diff --git a/auth.go b/auth.go
index 009f8d3..d87f7bd 100644
--- a/auth.go
+++ b/auth.go
@@ -11,7 +11,6 @@ import (
 	"crypto/ed25519"
 	"crypto/elliptic"
 	"crypto/rsa"
-	"encoding/asn1"
 	"errors"
 	"fmt"
 	"hash"
@@ -27,14 +26,7 @@ func verifyHandshakeSignature(sigType uint8, pubkey crypto.PublicKey, hashFunc c
 		if !ok {
 			return fmt.Errorf("expected an ECDSA public key, got %T", pubkey)
 		}
-		ecdsaSig := new(ecdsaSignature)
-		if _, err := asn1.Unmarshal(sig, ecdsaSig); err != nil {
-			return err
-		}
-		if ecdsaSig.R.Sign() <= 0 || ecdsaSig.S.Sign() <= 0 {
-			return errors.New("ECDSA signature contained zero or negative values")
-		}
-		if !ecdsa.Verify(pubKey, signed, ecdsaSig.R, ecdsaSig.S) {
+		if !ecdsa.VerifyASN1(pubKey, signed, sig) {
 			return errors.New("ECDSA verification failure")
 		}
 	case signatureEd25519:
diff --git a/common.go b/common.go
index c3de0b3..53719c4 100644
--- a/common.go
+++ b/common.go
@@ -19,7 +19,6 @@ import (
 	"fmt"
 	"internal/cpu"
 	"io"
-	"math/big"
 	"net"
 	"strings"
 	"sync"
@@ -1264,13 +1263,6 @@ func (c *lruSessionCache) Get(sessionKey string) (*ClientSessionState, bool) {
 	return nil, false
 }
 
-// TODO(jsing): Make these available to both crypto/x509 and crypto/tls.
-type dsaSignature struct {
-	R, S *big.Int
-}
-
-type ecdsaSignature dsaSignature
-
 var emptyConfig Config
 
 func defaultConfig() *Config {