Remove DSA* algorithms (#972)

This follows BIND9 and removed support for the DSA family of algorithms.
Any DNSSEC implementation should consider those zones using it,
insecure.

Signed-off-by: Miek Gieben <miek@miek.nl>

dnssec.go

@@ -141,8 +141,8 @@ func (k *DNSKEY) KeyTag() uint16 {
 	switch k.Algorithm {
 	case RSAMD5:
 		// Look at the bottom two bytes of the modules, which the last
-		// item in the pubkey. We could do this faster by looking directly
+		// item in the pubkey.
-		// at the base64 values. But I'm lazy.
+		// This algorithm has been deprecated, but keep this key-tag calculation.
 		modulus, _ := fromBase64([]byte(k.PublicKey))
 		if len(modulus) > 1 {
 			x := binary.BigEndian.Uint16(modulus[len(modulus)-2:])
@@ -318,7 +318,7 @@ func (rr *RRSIG) Sign(k crypto.Signer, rrset []RR) error {
 		}
 
 		rr.Signature = toBase64(signature)
-	case RSAMD5:
+	case RSAMD5, DSA, DSANSEC3SHA1:
 		// See RFC 6944.
 		return ErrAlg
 	default:

dnssec_keygen.go

@@ -2,7 +2,6 @@ package dns
 
 import (
 	"crypto"
-	"crypto/dsa"
 	"crypto/ecdsa"
 	"crypto/elliptic"
 	"crypto/rand"
@@ -20,12 +19,8 @@ import (
 // bits should be set to the size of the algorithm.
 func (k *DNSKEY) Generate(bits int) (crypto.PrivateKey, error) {
 	switch k.Algorithm {
-	case RSAMD5:
+	case RSAMD5, DSA, DSANSEC3SHA1:
 		return nil, ErrAlg
-	case DSA, DSANSEC3SHA1:
-		if bits != 1024 {
-			return nil, ErrKeySize
-		}
 	case RSASHA1, RSASHA256, RSASHA1NSEC3SHA1:
 		if bits < 512 || bits > 4096 {
 			return nil, ErrKeySize
@@ -49,19 +44,6 @@ func (k *DNSKEY) Generate(bits int) (crypto.PrivateKey, error) {
 	}
 
 	switch k.Algorithm {
-	case DSA, DSANSEC3SHA1:
-		params := new(dsa.Parameters)
-		if err := dsa.GenerateParameters(params, rand.Reader, dsa.L1024N160); err != nil {
-			return nil, err
-		}
-		priv := new(dsa.PrivateKey)
-		priv.PublicKey.Parameters = *params
-		err := dsa.GenerateKey(priv, rand.Reader)
-		if err != nil {
-			return nil, err
-		}
-		k.setPublicKeyDSA(params.Q, params.P, params.G, priv.PublicKey.Y)
-		return priv, nil
 	case RSASHA1, RSASHA256, RSASHA512, RSASHA1NSEC3SHA1:
 		priv, err := rsa.GenerateKey(rand.Reader, bits)
 		if err != nil {
@@ -122,16 +104,6 @@ func (k *DNSKEY) setPublicKeyECDSA(_X, _Y *big.Int) bool {
 	return true
 }
 
-// Set the public key for DSA
-func (k *DNSKEY) setPublicKeyDSA(_Q, _P, _G, _Y *big.Int) bool {
-	if _Q == nil || _P == nil || _G == nil || _Y == nil {
-		return false
-	}
-	buf := dsaToBuf(_Q, _P, _G, _Y)
-	k.PublicKey = toBase64(buf)
-	return true
-}
-
 // Set the public key for Ed25519
 func (k *DNSKEY) setPublicKeyED25519(_K ed25519.PublicKey) bool {
 	if _K == nil {
@@ -166,15 +138,3 @@ func curveToBuf(_X, _Y *big.Int, intlen int) []byte {
 	buf = append(buf, intToBytes(_Y, intlen)...)
 	return buf
 }
-
-// Set the public key for X and Y for Curve. The two
-// values are just concatenated.
-func dsaToBuf(_Q, _P, _G, _Y *big.Int) []byte {
-	t := divRoundUp(divRoundUp(_G.BitLen(), 8)-64, 8)
-	buf := []byte{byte(t)}
-	buf = append(buf, intToBytes(_Q, 20)...)
-	buf = append(buf, intToBytes(_P, 64+t*8)...)
-	buf = append(buf, intToBytes(_G, 64+t*8)...)
-	buf = append(buf, intToBytes(_Y, 64+t*8)...)
-	return buf
-}

dnssec_keyscan.go

@@ -3,7 +3,6 @@ package dns
 import (
 	"bufio"
 	"crypto"
-	"crypto/dsa"
 	"crypto/ecdsa"
 	"crypto/rsa"
 	"io"
@@ -44,19 +43,8 @@ func (k *DNSKEY) ReadPrivateKey(q io.Reader, file string) (crypto.PrivateKey, er
 		return nil, ErrPrivKey
 	}
 	switch uint8(algo) {
-	case RSAMD5:
+	case RSAMD5, DSA, DSANSEC3SHA1:
 		return nil, ErrAlg
-	case DSA:
-		priv, err := readPrivateKeyDSA(m)
-		if err != nil {
-			return nil, err
-		}
-		pub := k.publicKeyDSA()
-		if pub == nil {
-			return nil, ErrKey
-		}
-		priv.PublicKey = *pub
-		return priv, nil
 	case RSASHA1:
 		fallthrough
 	case RSASHA1NSEC3SHA1:
@@ -129,24 +117,6 @@ func readPrivateKeyRSA(m map[string]string) (*rsa.PrivateKey, error) {
 	return p, nil
 }
 
-func readPrivateKeyDSA(m map[string]string) (*dsa.PrivateKey, error) {
-	p := new(dsa.PrivateKey)
-	p.X = new(big.Int)
-	for k, v := range m {
-		switch k {
-		case "private_value(x)":
-			v1, err := fromBase64([]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) (*ecdsa.PrivateKey, error) {
 	p := new(ecdsa.PrivateKey)
 	p.D = new(big.Int)

parse_test.go

@@ -1212,7 +1212,6 @@ func TestNewPrivateKey(t *testing.T) {
 		{ECDSAP384SHA384, 384},
 		{RSASHA1, 1024},
 		{RSASHA256, 2048},
-		{DSA, 1024},
 		{ED25519, 256},
 	}