diff options
Diffstat (limited to 'src/pkg/crypto/openpgp/packet/signature.go')
| -rw-r--r-- | src/pkg/crypto/openpgp/packet/signature.go | 108 |
1 files changed, 85 insertions, 23 deletions
diff --git a/src/pkg/crypto/openpgp/packet/signature.go b/src/pkg/crypto/openpgp/packet/signature.go index fd2518ab4..719657e76 100644 --- a/src/pkg/crypto/openpgp/packet/signature.go +++ b/src/pkg/crypto/openpgp/packet/signature.go @@ -5,7 +5,9 @@ package packet import ( + "big" "crypto" + "crypto/dsa" "crypto/openpgp/error" "crypto/openpgp/s2k" "crypto/rand" @@ -29,7 +31,9 @@ type Signature struct { // of bad signed data. HashTag [2]byte CreationTime uint32 // Unix epoch time - Signature []byte + + RSASignature []byte + DSASigR, DSASigS *big.Int // The following are optional so are nil when not included in the // signature. @@ -66,7 +70,7 @@ func (sig *Signature) parse(r io.Reader) (err os.Error) { sig.SigType = SignatureType(buf[0]) sig.PubKeyAlgo = PublicKeyAlgorithm(buf[1]) switch sig.PubKeyAlgo { - case PubKeyAlgoRSA, PubKeyAlgoRSASignOnly: + case PubKeyAlgoRSA, PubKeyAlgoRSASignOnly, PubKeyAlgoDSA: default: err = error.UnsupportedError("public key algorithm " + strconv.Itoa(int(sig.PubKeyAlgo))) return @@ -122,8 +126,20 @@ func (sig *Signature) parse(r io.Reader) (err os.Error) { return } - // We have already checked that the public key algorithm is RSA. - sig.Signature, _, err = readMPI(r) + switch sig.PubKeyAlgo { + case PubKeyAlgoRSA, PubKeyAlgoRSASignOnly: + sig.RSASignature, _, err = readMPI(r) + case PubKeyAlgoDSA: + var rBytes, sBytes []byte + rBytes, _, err = readMPI(r) + sig.DSASigR = new(big.Int).SetBytes(rBytes) + if err == nil { + sBytes, _, err = readMPI(r) + sig.DSASigS = new(big.Int).SetBytes(sBytes) + } + default: + panic("unreachable") + } return } @@ -316,8 +332,8 @@ func subpacketLengthLength(length int) int { return 5 } -// serialiseSubpacketLength marshals the given length into to. -func serialiseSubpacketLength(to []byte, length int) int { +// serializeSubpacketLength marshals the given length into to. +func serializeSubpacketLength(to []byte, length int) int { if length < 192 { to[0] = byte(length) return 1 @@ -336,7 +352,7 @@ func serialiseSubpacketLength(to []byte, length int) int { return 5 } -// subpacketsLength returns the serialised length, in bytes, of the given +// subpacketsLength returns the serialized length, in bytes, of the given // subpackets. func subpacketsLength(subpackets []outputSubpacket, hashed bool) (length int) { for _, subpacket := range subpackets { @@ -349,11 +365,11 @@ func subpacketsLength(subpackets []outputSubpacket, hashed bool) (length int) { return } -// serialiseSubpackets marshals the given subpackets into to. -func serialiseSubpackets(to []byte, subpackets []outputSubpacket, hashed bool) { +// serializeSubpackets marshals the given subpackets into to. +func serializeSubpackets(to []byte, subpackets []outputSubpacket, hashed bool) { for _, subpacket := range subpackets { if subpacket.hashed == hashed { - n := serialiseSubpacketLength(to, len(subpacket.contents)+1) + n := serializeSubpacketLength(to, len(subpacket.contents)+1) to[n] = byte(subpacket.subpacketType) to = to[1+n:] n = copy(to, subpacket.contents) @@ -381,7 +397,7 @@ func (sig *Signature) buildHashSuffix() (err os.Error) { } sig.HashSuffix[4] = byte(hashedSubpacketsLen >> 8) sig.HashSuffix[5] = byte(hashedSubpacketsLen) - serialiseSubpackets(sig.HashSuffix[6:l], sig.outSubpackets, true) + serializeSubpackets(sig.HashSuffix[6:l], sig.outSubpackets, true) trailer := sig.HashSuffix[l:] trailer[0] = 4 trailer[1] = 0xff @@ -392,32 +408,66 @@ func (sig *Signature) buildHashSuffix() (err os.Error) { return } -// SignRSA signs a message with an RSA private key. The