func addSubkey(e *Entity, packets *packet.Reader, pub *packet.PublicKey, priv *packet.PrivateKey) error {
var subKey Subkey
subKey.PublicKey = pub
subKey.PrivateKey = priv
p, err := packets.Next()
if err == io.EOF {
return io.ErrUnexpectedEOF
}
if err != nil {
return errors.StructuralError("subkey signature invalid: " + err.Error())
}
var ok bool
subKey.Sig, ok = p.(*packet.Signature)
if !ok {
return errors.StructuralError("subkey packet not followed by signature")
}
if subKey.Sig.SigType != packet.SigTypeSubkeyBinding && subKey.Sig.SigType != packet.SigTypeSubkeyRevocation {
return errors.StructuralError("subkey signature with wrong type")
}
err = e.PrimaryKey.VerifyKeySignature(subKey.PublicKey, subKey.Sig)
if err != nil {
return errors.StructuralError("subkey signature invalid: " + err.Error())
}
e.Subkeys = append(e.Subkeys, subKey)
return nil
}
// Decrypt attempts to decrypt an encrypted session key. If it returns nil,
// ske.Key will contain the session key.
func (ske *SymmetricKeyEncrypted) Decrypt(passphrase []byte) error {
if !ske.Encrypted {
return nil
}
key := make([]byte, ske.CipherFunc.KeySize())
ske.s2k(key, passphrase)
if len(ske.encryptedKey) == 0 {
ske.Key = key
} else {
// the IV is all zeros
iv := make([]byte, ske.CipherFunc.blockSize())
c := cipher.NewCFBDecrypter(ske.CipherFunc.new(key), iv)
c.XORKeyStream(ske.encryptedKey, ske.encryptedKey)
ske.CipherFunc = CipherFunction(ske.encryptedKey[0])
if ske.CipherFunc.blockSize() == 0 {
return errors.UnsupportedError("unknown cipher: " + strconv.Itoa(int(ske.CipherFunc)))
}
ske.CipherFunc = CipherFunction(ske.encryptedKey[0])
ske.Key = ske.encryptedKey[1:]
if len(ske.Key)%ske.CipherFunc.blockSize() != 0 {
ske.Key = nil
return errors.StructuralError("length of decrypted key not a multiple of block size")
}
}
ske.Encrypted = false
return nil
}
// Decrypt decrypts an encrypted session key with the given private key. The
// private key must have been decrypted first.
// If config is nil, sensible defaults will be used.
func (e *EncryptedKey) Decrypt(priv *PrivateKey, config *Config) error {
var err error
var b []byte
// TODO(agl): use session key decryption routines here to avoid
// padding oracle attacks.
switch priv.PubKeyAlgo {
case PubKeyAlgoRSA, PubKeyAlgoRSAEncryptOnly:
b, err = rsa.DecryptPKCS1v15(config.Random(), priv.PrivateKey.(*rsa.PrivateKey), e.encryptedMPI1)
case PubKeyAlgoElGamal:
c1 := new(big.Int).SetBytes(e.encryptedMPI1)
c2 := new(big.Int).SetBytes(e.encryptedMPI2)
b, err = elgamal.Decrypt(priv.PrivateKey.(*elgamal.PrivateKey), c1, c2)
default:
err = errors.InvalidArgumentError("cannot decrypted encrypted session key with private key of type " + strconv.Itoa(int(priv.PubKeyAlgo)))
}
if err != nil {
return err
}
e.CipherFunc = CipherFunction(b[0])
e.Key = b[1 : len(b)-2]
expectedChecksum := uint16(b[len(b)-2])<<8 | uint16(b[len(b)-1])
checksum := checksumKeyMaterial(e.Key)
if checksum != expectedChecksum {
return errors.StructuralError("EncryptedKey checksum incorrect")
}
return nil
}
// Decrypt decrypts an encrypted private key using a passphrase.
