cryptix.provider.mode
public class OFB extends FeedbackMode
The full block size of the supplied cipher is used for the Output Feedback Mode. The bytes supplied are processed and returned immediately.
References:
sci.crypt
FAQ, "Part 5: Product Ciphers,"
ftp://ftp.rtfm.mit.edu/pub/usenet/news.answers/cryptography-faq/part05
Copyright © 1997
Systemics Ltd on behalf of the
Cryptix Development Team.
All rights reserved.
$Revision: 1.6 $
Since: Cryptix 2.2.2
Constructor Summary | |
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OFB()
Constructs an OFB cipher, assuming that the IV will be provided
via setInitializationVector .
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OFB(Cipher cipher)
Constructs an OFB cipher, assuming that the IV will be provided
via setInitializationVector .
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OFB(Cipher cipher, byte[] iv)
Constructs a OFB cipher, using an initialization vector
provided in the constructor.
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Method Summary | |
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protected int | engineBlockSize() |
protected void | engineInitDecrypt(Key newkey) |
protected void | engineInitEncrypt(Key newkey) |
protected int | engineUpdate(byte[] in, int inOffset, int inLen, byte[] out, int outOffset)
SPI: This is the main engine method for updating data.
|
setInitializationVector
.
The IV value must be unique during the lifetime of the key. If it is not unique, and an attacker has access to a different message encrypted under the same IV and key, all of the plaintext can normally be recovered.
setInitializationVector
.
See the previous constructor for more details.
Parameters: cipher the cipher object to use in OFB mode.
Throws: NullPointerException if cipher == null IllegalBlockSizeException if cipher.getPlaintextBlockSize() != cipher.getCiphertextBlockSize()
The IV value must be unique during the lifetime of the key. If it is not unique, and an attacker has access to a different message encrypted under the same IV and key, all of the plaintext can normally be recovered.
Parameters: cipher the block cipher to use iv the initial value for the shift register (IV)
Throws: NullPointerException if cipher == null
in
and out
may be the same array, and the
input and output regions may overlap.
Parameters: in the input data. inOffset the offset into in
specifying where
the data starts. inLen the length of the subarray. out the output array. outOffset the offset indicating where to start writing into
the out
array.
Returns: the number of bytes written.