fix dsa patches: truncate hash

[epoint] / patches / sig.diff

diff --git a/patches/sig.diff b/patches/sig.diff
index d3c49b5..7d00a73 100644 (file)
--- a/patches/sig.diff
+++ b/patches/sig.diff
@@ -1,6 +1,6 @@
 diff -r 7ec969250bfc src/pkg/crypto/openpgp/packet/signature.go
 --- a/src/pkg/crypto/openpgp/packet/signature.go       Tue Dec 27 09:49:19 2011 -0500
-+++ b/src/pkg/crypto/openpgp/packet/signature.go       Fri Dec 30 22:56:55 2011 +0100
++++ b/src/pkg/crypto/openpgp/packet/signature.go       Sat Dec 31 02:23:37 2011 +0100
 @@ -164,7 +164,7 @@
  const (
        creationTimeSubpacket        signatureSubpacketType = 2
@@ -32,7 +32,23 @@ diff -r 7ec969250bfc src/pkg/crypto/openpgp/packet/signature.go
                // Key expiration time, section 5.2.3.6
                if !isHashed {
                        return
-@@ -556,5 +552,59 @@
+@@ -443,7 +439,14 @@
+               sig.RSASignature.bytes, err = rsa.SignPKCS1v15(rand.Reader, priv.PrivateKey.(*rsa.PrivateKey), sig.Hash, digest)
+               sig.RSASignature.bitLength = uint16(8 * len(sig.RSASignature.bytes))
+       case PubKeyAlgoDSA:
+-              r, s, err := dsa.Sign(rand.Reader, priv.PrivateKey.(*dsa.PrivateKey), digest)
++              dsaPrivateKey := priv.PrivateKey.(*dsa.PrivateKey)
++              // hash truncation according to FIPS 186-3 section 4.6
++              n := len(digest)
++              k := (dsaPrivateKey.Q.BitLen() + 7) / 8
++              if n > k {
++                      n = k
++              }
++              r, s, err := dsa.Sign(rand.Reader, dsaPrivateKey, digest[:n])
+               if err == nil {
+                       sig.DSASigR.bytes = r.Bytes()
+                       sig.DSASigR.bitLength = uint16(8 * len(sig.DSASigR.bytes))
+@@ -556,5 +559,59 @@
                subpackets = append(subpackets, outputSubpacket{true, issuerSubpacket, false, keyId})
        }