open for different alphabets - check for encodeTable length

Author: cljk

src/main/java/org/apache/commons/codec/binary/Base64.java

@@ -310,6 +310,9 @@ public Base64(final int lineLength, final byte[] lineSeparator, byte[] encodeTab
         if (encodeTable == STANDARD_ENCODE_TABLE || encodeTable == URL_SAFE_ENCODE_TABLE) {
             decodeTable = DEFAULT_DECODE_TABLE;
         } else {
+            if (encodeTable.length != 64) {
+                throw new IllegalArgumentException("encodeTable must be exactly 64 bytes long");
+            }
             decodeTable = calculateDecodeTable(encodeTable);
         }
 

src/test/java/org/apache/commons/codec/binary/Base64Test.java

@@ -116,6 +116,14 @@ public void testBase64() {
         assertEquals("decode hello world", "Hello World", decodeString);
     }
 
+    @Test(expected = IllegalArgumentException.class)
+    public void testCustomEncodingAlphabet_illegal() {
+        byte[] encodeTable = {
+                '.', '-', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M'
+        };
+        Base64 b64customEncoding = new Base64(encodeTable);
+    }
+
     @Test
     public void testCustomEncodingAlphabet() {
         // created a duplicate of STANDARD_ENCODE_TABLE and replaced two chars with