public class

GCMBlockCipher

extends Object
implements AEADBlockCipher
java.lang.Object
   ↳ org.bouncycastle.crypto.modes.GCMBlockCipher

Class Overview

Implements the Galois/Counter mode (GCM) detailed in NIST Special Publication 800-38D.

Summary

Public Constructors
GCMBlockCipher(BlockCipher c)
GCMBlockCipher(BlockCipher c, GCMMultiplier m)
Public Methods
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.
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.
[Expand]
Inherited Methods
From class java.lang.Object
From interface org.bouncycastle.crypto.modes.AEADBlockCipher

Public Constructors

public GCMBlockCipher (BlockCipher c)

public GCMBlockCipher (BlockCipher c, GCMMultiplier m)

Public Methods

public int doFinal (byte[] out, int outOff)

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
InvalidCipherTextException

public String getAlgorithmName ()

Return the name of the algorithm.

Returns
  • the algorithm name.

public byte[] getMac ()

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

Returns
  • MAC for plaintext data.

public int getOutputSize (int len)

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

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

public BlockCipher getUnderlyingCipher ()

return the cipher this object wraps.

Returns
  • the cipher this object wraps.

public int getUpdateOutputSize (int len)

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

Parameters
len the length of the input.
Returns
  • the space required to accommodate a call to processBytes with len bytes of input.

public void init (boolean forEncryption, CipherParameters params)

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

public int processByte (byte in, byte[] out, int outOff)

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

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

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

public 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).