Bug in SimpleAheadCipher

[Aaron Daisley-Harrison]

It looks like line 54: GCMParameterSpec parameterSpec = new GCMParameterSpec(ByteUtil.bitLength(tagByteLength), iv);

should NOT use tagByteLength but instead ivByteLength passed through from AesGcmContentEncryptionAlgorithm where the tag length is 16 and the iv length is 12.

[Brian Campbell]

https://docs.oracle.com/javase/8/docs/api/javax/crypto/spec/GCMParameterSpec.html is pretty clear that about tLen being the length (in bits) of the authentication tag.