hash, h, must contain -// the hash of message to be signed and will be mutated by this function. -func (sig *Signature) SignRSA(h hash.Hash, priv *rsa.PrivateKey) (err os.Error) { +func (sig *Signature) signPrepareHash(h hash.Hash) (digest []byte, err os.Error) { err = sig.buildHashSuffix() if err != nil { return } h.Write(sig.HashSuffix) - digest := h.Sum() + digest = h.Sum() copy(sig.HashTag[:], digest) - sig.Signature, err = rsa.SignPKCS1v15(rand.Reader, priv, sig.Hash, digest) return } -// Serialize marshals sig to w. SignRSA must have been called first. +// SignRSA signs a message with an RSA private key. The hash, h, must contain +// the hash of the message to be signed and will be mutated by this function. +// On success, the signature is stored in sig. Call Serialize to write it out. +func (sig *Signature) SignRSA(h hash.Hash, priv *rsa.PrivateKey) (err os.Error) { + digest, err := sig.signPrepareHash(h) + if err != nil { + return + } + sig.RSASignature, err = rsa.SignPKCS1v15(rand.Reader, priv, sig.Hash, digest) + return +} + +// SignDSA signs a message with a DSA private key. The hash, h, must contain +// the hash of the message to be signed and will be mutated by this function. +// On success, the signature is stored in sig. Call Serialize to write it out. +func (sig *Signature) SignDSA(h hash.Hash, priv *dsa.PrivateKey) (err os.Error) { + digest, err := sig.signPrepareHash(h) + if err != nil { + return + } + sig.DSASigR, sig.DSASigS, err = dsa.Sign(rand.Reader, priv, digest) + return +} + +// Serialize marshals sig to w. SignRSA or SignDSA must have been called first. func (sig *Signature) Serialize(w io.Writer) (err os.Error) { - if sig.Signature == nil { - return error.InvalidArgumentError("Signature: need to call SignRSA before Serialize") + if sig.RSASignature == nil && sig.DSASigR == nil { + return error.InvalidArgumentError("Signature: need to call SignRSA or SignDSA before Serialize") + } + + sigLength := 0 + switch sig.PubKeyAlgo { + case PubKeyAlgoRSA, PubKeyAlgoRSASignOnly: + sigLength = len(sig.RSASignature) + case PubKeyAlgoDSA: + sigLength = 2 /* MPI length */ + sigLength += (sig.DSASigR.BitLen() + 7) / 8 + sigLength += 2 /* MPI length */ + sigLength += (sig.DSASigS.BitLen() + 7) / 8 + default: + panic("impossible") } unhashedSubpacketsLen := subpacketsLength(sig.outSubpackets, false) length := len(sig.HashSuffix) - 6 /* trailer not included */ + 2 /* length of unhashed subpackets */ + unhashedSubpacketsLen + - 2 /* hash tag */ + 2 /* length of signature MPI */ + len(sig.Signature) - err = serialiseHeader(w, packetTypeSignature, length) + 2 /* hash tag */ + 2 /* length of signature MPI */ + sigLength + err = serializeHeader(w, packetTypeSignature, length) if err != nil { return } @@ -430,7 +480,7 @@ func (sig *Signature) Serialize(w io.Writer) (err os.Error) { unhashedSubpackets := make([]byte, 2+unhashedSubpacketsLen) unhashedSubpackets[0] = byte(unhashedSubpacketsLen >> 8) unhashedSubpackets[1] = byte(unhashedSubpacketsLen) - serialiseSubpackets(unhashedSubpackets[2:], sig.outSubpackets, false) + serializeSubpackets(unhashedSubpackets[2:], sig.outSubpackets, false) _, err = w.Write(unhashedSubpackets) if err != nil { @@ -440,7 +490,19 @@ func (sig *Signature) Serialize(w io.Writer) (err os.Error) { if err != nil { return } - return writeMPI(w, 8*uint16(len(sig.Signature)), sig.Signature) + + switch sig.PubKeyAlgo { + case PubKeyAlgoRSA, PubKeyAlgoRSASignOnly: + err = writeMPI(w, 8*uint16(len(sig.RSASignature)), sig.RSASignature) + case PubKeyAlgoDSA: + err = writeBig(w, sig.DSASigR) + if err == nil { + err = writeBig(w, sig.DSASigS) + } + default: + panic("impossible") + } + return } // outputSubpacket represents a subpacket to be marshaled. |