//
// System.Security.Cryptography.SHA1CryptoServiceProvider.cs
//
// Authors:
//	Matthew S. Ford (Matthew.S.Ford@Rose-Hulman.Edu)
//	Sebastien Pouliot (sebastien@ximian.com)
//
// Copyright 2001 by Matthew S. Ford.
// Copyright (C) 2004, 2005, 2008 Novell, Inc (http://www.novell.com)
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
// 
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//

// Note:
// The MS Framework includes two (almost) identical class for SHA1.
//	SHA1Managed is a 100% managed implementation.
//	SHA1CryptoServiceProvider (this file) is a wrapper on CryptoAPI.
// Mono must provide those two class for binary compatibility.
// In our case both class are wrappers around a managed internal class SHA1Internal.

using System;
using System.Runtime.InteropServices;
using System.Security.Cryptography;

namespace Mono.Security.Cryptography {

    internal class SHA1Internal {
        private const int BLOCK_SIZE_BYTES = 64;
        private uint[] _H;  // these are my chaining variables
        private ulong count;
        private byte[] _ProcessingBuffer;   // Used to start data when passed less than a block worth.
        private int _ProcessingBufferCount; // Counts how much data we have stored that still needs processed.
        private uint[] buff;

        public SHA1Internal() {
            _H = new uint[5];
            _ProcessingBuffer = new byte[BLOCK_SIZE_BYTES];
            buff = new uint[80];

            Initialize();
        }

        public void HashCore(byte[] rgb, int ibStart, int cbSize) {
            int i;

            if (_ProcessingBufferCount != 0) {
                if (cbSize < (BLOCK_SIZE_BYTES - _ProcessingBufferCount)) {
                    System.Buffer.BlockCopy(rgb, ibStart, _ProcessingBuffer, _ProcessingBufferCount, cbSize);
                    _ProcessingBufferCount += cbSize;
                    return;
                } else {
                    i = (BLOCK_SIZE_BYTES - _ProcessingBufferCount);
                    System.Buffer.BlockCopy(rgb, ibStart, _ProcessingBuffer, _ProcessingBufferCount, i);
                    ProcessBlock(_ProcessingBuffer, 0);
                    _ProcessingBufferCount = 0;
                    ibStart += i;
                    cbSize -= i;
                }
            }

            for (i = 0; i < cbSize - cbSize % BLOCK_SIZE_BYTES; i += BLOCK_SIZE_BYTES) {
                ProcessBlock(rgb, (uint)(ibStart + i));
            }

            if (cbSize % BLOCK_SIZE_BYTES != 0) {
                System.Buffer.BlockCopy(rgb, cbSize - cbSize % BLOCK_SIZE_BYTES + ibStart, _ProcessingBuffer, 0, cbSize % BLOCK_SIZE_BYTES);
                _ProcessingBufferCount = cbSize % BLOCK_SIZE_BYTES;
            }
        }

        public byte[] HashFinal() {
            byte[] hash = new byte[20];

            ProcessFinalBlock(_ProcessingBuffer, 0, _ProcessingBufferCount);

            for (int i = 0; i < 5; i++) {
                for (int j = 0; j < 4; j++) {
                    hash[i * 4 + j] = (byte)(_H[i] >> (8 * (3 - j)));
                }
            }

            return hash;
        }

        public void Initialize() {
            count = 0;
            _ProcessingBufferCount = 0;

            _H[0] = 0x67452301;
            _H[1] = 0xefcdab89;
            _H[2] = 0x98badcfe;
            _H[3] = 0x10325476;
            _H[4] = 0xC3D2E1F0;
        }

        private void ProcessBlock(byte[] inputBuffer, uint inputOffset) {
            uint a, b, c, d, e;

            count += BLOCK_SIZE_BYTES;

            // abc removal would not work on the fields
            uint[] _H = this._H;
            uint[] buff = this.buff;
            InitialiseBuff(buff, inputBuffer, inputOffset);
            FillBuff(buff);

            a = _H[0];
            b = _H[1];
            c = _H[2];
            d = _H[3];
            e = _H[4];

            // This function was unrolled because it seems to be doubling our performance with current compiler/VM.
            // Possibly roll up if this changes.

