Package org.bouncycastle.pqc.jcajce.provider.util

## Class AsymmetricBlockCipher

- java.lang.Object
- - javax.crypto.CipherSpi
  - - org.bouncycastle.pqc.jcajce.provider.util.CipherSpiExt
    - - org.bouncycastle.pqc.jcajce.provider.util.AsymmetricBlockCipher

- Direct Known Subclasses:
    `McEliecePKCSCipherSpi`

      public abstract class AsymmetricBlockCipher
      extends CipherSpiExt

  The AsymmetricBlockCipher class extends CipherSpiExt. NOTE: Some Ciphers are using Padding. OneAndZeroesPadding is used as default padding. However padding can still be specified, but mode is not supported; if you try to instantiate the cipher with something else than "NONE" as mode NoSuchAlgorithmException is thrown.

- - ### Field Summary

    Fields
    Modifier and Type | Field | Description
    --- | --- | ---
    `protected java.io.ByteArrayOutputStream` | `buf` | Internal buffer
    `protected int` | `cipherTextSize` | The maximum number of bytes the cipher can encrypt.
    `protected int` | `maxPlainTextSize` | The maximum number of bytes the cipher can decrypt.
    `protected java.security.spec.AlgorithmParameterSpec` | `paramSpec` | ParameterSpec used with this cipher

    - ### Fields inherited from class org.bouncycastle.pqc.jcajce.provider.util.CipherSpiExt

      `DECRYPT_MODE, ENCRYPT_MODE, opMode`

  - ### Constructor Summary

    Constructors
    Constructor | Description
    --- | ---
    `AsymmetricBlockCipher()` | The AsymmetricBlockCipher() constructor

  - ### Method Summary

    All Methods Instance Methods Abstract Methods Concrete Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `protected void` | `checkLength​(int inLen)` | Check if the message length plus the length of the input length can be en/decrypted.
    `byte[]` | `doFinal​(byte[] input, int inOff, int inLen)` | Finish a multiple-part encryption or decryption operation (depending on how this cipher was initialized).
    `int` | `doFinal​(byte[] input, int inOff, int inLen, byte[] output, int outOff)` | Finish a multiple-part encryption or decryption operation (depending on how this cipher was initialized).
    `int` | `getBlockSize()` | Return the block size (in bytes).
    `byte[]` | `getIV()` | Return the initialization vector.
    `int` | `getOutputSize​(int inLen)` | Return the length in bytes that an output buffer would need to be in order to hold the result of the next update or doFinal operation, given the input length `inLen` (in bytes).
    `java.security.spec.AlgorithmParameterSpec` | `getParameters()` | Returns the parameters used with this cipher.
    `protected abstract void` | `initCipherDecrypt​(java.security.Key key, java.security.spec.AlgorithmParameterSpec params)` | Initialize the AsymmetricBlockCipher with a certain key for data encryption.
    `protected abstract void` | `initCipherEncrypt​(java.security.Key key, java.security.spec.AlgorithmParameterSpec params, java.security.SecureRandom sr)` | Initialize the AsymmetricBlockCipher with a certain key for data encryption.
    `void` | `initDecrypt​(java.security.Key key)` | Initialize the cipher for decryption by forwarding it to `initDecrypt(Key, AlgorithmParameterSpec)`.
    `void` | `initDecrypt​(java.security.Key key, java.security.spec.AlgorithmParameterSpec params)` | This method initializes the AsymmetricBlockCipher with a certain key for data decryption.
    `void` | `initEncrypt​(java.security.Key key)` | Initializes the cipher for encryption by forwarding it to initEncrypt(Key, FlexiSecureRandom).
    `void` | `initEncrypt​(java.security.Key key, java.security.SecureRandom random)` | Initialize this cipher for encryption by forwarding it to initEncrypt(Key, FlexiSecureRandom, AlgorithmParameterSpec).
    `void` | `initEncrypt​(java.security.Key key, java.security.spec.AlgorithmParameterSpec params)` | Initializes the cipher for encryption by forwarding it to initEncrypt(Key, FlexiSecureRandom, AlgorithmParameterSpec).
    `void` | `initEncrypt​(java.security.Key key, java.security.spec.AlgorithmParameterSpec params, java.security.SecureRandom secureRandom)` | This method initializes the AsymmetricBlockCipher with a certain key for data encryption.
    `protected abstract byte[]` | `messageDecrypt​(byte[] input)` | Decrypt the ciphertext stored in input.
    `protected abstract byte[]` | `messageEncrypt​(byte[] input)` | Encrypt the message stored in input.
    `protected void` | `setMode​(java.lang.String modeName)` | Since asymmetric block ciphers do not support modes, this method does nothing.
    `protected void` | `setPadding​(java.lang.String paddingName)` | Since asymmetric block ciphers do not support padding, this method does nothing.
    `byte[]` | `update​(byte[] input, int inOff, int inLen)` | Continue a multiple-part encryption or decryption operation.
    `int` | `update​(byte[] input, int inOff, int inLen, byte[] output, int outOff)` | Continue a multiple-part encryption or decryption operation (depending on how this cipher was initialized), processing another data part.

