gnu.javax.crypto.sasl.srp
Class CALG
A Factory class that returns CALG (Confidentiality Algorithm) instances that
operate as described in the draft-burdis-cat-sasl-srp-08.
The designated CALG block cipher should be used in OFB (Output Feedback
Block) mode in the ISO variant, as described in
The Handbook of Applied
Cryptography, algorithm 7.20.
Let
k be the block size of the chosen symmetric key block
cipher algorithm; e.g. for AES this is
128 bits or
16 octets. The OFB mode used shall be of length/size
k.
It is recommended that block ciphers operating in OFB mode be used with an
Initial Vector (the mode's IV). In such a mode of operation - OFB with key
re-use - the IV need not be secret. For the mechanism in question the IVs
shall be a random octet sequence of
k bytes.
The input data to the confidentiality protection algorithm shall be a
multiple of the symmetric cipher block size
k. When the input
length is not a multiple of
k octets, the data shall be padded
according to the following scheme:
Assuming the length of the input is
l octets,
(k - (l mod k)) octets, all having the value
(k - (l mod k)), shall be appended to the original data. In
other words, the input is padded at the trailing end with one of the
following sequences:
01 -- if l mod k = k-1
02 02 -- if l mod k = k-2
...
...
...
k k ... k k -- if l mod k = 0
The padding can be removed unambiguously since all input is padded and no
padding sequence is a suffix of another. This padding method is well-defined
if and only if
k < 256 octets, which is the case with
symmetric key block ciphers today, and in the forseeable future.
byte[] | doFinal(byte[] data)- Encrypts or decrypts, depending on the mode already set, a designated array
of bytes and returns the result.
|
byte[] | doFinal(byte[] data, int offset, int length)- Encrypts or decrypts, depending on the mode already set, a designated array
of bytes and returns the result.
|
void | init(KDF kdf, byte[] iv, Direction dir)- Initialises a SASL-SRP CALG implementation.
|
clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait |
doFinal
public byte[] doFinal(byte[] data)
throws ConfidentialityException Encrypts or decrypts, depending on the mode already set, a designated array
of bytes and returns the result.
data - the data to encrypt/decrypt.
- the decrypted/encrypted result.
doFinal
public byte[] doFinal(byte[] data,
int offset,
int length)
throws ConfidentialityException Encrypts or decrypts, depending on the mode already set, a designated array
of bytes and returns the result.
data - the data to encrypt/decrypt.offset - where to start in data.length - how many bytes to consider in data.
- the decrypted/encrypted result.
init
public void init(KDF kdf,
byte[] iv,
Direction dir)
throws SaslException Initialises a SASL-SRP CALG implementation.
kdf - the key derivation function.iv - the initial vector value to use.dir - whether this CALG is used for encryption or decryption.
CALG.java --
Copyright (C) 2003, 2006 Free Software Foundation, Inc.
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