Package org.bouncycastle.crypto.macs

Class Poly1305

java.lang.Object
org.bouncycastle.crypto.macs.Poly1305
All Implemented Interfaces:
Mac
public class Poly1305 extends Object implements Mac
Poly1305 message authentication code, designed by D. J. Bernstein.

Poly1305 computes a 128-bit (16 bytes) authenticator, using a 128 bit nonce and a 256 bit key consisting of a 128 bit key applied to an underlying cipher, and a 128 bit key (with 106 effective key bits) used in the authenticator.

The polynomial calculation in this implementation is adapted from the public domain poly1305-donna-unrolled C implementation by Andrew M (@floodyberry).

See Also:

  • Constructor Summary

    Constructors
    Constructor
    Description
    Poly1305()
    Constructs a Poly1305 MAC, where the key passed to init() will be used directly.
    Poly1305(BlockCipher cipher)
    Constructs a Poly1305 MAC, using a 128 bit block cipher.

  • Method Summary

    Modifier and Type
    Method
    Description
    int
    doFinal(byte[] out, int outOff)
    Compute the final stage of the MAC writing the output to the out parameter.
    String
    getAlgorithmName()
    Return the name of the algorithm the MAC implements.
    int
    getMacSize()
    Return the block size for this MAC (in bytes).
    void
    init(CipherParameters params)
    Initialises the Poly1305 MAC.
    void
    reset()
    Reset the MAC.
    void
    update(byte in)
    add a single byte to the mac for processing.
    void
    update(byte[] in, int inOff, int len)
     

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • Poly1305

      public Poly1305()
      Constructs a Poly1305 MAC, where the key passed to init() will be used directly.

    • Poly1305

      public Poly1305(BlockCipher cipher)
      Constructs a Poly1305 MAC, using a 128 bit block cipher.

  • Method Details

    • init

      public void init(CipherParameters params) throws IllegalArgumentException
      Initialises the Poly1305 MAC.
      Specified by:
      init in interface Mac
      Parameters:
      params - if used with a block cipher, then a ParametersWithIV containing a 128 bit nonce and a KeyParameter with a 256 bit key complying to the Poly1305 key format, otherwise just the KeyParameter.
      Throws:
      IllegalArgumentException - if the params argument is inappropriate.

    • getAlgorithmName

      public String getAlgorithmName()
      Description copied from interface: Mac
      Return the name of the algorithm the MAC implements.
      Specified by:
      getAlgorithmName in interface Mac
      Returns:
      the name of the algorithm the MAC implements.

    • getMacSize

      public int getMacSize()
      Description copied from interface: Mac
      Return the block size for this MAC (in bytes).
      Specified by:
      getMacSize in interface Mac
      Returns:
      the block size for this MAC in bytes.

    • update

      public void update(byte in) throws IllegalStateException
      Description copied from interface: Mac
      add a single byte to the mac for processing.
      Specified by:
      update in interface Mac
      Parameters:
      in - the byte to be processed.
      Throws:
      IllegalStateException - if the MAC is not initialised.

    • update

      public void update(byte[] in, int inOff, int len) throws DataLengthException, IllegalStateException
      Specified by:
      update in interface Mac
      Parameters:
      in - the array containing the input.
      inOff - the index in the array the data begins at.
      len - the length of the input starting at inOff.
      Throws:
      DataLengthException - if there isn't enough data in in.
      IllegalStateException - if the MAC is not initialised.

    • doFinal

      public int doFinal(byte[] out, int outOff) throws DataLengthException, IllegalStateException
      Description copied from interface: Mac
      Compute the final stage of the MAC writing the output to the out parameter.

      doFinal leaves the MAC in the same state it was after the last init.

      Specified by:
      doFinal in interface Mac
      Parameters:
      out - the array the MAC is to be output to.
      outOff - the offset into the out buffer the output is to start at.
      Throws:
      DataLengthException - if there isn't enough space in out.
      IllegalStateException - if the MAC is not initialised.

    • reset

      public void reset()
      Description copied from interface: Mac
      Reset the MAC. At the end of resetting the MAC should be in the in the same state it was after the last init (if there was one).
      Specified by:
      reset in interface Mac