            // ---- Round 1 --------
            int i = 0;
            while (i < 20) {
                e += ((a << 5) | (a >> 27)) + (((c ^ d) & b) ^ d) + 0x5A827999 + buff[i];
                b = (b << 30) | (b >> 2);

                d += ((e << 5) | (e >> 27)) + (((b ^ c) & a) ^ c) + 0x5A827999 + buff[i + 1];
                a = (a << 30) | (a >> 2);

                c += ((d << 5) | (d >> 27)) + (((a ^ b) & e) ^ b) + 0x5A827999 + buff[i + 2];
                e = (e << 30) | (e >> 2);

                b += ((c << 5) | (c >> 27)) + (((e ^ a) & d) ^ a) + 0x5A827999 + buff[i + 3];
                d = (d << 30) | (d >> 2);

                a += ((b << 5) | (b >> 27)) + (((d ^ e) & c) ^ e) + 0x5A827999 + buff[i + 4];
                c = (c << 30) | (c >> 2);
                i += 5;
            }

            // ---- Round 2 --------
            while (i < 40) {
                e += ((a << 5) | (a >> 27)) + (b ^ c ^ d) + 0x6ED9EBA1 + buff[i];
                b = (b << 30) | (b >> 2);

                d += ((e << 5) | (e >> 27)) + (a ^ b ^ c) + 0x6ED9EBA1 + buff[i + 1];
                a = (a << 30) | (a >> 2);

                c += ((d << 5) | (d >> 27)) + (e ^ a ^ b) + 0x6ED9EBA1 + buff[i + 2];
                e = (e << 30) | (e >> 2);

                b += ((c << 5) | (c >> 27)) + (d ^ e ^ a) + 0x6ED9EBA1 + buff[i + 3];
                d = (d << 30) | (d >> 2);

                a += ((b << 5) | (b >> 27)) + (c ^ d ^ e) + 0x6ED9EBA1 + buff[i + 4];
                c = (c << 30) | (c >> 2);
                i += 5;
            }

            // ---- Round 3 --------
            while (i < 60) {
                e += ((a << 5) | (a >> 27)) + ((b & c) | (b & d) | (c & d)) + 0x8F1BBCDC + buff[i];
                b = (b << 30) | (b >> 2);

                d += ((e << 5) | (e >> 27)) + ((a & b) | (a & c) | (b & c)) + 0x8F1BBCDC + buff[i + 1];
                a = (a << 30) | (a >> 2);

                c += ((d << 5) | (d >> 27)) + ((e & a) | (e & b) | (a & b)) + 0x8F1BBCDC + buff[i + 2];
                e = (e << 30) | (e >> 2);

                b += ((c << 5) | (c >> 27)) + ((d & e) | (d & a) | (e & a)) + 0x8F1BBCDC + buff[i + 3];
                d = (d << 30) | (d >> 2);

                a += ((b << 5) | (b >> 27)) + ((c & d) | (c & e) | (d & e)) + 0x8F1BBCDC + buff[i + 4];
                c = (c << 30) | (c >> 2);
                i += 5;
            }

            // ---- Round 4 --------
            while (i < 80) {
                e += ((a << 5) | (a >> 27)) + (b ^ c ^ d) + 0xCA62C1D6 + buff[i];
                b = (b << 30) | (b >> 2);

                d += ((e << 5) | (e >> 27)) + (a ^ b ^ c) + 0xCA62C1D6 + buff[i + 1];
                a = (a << 30) | (a >> 2);

                c += ((d << 5) | (d >> 27)) + (e ^ a ^ b) + 0xCA62C1D6 + buff[i + 2];
                e = (e << 30) | (e >> 2);

                b += ((c << 5) | (c >> 27)) + (d ^ e ^ a) + 0xCA62C1D6 + buff[i + 3];
                d = (d << 30) | (d >> 2);

                a += ((b << 5) | (b >> 27)) + (c ^ d ^ e) + 0xCA62C1D6 + buff[i + 4];
                c = (c << 30) | (c >> 2);
                i += 5;
            }

