com.runehive.net.codec.IsaacCipher Class Reference

An implementation of an ISAAC cipher. More...

Public Member Functions
int	getKey ()
	Gets the next value.
void	init (boolean flag)
	Initializes the ISAAC.
void	isaac ()
	Generates 256 results.
	IsaacCipher (int[] seed)
	Creates the ISAAC cipher.

Private Attributes
int	a
	The accumulator.
int	b
	The last result.
int	c
	The counter.
int	count = 0
	The count through the results.
int	memory [] = new int[SIZE]
	The internal memory state.
int	results [] = new int[SIZE]
	The results.

Static Private Attributes
static final int	MASK = (SIZE - 1) << 2
	For pseudorandom lookup.
static final int	RATIO = 0x9e3779b9
	The golden ratio.
static final int	SIZE = 1 << SIZE_LOG
	The size of the results and memory arrays.
static final int	SIZE_LOG = 8
	The log of the size of the results and memory arrays.

Detailed Description

An implementation of an ISAAC cipher.

See http://en.wikipedia.org/wiki/ISAAC_(cipher) for more information.

This implementation is based on the one written by Bob Jenkins, which is available at http://www.burtleburtle.net/bob/java/rand/Rand.java.

Author

Graham Edgecombe

Definition at line 36 of file IsaacCipher.java.

Constructor & Destructor Documentation

IsaacCipher()

com.runehive.net.codec.IsaacCipher.IsaacCipher

(

int[]

seed

)

Creates the ISAAC cipher.

Parameters

seed

The seed.

Definition at line 93 of file IsaacCipher.java.

                                  {
       for (int i = 0; i < seed.length; i++) {
           results[i] = seed[i];
       }
       init(true);
   }

References init(), and results.

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Member Function Documentation

getKey()

int com.runehive.net.codec.IsaacCipher.getKey

(

)

Gets the next value.

Returns

The next value.

Definition at line 105 of file IsaacCipher.java.

                       {
       if (count-- == 0) {
           isaac();
           count = SIZE - 1;
       }
       return results[count];
   }

References count, isaac(), results, and SIZE.

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init()

void com.runehive.net.codec.IsaacCipher.init

(

boolean

flag

)

Initializes the ISAAC.

Parameters

flag	Flag indicating if we should perform a second pass.

Definition at line 176 of file IsaacCipher.java.

                                  {
       int i;
       int a, b, c, d, e, f, g, h;
       a = b = c = d = e = f = g = h = RATIO;
       for (i = 0; i < 4; ++i) {
           a ^= b << 11;
           d += a;
           b += c;
           b ^= c >>> 2;
           e += b;
           c += d;
           c ^= d << 8;
           f += c;
           d += e;
           d ^= e >>> 16;
           g += d;
           e += f;
           e ^= f << 10;
           h += e;
           f += g;
           f ^= g >>> 4;
           a += f;
           g += h;
           g ^= h << 8;
           b += g;
           h += a;
           h ^= a >>> 9;
           c += h;
           a += b;
       }
       for (i = 0; i < SIZE; i += 8) {
           if (flag) {
               a += results[i];
               b += results[i + 1];
               c += results[i + 2];
               d += results[i + 3];
               e += results[i + 4];
               f += results[i + 5];
               g += results[i + 6];
               h += results[i + 7];
           }
           a ^= b << 11;
           d += a;
           b += c;
           b ^= c >>> 2;
           e += b;
           c += d;
           c ^= d << 8;
           f += c;
           d += e;
           d ^= e >>> 16;
           g += d;
           e += f;
           e ^= f << 10;
           h += e;
           f += g;
           f ^= g >>> 4;
           a += f;
           g += h;
           g ^= h << 8;
           b += g;
           h += a;
           h ^= a >>> 9;
           c += h;
           a += b;
           memory[i] = a;
           memory[i + 1] = b;
           memory[i + 2] = c;
           memory[i + 3] = d;
           memory[i + 4] = e;
           memory[i + 5] = f;
           memory[i + 6] = g;
           memory[i + 7] = h;
       }
       if (flag) {
           for (i = 0; i < SIZE; i += 8) {
               a += memory[i];
               b += memory[i + 1];
               c += memory[i + 2];
               d += memory[i + 3];
               e += memory[i + 4];
               f += memory[i + 5];
               g += memory[i + 6];
               h += memory[i + 7];
               a ^= b << 11;
               d += a;
               b += c;
               b ^= c >>> 2;
               e += b;
               c += d;
               c ^= d << 8;
               f += c;
               d += e;
               d ^= e >>> 16;
               g += d;
               e += f;
               e ^= f << 10;
               h += e;
               f += g;
               f ^= g >>> 4;
               a += f;
               g += h;
               g ^= h << 8;
               b += g;
               h += a;
               h ^= a >>> 9;
               c += h;
               a += b;
               memory[i] = a;
               memory[i + 1] = b;
               memory[i + 2] = c;
               memory[i + 3] = d;
               memory[i + 4] = e;
               memory[i + 5] = f;
               memory[i + 6] = g;
               memory[i + 7] = h;
           }
       }
       isaac();
       count = SIZE;
   }

References a, b, c, count, isaac(), memory, RATIO, results, and SIZE.

