crypto/x509: add PublicKeyAlgorithm.String()

Change-Id: I77d9c77875519d77bac49cc8870c2e0c4563fe55
Reviewed-on: https://go-review.googlesource.com/44313Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Adam Langley <agl@golang.org>
Run-TryBot: Adam Langley <agl@golang.org>

src/crypto/x509/x509.go

@@ -194,7 +194,7 @@ func (algo SignatureAlgorithm) isRSAPSS() bool {
 	}
 }
 
-var algoName = [...]string{
+var signatureAlgoName = [...]string{
 	MD2WithRSA:       "MD2-RSA",
 	MD5WithRSA:       "MD5-RSA",
 	SHA1WithRSA:      "SHA1-RSA",
@@ -213,8 +213,8 @@ var algoName = [...]string{
 }
 
 func (algo SignatureAlgorithm) String() string {
-	if 0 < algo && int(algo) < len(algoName) {
-		return algoName[algo]
+	if 0 < algo && int(algo) < len(signatureAlgoName) {
+		return signatureAlgoName[algo]
 	}
 	return strconv.Itoa(int(algo))
 }
@@ -228,6 +228,19 @@ const (
 	ECDSA
 )
 
+var publicKeyAlgoName = [...]string{
+	RSA:   "RSA",
+	DSA:   "DSA",
+	ECDSA: "ECDSA",
+}
+
+func (algo PublicKeyAlgorithm) String() string {
+	if 0 < algo && int(algo) < len(publicKeyAlgoName) {
+		return publicKeyAlgoName[algo]
+	}
+	return strconv.Itoa(int(algo))
+}
+
 // OIDs for signature algorithms
 //
 // pkcs-1 OBJECT IDENTIFIER ::= {