mono/mcs/class/corlib/System.Security.Cryptography/RC2CryptoServiceProvider.cs

//
// System.Security.Cryptography.RC2CryptoServiceProvider.cs
//
// Authors:
//	Andrew Birkett ([email protected])
//	Sebastien Pouliot ([email protected])
//
// Portions (C) 2002 Motus Technologies Inc. (http://www.motus.com)
//          

using System;

namespace System.Security.Cryptography {

// References:
// a.	IETF RFC2286: A Description of the RC2(r) Encryption Algorithm
//	http://www.ietf.org/rfc/rfc2268.txt

public sealed class RC2CryptoServiceProvider : RC2 {

	public RC2CryptoServiceProvider() {}

	// included to (exactly) match corlib
	public override int EffectiveKeySize {
		get { return base.EffectiveKeySize; }
		set { base.EffectiveKeySize = value; }
	}

	public override ICryptoTransform CreateDecryptor(byte[] rgbKey, byte[] rgbIV)
	{
		Key = rgbKey;
		IV = rgbIV;
		return new RC2Transform (this, false);
	}

	public override ICryptoTransform CreateEncryptor(byte[] rgbKey, byte[] rgbIV)
	{
		Key = rgbKey;
		IV = rgbIV;
		return new RC2Transform (this, true);
	}

	public override void GenerateIV ()
	{
		IVValue = KeyBuilder.IV (BlockSizeValue >> 3);
	}

	public override void GenerateKey ()
	{
		KeyValue = KeyBuilder.Key (KeySizeValue >> 3);
	}
}

internal class RC2Transform : SymmetricTransform {

	private UInt16 R0, R1, R2, R3;	// state
	private UInt16[] K;		// expanded key
	private int j;			// Key indexer

	public RC2Transform (RC2 rc2Algo, bool encryption) : base (rc2Algo, encryption, rc2Algo.IV)
	{
		byte[] key = rc2Algo.Key;
		int t1 = rc2Algo.EffectiveKeySize;
		// Expand key into a byte array, then convert to word
		// array since we always access the key in 16bit chunks.
		byte[] L = new byte [128];

		int t = key.Length;
		int t8 = ((t1 + 7) >> 3); // divide by 8
		int tm = 255 % (2 << (8 + t1 - (t8 << 3) - 1));

		for (int i=0; i < t; i++)
			L [i] = key [i];
		for (int i=t; i < 128; i++) 
			L [i] = (byte) (pitable [(L [i-1] + L [i-t]) & 0xff]);

		L [128-t8] = pitable [L [128-t8] & tm];

		for (int i=127-t8; i >= 0; i--) 
			L [i] = pitable [L [i+1] ^ L [i+t8]];

		K = new UInt16 [64];
		int pos = 0;
		for (int i=0; i < 64; i++) 
			K [i] = (UInt16) (L [pos++] + (L [pos++] << 8));
	}

	protected override void ECB (byte[] input, byte[] output) 
	{
		// unrolled loop, eliminated mul
		R0 = (UInt16) (input [0] | (input [1] << 8));
		R1 = (UInt16) (input [2] | (input [3] << 8));
		R2 = (UInt16) (input [4] | (input [5] << 8));
		R3 = (UInt16) (input [6] | (input [7] << 8));

		if (encrypt) {
			j = 0;
			// inline, but looped, Mix(); Mix(); Mix(); Mix(); Mix();
			while (j <= 16) {
				R0 += (UInt16) (K[j++] + (R3 & R2) + ((~R3) & R1));
				R0 = (UInt16) ((R0 << 1) | (R0 >> 15));

				R1 += (UInt16) (K[j++] + (R0 & R3) + ((~R0) & R2));
				R1 = (UInt16) ((R1 << 2) | (R1 >> 14));

				R2 += (UInt16) (K[j++] + (R1 & R0) + ((~R1) & R3));
				R2 = (UInt16) ((R2 << 3) | (R2 >> 13));

				R3 += (UInt16) (K[j++] + (R2 & R1) + ((~R2) & R0));
				R3 = (UInt16) ((R3 << 5) | (R3 >> 11));
			}

			// inline Mash(); j == 20
			R0 += K [R3 & 63];
			R1 += K [R0 & 63];
			R2 += K [R1 & 63];
			R3 += K [R2 & 63];

