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// Copyright 2011 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"
"io"
"strconv"
"github.com/ProtonMail/go-crypto/openpgp/errors"
"github.com/ProtonMail/go-crypto/openpgp/internal/algorithm"
)
// OnePassSignature represents a one-pass signature packet. See RFC 4880,
// section 5.4.
type OnePassSignature struct {
Version int
SigType SignatureType
Hash crypto.Hash
PubKeyAlgo PublicKeyAlgorithm
KeyId uint64
IsLast bool
Salt []byte // v6 only
KeyFingerprint []byte // v6 only
}
func (ops *OnePassSignature) parse(r io.Reader) (err error) {
var buf [8]byte
// Read: version | signature type | hash algorithm | public-key algorithm
_, err = readFull(r, buf[:4])
if err != nil {
return
}
if buf[0] != 3 && buf[0] != 6 {
return errors.UnsupportedError("one-pass-signature packet version " + strconv.Itoa(int(buf[0])))
}
ops.Version = int(buf[0])
var ok bool
ops.Hash, ok = algorithm.HashIdToHashWithSha1(buf[2])
if !ok {
return errors.UnsupportedError("hash function: " + strconv.Itoa(int(buf[2])))
}
ops.SigType = SignatureType(buf[1])
ops.PubKeyAlgo = PublicKeyAlgorithm(buf[3])
if ops.Version == 6 {
// Only for v6, a variable-length field containing the salt
_, err = readFull(r, buf[:1])
if err != nil {
return
}
saltLength := int(buf[0])
var expectedSaltLength int
expectedSaltLength, err = SaltLengthForHash(ops.Hash)
if err != nil {
return
}
if saltLength != expectedSaltLength {
err = errors.StructuralError("unexpected salt size for the given hash algorithm")
return
}
salt := make([]byte, expectedSaltLength)
_, err = readFull(r, salt)
if err != nil {
return
}
ops.Salt = salt
// Only for v6 packets, 32 octets of the fingerprint of the signing key.
fingerprint := make([]byte, 32)
_, err = readFull(r, fingerprint)
if err != nil {
return
}
ops.KeyFingerprint = fingerprint
ops.KeyId = binary.BigEndian.Uint64(ops.KeyFingerprint[:8])
} else {
_, err = readFull(r, buf[:8])
if err != nil {
return
}
ops.KeyId = binary.BigEndian.Uint64(buf[:8])
}
_, err = readFull(r, buf[:1])
if err != nil {
return
}
ops.IsLast = buf[0] != 0
return
}
// Serialize marshals the given OnePassSignature to w.
func (ops *OnePassSignature) Serialize(w io.Writer) error {
//v3 length 1+1+1+1+8+1 =
packetLength := 13
if ops.Version == 6 {
// v6 length 1+1+1+1+1+len(salt)+32+1 =
packetLength = 38 + len(ops.Salt)
}
if err := serializeHeader(w, packetTypeOnePassSignature, packetLength); err != nil {
return err
}
var buf [8]byte
buf[0] = byte(ops.Version)
buf[1] = uint8(ops.SigType)
var ok bool
buf[2], ok = algorithm.HashToHashIdWithSha1(ops.Hash)
if !ok {
return errors.UnsupportedError("hash type: " + strconv.Itoa(int(ops.Hash)))
}
buf[3] = uint8(ops.PubKeyAlgo)
_, err := w.Write(buf[:4])
if err != nil {
return err
}
if ops.Version == 6 {
// write salt for v6 signatures
_, err := w.Write([]byte{uint8(len(ops.Salt))})
if err != nil {
return err
}
_, err = w.Write(ops.Salt)
if err != nil {
return err
}
// write fingerprint v6 signatures
_, err = w.Write(ops.KeyFingerprint)
if err != nil {
return err
}
} else {
binary.BigEndian.PutUint64(buf[:8], ops.KeyId)
_, err := w.Write(buf[:8])
if err != nil {
return err
}
}
isLast := []byte{byte(0)}
if ops.IsLast {
isLast[0] = 1
}
_, err = w.Write(isLast)
return err
}
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