    - ### Methods inherited from class org.bouncycastle.pqc.jcajce.provider.util.CipherSpiExt

      `doFinal, doFinal, engineDoFinal, engineDoFinal, engineGetBlockSize, engineGetIV, engineGetKeySize, engineGetOutputSize, engineGetParameters, engineInit, engineInit, engineInit, engineSetMode, engineSetPadding, engineUpdate, engineUpdate, getKeySize, getName, update`

    - ### Methods inherited from class javax.crypto.CipherSpi

      `engineDoFinal, engineUnwrap, engineUpdate, engineUpdateAAD, engineUpdateAAD, engineWrap`

    - ### Methods inherited from class java.lang.Object

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

- - ### Field Detail

    - #### paramSpec

          protected java.security.spec.AlgorithmParameterSpec paramSpec

      ParameterSpec used with this cipher

    - #### buf

          protected java.io.ByteArrayOutputStream buf

      Internal buffer

    - #### maxPlainTextSize

          protected int maxPlainTextSize

      The maximum number of bytes the cipher can decrypt.

    - #### cipherTextSize

          protected int cipherTextSize

      The maximum number of bytes the cipher can encrypt.

  - ### Constructor Detail

    - #### AsymmetricBlockCipher

          public AsymmetricBlockCipher()

      The AsymmetricBlockCipher() constructor

  - ### Method Detail

    - #### getBlockSize

          public final int getBlockSize()

      Return the block size (in bytes). Note: although the ciphers extending this class are not block ciphers, the method was adopted to return the maximal plaintext and ciphertext sizes for non hybrid ciphers. If the cipher is hybrid, it returns 0.
      Specified by:
        `getBlockSize` in class `CipherSpiExt`
      Returns:
        if the cipher is not a hybrid one the max plain/cipher text size is returned, otherwise 0 is returned

    - #### getIV

          public final byte[] getIV()

      Description copied from class: `CipherSpiExt`
      Return the initialization vector. This is useful in the context of password-based encryption or decryption, where the IV is derived from a user-provided passphrase.
      Specified by:
        `getIV` in class `CipherSpiExt`
      Returns:
        `null` since no initialization vector is used.

    - #### getOutputSize

          public final int getOutputSize​(int inLen)

      Return the length in bytes that an output buffer would need to be in order to hold the result of the next update or doFinal operation, given the input length `inLen` (in bytes). This call takes into account any unprocessed (buffered) data from a previous update call, and padding. The actual output length of the next update() or doFinal() call may be smaller than the length returned by this method.

      If the input length plus the length of the buffered data exceeds the maximum length, `0` is returned.

      Specified by:
        `getOutputSize` in class `CipherSpiExt`
      Parameters:
        `inLen` - the length of the input
      Returns:
        the length of the ciphertext or `0` if the input is too long.

    - #### getParameters

          public final java.security.spec.AlgorithmParameterSpec getParameters()

      Returns the parameters used with this cipher.

