org.bouncycastle.crypto.modes

Interface AEADBlockCipher

All Known Implementing Classes:

GCMBlockCipher

public interface AEADBlockCipher

A block cipher mode that includes authenticated encryption with a streaming mode and optional associated data.

Implementations of this interface may operate in a packet mode (where all input data is buffered and processed dugin the call to doFinal(byte[], int)), or in a streaming mode (where output data is incrementally produced with each call to processByte(byte, byte[], int) or processBytes(byte[], int, int, byte[], int).

This is important to consider during decryption: in a streaming mode, unauthenticated plaintext data may be output prior to the call to doFinal(byte[], int) that results in an authentication failure. The higher level protocol utilising this cipher must ensure the plaintext data is handled appropriately until the end of data is reached and the entire ciphertext is authenticated.

See Also:

AEADParameters

Method Summary

Methods

Modifier and Type	Method and Description
int	doFinal(byte[] out, int outOff) Finish the operation either appending or verifying the MAC at the end of the data.
String	getAlgorithmName() Return the name of the algorithm.
byte[]	getMac() Return the value of the MAC associated with the last stream processed.
int	getOutputSize(int len) return the size of the output buffer required for a processBytes plus a doFinal with an input of len bytes.
BlockCipher	getUnderlyingCipher() return the cipher this object wraps.
int	getUpdateOutputSize(int len) return the size of the output buffer required for a processBytes an input of len bytes.
void	init(boolean forEncryption, CipherParameters params) initialise the underlying cipher.
void	processAADByte(byte in) Add a single byte to the associated data check.
void	processAADBytes(byte[] in, int inOff, int len) Add a sequence of bytes to the associated data check.
int	processByte(byte in, byte[] out, int outOff) encrypt/decrypt a single byte.
int	processBytes(byte[] in, int inOff, int len, byte[] out, int outOff) process a block of bytes from in putting the result into out.
void	reset() Reset the cipher.

Method Detail

init

void init(boolean forEncryption,
        CipherParameters params)
          throws IllegalArgumentException

initialise the underlying cipher. Parameter can either be an AEADParameters or a ParametersWithIV object.

Parameters:

forEncryption - true if we are setting up for encryption, false otherwise.

params - the necessary parameters for the underlying cipher to be initialised.

Throws:

IllegalArgumentException - if the params argument is inappropriate.

getAlgorithmName

String getAlgorithmName()

Return the name of the algorithm.

Returns:

the algorithm name.

getUnderlyingCipher

BlockCipher getUnderlyingCipher()

return the cipher this object wraps.

Returns:

the cipher this object wraps.

processAADByte

void processAADByte(byte in)

Add a single byte to the associated data check.
If the implementation supports it, this will be an online operation and will not retain the associated data.

Parameters:

in - the byte to be processed.

processAADBytes

void processAADBytes(byte[] in,
                   int inOff,
                   int len)

Add a sequence of bytes to the associated data check.
If the implementation supports it, this will be an online operation and will not retain the associated data.

Parameters:

in - the input byte array.

inOff - the offset into the in array where the data to be processed starts.

len - the number of bytes to be processed.

processByte

int processByte(byte in,
              byte[] out,
              int outOff)
                throws DataLengthException

encrypt/decrypt a single byte.

Parameters:

in - the byte to be processed.

out - the output buffer the processed byte goes into.

outOff - the offset into the output byte array the processed data starts at.

Returns:

the number of bytes written to out.

Throws:

DataLengthException - if the output buffer is too small.

processBytes

int processBytes(byte[] in,
               int inOff,
               int len,
               byte[] out,
               int outOff)
                 throws DataLengthException

process a block of bytes from in putting the result into out.

Parameters:

in - the input byte array.

inOff - the offset into the in array where the data to be processed starts.

len - the number of bytes to be processed.

out - the output buffer the processed bytes go into.

outOff - the offset into the output byte array the processed data starts at.

Returns:

the number of bytes written to out.

Throws:

DataLengthException - if the output buffer is too small.

doFinal

int doFinal(byte[] out,
          int outOff)
            throws IllegalStateException,
                   InvalidCipherTextException

Finish the operation either appending or verifying the MAC at the end of the data.

Parameters:

out - space for any resulting output data.

outOff - offset into out to start copying the data at.

Returns:

number of bytes written into out.

Throws:

IllegalStateException - if the cipher is in an inappropriate state.

InvalidCipherTextException - if the MAC fails to match.

getMac

byte[] getMac()

Return the value of the MAC associated with the last stream processed.

Returns:

MAC for plaintext data.

getUpdateOutputSize

int getUpdateOutputSize(int len)

return the size of the output buffer required for a processBytes an input of len bytes.

The returned size may be dependent on the initialisation of this cipher and may not be accurate once subsequent input data is processed - this method should be invoked immediately prior to input data being processed.

Parameters:

len - the length of the input.

Returns:

the space required to accommodate a call to processBytes with len bytes of input.

getOutputSize

int getOutputSize(int len)

return the size of the output buffer required for a processBytes plus a doFinal with an input of len bytes.

The returned size may be dependent on the initialisation of this cipher and may not be accurate once subsequent input data is processed - this method should be invoked immediately prior to a call to final processing of input data and a call to doFinal(byte[], int).

Parameters:

len - the length of the input.

Returns:

the space required to accommodate a call to processBytes and doFinal with len bytes of input.

reset

void reset()

Reset the cipher. After resetting the cipher is in the same state as it was after the last init (if there was one).