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

        private static byte[] GenerateAEADNonceExplicit(byte[] recordIV, UInt64 seqNum)
        {
            // Generate explicit part of defined length
            byte[] nonceExplicit = new byte[recordIV.Length];

            // Copy the sequence number to the end of the explicit part
            byte[] seqData = BitConverter.GetBytes(seqNum);
            if (BitConverter.IsLittleEndian) {
                Array.Reverse(seqData);
            }
            int seqSrcIdx = Math.Max(0, seqData.Length-nonceExplicit.Length);
            int seqDstIdx = Math.Max(0, nonceExplicit.Length-seqData.Length);
            int seqLength = Math.Min(seqData.Length, nonceExplicit.Length);
            Buffer.BlockCopy(seqData, seqSrcIdx, nonceExplicit, seqDstIdx, seqLength);

            // XOR with the random recordIV and return
            for (int i=0; i<nonceExplicit.Length; i++) {
                nonceExplicit[i] ^= recordIV[i];
            }
            return nonceExplicit;
        }