using System;
using Org.BouncyCastle.Crypto.Engines;
using Org.BouncyCastle.Crypto.Parameters;
namespace Org.BouncyCastle.Crypto.Digests{
/**
* implementation of GOST R 34.11-94
*/
public class Gost3411Digest
: IDigest
{
private const int DIGEST_LENGTH = 32;
private byte[] H = new byte[32], L = new byte[32],
M = new byte[32], Sum = new byte[32];
private byte[][] C = new byte[4][];
private byte[] xBuf = new byte[32];
private int xBufOff;
private long byteCount;
private readonly IBlockCipher cipher = new Gost28147Engine();
/**
* Standard constructor
*/
public Gost3411Digest()
{
// TODO Is it possible to declare multi-dimensional arrays as in Java?
for (int i = 0; i < 4; ++i)
{
C[i] = new byte[32];
}
cipher.Init(true, new ParametersWithSBox(null, Gost28147Engine.GetSBox("D-A")));
Reset();
}
/**
* Copy constructor. This will copy the state of the provided
* message digest.
*/
public Gost3411Digest(Gost3411Digest t)
: this()
{
// cipher.Init(true, new ParametersWithSBox(null, Gost28147Engine.GetSBox("D-A")));
//
// Reset();
Array.Copy(t.H, 0, this.H, 0, t.H.Length);
Array.Copy(t.L, 0, this.L, 0, t.L.Length);
Array.Copy(t.M, 0, this.M, 0, t.M.Length);
Array.Copy(t.Sum, 0, this.Sum, 0, t.Sum.Length);
Array.Copy(t.C[1], 0, this.C[1], 0, t.C[1].Length);
Array.Copy(t.C[2], 0, this.C[2], 0, t.C[2].Length);
Array.Copy(t.C[3], 0, this.C[3], 0, t.C[3].Length);
Array.Copy(t.xBuf, 0, this.xBuf, 0, t.xBuf.Length);
this.xBufOff = t.xBufOff;
this.byteCount = t.byteCount;
}
public string AlgorithmName
{
get { return "Gost3411"; }
}
public int GetDigestSize()
{
return DIGEST_LENGTH;
}
public void Update(
byte input)
{
xBuf[xBufOff++] = input;
if (xBufOff == xBuf.Length)
{
sumByteArray(xBuf); // calc sum M
processBlock(xBuf, 0);
xBufOff = 0;
}
byteCount++;
}
public void BlockUpdate(
byte[] input,
int inOff,
int length)
{
while ((xBufOff != 0) && (length > 0))
{
Update(input[inOff]);
inOff++;
length--;
}
while (length > xBuf.Length)
{
Array.Copy(input, inOff, xBuf, 0, xBuf.Length);
sumByteArray(xBuf); // calc sum M
processBlock(xBuf, 0);
inOff += xBuf.Length;
length -= xBuf.Length;
byteCount += xBuf.Length;
}
// load in the remainder.
while (length > 0)
{
Update(input[inOff]);
inOff++;
length--;
}
}
// (i + 1 + 4(k - 1)) = 8i + k i = 0-3, k = 1-8
private byte[] K = new byte[32];
private byte[] P(byte[] input)
{
int fourK = 0;
for(int k = 0; k < 8; k++)
{
K[fourK++] = input[k];
K[fourK++] = input[8 + k];
K[fourK++] = input[16 + k];
K[fourK++] = input[24 + k];
}
return K;
}
//A (x) = (x0 ^ x1) || x3 || x2 || x1
byte[] a = new byte[8];
private byte[] A(byte[] input)
{
for(int j=0; j<8; j++)
{
a[j]=(byte)(input[j] ^ input[j+8]);
}
Array.Copy(input, 8, input, 0, 24);
Array.Copy(a, 0, input, 24, 8);
return input;
}
//Encrypt function, ECB mode
private void E(byte[] key, byte[] s, int sOff, byte[] input, int inOff)
{
cipher.Init(true, new KeyParameter(key));
cipher.ProcessBlock(input, inOff, s, sOff);
}
// (in:) n16||..||n1 ==> (out:) n1^n2^n3^n4^n13^n16||n16||..||n2
internal short[] wS = new short[16], w_S = new short[16];
private void fw(byte[] input)
{
cpyBytesToShort(input, wS);