      The returned parameters may be the same that were used to initialize this cipher, or may contain the default set of parameters or a set of randomly generated parameters used by the underlying cipher implementation (provided that the underlying cipher implementation uses a default set of parameters or creates new parameters if it needs parameters but was not initialized with any).

      Specified by:
        `getParameters` in class `CipherSpiExt`
      Returns:
        the parameters used with this cipher, or null if this cipher does not use any parameters.

    - #### initEncrypt

          public final void initEncrypt​(java.security.Key key)
                                 throws java.security.InvalidKeyException

      Initializes the cipher for encryption by forwarding it to initEncrypt(Key, FlexiSecureRandom).

      If this cipher requires any algorithm parameters that cannot be derived from the given key, the underlying cipher implementation is supposed to generate the required parameters itself (using provider-specific default or random values) if it is being initialized for encryption, and raise an InvalidKeyException if it is being initialized for decryption. The generated parameters can be retrieved using engineGetParameters or engineGetIV (if the parameter is an IV).

      Parameters:
        `key` - the encryption or decryption key.
      Throws:
        `java.security.InvalidKeyException` - if the given key is inappropriate for initializing this cipher.

    - #### initEncrypt

          public final void initEncrypt​(java.security.Key key,
                                        java.security.SecureRandom random)
                                 throws java.security.InvalidKeyException

      Initialize this cipher for encryption by forwarding it to initEncrypt(Key, FlexiSecureRandom, AlgorithmParameterSpec).

      If this cipher requires any algorithm parameters that cannot be derived from the given key, the underlying cipher implementation is supposed to generate the required parameters itself (using provider-specific default or random values) if it is being initialized for encryption, and raise an InvalidKeyException if it is being initialized for decryption. The generated parameters can be retrieved using engineGetParameters or engineGetIV (if the parameter is an IV).

      Parameters:
        `key` - the encryption or decryption key.
        `random` - the source of randomness.
      Throws:
        `java.security.InvalidKeyException` - if the given key is inappropriate for initializing this cipher.

    - #### initEncrypt

          public final void initEncrypt​(java.security.Key key,
                                        java.security.spec.AlgorithmParameterSpec params)
                                 throws java.security.InvalidKeyException,
                                        java.security.InvalidAlgorithmParameterException

      Initializes the cipher for encryption by forwarding it to initEncrypt(Key, FlexiSecureRandom, AlgorithmParameterSpec).
      Parameters:
        `key` - the encryption or decryption key.
        `params` - the algorithm parameters.
      Throws:
        `java.security.InvalidKeyException` - if the given key is inappropriate for initializing this cipher.
        `java.security.InvalidAlgorithmParameterException` - if the given algortihm parameters are inappropriate for this cipher, or if this cipher is being initialized for decryption and requires algorithm parameters and params is null.

    - #### initEncrypt

          public final void initEncrypt​(java.security.Key key,
                                        java.security.spec.AlgorithmParameterSpec params,
                                        java.security.SecureRandom secureRandom)
                                 throws java.security.InvalidKeyException,
                                        java.security.InvalidAlgorithmParameterException

      This method initializes the AsymmetricBlockCipher with a certain key for data encryption.

      If this cipher (including its underlying feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them from random.

      Note that when a Cipher object is initialized, it loses all previously-acquired state. In other words, initializing a Cipher is equivalent to creating a new instance of that Cipher and initializing it

      Specified by:
        `initEncrypt` in class `CipherSpiExt`
      Parameters:
        `key` - the key which has to be used to encrypt data.
        `secureRandom` - the source of randomness.
        `params` - the algorithm parameters.
      Throws:
        `java.security.InvalidKeyException` - if the given key is inappropriate for initializing this cipher
        `java.security.InvalidAlgorithmParameterException` - if the given algorithm parameters are inappropriate for this cipher, or if this cipher is being initialized for decryption and requires algorithm parameters and params is null.

    - #### initDecrypt

          public final void initDecrypt​(java.security.Key key)
                                 throws java.security.InvalidKeyException

      Initialize the cipher for decryption by forwarding it to `initDecrypt(Key, AlgorithmParameterSpec)`.

