Package org.bouncycastle.crypto.engines

Class RSABlindingEngine

  • All Implemented Interfaces:
    AsymmetricBlockCipher
    public class RSABlindingEngine
extends java.lang.Object
implements AsymmetricBlockCipher
    This does your basic RSA Chaum's blinding and unblinding as outlined in "Handbook of Applied Cryptography", page 475. You need to use this if you are trying to get another party to generate signatures without them being aware of the message they are signing.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      int getInputBlockSize()
      Return the maximum size for an input block to this engine.
      int getOutputBlockSize()
      Return the maximum size for an output block to this engine.
      void init​(boolean forEncryption, CipherParameters param)
      Initialise the blinding engine.
      byte[] processBlock​(byte[] in, int inOff, int inLen)
      Process a single block using the RSA blinding algorithm.

      • Methods inherited from class java.lang.Object

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

    • Constructor Detail

      • RSABlindingEngine

        public RSABlindingEngine()

    • Method Detail

      • init

        public void init​(boolean forEncryption,
                 CipherParameters param)
        Initialise the blinding engine.
        Specified by:
        init in interface AsymmetricBlockCipher
        Parameters:
        forEncryption - true if we are encrypting (blinding), false otherwise.
        param - the necessary RSA key parameters.

      • getInputBlockSize

        public int getInputBlockSize()
        Return the maximum size for an input block to this engine. For RSA this is always one byte less than the key size on encryption, and the same length as the key size on decryption.
        Specified by:
        getInputBlockSize in interface AsymmetricBlockCipher
        Returns:
        maximum size for an input block.

      • getOutputBlockSize

        public int getOutputBlockSize()
        Return the maximum size for an output block to this engine. For RSA this is always one byte less than the key size on decryption, and the same length as the key size on encryption.
        Specified by:
        getOutputBlockSize in interface AsymmetricBlockCipher
        Returns:
        maximum size for an output block.

      • processBlock

        public byte[] processBlock​(byte[] in,
                           int inOff,
                           int inLen)
        Process a single block using the RSA blinding algorithm.
        Specified by:
        processBlock in interface AsymmetricBlockCipher
        Parameters:
        in - the input array.
        inOff - the offset into the input buffer where the data starts.
        inLen - the length of the data to be processed.
        Returns:
        the result of the RSA process.
        Throws:
        DataLengthException - the input block is too large.