func (pk *PrivateKey) Decrypt(passphrase []byte) error {
if !pk.Encrypted {
return nil
}
key := make([]byte, pk.cipher.KeySize())
pk.s2k(key, passphrase)
block := pk.cipher.new(key)
cfb := cipher.NewCFBDecrypter(block, pk.iv)
data := make([]byte, len(pk.encryptedData))
cfb.XORKeyStream(data, pk.encryptedData)
if pk.sha1Checksum {
if len(data) < sha1.Size {
return errors.StructuralError("truncated private key data")
}
h := sha1.New()
h.Write(data[:len(data)-sha1.Size])
sum := h.Sum(nil)
if !bytes.Equal(sum, data[len(data)-sha1.Size:]) {
return errors.StructuralError("private key checksum failure")
}
data = data[:len(data)-sha1.Size]
} else {
if len(data) < 2 {
return errors.StructuralError("truncated private key data")
}
var sum uint16
for i := 0; i < len(data)-2; i++ {
sum += uint16(data[i])
}
if data[len(data)-2] != uint8(sum>>8) ||
data[len(data)-1] != uint8(sum) {
return errors.StructuralError("private key checksum failure")
}
data = data[:len(data)-2]
}
return pk.parsePrivateKey(data)
}
// parseSignatureSubpackets parses subpackets of the main signature packet. See
// RFC 4880, section 5.2.3.1.
func parseSignatureSubpackets(sig *Signature, subpackets []byte, isHashed bool) (err error) {
for len(subpackets) > 0 {
subpackets, err = parseSignatureSubpacket(sig, subpackets, isHashed)
if err != nil {
return
}
}
if sig.CreationTime.IsZero() {
err = errors.StructuralError("no creation time in signature")
}
return
}
// readHeader parses a packet header and returns an io.Reader which will return
// the contents of the packet. See RFC 4880, section 4.2.
func readHeader(r io.Reader) (tag packetType, length int64, contents io.Reader, err error) {
var buf [4]byte
_, err = io.ReadFull(r, buf[:1])
if err != nil {
return
}
if buf[0]&0x80 == 0 {
err = errors.StructuralError("tag byte does not have MSB set")
return
}
if buf[0]&0x40 == 0 {
// Old format packet
tag = packetType((buf[0] & 0x3f) >> 2)
lengthType := buf[0] & 3
if lengthType == 3 {
length = -1
contents = r
return
}
lengthBytes := 1 << lengthType
_, err = readFull(r, buf[0:lengthBytes])
if err != nil {
return
}
for i := 0; i < lengthBytes; i++ {
length <<= 8
length |= int64(buf[i])
}
contents = &spanReader{r, length}
return
}
// New format packet
tag = packetType(buf[0] & 0x3f)
length, isPartial, err := readLength(r)
if err != nil {
return
}
if isPartial {
contents = &partialLengthReader{
remaining: length,
isPartial: true,
r: r,
}
length = -1
} else {
contents = &spanReader{r, length}
}
return
}
func nextSubpacket(contents []byte) (subHeaderLen int, subPacket *OpaqueSubpacket, err error) {
// RFC 4880, section 5.2.3.1
var subLen uint32
if len(contents) < 1 {
goto Truncated
}
subPacket = &OpaqueSubpacket{}
switch {
case contents[0] < 192:
subHeaderLen = 2 // 1 length byte, 1 subtype byte
if len(contents) < subHeaderLen {
goto Truncated
}
subLen = uint32(contents[0])
contents = contents[1:]
case contents[0] < 255:
subHeaderLen = 3 // 2 length bytes, 1 subtype
if len(contents) < subHeaderLen {
goto Truncated
}
subLen = uint32(contents[0]-192)<<8 + uint32(contents[1]) + 192
contents = contents[2:]
default:
subHeaderLen = 6 // 5 length bytes, 1 subtype
if len(contents) < subHeaderLen {
goto Truncated
}
subLen = uint32(contents[1])<<24 |
uint32(contents[2])<<16 |
uint32(contents[3])<<8 |
uint32(contents[4])
contents = contents[5:]
}
if subLen > uint32(len(contents)) {
goto Truncated
}
subPacket.SubType = contents[0]
subPacket.Contents = contents[1:subLen]
return
Truncated:
err = errors.StructuralError("subpacket truncated")
return
}
// parseSignatureSubpacket parses a single subpacket. len(subpacket) is >= 1.
