From 45362590377a7a6b8194c32da1f0772cbeac39ec Mon Sep 17 00:00:00 2001
From: Miek Gieben <miek@miek.nl>
Date: Tue, 17 Apr 2012 11:39:58 +0200
Subject: [PATCH] 1/2 support for DSA

---
 TODO.markdown |  2 +-
 dnssec.go     | 43 ++++++++++++++++++++++++++++++++++++++++++-
 kscan.go      | 32 ++++++++++++++++++++++++++++++--
 3 files changed, 73 insertions(+), 4 deletions(-)

diff --git a/TODO.markdown b/TODO.markdown
index f6a12b63..f6502862 100644
--- a/TODO.markdown
+++ b/TODO.markdown
@@ -6,7 +6,7 @@ need to be fixed.
 * Speed, we can always go faster. A simple reflect server now hits 35/45K qps
 * go test; only works correct on my machine
 * Add handy zone data structure (r/b tree)? Or not...
-* dnssec: DSA (also the keytag)
+* privatekey.Precompute() when signing? 
 
 ## Examples to add
 
diff --git a/dnssec.go b/dnssec.go
index ec946d00..3d9d7898 100644
--- a/dnssec.go
+++ b/dnssec.go
@@ -16,6 +16,7 @@ package dns
 import (
 	"bytes"
 	"crypto"
+	"crypto/dsa"
 	"crypto/ecdsa"
 	"crypto/elliptic"
 	"crypto/md5"
@@ -432,8 +433,18 @@ func (s *RR_RRSIG) sigBuf() []byte {
 // setPublicKeyInPrivate sets the public key in the private key. 
 func (k *RR_DNSKEY) setPublicKeyInPrivate(p PrivateKey) bool {
 	switch t := p.(type) {
+	case *dsa.PrivateKey:
+		x := k.publicKeyDSA()
+		if x == nil {
+			return false
+		}
+		t.PublicKey = *x
 	case *rsa.PrivateKey:
-		// Something - but the
+		x := k.publicKeyRSA()
+		if x == nil {
+			return false
+		}
+		t.PublicKey = *x
 	case *ecdsa.PrivateKey:
 		x := k.publicKeyCurve()
 		if x == nil {
@@ -510,6 +521,28 @@ func (k *RR_DNSKEY) publicKeyCurve() *ecdsa.PublicKey {
 	return pubkey
 }
 
+func (k *RR_DNSKEY) publicKeyDSA() *dsa.PublicKey {
+	keybuf, err := packBase64([]byte(k.PublicKey))
+	if err != nil {
+		return nil
+	}
+	if len(keybuf) < 22 { // TODO: check
+		return nil
+	}
+	t := int(keybuf[0])
+	size := 64 + t*8
+	pubkey := new(dsa.PublicKey)
+	pubkey.Parameters.Q = big.NewInt(0)
+	pubkey.Parameters.Q.SetBytes(keybuf[1:21]) // +/- 1 ?
+	pubkey.Parameters.P = big.NewInt(0)
+	pubkey.Parameters.P.SetBytes(keybuf[22:22+size])
+	pubkey.Parameters.G = big.NewInt(0)
+	pubkey.Parameters.G.SetBytes(keybuf[22+size+1:22+size*2])
+	pubkey.Y = big.NewInt(0)
+	pubkey.Y.SetBytes(keybuf[22+size*2+1:22+size*3])
+	return pubkey
+}
+
 // Set the public key (the value E and N)
 func (k *RR_DNSKEY) setPublicKeyRSA(_E int, _N *big.Int) bool {
 	if _E == 0 || _N == nil {
@@ -532,6 +565,14 @@ func (k *RR_DNSKEY) setPublicKeyCurve(_X, _Y *big.Int) bool {
 	return true
 }
 
+// Set the public key for DSA
+func (k RR_DNSKEY) setPublicKeyDSA(_P, _Q, _G, _Y *big.Int) bool {
+	if _P == nil || _Q == nil || _G == nil || _Y == nil {
+		return false
+	}
+	return true
+}
+
 // Set the public key (the values E and N) for RSA
 // RFC 3110: Section 2. RSA Public KEY Resource Records
 func exponentToBuf(_E int) []byte {
diff --git a/kscan.go b/kscan.go
index 0fea1625..c41e16b4 100644
--- a/kscan.go
+++ b/kscan.go
@@ -3,6 +3,7 @@ package dns
 import (
 	"crypto/ecdsa"
 	"crypto/rsa"
+	"crypto/dsa"
 	"io"
 	"math/big"
 	"strings"
@@ -30,15 +31,24 @@ func (k *RR_DNSKEY) ReadPrivateKey(q io.Reader, file string) (PrivateKey, error)
 	}
 	// TODO(mg): check if the pubkey matches the private key
 	switch m["algorithm"] {
+	case "3 (DSA)":
+		p, e := readPrivateKeyDSA(m)
+		if e != nil {
+			return nil, e
+		}
+		if !k.setPublicKeyInPrivate(p) {
+			return nil, ErrPrivKey
+		}
+		return p, e
 	case "1 (RSAMD5)":
 		fallthrough
 	case "5 (RSASHA1)":
 		fallthrough
+	case "7 (RSASHA1NSEC3SHA1)":
+		fallthrough
 	case "8 (RSASHA256)":
 		fallthrough
 	case "10 (RSASHA512)":
-		fallthrough
-	case "7 (RSASHA1NSEC3SHA1)":
 		p, e := readPrivateKeyRSA(m)
 		if e != nil {
 			return nil, e
@@ -107,6 +117,24 @@ func readPrivateKeyRSA(m map[string]string) (PrivateKey, error) {
 	return p, nil
 }
 
+func readPrivateKeyDSA(m map[string]string) (PrivateKey, error) {
+	p := new(dsa.PrivateKey)
+	p.X = big.NewInt(0)
+	for k, v := range m {
+		switch k {
+		case "private_value(x):":
+			v1, err := packBase64([]byte(v))
+			if err != nil {
+				return nil, err
+			}
+			p.X.SetBytes(v1)
+		case "created:", "publish:", "activate:":
+			/* not used in Go (yet) */
+		}
+	}
+	return p, nil
+}
+
 func readPrivateKeyECDSA(m map[string]string) (PrivateKey, error) {
 	p := new(ecdsa.PrivateKey)
 	p.D = big.NewInt(0)