgp/packet/signature.go +++ b/openpgp/packet/signature.go @@ -30,8 +30,9 @@ type Signature struct { HashTag [2]byte CreationTime time.Time - RSASignature parsedMPI - DSASigR, DSASigS parsedMPI + RSASignature parsedMPI + DSASigR, DSASigS parsedMPI + ECDSASigR, ECDSASigS parsedMPI // rawSubpackets contains the unparsed subpackets, in order. rawSubpackets []outputSubpacket @@ -71,7 +72,7 @@ func (sig *Signature) parse(r io.Reader) (err error) { sig.SigType = SignatureType(buf[0]) sig.PubKeyAlgo = PublicKeyAlgorithm(buf[1]) switch sig.PubKeyAlgo { - case PubKeyAlgoRSA, PubKeyAlgoRSASignOnly, PubKeyAlgoDSA: + case PubKeyAlgoRSA, PubKeyAlgoRSASignOnly, PubKeyAlgoDSA, PubKeyAlgoECDSA: default: err = errors.UnsupportedError("public key algorithm " + strconv.Itoa(int(sig.PubKeyAlgo))) return @@ -135,6 +136,11 @@ func (sig *Signature) parse(r io.Reader) (err error) { if err == nil { sig.DSASigS.bytes, sig.DSASigS.bitLength, err = readMPI(r) } + case PubKeyAlgoECDSA: + sig.ECDSASigR.bytes, sig.ECDSASigR.bitLength, err = readMPI(r) + if err == nil { + sig.ECDSASigS.bytes, sig.ECDSASigS.bitLength, err = readMPI(r) + } default: panic("unreachable") } @@ -499,7 +505,7 @@ func (sig *Signature) Serialize(w io.Writer) (err error) { if len(sig.outSubpackets) == 0 { sig.outSubpackets = sig.rawSubpackets } - if sig.RSASignature.bytes == nil && sig.DSASigR.bytes == nil { + if sig.RSASignature.bytes == nil && sig.DSASigR.bytes == nil && sig.ECDSASigR.bytes == nil { return errors.InvalidArgumentError("Signature: need to call Sign, SignUserId or SignKey before Serialize") } @@ -510,6 +516,9 @@ func (sig *Signature) Serialize(w io.Writer) (err error) { case PubKeyAlgoDSA: sigLength = 2 + len(sig.DSASigR.bytes) sigLength += 2 + len(sig.DSASigS.bytes) + case PubKeyAlgoECDSA: + sigLength = 2 + len(sig.ECDSASigR.bytes) + sigLength += 2 + len(sig.ECDSASigS.bytes) default: panic("impossible") } @@ -547,6 +556,8 @@ func (sig *Signature) Serialize(w io.Writer) (err error) { err = writeMPIs(w, sig.RSASignature) case PubKeyAlgoDSA: err = writeMPIs(w, sig.DSASigR, sig.DSASigS) + case PubKeyAlgoECDSA: + err = writeMPIs(w, sig.ECDSASigR, sig.ECDSASigS) default: panic("impossible") }