AddressFormatException: Add InvalidChecksum exception that is thrown when a Base58 or Bech32 checksum is invalid.

core/src/main/java/org/bitcoinj/core/AddressFormatException.java

@@ -27,6 +27,21 @@ public class AddressFormatException extends IllegalArgumentException {
         super(message);
     }
 
+    /**
+     * This exception is thrown by {@link Base58}, {@link Bech32} and the {@link PrefixedChecksummedBytes} hierarchy of
+     * classes when you try to decode data and the checksum isn't valid. You shouldn't allow the user to proceed in this
+     * case.
+     */
+    public static class InvalidChecksum extends AddressFormatException {
+        public InvalidChecksum() {
+            super("Checksum does not validate");
+        }
+
+        public InvalidChecksum(String message) {
+            super(message);
+        }
+    }
+
     /**
      * This exception is thrown by the {@link PrefixedChecksummedBytes} hierarchy of classes when you try and decode an
      * address with a version header that isn't used by that network. You shouldn't allow the user to proceed in this

core/src/main/java/org/bitcoinj/core/Base58.java

@@ -175,7 +175,7 @@ public class Base58 {
         byte[] checksum = Arrays.copyOfRange(decoded, decoded.length - 4, decoded.length);
         byte[] actualChecksum = Arrays.copyOfRange(Sha256Hash.hashTwice(data), 0, 4);
         if (!Arrays.equals(checksum, actualChecksum))
-            throw new AddressFormatException("Checksum does not validate");
+            throw new AddressFormatException.InvalidChecksum();
         return data;
     }
 

core/src/main/java/org/bitcoinj/core/Bech32.java

@@ -141,7 +141,7 @@ public class Bech32 {
             values[i] = CHARSET_REV[c];
         }
         String hrp = str.substring(0, pos).toLowerCase(Locale.ROOT);
-        if (!verifyChecksum(hrp, values)) throw new AddressFormatException("Invalid checksum");
+        if (!verifyChecksum(hrp, values)) throw new AddressFormatException.InvalidChecksum();
         return new Bech32Data(hrp, Arrays.copyOfRange(values, 0, values.length - 6));
     }
 }

core/src/test/java/org/bitcoinj/core/Base58Test.java

@@ -83,8 +83,8 @@ public class Base58Test {
         Base58.decodeChecked("93VYUMzRG9DdbRP72uQXjaWibbQwygnvaCu9DumcqDjGybD864T");
     }
 
-    @Test(expected = AddressFormatException.class)
-    public void testDecodeChecked_badChecksum() {
+    @Test(expected = AddressFormatException.InvalidChecksum.class)
+    public void testDecodeChecked_invalidChecksum() {
         Base58.decodeChecked("4stwEBjT6FYyVW");
     }
 

core/src/test/java/org/bitcoinj/core/Bech32Test.java

@@ -70,4 +70,9 @@ public class Bech32Test {
             "li1dgmt3",
             "de1lg7wt" + new String(new char[] { 0xff }),
     };
+
+    @Test(expected = AddressFormatException.InvalidChecksum.class)
+    public void decode_invalidNetwork() {
+        Bech32.decode("A12UEL5X");
+    }
 }