// NewEntity returns an Entity that contains a fresh RSA/RSA keypair with a
// single identity composed of the given full name, comment and email, any of
// which may be empty but must not contain any of "()<>\x00".
// If config is nil, sensible defaults will be used.
func NewEntity(name, comment, email string, config *packet.Config) (*Entity, error) {
currentTime := config.Now()
uid := packet.NewUserId(name, comment, email)
if uid == nil {
return nil, errors.InvalidArgumentError("user id field contained invalid characters")
}
signingPriv, err := rsa.GenerateKey(config.Random(), defaultRSAKeyBits)
if err != nil {
return nil, err
}
encryptingPriv, err := rsa.GenerateKey(config.Random(), defaultRSAKeyBits)
if err != nil {
return nil, err
}
e := &Entity{
PrimaryKey: packet.NewRSAPublicKey(currentTime, &signingPriv.PublicKey),
PrivateKey: packet.NewRSAPrivateKey(currentTime, signingPriv),
Identities: make(map[string]*Identity),
}
isPrimaryId := true
e.Identities[uid.Id] = &Identity{
Name: uid.Name,
UserId: uid,
SelfSignature: &packet.Signature{
CreationTime: currentTime,
SigType: packet.SigTypePositiveCert,
PubKeyAlgo: packet.PubKeyAlgoRSA,
Hash: config.Hash(),
IsPrimaryId: &isPrimaryId,
FlagsValid: true,
FlagSign: true,
FlagCertify: true,
IssuerKeyId: &e.PrimaryKey.KeyId,
},
}
e.Subkeys = make([]Subkey, 1)
e.Subkeys[0] = Subkey{
PublicKey: packet.NewRSAPublicKey(currentTime, &encryptingPriv.PublicKey),
PrivateKey: packet.NewRSAPrivateKey(currentTime, encryptingPriv),
Sig: &packet.Signature{
CreationTime: currentTime,
SigType: packet.SigTypeSubkeyBinding,
PubKeyAlgo: packet.PubKeyAlgoRSA,
Hash: config.Hash(),
FlagsValid: true,
FlagEncryptStorage: true,
FlagEncryptCommunications: true,
IssuerKeyId: &e.PrimaryKey.KeyId,
},
}
e.Subkeys[0].PublicKey.IsSubkey = true
e.Subkeys[0].PrivateKey.IsSubkey = true
return e, nil
}
// copied from crypto/openpgp/packet.(*Signature).Sign()
func MakeSignature(pgpsig *packet.Signature, priv *packet.PrivateKey, digest []byte) (err error) {
sig := (*Signature)(unsafe.Pointer(pgpsig))
var config *packet.Config
switch priv.PubKeyAlgo {
case packet.PubKeyAlgoRSA, packet.PubKeyAlgoRSASignOnly:
sig.RSASignature.bytes, err = rsa.SignPKCS1v15(config.Random(), priv.PrivateKey.(*rsa.PrivateKey), sig.Hash, digest)
sig.RSASignature.bitLength = uint16(8 * len(sig.RSASignature.bytes))
case packet.PubKeyAlgoDSA:
dsaPriv := priv.PrivateKey.(*dsa.PrivateKey)
r, s, err := dsa.Sign(config.Random(), dsaPriv, digest)
if err == nil {
sig.DSASigR.bytes = r.Bytes()
sig.DSASigR.bitLength = uint16(8 * len(sig.DSASigR.bytes))
sig.DSASigS.bytes = s.Bytes()
sig.DSASigS.bitLength = uint16(8 * len(sig.DSASigS.bytes))
}
default:
err = errors.UnsupportedError("public key algorithm: " + strconv.Itoa(int(sig.PubKeyAlgo)))
}
return
}
// Encrypt encrypts a message to a number of recipients and, optionally, signs
// it. hints contains optional information, that is also encrypted, that aids
// the recipients in processing the message. The resulting WriteCloser must
// be closed after the contents of the file have been written.
