Salsa20Engine (Bouncy Castle Cryptography 1.53 API Specification)

java.lang.Object
- org.bouncycastle.crypto.engines.Salsa20Engine

All Implemented Interfaces:

SkippingCipher, SkippingStreamCipher, StreamCipher

Direct Known Subclasses:

ChaChaEngine, XSalsa20Engine
```
public class Salsa20Engine
extends java.lang.Object
implements SkippingStreamCipher
```
Implementation of Daniel J. Bernstein's Salsa20 stream cipher, Snuffle 2005

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`DEFAULT_ROUNDS`
`protected int[]`	`engineState`
`protected int`	`rounds`
`protected static byte[]`	`sigma`
`protected static byte[]`	`tau`
`protected int[]`	`x`

Constructor Summary

Constructors
Constructor and Description

Salsa20Engine()
Creates a 20 round Salsa20 engine.

Salsa20Engine(int rounds)
Creates a Salsa20 engine with a specific number of rounds.

Constructors
Constructor and Description
`Salsa20Engine()` Creates a 20 round Salsa20 engine.
`Salsa20Engine(int rounds)` Creates a Salsa20 engine with a specific number of rounds.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`protected void`	`advanceCounter()`
`protected void`	`advanceCounter(long diff)`
`protected void`	`generateKeyStream(byte[] output)`
`java.lang.String`	`getAlgorithmName()` Return the name of the algorithm the cipher implements.
`protected long`	`getCounter()`
`protected int`	`getNonceSize()`
`long`	`getPosition()` Return the current "position" of the cipher
`void`	`init(boolean forEncryption, CipherParameters params)` initialise a Salsa20 cipher.
`int`	`processBytes(byte[] in, int inOff, int len, byte[] out, int outOff)` process a block of bytes from in putting the result into out.
`void`	`reset()` reset the cipher.
`protected void`	`resetCounter()`
`protected void`	`retreatCounter()`
`protected void`	`retreatCounter(long diff)`
`byte`	`returnByte(byte in)` encrypt/decrypt a single byte returning the result.
`protected static int`	`rotl(int x, int y)` Rotate left
`static void`	`salsaCore(int rounds, int[] input, int[] x)` Salsa20 function
`long`	`seekTo(long position)` Reset the cipher and then skip forward to a given position.
`protected void`	`setKey(byte[] keyBytes, byte[] ivBytes)`
`long`	`skip(long numberOfBytes)` Skip numberOfBytes forwards, or backwards.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - DEFAULT_ROUNDS
```
public static final int DEFAULT_ROUNDS
```
    See Also:
    
    Constant Field Values
  - sigma
```
protected static final byte[] sigma
```
  - tau
```
protected static final byte[] tau
```
  - rounds
```
protected int rounds
```
  - engineState
```
protected int[] engineState
```
  - x
```
protected int[] x
```
- Constructor Detail
  - Salsa20Engine
```
public Salsa20Engine()
```
    Creates a 20 round Salsa20 engine.
  - Salsa20Engine
```
public Salsa20Engine(int rounds)
```
    Creates a Salsa20 engine with a specific number of rounds.
    
    Parameters:
    
    rounds - the number of rounds (must be an even number).
- Method Detail
  - init
```
public void init(boolean forEncryption,
                 CipherParameters params)
```
    initialise a Salsa20 cipher.
    
    Specified by:
    
    init in interface StreamCipher
    
    Parameters:
    
    forEncryption - whether or not we are for encryption.
    
    params - the parameters required to set up the cipher.
    
    Throws:
    
    java.lang.IllegalArgumentException - if the params argument is inappropriate.
  - getNonceSize
```
protected int getNonceSize()
```
  - getAlgorithmName
```
public java.lang.String getAlgorithmName()
```
    Description copied from interface: StreamCipher
    
    Return the name of the algorithm the cipher implements.
    
    Specified by:
    
    getAlgorithmName in interface StreamCipher
    
    Returns:
    
    the name of the algorithm the cipher implements.
  - returnByte
```
public byte returnByte(byte in)
```
    Description copied from interface: StreamCipher
    
    encrypt/decrypt a single byte returning the result.
    
    Specified by:
    
    returnByte in interface StreamCipher
    
    Parameters:
    
    in - the byte to be processed.
    
    Returns:
    
    the result of processing the input byte.
  - advanceCounter
```
protected void advanceCounter(long diff)
```
  - advanceCounter
```
protected void advanceCounter()
```
  - retreatCounter
```
protected void retreatCounter(long diff)
```
  - retreatCounter
```
protected void retreatCounter()
```
  - processBytes
```
public int processBytes(byte[] in,
                        int inOff,
                        int len,
                        byte[] out,
                        int outOff)
```
    Description copied from interface: StreamCipher
    
    process a block of bytes from in putting the result into out.
    
    Specified by:
    
    processBytes in interface StreamCipher
    
    Parameters:
    
    in - the input byte array.
    
    inOff - the offset into the in array where the data to be processed starts.
    
    len - the number of bytes to be processed.
    
    out - the output buffer the processed bytes go into.
    
    outOff - the offset into the output byte array the processed data starts at.
    
    Returns:
    
    the number of bytes produced - should always be len.
  - skip
```
public long skip(long numberOfBytes)
```
    Description copied from interface: SkippingCipher
    
    Skip numberOfBytes forwards, or backwards.
    
    Specified by:
    
    skip in interface SkippingCipher
    
    Parameters:
    
    numberOfBytes - the number of bytes to skip (positive forward, negative backwards).
    
    Returns:
    
    the number of bytes actually skipped.
  - seekTo
```
public long seekTo(long position)
```
    Description copied from interface: SkippingCipher
    
    Reset the cipher and then skip forward to a given position.
    
    Specified by:
    
    seekTo in interface SkippingCipher
    
    Parameters:
    
    position - the number of bytes in to set the cipher state to.
    
    Returns:
    
    the byte position moved to.
  - getPosition
```
public long getPosition()
```
    Description copied from interface: SkippingCipher
    
    Return the current "position" of the cipher
    
    Specified by:
    
    getPosition in interface SkippingCipher
    
    Returns:
    
    the current byte position.
  - reset
```
public void reset()
```
    Description copied from interface: StreamCipher
    
    reset the cipher. This leaves it in the same state it was at after the last init (if there was one).
    
    Specified by:
    
    reset in interface StreamCipher
  - getCounter
```
protected long getCounter()
```
  - resetCounter
```
protected void resetCounter()
```
  - setKey
```
protected void setKey(byte[] keyBytes,
                      byte[] ivBytes)
```
  - generateKeyStream
```
protected void generateKeyStream(byte[] output)
```
  - salsaCore
```
public static void salsaCore(int rounds,
                             int[] input,
                             int[] x)
```
    Salsa20 function
    
    Parameters:
    
    input - input data
  - rotl
```
protected static int rotl(int x,
                          int y)
```
    Rotate left
    
    Parameters:
    
    x - value to rotate
    
    y - amount to rotate x
    
    Returns:
    
    rotated x

Class Salsa20Engine

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

DEFAULT_ROUNDS

sigma

tau

rounds

engineState

x

Constructor Detail

Salsa20Engine

Salsa20Engine

Method Detail

init

getNonceSize

getAlgorithmName

returnByte

advanceCounter

advanceCounter

retreatCounter

retreatCounter

processBytes

skip

seekTo

getPosition

reset

getCounter

resetCounter

setKey

generateKeyStream

salsaCore

rotl