// buildHashSuffix constructs the HashSuffix member of sig in preparation for signing.
func (sig *Signature) buildHashSuffix() (err error) {
hashedSubpacketsLen := subpacketsLength(sig.outSubpackets, true)
var ok bool
l := 6 + hashedSubpacketsLen
sig.HashSuffix = make([]byte, l+6)
sig.HashSuffix[0] = 4
sig.HashSuffix[1] = uint8(sig.SigType)
sig.HashSuffix[2] = uint8(sig.PubKeyAlgo)
sig.HashSuffix[3], ok = s2k.HashToHashId(sig.Hash)
if !ok {
sig.HashSuffix = nil
return errors.InvalidArgumentError("hash cannot be represented in OpenPGP: " + strconv.Itoa(int(sig.Hash)))
}
sig.HashSuffix[4] = byte(hashedSubpacketsLen >> 8)
sig.HashSuffix[5] = byte(hashedSubpacketsLen)
serializeSubpackets(sig.HashSuffix[6:l], sig.outSubpackets, true)
trailer := sig.HashSuffix[l:]
trailer[0] = 4
trailer[1] = 0xff
trailer[2] = byte(l >> 24)
trailer[3] = byte(l >> 16)
trailer[4] = byte(l >> 8)
trailer[5] = byte(l)
return
}
func hashToHashId(h crypto.Hash) uint8 {
v, ok := s2k.HashToHashId(h)
if !ok {
panic("tried to convert unknown hash")
}
return v
}
// Serialize marshals the given OnePassSignature to w.
func (ops *OnePassSignature) Serialize(w io.Writer) error {
var buf [13]byte
buf[0] = onePassSignatureVersion
buf[1] = uint8(ops.SigType)
var ok bool
buf[2], ok = s2k.HashToHashId(ops.Hash)
if !ok {
return errors.UnsupportedError("hash type: " + strconv.Itoa(int(ops.Hash)))
}
buf[3] = uint8(ops.PubKeyAlgo)
binary.BigEndian.PutUint64(buf[4:12], ops.KeyId)
if ops.IsLast {
buf[12] = 1
}
if err := serializeHeader(w, packetTypeOnePassSignature, len(buf)); err != nil {
return err
}
_, err := w.Write(buf[:])
return err
}