			// inline, but looped, Mix(); Mix(); Mix(); Mix(); Mix(); Mix();
			while (j <= 40) {
				R0 += (UInt16) (K[j++] + (R3 & R2) + ((~R3) & R1));
				R0 = (UInt16) ((R0 << 1) | (R0 >> 15));

				R1 += (UInt16) (K[j++] + (R0 & R3) + ((~R0) & R2));
				R1 = (UInt16) ((R1 << 2) | (R1 >> 14));

				R2 += (UInt16) (K[j++] + (R1 & R0) + ((~R1) & R3));
				R2 = (UInt16) ((R2 << 3) | (R2 >> 13));

				R3 += (UInt16) (K[j++] + (R2 & R1) + ((~R2) & R0));
				R3 = (UInt16) ((R3 << 5) | (R3 >> 11));
			}

			// inline Mash(); j == 44
			R0 += K [R3 & 63];
			R1 += K [R0 & 63];
			R2 += K [R1 & 63];
			R3 += K [R2 & 63];

			// inline, but looped, Mix(); Mix(); Mix(); Mix(); Mix();
			while (j < 64) {
				R0 += (UInt16) (K[j++] + (R3 & R2) + ((~R3) & R1));
				R0 = (UInt16) ((R0 << 1) | (R0 >> 15));

				R1 += (UInt16) (K[j++] + (R0 & R3) + ((~R0) & R2));
				R1 = (UInt16) ((R1 << 2) | (R1 >> 14));

				R2 += (UInt16) (K[j++] + (R1 & R0) + ((~R1) & R3));
				R2 = (UInt16) ((R2 << 3) | (R2 >> 13));

				R3 += (UInt16) (K[j++] + (R2 & R1) + ((~R2) & R0));
				R3 = (UInt16) ((R3 << 5) | (R3 >> 11));
			}
		} 
		else {
			j = 63;
			// inline, but looped, RMix(); RMix(); RMix(); RMix(); RMix();
			while (j >= 44) {
				R3 = (UInt16) ((R3 >> 5) | (R3 << 11));
				R3 -= (UInt16) (K[j--] + (R2 & R1) + ((~R2) & R0));

				R2 = (UInt16) ((R2 >> 3) | (R2 << 13));
				R2 -= (UInt16) (K[j--] + (R1 & R0) + ((~R1) & R3));

				R1 = (UInt16) ((R1 >> 2) | (R1 << 14));
				R1 -= (UInt16) (K[j--] + (R0 & R3) + ((~R0) & R2));

				R0 = (UInt16) ((R0 >> 1) | (R0 << 15));
				R0 -= (UInt16) (K[j--] + (R3 & R2) + ((~R3) & R1));
			}

			// inline RMash();
			R3 -= K [R2 & 63];
			R2 -= K [R1 & 63];
			R1 -= K [R0 & 63];
			R0 -= K [R3 & 63];

			// inline, but looped, RMix(); RMix(); RMix(); RMix(); RMix(); RMix();
			while (j >= 20) {
				R3 = (UInt16) ((R3 >> 5) | (R3 << 11));
				R3 -= (UInt16) (K[j--] + (R2 & R1) + ((~R2) & R0));

				R2 = (UInt16) ((R2 >> 3) | (R2 << 13));
				R2 -= (UInt16) (K[j--] + (R1 & R0) + ((~R1) & R3));

				R1 = (UInt16) ((R1 >> 2) | (R1 << 14));
				R1 -= (UInt16) (K[j--] + (R0 & R3) + ((~R0) & R2));

				R0 = (UInt16) ((R0 >> 1) | (R0 << 15));
				R0 -= (UInt16) (K[j--] + (R3 & R2) + ((~R3) & R1));
			}

			// inline RMash();
			R3 -= K [R2 & 63];
			R2 -= K [R1 & 63];
			R1 -= K [R0 & 63];
			R0 -= K [R3 & 63];

			// inline, but looped, RMix(); RMix(); RMix(); RMix(); RMix();
			while (j >= 0) {
				R3 = (UInt16) ((R3 >> 5) | (R3 << 11));
				R3 -= (UInt16) (K[j--] + (R2 & R1) + ((~R2) & R0));

				R2 = (UInt16) ((R2 >> 3) | (R2 << 13));
				R2 -= (UInt16) (K[j--] + (R1 & R0) + ((~R1) & R3));

				R1 = (UInt16) ((R1 >> 2) | (R1 << 14));
				R1 -= (UInt16) (K[j--] + (R0 & R3) + ((~R0) & R2));