// If config is nil, sensible defaults will be used.
func Encrypt(ciphertext io.Writer, to []*Entity, signed *Entity, hints *FileHints, config *packet.Config) (plaintext io.WriteCloser, err error) {
var signer *packet.PrivateKey
if signed != nil {
signer = signed.signingKey().PrivateKey
if signer == nil || signer.Encrypted {
return nil, errors.InvalidArgumentError("signing key must be decrypted")
}
}
// These are the possible ciphers that we'll use for the message.
candidateCiphers := []uint8{
uint8(packet.CipherAES128),
uint8(packet.CipherAES256),
uint8(packet.CipherCAST5),
}
// These are the possible hash functions that we'll use for the signature.
candidateHashes := []uint8{
hashToHashId(crypto.SHA256),
hashToHashId(crypto.SHA512),
hashToHashId(crypto.SHA1),
hashToHashId(crypto.RIPEMD160),
}
// In the event that a recipient doesn't specify any supported ciphers
// or hash functions, these are the ones that we assume that every
// implementation supports.
defaultCiphers := candidateCiphers[len(candidateCiphers)-1:]
defaultHashes := candidateHashes[len(candidateHashes)-1:]
encryptKeys := make([]Key, len(to))
for i := range to {
encryptKeys[i] = to[i].encryptionKey()
if encryptKeys[i].PublicKey == nil {
return nil, errors.InvalidArgumentError("cannot encrypt a message to key id " + strconv.FormatUint(to[i].PrimaryKey.KeyId, 16) + " because it has no encryption keys")
}
sig := to[i].primaryIdentity().SelfSignature
preferredSymmetric := sig.PreferredSymmetric
if len(preferredSymmetric) == 0 {
preferredSymmetric = defaultCiphers
}
preferredHashes := sig.PreferredHash
if len(preferredHashes) == 0 {
preferredHashes = defaultHashes
}
candidateCiphers = intersectPreferences(candidateCiphers, preferredSymmetric)
candidateHashes = intersectPreferences(candidateHashes, preferredHashes)
}
if len(candidateCiphers) == 0 || len(candidateHashes) == 0 {
return nil, errors.InvalidArgumentError("cannot encrypt because recipient set shares no common algorithms")
}
cipher := packet.CipherFunction(candidateCiphers[0])
// If the cipher specifed by config is a candidate, we'll use that.
configuredCipher := config.Cipher()
for _, c := range candidateCiphers {
cipherFunc := packet.CipherFunction(c)
if cipherFunc == configuredCipher {
cipher = cipherFunc
break
}
}
hashFunc := candidateHashes[0]
// If the hash specified by config is a candidate, we'll use that.
configuredHash := config.Hash()
for _, h := range candidateHashes {
if h == uint8(configuredHash) {
hashFunc = h
break
}
}
hash, _ := s2k.HashIdToHash(hashFunc)
symKey := make([]byte, cipher.KeySize())
if _, err := io.ReadFull(config.Random(), symKey); err != nil {
return nil, err
}
for _, key := range encryptKeys {
if err := packet.SerializeEncryptedKey(ciphertext, key.PublicKey, cipher, symKey, config); err != nil {
return nil, err
}
}
encryptedData, err := packet.SerializeSymmetricallyEncrypted(ciphertext, cipher, symKey, config)
if err != nil {
return
}
if signer != nil {
ops := &packet.OnePassSignature{
SigType: packet.SigTypeBinary,
Hash: hash,
PubKeyAlgo: signer.PubKeyAlgo,
KeyId: signer.KeyId,
IsLast: true,
}
if err := ops.Serialize(encryptedData); err != nil {
return nil, err
}
}
if hints == nil {
hints = &FileHints{}
}
w := encryptedData
if signer != nil {
// If we need to write a signature packet after the literal
// data then we need to stop literalData from closing
// encryptedData.
w = noOpCloser{encryptedData}
}
var epochSeconds uint32
if !hints.ModTime.IsZero() {
epochSeconds = uint32(hints.ModTime.Unix())
}
literalData, err := packet.SerializeLiteral(w, hints.IsBinary, hints.FileName, epochSeconds)
if err != nil {
return nil, err
}
if signer != nil {
return signatureWriter{encryptedData, literalData, hash, hash.New(), signer, config}, nil
}
return literalData, nil
}