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## org.bouncycastle.crypto.engines
Class RSABlindingEngine

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

Constructor Summary
`RSABlindingEngine()`

Method Summary
`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.

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