      If this cipher requires any algorithm parameters that cannot be derived from the given key, the underlying cipher implementation is supposed to generate the required parameters itself (using provider-specific default or random values) if it is being initialized for encryption, and raise an InvalidKeyException if it is being initialized for decryption. The generated parameters can be retrieved using engineGetParameters or engineGetIV (if the parameter is an IV).

      Parameters:
        `key` - the encryption or decryption key.
      Throws:
        `java.security.InvalidKeyException` - if the given key is inappropriate for initializing this cipher.

    - #### initDecrypt

          public final void initDecrypt​(java.security.Key key,
                                        java.security.spec.AlgorithmParameterSpec params)
                                 throws java.security.InvalidKeyException,
                                        java.security.InvalidAlgorithmParameterException

      This method initializes the AsymmetricBlockCipher with a certain key for data decryption.

      If this cipher (including its underlying feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them from random.

      Note that when a Cipher object is initialized, it loses all previously-acquired state. In other words, initializing a Cipher is equivalent to creating a new instance of that Cipher and initializing it

      Specified by:
        `initDecrypt` in class `CipherSpiExt`
      Parameters:
        `key` - the key which has to be used to decrypt data.
        `params` - the algorithm parameters.
      Throws:
        `java.security.InvalidKeyException` - if the given key is inappropriate for initializing this cipher
        `java.security.InvalidAlgorithmParameterException` - if the given algorithm parameters are inappropriate for this cipher, or if this cipher is being initialized for decryption and requires algorithm parameters and params is null.

    - #### update

          public final byte[] update​(byte[] input,
                                     int inOff,
                                     int inLen)

      Continue a multiple-part encryption or decryption operation. This method just writes the input into an internal buffer.
      Specified by:
        `update` in class `CipherSpiExt`
      Parameters:
        `input` - byte array containing the next part of the input
        `inOff` - index in the array where the input starts
        `inLen` - length of the input
      Returns:
        a new buffer with the result (always empty)

    - #### update

          public final int update​(byte[] input,
                                  int inOff,
                                  int inLen,
                                  byte[] output,
                                  int outOff)

      Continue a multiple-part encryption or decryption operation (depending on how this cipher was initialized), processing another data part.
      Specified by:
        `update` in class `CipherSpiExt`
      Parameters:
        `input` - the input buffer
        `inOff` - the offset where the input starts
        `inLen` - the input length
        `output` - the output buffer
        `outOff` - the offset where the result is stored
      Returns:
        the length of the output (always 0)

    - #### doFinal

          public final byte[] doFinal​(byte[] input,
                                      int inOff,
                                      int inLen)
                               throws javax.crypto.IllegalBlockSizeException,
                                      javax.crypto.BadPaddingException

      Finish a multiple-part encryption or decryption operation (depending on how this cipher was initialized).
      Specified by:
        `doFinal` in class `CipherSpiExt`
      Parameters:
        `input` - the input buffer
        `inOff` - the offset where the input starts
        `inLen` - the input length
      Returns:
        a new buffer with the result
      Throws:
        `javax.crypto.IllegalBlockSizeException` - if the plaintext or ciphertext size is too large.
        `javax.crypto.BadPaddingException` - if the ciphertext is invalid.

    - #### doFinal

          public final int doFinal​(byte[] input,
                                   int inOff,
                                   int inLen,
                                   byte[] output,
                                   int outOff)
                            throws javax.crypto.ShortBufferException,
                                   javax.crypto.IllegalBlockSizeException,
                                   javax.crypto.BadPaddingException

      Finish a multiple-part encryption or decryption operation (depending on how this cipher was initialized).
      Specified by:
        `doFinal` in class `CipherSpiExt`
      Parameters:
        `input` - the input buffer
        `inOff` - the offset where the input starts
        `inLen` - the input length
        `output` - the buffer for the result
        `outOff` - the offset where the result is stored
      Returns:
        the output length
      Throws:
        `javax.crypto.ShortBufferException` - if the output buffer is too small to hold the result.
        `javax.crypto.IllegalBlockSizeException` - if the plaintext or ciphertext size is too large.
        `javax.crypto.BadPaddingException` - if the ciphertext is invalid.

