com.microej.crypto.internal.cipher

Class NativeCipherSpi

java.lang.Object

javax.crypto.CipherSpi

com.microej.crypto.internal.cipher.AbstractCipherSpi

com.microej.crypto.internal.cipher.NativeCipherSpi

public class NativeCipherSpi
extends AbstractCipherSpi

Generic Cipher SPI to expose the cipher algorithms provided by a native crypto engine.

It can be used with NativeSecretKey, or raw-encoded keys that are dynamically imported as NativeSecretKey for the duration of this cipher.

Constructor Summary

Constructors

Constructor and Description
NativeCipherSpi(int nativeTransformationId, int blockSize, int unitBytes, int cipherMode)

Method Summary

Modifier and Type	Method and Description
protected int	decrypt(byte[] buffer, int i, int len, byte[] output, int outputOffset, boolean doFinal) Performs decryption operation.
protected int	encrypt(byte[] buffer, int i, int len, byte[] output, int outputOffset, boolean doFinal) Performs encryption operation.
protected byte[]	engineGetIV() Returns the initialization vector (IV) in a new buffer.
protected void	engineInit(boolean decrypting, String algorithm, SecretKey key, byte[] iv, int tagLength) Initializes the cipher in the specified mode with the given key and iv.
protected void	engineSetIV(byte[] iv) Sets the initial vector.
protected int	getBufferedLength() TODO
static CipherSpi	getInstance(String transformation) Create a cipher context for the given transformation.
static int	nativeGetTransformationDescription(byte[] transformation, byte[] description) Gets for the given transformation the cipher description.
protected void	updateAAD(byte[] src, int offset, int len) Continues a multi-part update of the Additional Authentication Data (AAD), using a subset of the provided buffer.

Methods inherited from class com.microej.crypto.internal.cipher.AbstractCipherSpi

addExact, engineDoFinal, engineDoFinal, engineGetBlockSize, engineGetOutputSize, engineInit, engineInit, engineUpdate, engineUpdate, engineUpdateAAD

Methods inherited from class javax.crypto.CipherSpi

engineUnwrap, engineWrap

Methods inherited from class java.lang.Object

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

Constructor Detail

NativeCipherSpi

public NativeCipherSpi(int nativeTransformationId,
                       int blockSize,
                       int unitBytes,
                       int cipherMode)

Method Detail

decrypt

protected int decrypt(byte[] buffer,
                      int i,
                      int len,
                      byte[] output,
                      int outputOffset,
                      boolean doFinal)

Description copied from class: AbstractCipherSpi

Performs decryption operation.

The input cipher, starting at cipherOffset and ending at (cipherOffset+cipherLen-1), is decrypted. The result is stored in plain, starting at plainOffset.

The subclass that implements Cipher should ensure that init has been called before this method is called.

Specified by:

decrypt in class AbstractCipherSpi

Parameters:

buffer - the input buffer with the data to be decrypted

i - the offset in cipher

len - the length of the input data

output - the buffer for the decryption result

outputOffset - the offset in plain

Returns:

the number of bytes placed into plain

encrypt

protected int encrypt(byte[] buffer,
                      int i,
                      int len,
                      byte[] output,
                      int outputOffset,
                      boolean doFinal)

Description copied from class: AbstractCipherSpi

Performs encryption operation.

The input plain, starting at plainOffset and ending at (plainOffset+plainLen-1), is encrypted. The result is stored in cipher, starting at cipherOffset.

The subclass that implements Cipher should ensure that init has been called before this method is called.

Specified by:

encrypt in class AbstractCipherSpi

Parameters:

buffer - the input buffer with the data to be encrypted

i - the offset in plain

len - the length of the input data

output - the buffer for the encryption result

outputOffset - the offset in cipher

Returns:

the number of bytes placed into cipher

engineGetIV

protected byte[] engineGetIV()

Description copied from class: CipherSpi

Returns the initialization vector (IV) in a new buffer.

This is useful in the context of password-based encryption or decryption, where the IV is derived from a user-provided passphrase.

Specified by:

engineGetIV in class CipherSpi

Returns:

the initialization vector in a new buffer, or null if the underlying algorithm does not use an IV, or if the IV has not yet been set.

engineInit

protected void engineInit(boolean decrypting,
                          String algorithm,
                          SecretKey key,
                          byte[] iv,
                          int tagLength)
                   throws InvalidKeyException,
                          InvalidAlgorithmParameterException

Description copied from class: AbstractCipherSpi

Initializes the cipher in the specified mode with the given key and iv.

Specified by:

engineInit in class AbstractCipherSpi

Parameters:

decrypting - flag indicating encryption or decryption mode

algorithm - the algorithm name (never null)

key - the key (never null)

iv - the iv (either null or blockSize bytes long)

tagLength - the tag Length (only for GCM)

Throws:

InvalidKeyException - if the given key is inappropriate for initializing this cipher

InvalidAlgorithmParameterException - if the given algorithm parameters are inappropriate for this cipher.

engineSetIV

protected void engineSetIV(byte[] iv)

Description copied from class: AbstractCipherSpi

Sets the initial vector.

Specified by:

engineSetIV in class AbstractCipherSpi

Parameters:

iv - the iv (either null or blockSize bytes long)

getBufferedLength

protected int getBufferedLength()

Description copied from class: AbstractCipherSpi

TODO

Specified by:

getBufferedLength in class AbstractCipherSpi

Returns:

natively buffered length

getInstance

@Nullable
public static CipherSpi getInstance(String transformation)

Create a cipher context for the given transformation.

Parameters:

transformation - the cipher transformation to be used

Returns:

the cipher SPI context, or null if the transformation is not supported.

nativeGetTransformationDescription

public static int nativeGetTransformationDescription(byte[] transformation,
                                                     byte[] description)

Gets for the given transformation the cipher description.

Parameters:

transformation - Null terminated string that describes the transformation

description - a 12-byte buffer to be filled-in with:

• [0-3]: blockSize: the block size (in bytes), or 0 if the underlying algorithm is not a block cipher
• [4-7]: unitBytes: unit size (number of input bytes that can be processed at a time)
• [8-11]: cipherMode: one of the *_MODE values defined in AbstractCipherSpi

Returns:

the native ID for the given transformation, or NativeConstants.ERROR on error.

updateAAD

protected void updateAAD(byte[] src,
                         int offset,
                         int len)

Description copied from class: AbstractCipherSpi

Continues a multi-part update of the Additional Authentication Data (AAD), using a subset of the provided buffer.

Calls to this method provide AAD to the cipher when operating in modes such as AEAD (GCM/CCM). If this cipher is operating in either GCM or CCM mode, all AAD must be supplied before beginning operations on the ciphertext (via the update and doFinal methods).

Specified by:

updateAAD in class AbstractCipherSpi

Parameters:

src - the buffer containing the AAD

offset - the offset in src where the AAD input starts

len - the number of AAD bytes