AaltoTLS.RecordLayer.RecordHandler.CreateAEADDecryptor C# (CSharp) Method

        private static ICryptoTransform CreateAEADDecryptor(CipherSuite cipherSuite, Record record,
		                                                    byte[] key, byte[] fixedIV, UInt64 seqNum)
        {
            // Get the explicit nonce from the beginning of fragment
            int recordIVLength = cipherSuite.BulkCipherAlgorithm.RecordIVLength;
            byte[] nonceExplicit = new byte[recordIVLength];
            Buffer.BlockCopy(record.Fragment, 0, nonceExplicit, 0, nonceExplicit.Length);

            // Construct the nonce for AEAD cipher
            byte[] nonce = GenerateAEADNonce(fixedIV, nonceExplicit);

            // Construct the additional bytes for AEAD cipher
            int compressedLength = record.Fragment.Length - recordIVLength - cipherSuite.BulkCipherAlgorithm.AuthenticationTagSize;
            byte[] additional = GetAdditionalBytes(seqNum, record.Type, record.Version, compressedLength);

            return cipherSuite.BulkCipherAlgorithm.CreateDecryptor(key, nonce, additional);
        }