    - #### setMode

          protected final void setMode​(java.lang.String modeName)

      Since asymmetric block ciphers do not support modes, this method does nothing.
      Specified by:
        `setMode` in class `CipherSpiExt`
      Parameters:
        `modeName` - the cipher mode (unused)

    - #### setPadding

          protected final void setPadding​(java.lang.String paddingName)

      Since asymmetric block ciphers do not support padding, this method does nothing.
      Specified by:
        `setPadding` in class `CipherSpiExt`
      Parameters:
        `paddingName` - the name of the padding scheme (not used)

    - #### checkLength

          protected void checkLength​(int inLen)
                              throws javax.crypto.IllegalBlockSizeException

      Check if the message length plus the length of the input length can be en/decrypted. This method uses the specific values `maxPlainTextSize` and `cipherTextSize` which are set by the implementations. If the input length plus the length of the internal buffer is greater than `maxPlainTextSize` for encryption or not equal to `cipherTextSize` for decryption, an `IllegalBlockSizeException` will be thrown.
      Parameters:
        `inLen` - length of the input to check
      Throws:
        `javax.crypto.IllegalBlockSizeException` - if the input length is invalid.

    - #### initCipherEncrypt

          protected abstract void initCipherEncrypt​(java.security.Key key,
                                                    java.security.spec.AlgorithmParameterSpec params,
                                                    java.security.SecureRandom sr)
                                             throws java.security.InvalidKeyException,
                                                    java.security.InvalidAlgorithmParameterException

      Initialize the AsymmetricBlockCipher with a certain key for data encryption.
      Parameters:
        `key` - the key which has to be used to encrypt data
        `params` - the algorithm parameters
        `sr` - the source of randomness
      Throws:
        `java.security.InvalidKeyException` - if the given key is inappropriate for initializing this cipher.
        `java.security.InvalidAlgorithmParameterException` - if the given parameters are inappropriate for initializing this cipher.

    - #### initCipherDecrypt

          protected abstract void initCipherDecrypt​(java.security.Key key,
                                                    java.security.spec.AlgorithmParameterSpec params)
                                             throws java.security.InvalidKeyException,
                                                    java.security.InvalidAlgorithmParameterException

      Initialize the AsymmetricBlockCipher with a certain key for data encryption.
      Parameters:
        `key` - the key which has to be used to decrypt data
        `params` - the algorithm parameters
      Throws:
        `java.security.InvalidKeyException` - if the given key is inappropriate for initializing this cipher
        `java.security.InvalidAlgorithmParameterException` - if the given parameters are inappropriate for initializing this cipher.

    - #### messageEncrypt

          protected abstract byte[] messageEncrypt​(byte[] input)
                                            throws javax.crypto.IllegalBlockSizeException,
                                                   javax.crypto.BadPaddingException

      Encrypt the message stored in input. The method should also perform an additional length check.
      Parameters:
        `input` - the message to be encrypted (usually the message length is less than or equal to maxPlainTextSize)
      Returns:
        the encrypted message (it has length equal to maxCipherTextSize_)
      Throws:
        `javax.crypto.IllegalBlockSizeException` - if the input is inappropriate for this cipher.
        `javax.crypto.BadPaddingException` - if the input format is invalid.

    - #### messageDecrypt

          protected abstract byte[] messageDecrypt​(byte[] input)
                                            throws javax.crypto.IllegalBlockSizeException,
                                                   javax.crypto.BadPaddingException

      Decrypt the ciphertext stored in input. The method should also perform an additional length check.
      Parameters:
        `input` - the ciphertext to be decrypted (the ciphertext length is less than or equal to maxCipherTextSize)
      Returns:
        the decrypted message
      Throws:
        `javax.crypto.IllegalBlockSizeException` - if the input is inappropriate for this cipher.
        `javax.crypto.BadPaddingException` - if the input format is invalid.