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ISAACCipher.java
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ISAACCipher.java
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package com.runescape.client.io;
/**
* A generic ISAAC cipher implementation.
*/
public final class ISAACCipher {
private static final int RATIO = 0x9e3779b9;
private final int[] results;
private final int[] memory;
private int count;
private int accumulator;
private int lastResult;
private int counter;
public ISAACCipher(int seed[]) {
memory = new int[256];
results = new int[256];
System.arraycopy(seed, 0, results, 0, seed.length);
init();
}
public int getNextKey() {
if (count-- == 0) {
isaac();
count = 255;
}
return results[count];
}
private void isaac() {
lastResult += ++counter;
for (int i = 0; i < 256; i++) {
int j = memory[i];
if ((i & 3) == 0) {
accumulator ^= accumulator << 13;
} else if ((i & 3) == 1) {
accumulator ^= accumulator >>> 6;
} else if ((i & 3) == 2) {
accumulator ^= accumulator << 2;
} else if ((i & 3) == 3) {
accumulator ^= accumulator >>> 16;
}
accumulator += memory[i + 128 & 0xff];
int k;
memory[i] = k = memory[(j & 0x3fc) >> 2] + accumulator + lastResult;
results[i] = lastResult = memory[(k >> 8 & 0x3fc) >> 2] + j;
}
}
private void init() {
int i1;
int j1;
int k1;
int l1;
int i2;
int j2;
int k2;
int l = i1 = j1 = k1 = l1 = i2 = j2 = k2 = RATIO;
for (int i = 0; i < 4; i++) {
l ^= i1 << 11;
k1 += l;
i1 += j1;
i1 ^= j1 >>> 2;
l1 += i1;
j1 += k1;
j1 ^= k1 << 8;
i2 += j1;
k1 += l1;
k1 ^= l1 >>> 16;
j2 += k1;
l1 += i2;
l1 ^= i2 << 10;
k2 += l1;
i2 += j2;
i2 ^= j2 >>> 4;
l += i2;
j2 += k2;
j2 ^= k2 << 8;
i1 += j2;
k2 += l;
k2 ^= l >>> 9;
j1 += k2;
l += i1;
}
for (int j = 0; j < 256; j += 8) {
l += results[j];
i1 += results[j + 1];
j1 += results[j + 2];
k1 += results[j + 3];
l1 += results[j + 4];
i2 += results[j + 5];
j2 += results[j + 6];
k2 += results[j + 7];
l ^= i1 << 11;
k1 += l;
i1 += j1;
i1 ^= j1 >>> 2;
l1 += i1;
j1 += k1;
j1 ^= k1 << 8;
i2 += j1;
k1 += l1;
k1 ^= l1 >>> 16;
j2 += k1;
l1 += i2;
l1 ^= i2 << 10;
k2 += l1;
i2 += j2;
i2 ^= j2 >>> 4;
l += i2;
j2 += k2;
j2 ^= k2 << 8;
i1 += j2;
k2 += l;
k2 ^= l >>> 9;
j1 += k2;
l += i1;
memory[j] = l;
memory[j + 1] = i1;
memory[j + 2] = j1;
memory[j + 3] = k1;
memory[j + 4] = l1;
memory[j + 5] = i2;
memory[j + 6] = j2;
memory[j + 7] = k2;
}
for (int k = 0; k < 256; k += 8) {
l += memory[k];
i1 += memory[k + 1];
j1 += memory[k + 2];
k1 += memory[k + 3];
l1 += memory[k + 4];
i2 += memory[k + 5];
j2 += memory[k + 6];
k2 += memory[k + 7];
l ^= i1 << 11;
k1 += l;
i1 += j1;
i1 ^= j1 >>> 2;
l1 += i1;
j1 += k1;
j1 ^= k1 << 8;
i2 += j1;
k1 += l1;
k1 ^= l1 >>> 16;
j2 += k1;
l1 += i2;
l1 ^= i2 << 10;
k2 += l1;
i2 += j2;
i2 ^= j2 >>> 4;
l += i2;
j2 += k2;
j2 ^= k2 << 8;
i1 += j2;
k2 += l;
k2 ^= l >>> 9;
j1 += k2;
l += i1;
memory[k] = l;
memory[k + 1] = i1;
memory[k + 2] = j1;
memory[k + 3] = k1;
memory[k + 4] = l1;
memory[k + 5] = i2;
memory[k + 6] = j2;
memory[k + 7] = k2;
}
isaac();
count = 256;
}
}