Referenced by IsaacCipher().

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isaac()

void com.runehive.net.codec.IsaacCipher.isaac

(

)

Generates 256 results.

Definition at line 116 of file IsaacCipher.java.

                       {
       int i, j, x, y;
       b += ++c;
       for (i = 0, j = SIZE / 2; i < SIZE / 2; ) {
           x = memory[i];
           a ^= a << 13;
           a += memory[j++];
           memory[i] = y = memory[(x & MASK) >> 2] + a + b;
           results[i++] = b = memory[((y >> SIZE_LOG) & MASK) >> 2] + x;
 
           x = memory[i];
           a ^= a >>> 6;
           a += memory[j++];
           memory[i] = y = memory[(x & MASK) >> 2] + a + b;
           results[i++] = b = memory[((y >> SIZE_LOG) & MASK) >> 2] + x;
 
           x = memory[i];
           a ^= a << 2;
           a += memory[j++];
           memory[i] = y = memory[(x & MASK) >> 2] + a + b;
           results[i++] = b = memory[((y >> SIZE_LOG) & MASK) >> 2] + x;
 
           x = memory[i];
           a ^= a >>> 16;
           a += memory[j++];
           memory[i] = y = memory[(x & MASK) >> 2] + a + b;
           results[i++] = b = memory[((y >> SIZE_LOG) & MASK) >> 2] + x;
       }
       for (j = 0; j < SIZE / 2; ) {
           x = memory[i];
           a ^= a << 13;
           a += memory[j++];
           memory[i] = y = memory[(x & MASK) >> 2] + a + b;
           results[i++] = b = memory[((y >> SIZE_LOG) & MASK) >> 2] + x;
 
           x = memory[i];
           a ^= a >>> 6;
           a += memory[j++];
           memory[i] = y = memory[(x & MASK) >> 2] + a + b;
           results[i++] = b = memory[((y >> SIZE_LOG) & MASK) >> 2] + x;
 
           x = memory[i];
           a ^= a << 2;
           a += memory[j++];
           memory[i] = y = memory[(x & MASK) >> 2] + a + b;
           results[i++] = b = memory[((y >> SIZE_LOG) & MASK) >> 2] + x;
 
           x = memory[i];
           a ^= a >>> 16;
           a += memory[j++];
           memory[i] = y = memory[(x & MASK) >> 2] + a + b;
           results[i++] = b = memory[((y >> SIZE_LOG) & MASK) >> 2] + x;
       }
   }

References a, b, c, MASK, memory, results, SIZE, and SIZE_LOG.

Referenced by getKey(), and init().

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Member Data Documentation

a

int com.runehive.net.codec.IsaacCipher.a

private

The accumulator.

Definition at line 76 of file IsaacCipher.java.

Referenced by init(), and isaac().

b

int com.runehive.net.codec.IsaacCipher.b

private

The last result.

Definition at line 81 of file IsaacCipher.java.

Referenced by init(), and isaac().

c

int com.runehive.net.codec.IsaacCipher.c

private

The counter.

Definition at line 86 of file IsaacCipher.java.

Referenced by init(), and isaac().

count

int com.runehive.net.codec.IsaacCipher.count = 0

private

The count through the results.

Definition at line 61 of file IsaacCipher.java.

Referenced by getKey(), and init().

MASK

final int com.runehive.net.codec.IsaacCipher.MASK = (SIZE - 1) << 2

staticprivate

For pseudorandom lookup.

Definition at line 56 of file IsaacCipher.java.

Referenced by isaac().

memory

int com.runehive.net.codec.IsaacCipher.memory[] = new int[SIZE]

private

The internal memory state.

Definition at line 71 of file IsaacCipher.java.

Referenced by init(), and isaac().

RATIO

final int com.runehive.net.codec.IsaacCipher.RATIO = 0x9e3779b9

staticprivate

The golden ratio.

Definition at line 41 of file IsaacCipher.java.

Referenced by init().

results

int com.runehive.net.codec.IsaacCipher.results[] = new int[SIZE]

private

The results.

Definition at line 66 of file IsaacCipher.java.

Referenced by getKey(), init(), isaac(), and IsaacCipher().

SIZE

final int com.runehive.net.codec.IsaacCipher.SIZE = 1 << SIZE_LOG

staticprivate

The size of the results and memory arrays.

Definition at line 51 of file IsaacCipher.java.

Referenced by getKey(), init(), and isaac().

SIZE_LOG

final int com.runehive.net.codec.IsaacCipher.SIZE_LOG = 8

staticprivate

The log of the size of the results and memory arrays.

Definition at line 46 of file IsaacCipher.java.

Referenced by isaac().

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The documentation for this class was generated from the following file:

• java/com/runehive/net/codec/IsaacCipher.java