Base64Utils class cuts leading zeroes from encoded bytes

Vault util is failing for some password/salt/iteration combinations because Base64Utils class strips zeroes from provided byte array.

So if a user encodes a key with length 8 and the leading byte of the key is zero, then after decoding he only gets 7 (or less) bytes.

For instance:

encode ( { 0, 81, 121, -37, 46, -64, 20, 114 } ) -> "1HUTikm1Ho"
decode ("1HUTikm1Ho") -> {  81, 121, -37, 46, -64, 20, 114  }

As a result the PBEUtil will fail with javax.crypto.IllegalBlockSizeException.

IMHO the same problem can occur on other places where the Base64Utils class is used (not only the Vault).