            _H[0] += a;
            _H[1] += b;
            _H[2] += c;
            _H[3] += d;
            _H[4] += e;
        }

        private static void InitialiseBuff(uint[] buff, byte[] input, uint inputOffset) {
            buff[0] = (uint)((input[inputOffset + 0] << 24) | (input[inputOffset + 1] << 16) | (input[inputOffset + 2] << 8) | (input[inputOffset + 3]));
            buff[1] = (uint)((input[inputOffset + 4] << 24) | (input[inputOffset + 5] << 16) | (input[inputOffset + 6] << 8) | (input[inputOffset + 7]));
            buff[2] = (uint)((input[inputOffset + 8] << 24) | (input[inputOffset + 9] << 16) | (input[inputOffset + 10] << 8) | (input[inputOffset + 11]));
            buff[3] = (uint)((input[inputOffset + 12] << 24) | (input[inputOffset + 13] << 16) | (input[inputOffset + 14] << 8) | (input[inputOffset + 15]));
            buff[4] = (uint)((input[inputOffset + 16] << 24) | (input[inputOffset + 17] << 16) | (input[inputOffset + 18] << 8) | (input[inputOffset + 19]));
            buff[5] = (uint)((input[inputOffset + 20] << 24) | (input[inputOffset + 21] << 16) | (input[inputOffset + 22] << 8) | (input[inputOffset + 23]));
            buff[6] = (uint)((input[inputOffset + 24] << 24) | (input[inputOffset + 25] << 16) | (input[inputOffset + 26] << 8) | (input[inputOffset + 27]));
            buff[7] = (uint)((input[inputOffset + 28] << 24) | (input[inputOffset + 29] << 16) | (input[inputOffset + 30] << 8) | (input[inputOffset + 31]));
            buff[8] = (uint)((input[inputOffset + 32] << 24) | (input[inputOffset + 33] << 16) | (input[inputOffset + 34] << 8) | (input[inputOffset + 35]));
            buff[9] = (uint)((input[inputOffset + 36] << 24) | (input[inputOffset + 37] << 16) | (input[inputOffset + 38] << 8) | (input[inputOffset + 39]));
            buff[10] = (uint)((input[inputOffset + 40] << 24) | (input[inputOffset + 41] << 16) | (input[inputOffset + 42] << 8) | (input[inputOffset + 43]));
            buff[11] = (uint)((input[inputOffset + 44] << 24) | (input[inputOffset + 45] << 16) | (input[inputOffset + 46] << 8) | (input[inputOffset + 47]));
            buff[12] = (uint)((input[inputOffset + 48] << 24) | (input[inputOffset + 49] << 16) | (input[inputOffset + 50] << 8) | (input[inputOffset + 51]));
            buff[13] = (uint)((input[inputOffset + 52] << 24) | (input[inputOffset + 53] << 16) | (input[inputOffset + 54] << 8) | (input[inputOffset + 55]));
            buff[14] = (uint)((input[inputOffset + 56] << 24) | (input[inputOffset + 57] << 16) | (input[inputOffset + 58] << 8) | (input[inputOffset + 59]));
            buff[15] = (uint)((input[inputOffset + 60] << 24) | (input[inputOffset + 61] << 16) | (input[inputOffset + 62] << 8) | (input[inputOffset + 63]));
        }

        private static void FillBuff(uint[] buff) {
            uint val;
            for (int i = 16; i < 80; i += 8) {
                val = buff[i - 3] ^ buff[i - 8] ^ buff[i - 14] ^ buff[i - 16];
                buff[i] = (val << 1) | (val >> 31);

                val = buff[i - 2] ^ buff[i - 7] ^ buff[i - 13] ^ buff[i - 15];
                buff[i + 1] = (val << 1) | (val >> 31);

