Class OFBBlockCipher
java.lang.Object
org.gudy.bouncycastle.crypto.modes.OFBBlockCipher
- All Implemented Interfaces:
BlockCipher
implements a Output-FeedBack (OFB) mode on top of a simple cipher.
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Field Summary
FieldsModifier and TypeFieldDescriptionprivate int
private BlockCipher
private boolean
private byte[]
private byte[]
private byte[]
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionreturn the algorithm name and mode.int
return the block size we are operating at (in bytes).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 feedback vector back to the IV and reset the underlying cipher.
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Field Details
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IV
private byte[] IV -
ofbV
private byte[] ofbV -
ofbOutV
private byte[] ofbOutV -
blockSize
private int blockSize -
cipher
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encrypting
private boolean encrypting
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Constructor Details
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OFBBlockCipher
Basic constructor.- Parameters:
cipher
- the block cipher to be used as the basis of the feedback mode.blockSize
- the block size in bits (note: a multiple of 8)
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Method Details
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getUnderlyingCipher
return the underlying block cipher that we are wrapping.- Returns:
- the underlying block cipher that we are wrapping.
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init
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. An IV which is too short is handled in FIPS compliant fashion.- Specified by:
init
in interfaceBlockCipher
- Parameters:
encrypting
- if true the cipher is initialised for encryption, if false for decryption.forEncryption
- if true the cipher is initialised for encryption, if false for decryption.param
- the key and other data required by the cipher.- Throws:
IllegalArgumentException
- if the params argument is inappropriate.
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getAlgorithmName
return the algorithm name and mode.- Specified by:
getAlgorithmName
in interfaceBlockCipher
- Returns:
- the name of the underlying algorithm followed by "/OFB" and the block size in bits
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getBlockSize
public int getBlockSize()return the block size we are operating at (in bytes).- Specified by:
getBlockSize
in interfaceBlockCipher
- Returns:
- the block size we are operating at (in bytes).
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processBlock
public int processBlock(byte[] in, int inOff, byte[] out, int outOff) throws DataLengthException, 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.IllegalStateException
- if the cipher isn't initialised.
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reset
public void reset()reset the feedback vector back to the IV and reset the underlying cipher.- Specified by:
reset
in interfaceBlockCipher
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