src/java.base/share/classes/sun/security/ssl/HandshakeMessage.java

@@ -1197,11 +1197,11 @@
             // Is it a local supported signature algorithm?
             if (!localSupportedSignAlgs.contains(
                     preferableSignatureAlgorithm)) {
                 throw new SSLHandshakeException(
                         "Unsupported SignatureAndHashAlgorithm in " +
-                        "ServerKeyExchange message");
+                        "ServerKeyExchange message: " + preferableSignatureAlgorithm);
             }
         } else {
             this.preferableSignatureAlgorithm = null;
         }
 

@@ -1230,11 +1230,11 @@
                         break;
                     case "RSA":
                         sig = RSASignature.getInstance();
                         break;
                     default:
-                        throw new SSLKeyException("neither an RSA or a DSA key");
+                        throw new SSLKeyException("neither an RSA or a DSA key: " + algorithm);
                 }
         }
 
         sig.initVerify(publicKey);
         updateSignature(sig, clntNonce, svrNonce);

@@ -1480,11 +1480,11 @@
             // Is it a local supported signature algorithm?
             if (!localSupportedSignAlgs.contains(
                     preferableSignatureAlgorithm)) {
                 throw new SSLHandshakeException(
                         "Unsupported SignatureAndHashAlgorithm in " +
-                        "ServerKeyExchange message");
+                        "ServerKeyExchange message: " + preferableSignatureAlgorithm);
             }
         }
 
         // read the signature
         signatureBytes = input.getBytes16();

@@ -1520,11 +1520,12 @@
                 case "EC":
                     return JsseJce.getSignature(JsseJce.SIGNATURE_ECDSA);
                 case "RSA":
                     return RSASignature.getInstance();
                 default:
-                    throw new NoSuchAlgorithmException("neither an RSA or a EC key");
+                    throw new NoSuchAlgorithmException(
+                        "neither an RSA or a EC key : " + keyAlgorithm);
             }
     }
 
     private void updateSignature(Signature sig, byte[] clntNonce,
             byte[] svrNonce) throws SignatureException {

@@ -1727,11 +1728,11 @@
         // Read the supported_signature_algorithms for TLS 1.2 or later.
         if (protocolVersion.useTLS12PlusSpec()) {
             algorithmsLen = input.getInt16();
             if (algorithmsLen < 2) {
                 throw new SSLProtocolException(
-                        "Invalid supported_signature_algorithms field");
+                    "Invalid supported_signature_algorithms field: " + algorithmsLen);
             }
 
             algorithms = new ArrayList<SignatureAndHashAlgorithm>();
             int remains = algorithmsLen;
             int sequence = 0;

@@ -1746,11 +1747,11 @@
                 remains -= 2;  // one byte for hash, one byte for signature
             }
 
             if (remains != 0) {
                 throw new SSLProtocolException(
-                        "Invalid supported_signature_algorithms field");
+                    "Invalid supported_signature_algorithms field. remains: " + remains);
             }
         } else {
             algorithms = new ArrayList<SignatureAndHashAlgorithm>();
             algorithmsLen = 0;
         }

@@ -1763,11 +1764,11 @@
             v.add(dn);
             len -= dn.length();
         }
 
         if (len != 0) {
-            throw new SSLProtocolException("Bad CertificateRequest DN length");
+            throw new SSLProtocolException("Bad CertificateRequest DN length: " + len);
         }
 
         authorities = v.toArray(new DistinguishedName[v.size()]);
     }
 

@@ -1994,11 +1995,11 @@
             // Is it a local supported signature algorithm?
             if (!localSupportedSignAlgs.contains(
                     preferableSignatureAlgorithm)) {
                 throw new SSLHandshakeException(
                         "Unsupported SignatureAndHashAlgorithm in " +
-                        "CertificateVerify message");
+                        "CertificateVerify message: " + preferableSignatureAlgorithm);
             }
         }
 
         // read the signature
         signature = input.getBytes16();

@@ -2362,11 +2363,12 @@
                 KeyGenerator kg = JsseJce.getKeyGenerator(prfAlg);
                 kg.init(spec);
                 SecretKey prfKey = kg.generateKey();
                 if ("RAW".equals(prfKey.getFormat()) == false) {
                     throw new ProviderException(
-                        "Invalid PRF output, format must be RAW");
+                        "Invalid PRF output, format must be RAW. Format received:" +
+                        prfKey.getFormat());
                 }
                 byte[] finished = prfKey.getEncoded();
                 return finished;
             } catch (GeneralSecurityException e) {
                 throw new RuntimeException("PRF failed", e);