AsymmetricBlockCipher (Bouncy Castle Library 1.85 API Specification)
Date: 2026-07-12

org.bouncycastle.crypto

## Interface AsymmetricBlockCipher

- All Known Implementing Classes:
    ElGamalEngine, ISO9796d1Encoding, NaccacheSternEngine, OAEPEncoding, PKCS1Encoding, RSABlindedEngine, RSABlindingEngine, RSAEngine

      public interface AsymmetricBlockCipher

  base interface that a public/private key block cipher needs to conform to.

- - ### Method Summary

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method and Description
    --- | ---
    `int` | `getInputBlockSize()` returns the largest size an input block can be.
    `int` | `getOutputBlockSize()` returns the maximum size of the block produced by this cipher.
    `void` | `init(boolean forEncryption, CipherParameters param)` initialise the cipher.
    `byte[]` | `processBlock(byte[] in, int inOff, int len)` process the block of len bytes stored in in from offset inOff.

- - ### Method Detail

    - #### init

          void init(boolean forEncryption,
                    CipherParameters param)

      initialise the cipher.
      Parameters:
        `forEncryption` - if true the cipher is initialised for encryption, if false for decryption.
        `param` - the key and other data required by the cipher.

    - #### getInputBlockSize

          int getInputBlockSize()

      returns the largest size an input block can be.
      Returns:
        maximum size for an input block.

    - #### getOutputBlockSize

          int getOutputBlockSize()

      returns the maximum size of the block produced by this cipher.
      Returns:
        maximum size of the output block produced by the cipher.

    - #### processBlock

          byte[] processBlock(byte[] in,
                              int inOff,
                              int len)
                       throws InvalidCipherTextException

      process the block of len bytes stored in in from offset inOff.
      Parameters:
        `in` - the input data
        `inOff` - offset into the in array where the data starts
        `len` - the length of the block to be processed.
      Returns:
        the resulting byte array of the encryption/decryption process.
      Throws:
        `InvalidCipherTextException` - data decrypts improperly.
        `DataLengthException` - the input data is too large for the cipher.