fix: Do not swallow security exceptions

There are two cases where the driver currently swallows security
exceptions. The first is in MD5Digest and the second is in
SingleCertValidatingFactory. In both cases the code will result in
partially initialized objects being used which will result in follow up
exceptions later on. These will be hard to track down since the
original exception was swallowed.

Wrap and propagate security exceptions instead of swallowing them.

closes #471

pgjdbc/src/main/java/org/postgresql/ssl/SingleCertValidatingFactory.java

@@ -225,11 +225,8 @@ public class SingleCertTrustManager implements X509TrustManager {
 
     public SingleCertTrustManager(InputStream in) throws IOException, GeneralSecurityException {
       KeyStore ks = KeyStore.getInstance(KeyStore.getDefaultType());
-      try {
-        // Note: KeyStore requires it be loaded even if you don't load anything into it:
-        ks.load(null);
-      } catch (Exception e) {
-      }
+      // Note: KeyStore requires it be loaded even if you don't load anything into it:
+      ks.load(null);
       CertificateFactory cf = CertificateFactory.getInstance("X509");
       cert = (X509Certificate) cf.generateCertificate(in);
       ks.setCertificateEntry(UUID.randomUUID().toString(), cert);

pgjdbc/src/main/java/org/postgresql/util/MD5Digest.java

@@ -15,6 +15,7 @@
  */
 
 import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
 
 public class MD5Digest {
   private MD5Digest() {
@@ -50,8 +51,8 @@ public static byte[] encode(byte user[], byte password[], byte salt[]) {
       hex_digest[0] = (byte) 'm';
       hex_digest[1] = (byte) 'd';
       hex_digest[2] = (byte) '5';
-    } catch (Exception e) {
-      ; // "MessageDigest failure; " + e
+    } catch (NoSuchAlgorithmException e) {
+      throw new IllegalStateException("Unable to encode password with MD5", e);
     }
 
     return hex_digest;