                val = buff[i - 1] ^ buff[i - 6] ^ buff[i - 12] ^ buff[i - 14];
                buff[i + 2] = (val << 1) | (val >> 31);

                val = buff[i + 0] ^ buff[i - 5] ^ buff[i - 11] ^ buff[i - 13];
                buff[i + 3] = (val << 1) | (val >> 31);

                val = buff[i + 1] ^ buff[i - 4] ^ buff[i - 10] ^ buff[i - 12];
                buff[i + 4] = (val << 1) | (val >> 31);

                val = buff[i + 2] ^ buff[i - 3] ^ buff[i - 9] ^ buff[i - 11];
                buff[i + 5] = (val << 1) | (val >> 31);

                val = buff[i + 3] ^ buff[i - 2] ^ buff[i - 8] ^ buff[i - 10];
                buff[i + 6] = (val << 1) | (val >> 31);

                val = buff[i + 4] ^ buff[i - 1] ^ buff[i - 7] ^ buff[i - 9];
                buff[i + 7] = (val << 1) | (val >> 31);
            }
        }

        private void ProcessFinalBlock(byte[] inputBuffer, int inputOffset, int inputCount) {
            ulong total = count + (ulong)inputCount;
            int paddingSize = (56 - (int)(total % BLOCK_SIZE_BYTES));

            if (paddingSize < 1)
                paddingSize += BLOCK_SIZE_BYTES;

            int length = inputCount + paddingSize + 8;
            byte[] fooBuffer = (length == 64) ? _ProcessingBuffer : new byte[length];

            for (int i = 0; i < inputCount; i++) {
                fooBuffer[i] = inputBuffer[i + inputOffset];
            }

            fooBuffer[inputCount] = 0x80;
            for (int i = inputCount + 1; i < inputCount + paddingSize; i++) {
                fooBuffer[i] = 0x00;
            }

            // I deal in bytes. The algorithm deals in bits.
            ulong size = total << 3;
            AddLength(size, fooBuffer, inputCount + paddingSize);
            ProcessBlock(fooBuffer, 0);

            if (length == 128)
                ProcessBlock(fooBuffer, 64);
        }

        internal void AddLength(ulong length, byte[] buffer, int position) {
            buffer[position++] = (byte)(length >> 56);
            buffer[position++] = (byte)(length >> 48);
            buffer[position++] = (byte)(length >> 40);
            buffer[position++] = (byte)(length >> 32);
            buffer[position++] = (byte)(length >> 24);
            buffer[position++] = (byte)(length >> 16);
            buffer[position++] = (byte)(length >> 8);
            buffer[position] = (byte)(length);
        }

        public SHA1Internal Clone() {
            return new SHA1Internal {
                _H = (uint[])_H.Clone(),
                count = count,
                _ProcessingBuffer = (byte[])_ProcessingBuffer.Clone(),
                _ProcessingBufferCount = _ProcessingBufferCount,
                buff = (uint[])buff.Clone()
            };
        }
    }

    [ComVisible(true)]
    internal sealed class SHA1CryptoServiceProvider : SHA1, ICloneable {
        private SHA1Internal sha;

        public SHA1CryptoServiceProvider() {
            sha = new SHA1Internal();
        }

        ~SHA1CryptoServiceProvider() {
            Dispose(false);
        }

        protected override void Dispose(bool disposing) {
            // nothing new to do (managed implementation)
            base.Dispose(disposing);
        }

        protected override void HashCore(byte[] rgb, int ibStart, int cbSize) {
            State = 1;
            sha.HashCore(rgb, ibStart, cbSize);
        }

        protected override byte[] HashFinal() {
            State = 0;
            return sha.HashFinal();
        }

        public override void Initialize() {
            sha.Initialize();
        }

        object ICloneable.Clone() {
            return new SHA1CryptoServiceProvider() {
                sha = sha.Clone()
            };
        }
    }
}
