2 files changed, 45 insertions, 1 deletions
diff --git a/src/pkg/crypto/openpgp/s2k/s2k.go b/src/pkg/crypto/openpgp/s2k/s2k.go
index 93b7582fa..da926a76e 100644
--- a/src/pkg/crypto/openpgp/s2k/s2k.go
+++ b/src/pkg/crypto/openpgp/s2k/s2k.go
@@ -90,7 +90,7 @@ func Parse(r io.Reader) (f func(out, in []byte), err os.Error) {
 	}
 	h := hash.New()
 	if h == nil {
-		return nil, error.UnsupportedError("hash not availible: " + strconv.Itoa(int(hash)))
+		return nil, error.UnsupportedError("hash not available: " + strconv.Itoa(int(hash)))
 	}
 
 	switch buf[0] {
@@ -123,6 +123,26 @@ func Parse(r io.Reader) (f func(out, in []byte), err os.Error) {
 	return nil, error.UnsupportedError("S2K function")
 }
 
+// Serialize salts and stretches the given passphrase and writes the resulting
+// key into key. It also serializes an S2K descriptor to w.
+func Serialize(w io.Writer, key []byte, rand io.Reader, passphrase []byte) os.Error {
+	var buf [11]byte
+	buf[0] = 3 /* iterated and salted */
+	buf[1], _ = HashToHashId(crypto.SHA1)
+	salt := buf[2:10]
+	if _, err := io.ReadFull(rand, salt); err != nil {
+		return err
+	}
+	const count = 65536 // this is the default in gpg
+	buf[10] = 96        // 65536 iterations
+	if _, err := w.Write(buf[:]); err != nil {
+		return err
+	}
+
+	Iterated(key, crypto.SHA1.New(), passphrase, salt, count)
+	return nil
+}
+
 // hashToHashIdMapping contains pairs relating OpenPGP's hash identifier with
 // Go's crypto.Hash type. See RFC 4880, section 9.4.
 var hashToHashIdMapping = []struct {
diff --git a/src/pkg/crypto/openpgp/s2k/s2k_test.go b/src/pkg/crypto/openpgp/s2k/s2k_test.go
index 75bc47ec1..27d2e9ae0 100644
--- a/src/pkg/crypto/openpgp/s2k/s2k_test.go
+++ b/src/pkg/crypto/openpgp/s2k/s2k_test.go
@@ -7,6 +7,7 @@ package s2k
 import (
 	"bytes"
 	"crypto/sha1"
+	"crypto/rand"
 	"encoding/hex"
 	"testing"
 )
@@ -95,3 +96,26 @@ func TestParse(t *testing.T) {
 		}
 	}
 }
+
+
+func TestSerialize(t *testing.T) {
+	buf := bytes.NewBuffer(nil)
+	key := make([]byte, 16)
+	passphrase := []byte("testing")
+	err := Serialize(buf, key, rand.Reader, passphrase)
+	if err != nil {
+		t.Errorf("failed to serialize: %s", err)
+		return
+	}
+
+	f, err := Parse(buf)
+	if err != nil {
+		t.Errorf("failed to reparse: %s", err)
+		return
+	}
+	key2 := make([]byte, len(key))
+	f(key2, passphrase)
+	if !bytes.Equal(key2, key) {
+		t.Errorf("keys don't match: %x (serialied) vs %x (parsed)", key, key2)
+	}
+}