sometimes r and s are < 20 bytes because of how go encodes big.Int, take this into account

lib/crypto/dsa.go

@@ -162,8 +162,12 @@ func (ds *DSASigner) SignHash(h []byte) (sig []byte, err error) {
 	r, s, err = dsa.Sign(rand.Reader, ds.k, h)
 	if err == nil {
 		sig = make([]byte, 40)
-		copy(sig, r.Bytes())
-		copy(sig[20:], s.Bytes())
+		rb := r.Bytes()
+		rl := len(rb)
+		copy(sig[20-rl:20], rb)
+		sb := s.Bytes()
+		sl := len(sb)
+		copy(sig[20+(20-sl):], sb)
 	}
 	return
 }

lib/crypto/dsa_test.go

@@ -1,6 +1,7 @@
 package crypto
 
 import (
+	log "github.com/sirupsen/logrus"
 	"testing"
 )
 
@@ -44,3 +45,43 @@ func TestDSA(t *testing.T) {
 		t.Fail()
 	}
 }
+
+
+func BenchmarkDSAGenerate(b *testing.B) {
+	var sk DSAPrivateKey
+	for n := 0 ; n < b.N ; n ++ { 
+		_, err := sk.Generate()
+		if err != nil {
+			panic(err.Error())
+		}
+	}
+}
+
+func BenchmarkDSASignVerify(b *testing.B) {
+	var sk DSAPrivateKey
+	var pk DSAPublicKey
+	var err error
+	sk, err = sk.Generate()
+	if err != nil {
+		panic(err.Error())
+	}
+	pk, err = sk.Public()
+	if err != nil {
+		panic(err.Error())
+	}
+	s, _ := sk.NewSigner()
+	v, _ := pk.NewVerifier()
+	data := make([]byte, 1024)
+	fail := 0
+	for n := 0 ; n < b.N ; n ++ {
+		sig, err := s.Sign(data)
+		if err != nil {
+			panic(err.Error())
+		}
+		err = v.Verify(data, sig)
+		if err != nil {
+			fail ++
+		}
+	}
+	log.Infof("%d fails %d signs", fail, b.N)
+}