code review 4639049: crypto/openpgp: add ElGamal support.

src/pkg/crypto/openpgp/packet/private_key.go

 // 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 (
         "big"
         "bytes"
         "crypto/cipher"
         "crypto/dsa"
+        "crypto/openpgp/elgamal"
         "crypto/openpgp/error"
         "crypto/openpgp/s2k"
         "crypto/rsa"
         "crypto/sha1"
         "io"
         "io/ioutil"
         "os"
         "strconv"
 )
 
@@ skipping 195 matching lines @@
 
         return pk.parsePrivateKey(data)
 }
 
 func (pk *PrivateKey) parsePrivateKey(data []byte) (err os.Error) {
         switch pk.PublicKey.PubKeyAlgo {
         case PubKeyAlgoRSA, PubKeyAlgoRSASignOnly, PubKeyAlgoRSAEncryptOnly:
                 return pk.parseRSAPrivateKey(data)
         case PubKeyAlgoDSA:
                 return pk.parseDSAPrivateKey(data)
+        case PubKeyAlgoElGamal:
+                return pk.parseElGamalPrivateKey(data)
         }
         panic("impossible")
 }
 
 func (pk *PrivateKey) parseRSAPrivateKey(data []byte) (err os.Error) {
         rsaPub := pk.PublicKey.PublicKey.(*rsa.PublicKey)
         rsaPriv := new(rsa.PrivateKey)
         rsaPriv.PublicKey = *rsaPub
 
         buf := bytes.NewBuffer(data)
@@ skipping 33 matching lines @@
                 return
         }
 
         dsaPriv.X = new(big.Int).SetBytes(x)
         pk.PrivateKey = dsaPriv
         pk.Encrypted = false
         pk.encryptedData = nil
 
         return nil
 }
+
+func (pk *PrivateKey) parseElGamalPrivateKey(data []byte) (err os.Error) {
+        pub := pk.PublicKey.PublicKey.(*elgamal.PublicKey)
+        priv := new(elgamal.PrivateKey)
+        priv.PublicKey = *pub
+
+        buf := bytes.NewBuffer(data)
+        x, _, err := readMPI(buf)
+        if err != nil {
+                return
+        }
+
+        priv.X = new(big.Int).SetBytes(x)
+        pk.PrivateKey = priv
+        pk.Encrypted = false
+        pk.encryptedData = nil
+
+        return nil
+}