				R0 = (UInt16) ((R0 >> 1) | (R0 << 15));
				R0 -= (UInt16) (K[j--] + (R3 & R2) + ((~R3) & R1));
			}
		}

		// unrolled loop
		output[0] = (byte) R0;
		output[1] = (byte) (R0 >> 8);
		output[2] = (byte) R1;
		output[3] = (byte) (R1 >> 8);
		output[4] = (byte) R2;
		output[5] = (byte) (R2 >> 8);
		output[6] = (byte) R3;
		output[7] = (byte) (R3 >> 8);
	}

	static private byte[] pitable = {
		0xd9, 0x78, 0xf9, 0xc4, 0x19, 0xdd, 0xb5, 0xed, 
		0x28, 0xe9, 0xfd, 0x79, 0x4a, 0xa0, 0xd8, 0x9d,
		0xc6, 0x7e, 0x37, 0x83, 0x2b, 0x76, 0x53, 0x8e, 
		0x62, 0x4c, 0x64, 0x88, 0x44, 0x8b, 0xfb, 0xa2,
		0x17, 0x9a, 0x59, 0xf5, 0x87, 0xb3, 0x4f, 0x13, 
		0x61, 0x45, 0x6d, 0x8d, 0x09, 0x81, 0x7d, 0x32,
		0xbd, 0x8f, 0x40, 0xeb, 0x86, 0xb7, 0x7b, 0x0b, 
		0xf0, 0x95, 0x21, 0x22, 0x5c, 0x6b, 0x4e, 0x82,
		0x54, 0xd6, 0x65, 0x93, 0xce, 0x60, 0xb2, 0x1c, 
		0x73, 0x56, 0xc0, 0x14, 0xa7, 0x8c, 0xf1, 0xdc,
		0x12, 0x75, 0xca, 0x1f, 0x3b, 0xbe, 0xe4, 0xd1, 
		0x42, 0x3d, 0xd4, 0x30, 0xa3, 0x3c, 0xb6, 0x26,
		0x6f, 0xbf, 0x0e, 0xda, 0x46, 0x69, 0x07, 0x57, 
		0x27, 0xf2, 0x1d, 0x9b, 0xbc, 0x94, 0x43, 0x03,
		0xf8, 0x11, 0xc7, 0xf6, 0x90, 0xef, 0x3e, 0xe7, 
		0x06, 0xc3, 0xd5, 0x2f, 0xc8, 0x66, 0x1e, 0xd7,
		0x08, 0xe8, 0xea, 0xde, 0x80, 0x52, 0xee, 0xf7, 
		0x84, 0xaa, 0x72, 0xac, 0x35, 0x4d, 0x6a, 0x2a,
		0x96, 0x1a, 0xd2, 0x71, 0x5a, 0x15, 0x49, 0x74, 
		0x4b, 0x9f, 0xd0, 0x5e, 0x04, 0x18, 0xa4, 0xec,
		0xc2, 0xe0, 0x41, 0x6e, 0x0f, 0x51, 0xcb, 0xcc, 
		0x24, 0x91, 0xaf, 0x50, 0xa1, 0xf4, 0x70, 0x39,
		0x99, 0x7c, 0x3a, 0x85, 0x23, 0xb8, 0xb4, 0x7a, 
		0xfc, 0x02, 0x36, 0x5b, 0x25, 0x55, 0x97, 0x31,
		0x2d, 0x5d, 0xfa, 0x98, 0xe3, 0x8a, 0x92, 0xae, 
		0x05, 0xdf, 0x29, 0x10, 0x67, 0x6c, 0xba, 0xc9,
		0xd3, 0x00, 0xe6, 0xcf, 0xe1, 0x9e, 0xa8, 0x2c, 
		0x63, 0x16, 0x01, 0x3f, 0x58, 0xe2, 0x89, 0xa9,
		0x0d, 0x38, 0x34, 0x1b, 0xab, 0x33, 0xff, 0xb0, 
		0xbb, 0x48, 0x0c, 0x5f, 0xb9, 0xb1, 0xcd, 0x2e,
		0xc5, 0xf3, 0xdb, 0x47, 0xe5, 0xa5, 0x9c, 0x77, 
		0x0a, 0xa6, 0x20, 0x68, 0xfe, 0x7f, 0xc1, 0xad 
	};
}

}