Package it.ipzs.cieid

Class AESFast


  • public class AESFast
    extends java.lang.Object
    an implementation of the AES (Rijndael), from FIPS-197.

    For further details see: http://csrc.nist.gov/encryption/aes/. This implementation is based on optimizations from Dr. Brian Gladman's paper and C code at http://fp.gladman.plus.com/cryptography_technology/rijndael/ There are three levels of tradeoff of speed vs memory Because java has no preprocessor, they are written as three separate classes from which to choose The fastest uses 8Kbytes of static tables to precompute round calculations, 4 256 word tables for encryption and 4 for decryption. The middle performance version uses only one 256 word table for each, for a total of 2Kbytes, adding 12 rotate operations per round to compute the values contained in the other tables from the contents of the first The slowest version uses no static tables at all and computes the values in each round

    This file contains the fast version with 8Kbytes of static tables for round precomputation

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description
      class  AESFast.AESException  
    • Constructor Summary

      Constructors 
      Constructor Description
      AESFast()
      default constructor - 128 bit block size.
    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      private void decryptBlock​(int[][] KW)  
      byte[] decryptCBC​(byte[] ciphertext, int nOffset, byte[] iv)  
      static byte[] decryptCBC​(byte[] ciphertext, int nOffset, byte[] key, int keylen, byte[] iv, int nBlockLen)
      Encrypt a palintext.
      byte[] decryptECB​(byte[] ciphertext, int nOffset)
      Encrypt a palintext.
      static byte[] decryptECB​(byte[] ciphertext, int nOffset, byte[] key, int keylen, int nBlockLen)
      Decrypt a ciphertext.
      private void encryptBlock​(int[][] KW)  
      private int FFmulX​(int x)  
      private int[][] generateWorkingKey​(byte[] key, boolean forEncryption)
      Calculate the necessary round keys The number of calculations depends on key size and block size AES specified a fixed block size of 128 bits and key sizes 128/192/256 bits This code is written assuming those are the only possible values
      java.lang.String getAlgorithmName()  
      int getBlockSize()  
      void init​(boolean forEncryption, byte[] key)
      initialise an AES cipher.
      private int inv_mcol​(int x)  
      static byte[] makeSafeKey​(byte[] k, int keysize)  
      private void packBlock​(byte[] bytes, int off)  
      int processBlock​(byte[] in, int inOff, byte[] out, int outOff)  
      void reset()  
      private int shift​(int r, int shift)  
      private int subWord​(int x)  
      private void unpackBlock​(byte[] bytes, int off)  
      private byte[] unpad​(byte[] plaintext)  
      private void xor​(byte[] block, int offsetblok, byte[] iv, int offsetiv, byte[] xoredblock, int offserxored, int blocklen)  
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Field Detail

      • S

        private static final byte[] S
      • Si

        private static final byte[] Si
      • rcon

        private static final int[] rcon
      • T0

        private static final int[] T0
      • T1

        private static final int[] T1
      • T2

        private static final int[] T2
      • T3

        private static final int[] T3
      • Tinv0

        private static final int[] Tinv0
      • Tinv1

        private static final int[] Tinv1
      • Tinv2

        private static final int[] Tinv2
      • Tinv3

        private static final int[] Tinv3
      • ROUNDS

        private int ROUNDS
      • WorkingKey

        private int[][] WorkingKey
      • C0

        private int C0
      • C1

        private int C1
      • C2

        private int C2
      • C3

        private int C3
      • forEncryption

        private boolean forEncryption
    • Constructor Detail

      • AESFast

        public AESFast()
        default constructor - 128 bit block size.
    • Method Detail

      • shift

        private int shift​(int r,
                          int shift)
      • FFmulX

        private int FFmulX​(int x)
      • inv_mcol

        private int inv_mcol​(int x)
      • subWord

        private int subWord​(int x)
      • generateWorkingKey

        private int[][] generateWorkingKey​(byte[] key,
                                           boolean forEncryption)
        Calculate the necessary round keys The number of calculations depends on key size and block size AES specified a fixed block size of 128 bits and key sizes 128/192/256 bits This code is written assuming those are the only possible values
      • init

        public void init​(boolean forEncryption,
                         byte[] key)
        initialise an AES cipher.
        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.
      • getAlgorithmName

        public java.lang.String getAlgorithmName()
      • getBlockSize

        public int getBlockSize()
      • processBlock

        public int processBlock​(byte[] in,
                                int inOff,
                                byte[] out,
                                int outOff)
      • reset

        public void reset()
      • unpackBlock

        private final void unpackBlock​(byte[] bytes,
                                       int off)
      • packBlock

        private final void packBlock​(byte[] bytes,
                                     int off)
      • encryptBlock

        private final void encryptBlock​(int[][] KW)
      • decryptBlock

        private final void decryptBlock​(int[][] KW)
      • decryptECB

        public byte[] decryptECB​(byte[] ciphertext,
                                 int nOffset)
        Encrypt a palintext.
        Parameters:
        ciphertext - The ciphertext.
        nOffset - Index of in from which to start considering data.
        sessionKey - The session key to use for encryption.
        blockSize - The block size in bytes of this Rijndael.
        Returns:
        The plaintext generated from ciphertext using the session key.
      • decryptCBC

        public byte[] decryptCBC​(byte[] ciphertext,
                                 int nOffset,
                                 byte[] iv)
      • unpad

        private byte[] unpad​(byte[] plaintext)
      • xor

        private void xor​(byte[] block,
                         int offsetblok,
                         byte[] iv,
                         int offsetiv,
                         byte[] xoredblock,
                         int offserxored,
                         int blocklen)
      • decryptECB

        public static byte[] decryptECB​(byte[] ciphertext,
                                        int nOffset,
                                        byte[] key,
                                        int keylen,
                                        int nBlockLen)
        Decrypt a ciphertext.
        Parameters:
        ciphertext - The ciphertext.
        nOffset - Index of in from which to start considering data.
        key - The session key to use for encryption.
        blockSize - The block size in bytes of this Rijndael.
        Returns:
        The plaintext generated from ciphertext using the session key.
      • decryptCBC

        public static byte[] decryptCBC​(byte[] ciphertext,
                                        int nOffset,
                                        byte[] key,
                                        int keylen,
                                        byte[] iv,
                                        int nBlockLen)
        Encrypt a palintext.
        Parameters:
        ciphertext - The ciphertext.
        nOffset - Index of in from which to start considering data.
        key - The session key to use for encryption.
        blockSize - The block size in bytes of this Rijndael.
        Returns:
        The plaintext generated from ciphertext using the session key.
      • makeSafeKey

        public static byte[] makeSafeKey​(byte[] k,
                                         int keysize)