w_S[15] = (short)(wS[0] ^ wS[1] ^ wS[2] ^ wS[3] ^ wS[12] ^ wS[15]);
Array.Copy(wS, 1, w_S, 0, 15);
cpyShortToBytes(w_S, input);
}
// block processing
internal byte[] S = new byte[32], U = new byte[32], V = new byte[32], W = new byte[32];
private void processBlock(byte[] input, int inOff)
{
Array.Copy(input, inOff, M, 0, 32);
//key step 1
// H = h3 || h2 || h1 || h0
// S = s3 || s2 || s1 || s0
H.CopyTo(U, 0);
M.CopyTo(V, 0);
for (int j=0; j<32; j++)
{
W[j] = (byte)(U[j]^V[j]);
}
// Encrypt gost28147-ECB
E(P(W), S, 0, H, 0); // s0 = EK0 [h0]
//keys step 2,3,4
for (int i=1; i<4; i++)
{
byte[] tmpA = A(U);
for (int j=0; j<32; j++)
{
U[j] = (byte)(tmpA[j] ^ C[i][j]);
}
V = A(A(V));
for (int j=0; j<32; j++)
{
W[j] = (byte)(U[j]^V[j]);
}
// Encrypt gost28147-ECB
E(P(W), S, i * 8, H, i * 8); // si = EKi [hi]
}
// x(M, H) = y61(H^y(M^y12(S)))
for(int n = 0; n < 12; n++)
{
fw(S);
}
for(int n = 0; n < 32; n++)
{
S[n] = (byte)(S[n] ^ M[n]);
}
fw(S);
for(int n = 0; n < 32; n++)
{
S[n] = (byte)(H[n] ^ S[n]);
}
for(int n = 0; n < 61; n++)
{
fw(S);
}
Array.Copy(S, 0, H, 0, H.Length);
}
private void finish()
{
LongToBytes(byteCount * 8, L, 0); // get length into L (byteCount * 8 = bitCount)
while (xBufOff != 0)
{
Update((byte)0);
}
processBlock(L, 0);
processBlock(Sum, 0);
}
public int DoFinal(
byte[] output,
int outOff)
{
finish();
H.CopyTo(output, outOff);
Reset();
return DIGEST_LENGTH;
}
/**
* reset the chaining variables to the IV values.
*/
private static readonly byte[] C2 = {
0x00,(byte)0xFF,0x00,(byte)0xFF,0x00,(byte)0xFF,0x00,(byte)0xFF,
(byte)0xFF,0x00,(byte)0xFF,0x00,(byte)0xFF,0x00,(byte)0xFF,0x00,
0x00,(byte)0xFF,(byte)0xFF,0x00,(byte)0xFF,0x00,0x00,(byte)0xFF,
(byte)0xFF,0x00,0x00,0x00,(byte)0xFF,(byte)0xFF,0x00,(byte)0xFF
};
public void Reset()
{
byteCount = 0;
xBufOff = 0;
Array.Clear(H, 0, H.Length);
Array.Clear(L, 0, L.Length);
Array.Clear(M, 0, M.Length);
Array.Clear(C[1], 0, C[1].Length); // real index C = +1 because index array with 0.
Array.Clear(C[3], 0, C[3].Length);
Array.Clear(Sum, 0, Sum.Length);
Array.Clear(xBuf, 0, xBuf.Length);
C2.CopyTo(C[2], 0);
}
// 256 bitsblock modul -> (Sum + a mod (2^256))
private void sumByteArray(
byte[] input)
{
int carry = 0;
for (int i = 0; i != Sum.Length; i++)
{
int sum = (Sum[i] & 0xff) + (input[i] & 0xff) + carry;
Sum[i] = (byte)sum;
carry = sum >> 8;
}
}
// TODO Refactor as utility function
private static void LongToBytes(
long r,
byte[] output,
int outOff)
{
output[outOff + 7] = (byte)(r >> 56);
output[outOff + 6] = (byte)(r >> 48);
output[outOff + 5] = (byte)(r >> 40);
output[outOff + 4] = (byte)(r >> 32);
output[outOff + 3] = (byte)(r >> 24);
output[outOff + 2] = (byte)(r >> 16);
output[outOff + 1] = (byte)(r >> 8);
output[outOff] = (byte)r;
}
private static void cpyBytesToShort(byte[] S, short[] wS)
{
for(int i = 0; i < S.Length / 2; i++)
{
wS[i] = (short)(((S[i*2+1]<<8)&0xFF00)|(S[i*2]&0xFF));
}
}
private static void cpyShortToBytes(short[] wS, byte[] S)
{
for(int i=0; i<S.Length/2; i++)
{
S[i*2 + 1] = (byte)(wS[i] >> 8);
S[i*2] = (byte)wS[i];
}
}
public int GetByteLength()
{
return 32;
}
}
}
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