func parseSignatureSubpacket(sig *Signature, subpacket []byte, isHashed bool) (rest []byte, err error) {
// RFC 4880, section 5.2.3.1
var (
length uint32
packetType signatureSubpacketType
isCritical bool
)
switch {
case subpacket[0] < 192:
length = uint32(subpacket[0])
subpacket = subpacket[1:]
case subpacket[0] < 255:
if len(subpacket) < 2 {
goto Truncated
}
length = uint32(subpacket[0]-192)<<8 + uint32(subpacket[1]) + 192
subpacket = subpacket[2:]
default:
if len(subpacket) < 5 {
goto Truncated
}
length = uint32(subpacket[1])<<24 |
uint32(subpacket[2])<<16 |
uint32(subpacket[3])<<8 |
uint32(subpacket[4])
subpacket = subpacket[5:]
}
if length > uint32(len(subpacket)) {
goto Truncated
}
rest = subpacket[length:]
subpacket = subpacket[:length]
if len(subpacket) == 0 {
err = errors.StructuralError("zero length signature subpacket")
return
}
packetType = signatureSubpacketType(subpacket[0] & 0x7f)
isCritical = subpacket[0]&0x80 == 0x80
subpacket = subpacket[1:]
sig.rawSubpackets = append(sig.rawSubpackets, outputSubpacket{isHashed, packetType, isCritical, subpacket})
switch packetType {
case creationTimeSubpacket:
if !isHashed {
err = errors.StructuralError("signature creation time in non-hashed area")
return
}
if len(subpacket) != 4 {
err = errors.StructuralError("signature creation time not four bytes")
return
}
t := binary.BigEndian.Uint32(subpacket)
sig.CreationTime = time.Unix(int64(t), 0)
case signatureExpirationSubpacket:
// Signature expiration time, section 5.2.3.10
if !isHashed {
return
}
if len(subpacket) != 4 {
err = errors.StructuralError("expiration subpacket with bad length")
return
}
sig.SigLifetimeSecs = new(uint32)
*sig.SigLifetimeSecs = binary.BigEndian.Uint32(subpacket)
case keyExpirationSubpacket:
// Key expiration time, section 5.2.3.6
if !isHashed {
return
}
if len(subpacket) != 4 {
err = errors.StructuralError("key expiration subpacket with bad length")
return
}
sig.KeyLifetimeSecs = new(uint32)
*sig.KeyLifetimeSecs = binary.BigEndian.Uint32(subpacket)
case prefSymmetricAlgosSubpacket:
// Preferred symmetric algorithms, section 5.2.3.7
if !isHashed {
return
}
sig.PreferredSymmetric = make([]byte, len(subpacket))
copy(sig.PreferredSymmetric, subpacket)
case issuerSubpacket:
// Issuer, section 5.2.3.5
if len(subpacket) != 8 {
err = errors.StructuralError("issuer subpacket with bad length")
return
}
sig.IssuerKeyId = new(uint64)
*sig.IssuerKeyId = binary.BigEndian.Uint64(subpacket)
case prefHashAlgosSubpacket:
// Preferred hash algorithms, section 5.2.3.8
if !isHashed {
return
}
sig.PreferredHash = make([]byte, len(subpacket))
copy(sig.PreferredHash, subpacket)
case prefCompressionSubpacket:
// Preferred compression algorithms, section 5.2.3.9
if !isHashed {
return
}
sig.PreferredCompression = make([]byte, len(subpacket))
copy(sig.PreferredCompression, subpacket)
case primaryUserIdSubpacket:
// Primary User ID, section 5.2.3.19
if !isHashed {
return
}
if len(subpacket) != 1 {
err = errors.StructuralError("primary user id subpacket with bad length")
return
}
sig.IsPrimaryId = new(bool)
if subpacket[0] > 0 {
*sig.IsPrimaryId = true
}
case keyFlagsSubpacket:
// Key flags, section 5.2.3.21
if !isHashed {
return
}
if len(subpacket) == 0 {
err = errors.StructuralError("empty key flags subpacket")
return
}
sig.FlagsValid = true
if subpacket[0]&KeyFlagCertify != 0 {
sig.FlagCertify = true
}
if subpacket[0]&KeyFlagSign != 0 {
sig.FlagSign = true
}
if subpacket[0]&KeyFlagEncryptCommunications != 0 {
sig.FlagEncryptCommunications = true
}
if subpacket[0]&KeyFlagEncryptStorage != 0 {
sig.FlagEncryptStorage = true
}
case reasonForRevocationSubpacket:
// Reason For Revocation, section 5.2.3.23
if !isHashed {
return
}
if len(subpacket) == 0 {
err = errors.StructuralError("empty revocation reason subpacket")
return
}
sig.RevocationReason = new(uint8)
*sig.RevocationReason = subpacket[0]
sig.RevocationReasonText = string(subpacket[1:])
default:
if isCritical {
err = errors.UnsupportedError("unknown critical signature subpacket type " + strconv.Itoa(int(packetType)))
return
}
}
return
Truncated:
err = errors.StructuralError("signature subpacket truncated")
return
}
// ReadEntity reads an entity (public key, identities, subkeys etc) from the
// given Reader.
