System.Net.Security.NegotiateStreamPal.Decrypt C# (CSharp) Метод

        internal static int Decrypt(
            SafeDeleteContext securityContext,
            byte[] buffer,
            int offset,
            int count,
            bool isConfidential,
            bool isNtlm,
            out int newOffset,
            uint sequenceNumber)
        {
            if (offset < 0 || offset > (buffer == null ? 0 : buffer.Length))
            {
                NetEventSource.Fail(null, "Argument 'offset' out of range.");
                throw new ArgumentOutOfRangeException(nameof(offset));
            }

            if (count < 0 || count > (buffer == null ? 0 : buffer.Length - offset))
            {
                NetEventSource.Fail(null, "Argument 'count' out of range.");
                throw new ArgumentOutOfRangeException(nameof(count));
            }

            if (isNtlm)
            {
                return DecryptNtlm(securityContext, buffer, offset, count, isConfidential, out newOffset, sequenceNumber);
            }

            //
            // Kerberos and up
            //
            var securityBuffer = new SecurityBuffer[2];
            securityBuffer[0] = new SecurityBuffer(buffer, offset, count, SecurityBufferType.SECBUFFER_STREAM);
            securityBuffer[1] = new SecurityBuffer(0, SecurityBufferType.SECBUFFER_DATA);

            int errorCode;
            if (isConfidential)
            {
                errorCode = SSPIWrapper.DecryptMessage(GlobalSSPI.SSPIAuth, securityContext, securityBuffer, sequenceNumber);
            }
            else
            {
                errorCode = SSPIWrapper.VerifySignature(GlobalSSPI.SSPIAuth, securityContext, securityBuffer, sequenceNumber);
            }

            if (errorCode != 0)
            {
                Exception e = new Win32Exception(errorCode);
                if (NetEventSource.IsEnabled) NetEventSource.Error(null, e);
                throw e;
            }

            if (securityBuffer[1].type != SecurityBufferType.SECBUFFER_DATA)
            {
                throw new InternalException();
            }

            newOffset = securityBuffer[1].offset;
            return securityBuffer[1].size;
        }