// ReadKeyRing reads one or more public/private keys. Unsupported keys are
// ignored as long as at least a single valid key is found.
func ReadKeyRing(r io.Reader) (el EntityList, err error) {
packets := packet.NewReader(r)
var lastUnsupportedError error
for {
var e *Entity
e, err = ReadEntity(packets)
if err != nil {
// TODO: warn about skipped unsupported/unreadable keys
if _, ok := err.(errors.UnsupportedError); ok {
lastUnsupportedError = err
err = readToNextPublicKey(packets)
} else if _, ok := err.(errors.StructuralError); ok {
// Skip unreadable, badly-formatted keys
lastUnsupportedError = err
err = readToNextPublicKey(packets)
}
if err == io.EOF {
err = nil
break
}
if err != nil {
el = nil
break
}
} else {
el = append(el, e)
}
}
if len(el) == 0 && err == nil {
err = lastUnsupportedError
}
return
}
// ReadMessage parses an OpenPGP message that may be signed and/or encrypted.
// The given KeyRing should contain both public keys (for signature
// verification) and, possibly encrypted, private keys for decrypting.
// If config is nil, sensible defaults will be used.
func ReadMessage(r io.Reader, keyring KeyRing, prompt PromptFunction, config *packet.Config) (md *MessageDetails, err error) {
var p packet.Packet
var symKeys []*packet.SymmetricKeyEncrypted
var pubKeys []keyEnvelopePair
var se *packet.SymmetricallyEncrypted
packets := packet.NewReader(r)
md = new(MessageDetails)
md.IsEncrypted = true
// The message, if encrypted, starts with a number of packets
// containing an encrypted decryption key. The decryption key is either
// encrypted to a public key, or with a passphrase. This loop
// collects these packets.
ParsePackets:
for {
p, err = packets.Next()
if err != nil {
return nil, err
}
switch p := p.(type) {
case *packet.SymmetricKeyEncrypted:
// This packet contains the decryption key encrypted with a passphrase.
md.IsSymmetricallyEncrypted = true
symKeys = append(symKeys, p)
case *packet.EncryptedKey:
// This packet contains the decryption key encrypted to a public key.
md.EncryptedToKeyIds = append(md.EncryptedToKeyIds, p.KeyId)
switch p.Algo {
case packet.PubKeyAlgoRSA, packet.PubKeyAlgoRSAEncryptOnly, packet.PubKeyAlgoElGamal:
break
default:
continue
}
var keys []Key
if p.KeyId == 0 {
keys = keyring.DecryptionKeys()
} else {
keys = keyring.KeysById(p.KeyId)
}
for _, k := range keys {
pubKeys = append(pubKeys, keyEnvelopePair{k, p})
}
case *packet.SymmetricallyEncrypted:
se = p
break ParsePackets
case *packet.Compressed, *packet.LiteralData, *packet.OnePassSignature:
// This message isn't encrypted.
if len(symKeys) != 0 || len(pubKeys) != 0 {
return nil, errors.StructuralError("key material not followed by encrypted message")
}
packets.Unread(p)
return readSignedMessage(packets, nil, keyring)
}
}
var candidates []Key
var decrypted io.ReadCloser
// Now that we have the list of encrypted keys we need to decrypt at
// least one of them or, if we cannot, we need to call the prompt
// function so that it can decrypt a key or give us a passphrase.
FindKey:
for {
// See if any of the keys already have a private key available
candidates = candidates[:0]
candidateFingerprints := make(map[string]bool)
for _, pk := range pubKeys {
if pk.key.PrivateKey == nil {
continue
}
if !pk.key.PrivateKey.Encrypted {
if len(pk.encryptedKey.Key) == 0 {
pk.encryptedKey.Decrypt(pk.key.PrivateKey, config)
}
if len(pk.encryptedKey.Key) == 0 {
continue
}
decrypted, err = se.Decrypt(pk.encryptedKey.CipherFunc, pk.encryptedKey.Key)
if err != nil && err != errors.ErrKeyIncorrect {
return nil, err
}
if decrypted != nil {
md.DecryptedWith = pk.key
break FindKey
}
} else {
fpr := string(pk.key.PublicKey.Fingerprint[:])
if v := candidateFingerprints[fpr]; v {
continue
}
candidates = append(candidates, pk.key)
candidateFingerprints[fpr] = true
}
}
if len(candidates) == 0 && len(symKeys) == 0 {
return nil, errors.ErrKeyIncorrect
}
if prompt == nil {
return nil, errors.ErrKeyIncorrect
}
passphrase, err := prompt(candidates, len(symKeys) != 0)
if err != nil {
return nil, err
}
// Try the symmetric passphrase first
if len(symKeys) != 0 && passphrase != nil {
for _, s := range symKeys {
key, cipherFunc, err := s.Decrypt(passphrase)
if err == nil {
decrypted, err = se.Decrypt(cipherFunc, key)
if err != nil && err != errors.ErrKeyIncorrect {
return nil, err
}
if decrypted != nil {
break FindKey
}
}
}
}
}
md.decrypted = decrypted
if err := packets.Push(decrypted); err != nil {
return nil, err
}
return readSignedMessage(packets, md, keyring)
}
// CheckDetachedSignature takes a signed file and a detached signature and
// returns the signer if the signature is valid. If the signer isn't known,
// ErrUnknownIssuer is returned.
func CheckDetachedSignature(keyring KeyRing, signed, signature io.Reader) (signer *Entity, err error) {
var issuerKeyId uint64
var hashFunc crypto.Hash
var sigType packet.SignatureType
var keys []Key
var p packet.Packet
packets := packet.NewReader(signature)
for {
p, err = packets.Next()
if err == io.EOF {
return nil, errors.ErrUnknownIssuer
}
if err != nil {
return nil, err
}
switch sig := p.(type) {
case *packet.Signature:
if sig.IssuerKeyId == nil {
return nil, errors.StructuralError("signature doesn't have an issuer")
}
issuerKeyId = *sig.IssuerKeyId
hashFunc = sig.Hash
sigType = sig.SigType
case *packet.SignatureV3:
issuerKeyId = sig.IssuerKeyId
hashFunc = sig.Hash
sigType = sig.SigType
default:
return nil, errors.StructuralError("non signature packet found")
}
keys = keyring.KeysByIdUsage(issuerKeyId, packet.KeyFlagSign)
if len(keys) > 0 {
break
}
}
if len(keys) == 0 {
panic("unreachable")
}
h, wrappedHash, err := hashForSignature(hashFunc, sigType)
if err != nil {
return nil, err
}
if _, err := io.Copy(wrappedHash, signed); err != nil && err != io.EOF {
return nil, err
}
for _, key := range keys {
switch sig := p.(type) {
case *packet.Signature:
err = key.PublicKey.VerifySignature(h, sig)
case *packet.SignatureV3:
err = key.PublicKey.VerifySignatureV3(h, sig)
default:
panic("unreachable")
}
if err == nil {
return key.Entity, nil
}
}
return nil, err
}