Package org.bouncycastle.crypto.macs

Class Poly1305

  • All Implemented Interfaces:
    Mac
    public class Poly1305
extends java.lang.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:
    Poly1305KeyGenerator

    • 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

      All Methods Instance Methods Concrete Methods 
      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.
      java.lang.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 Detail

      • 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 Detail

      • init

        public void init​(CipherParameters params)
          throws java.lang.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:
        java.lang.IllegalArgumentException - if the params argument is inappropriate.

      • getAlgorithmName

        public java.lang.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 java.lang.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:
        java.lang.IllegalStateException - if the MAC is not initialised.

      • update

        public void update​(byte[] in,
                   int inOff,
                   int len)
            throws DataLengthException,
                   java.lang.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.
        java.lang.IllegalStateException - if the MAC is not initialised.

      • doFinal

        public int doFinal​(byte[] out,
                   int outOff)
            throws DataLengthException,
                   java.lang.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.
        java.lang.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