func ReadEntity(packets *packet.Reader) (*Entity, error) {
e := new(Entity)
e.Identities = make(map[string]*Identity)
p, err := packets.Next()
if err != nil {
return nil, err
}
var ok bool
if e.PrimaryKey, ok = p.(*packet.PublicKey); !ok {
if e.PrivateKey, ok = p.(*packet.PrivateKey); !ok {
packets.Unread(p)
return nil, errors.StructuralError("first packet was not a public/private key")
} else {
e.PrimaryKey = &e.PrivateKey.PublicKey
}
}
if !e.PrimaryKey.PubKeyAlgo.CanSign() {
return nil, errors.StructuralError("primary key cannot be used for signatures")
}
var current *Identity
var revocations []*packet.Signature
EachPacket:
for {
p, err := packets.Next()
if err == io.EOF {
break
} else if err != nil {
return nil, err
}
switch pkt := p.(type) {
case *packet.UserId:
current = new(Identity)
current.Name = pkt.Id
current.UserId = pkt
e.Identities[pkt.Id] = current
for {
p, err = packets.Next()
if err == io.EOF {
return nil, io.ErrUnexpectedEOF
} else if err != nil {
return nil, err
}
sig, ok := p.(*packet.Signature)
if !ok {
return nil, errors.StructuralError("user ID packet not followed by self-signature")
}
if (sig.SigType == packet.SigTypePositiveCert || sig.SigType == packet.SigTypeGenericCert) && sig.IssuerKeyId != nil && *sig.IssuerKeyId == e.PrimaryKey.KeyId {
if err = e.PrimaryKey.VerifyUserIdSignature(pkt.Id, e.PrimaryKey, sig); err != nil {
return nil, errors.StructuralError("user ID self-signature invalid: " + err.Error())
}
current.SelfSignature = sig
break
}
current.Signatures = append(current.Signatures, sig)
}
case *packet.Signature:
if pkt.SigType == packet.SigTypeKeyRevocation {
revocations = append(revocations, pkt)
} else if pkt.SigType == packet.SigTypeDirectSignature {
// TODO: RFC4880 5.2.1 permits signatures
// directly on keys (eg. to bind additional
// revocation keys).
} else if current == nil {
return nil, errors.StructuralError("signature packet found before user id packet")
} else {
current.Signatures = append(current.Signatures, pkt)
}
case *packet.PrivateKey:
if pkt.IsSubkey == false {
packets.Unread(p)
break EachPacket
}
err = addSubkey(e, packets, &pkt.PublicKey, pkt)
if err != nil {
return nil, err
}
case *packet.PublicKey:
if pkt.IsSubkey == false {
packets.Unread(p)
break EachPacket
}
err = addSubkey(e, packets, pkt, nil)
if err != nil {
return nil, err
}
default:
// we ignore unknown packets
}
}
if len(e.Identities) == 0 {
return nil, errors.StructuralError("entity without any identities")
}
for _, revocation := range revocations {
err = e.PrimaryKey.VerifyRevocationSignature(revocation)
if err == nil {
e.Revocations = append(e.Revocations, revocation)
} else {
// TODO: RFC 4880 5.2.3.15 defines revocation keys.
return nil, errors.StructuralError("revocation signature signed by alternate key")
}
}
return e, nil
}
// base64-encoded Bytes
// '=' base64 encoded checksum
// -----END Type-----
// where Headers is a possibly empty sequence of Key: Value lines.
//
// Since the armored data can be very large, this package presents a streaming
// interface.
type Block struct {
Type string // The type, taken from the preamble (i.e. "PGP SIGNATURE").
Header map[string]string // Optional headers.
Body io.Reader // A Reader from which the contents can be read
lReader lineReader
oReader openpgpReader
}
var ArmorCorrupt error = errors.StructuralError("armor invalid")
const crc24Init = 0xb704ce
const crc24Poly = 0x1864cfb
const crc24Mask = 0xffffff
// crc24 calculates the OpenPGP checksum as specified in RFC 4880, section 6.1
func crc24(crc uint32, d []byte) uint32 {
for _, b := range d {
crc ^= uint32(b) << 16
for i := 0; i < 8; i++ {
crc <<= 1
if crc&0x1000000 != 0 {
crc ^= crc24Poly
}
}