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Bouncy Castle Cryptography Library 1.49 | ||||||||
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java.lang.Objectorg.bouncycastle.crypto.macs.GMac
public class GMac
The GMAC specialisation of Galois/Counter mode (GCM) detailed in NIST Special Publication 800-38D.
GMac is an invocation of the GCM mode where no data is encrypted (i.e. all input data to the Mac is processed as additional authenticated data with the underlying GCM block cipher).
Constructor Summary | |
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GMac(GCMBlockCipher cipher)
Creates a GMAC based on the operation of a block cipher in GCM mode. |
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GMac(GCMBlockCipher cipher,
int macSizeBits)
Creates a GMAC based on the operation of a 128 bit block cipher in GCM mode. |
Method Summary | |
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int |
doFinal(byte[] out,
int outOff)
Compute the final stage of the MAC writing the output to the out parameter. |
java.lang.String |
getAlgorithmName()
Return the name of the algorithm the MAC implements. |
int |
getMacSize()
Return the block size for this MAC (in bytes). |
void |
init(CipherParameters params)
Initialises the GMAC - requires a ParametersWithIV providing a KeyParameter
and a nonce. |
void |
reset()
Reset the MAC. |
void |
update(byte in)
add a single byte to the mac for processing. |
void |
update(byte[] in,
int inOff,
int len)
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Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public GMac(GCMBlockCipher cipher)
cipher
- the cipher to be used in GCM mode to generate the MAC.public GMac(GCMBlockCipher cipher, int macSizeBits)
macSizeBits
- the mac size to generate, in bits. Must be a multiple of 8 and >= 96 and <= 128.cipher
- the cipher to be used in GCM mode to generate the MAC.Method Detail |
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public void init(CipherParameters params) throws java.lang.IllegalArgumentException
ParametersWithIV
providing a KeyParameter
and a nonce.
init
in interface Mac
params
- the key and other data required by the MAC.
java.lang.IllegalArgumentException
- if the params argument is
inappropriate.public java.lang.String getAlgorithmName()
Mac
getAlgorithmName
in interface Mac
public int getMacSize()
Mac
getMacSize
in interface Mac
public void update(byte in) throws java.lang.IllegalStateException
Mac
update
in interface Mac
in
- the byte to be processed.
java.lang.IllegalStateException
- if the MAC is not initialised.public void update(byte[] in, int inOff, int len) throws DataLengthException, java.lang.IllegalStateException
update
in interface Mac
in
- the array containing the input.inOff
- the index in the array the data begins at.len
- the length of the input starting at inOff.
DataLengthException
- if there isn't enough data in in.
java.lang.IllegalStateException
- if the MAC is not initialised.public int doFinal(byte[] out, int outOff) throws DataLengthException, java.lang.IllegalStateException
Mac
doFinal leaves the MAC in the same state it was after the last init.
doFinal
in interface Mac
out
- the array the MAC is to be output to.outOff
- the offset into the out buffer the output is to start at.
DataLengthException
- if there isn't enough space in out.
java.lang.IllegalStateException
- if the MAC is not initialised.public void reset()
Mac
reset
in interface Mac
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