Class CBCBlockCipher
- java.lang.Object
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- org.gudy.bouncycastle.crypto.modes.CBCBlockCipher
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- All Implemented Interfaces:
BlockCipher
public class CBCBlockCipher extends java.lang.Object implements BlockCipher
implements Cipher-Block-Chaining (CBC) mode on top of a simple cipher.
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Field Summary
Fields Modifier and Type Field Description private int
blockSize
private byte[]
cbcNextV
private byte[]
cbcV
private BlockCipher
cipher
private boolean
encrypting
private byte[]
IV
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Constructor Summary
Constructors Constructor Description CBCBlockCipher(BlockCipher cipher)
Basic constructor.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description private int
decryptBlock(byte[] in, int inOff, byte[] out, int outOff)
Do the appropriate chaining step for CBC mode decryption.private int
encryptBlock(byte[] in, int inOff, byte[] out, int outOff)
Do the appropriate chaining step for CBC mode encryption.java.lang.String
getAlgorithmName()
return the algorithm name and mode.int
getBlockSize()
return the block size of the underlying cipher.BlockCipher
getUnderlyingCipher()
return the underlying block cipher that we are wrapping.void
init(boolean encrypting, CipherParameters params)
Initialise the cipher and, possibly, the initialisation vector (IV).int
processBlock(byte[] in, int inOff, byte[] out, int outOff)
Process one block of input from the array in and write it to the out array.void
reset()
reset the chaining vector back to the IV and reset the underlying cipher.
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Field Detail
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IV
private byte[] IV
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cbcV
private byte[] cbcV
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cbcNextV
private byte[] cbcNextV
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blockSize
private int blockSize
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cipher
private BlockCipher cipher
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encrypting
private boolean encrypting
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Constructor Detail
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CBCBlockCipher
public CBCBlockCipher(BlockCipher cipher)
Basic constructor.- Parameters:
cipher
- the block cipher to be used as the basis of chaining.
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Method Detail
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getUnderlyingCipher
public BlockCipher getUnderlyingCipher()
return the underlying block cipher that we are wrapping.- Returns:
- the underlying block cipher that we are wrapping.
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init
public void init(boolean encrypting, CipherParameters params) throws java.lang.IllegalArgumentException
Initialise the cipher and, possibly, the initialisation vector (IV). If an IV isn't passed as part of the parameter, the IV will be all zeros.- Specified by:
init
in interfaceBlockCipher
- Parameters:
forEncryption
- if true the cipher is initialised for encryption, if false for decryption.param
- the key and other data required by the cipher.- Throws:
java.lang.IllegalArgumentException
- if the params argument is inappropriate.
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getAlgorithmName
public java.lang.String getAlgorithmName()
return the algorithm name and mode.- Specified by:
getAlgorithmName
in interfaceBlockCipher
- Returns:
- the name of the underlying algorithm followed by "/CBC".
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getBlockSize
public int getBlockSize()
return the block size of the underlying cipher.- Specified by:
getBlockSize
in interfaceBlockCipher
- Returns:
- the block size of the underlying cipher.
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processBlock
public int processBlock(byte[] in, int inOff, byte[] out, int outOff) throws DataLengthException, java.lang.IllegalStateException
Process one block of input from the array in and write it to the out array.- Specified by:
processBlock
in interfaceBlockCipher
- Parameters:
in
- the array containing the input data.inOff
- offset into the in array the data starts at.out
- the array the output data will be copied into.outOff
- the offset into the out array the output will start at.- Returns:
- the number of bytes processed and produced.
- Throws:
DataLengthException
- if there isn't enough data in in, or space in out.java.lang.IllegalStateException
- if the cipher isn't initialised.
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reset
public void reset()
reset the chaining vector back to the IV and reset the underlying cipher.- Specified by:
reset
in interfaceBlockCipher
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encryptBlock
private int encryptBlock(byte[] in, int inOff, byte[] out, int outOff) throws DataLengthException, java.lang.IllegalStateException
Do the appropriate chaining step for CBC mode encryption.- Parameters:
in
- the array containing the data to be encrypted.inOff
- offset into the in array the data starts at.out
- the array the encrypted data will be copied into.outOff
- the offset into the out array the output will start at.- Returns:
- the number of bytes processed and produced.
- Throws:
DataLengthException
- if there isn't enough data in in, or space in out.java.lang.IllegalStateException
- if the cipher isn't initialised.
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decryptBlock
private int decryptBlock(byte[] in, int inOff, byte[] out, int outOff) throws DataLengthException, java.lang.IllegalStateException
Do the appropriate chaining step for CBC mode decryption.- Parameters:
in
- the array containing the data to be decrypted.inOff
- offset into the in array the data starts at.out
- the array the decrypted data will be copied into.outOff
- the offset into the out array the output will start at.- Returns:
- the number of bytes processed and produced.
- Throws:
DataLengthException
- if there isn't enough data in in, or space in out.java.lang.IllegalStateException
- if the cipher isn't initialised.
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