org.logi.crypto.modes
Class DecryptOFB

java.lang.Object
  |
  +--org.logi.crypto.Crypto
        |
        +--org.logi.crypto.modes.DecryptMode
              |
              +--org.logi.crypto.modes.DecryptOFB

public class DecryptOFB
extends DecryptMode

Use this class to decrypt ciphertext generated by EncryptOFB.

Note that unlike ECB or CBC mode, OFB mode uses teh same key to encrypt and decrypt, even with asymmetric ciphers.

Author:
Logi Ragnarsson (logir@logi.org)
See Also:
EncryptOFB

Fields inherited from class org.logi.crypto.Crypto
BIT, cdsPath, EMPTY_ARRAY, FOUR, keySource, NIBBLE, ONE, primeCertainty, random, TWO, ZERO
 
Constructor Summary
DecryptOFB(CipherKey key, int bufSize)
          Create a new OFB-mode decrypt session with the specified key.
DecryptOFB(int bufSize)
          Create a new OFB-mode decrypt session with no key.
 
Method Summary
 void close()
          Close files and kill threads owned by the object.
 byte[] decrypt(byte[] source, int i, int length)
          Send bytes to the DecryptOFB object for encryption.
 CipherKey getKey()
          Return the key used for encryption.
 int plainBlockSize()
          Return the size of the blocks of plaintext output by this object.
 void setKey(CipherKey key)
          Set the key to use for encryption.
 
Methods inherited from class org.logi.crypto.modes.DecryptMode
finalize
 
Methods inherited from class org.logi.crypto.Crypto
binString, binString, equal, equalRelaxed, equalSub, fromHexNibble, fromHexString, fromString, fromString, hexString, hexString, hexString, hexString, hexString, initRandom, initRandom, makeClass, makeInt, makeLong, makeSessionKey, pastSpace, pickBits, pickBits, readBlock, readInt, writeBytes, writeBytes, writeInt
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

DecryptOFB

public DecryptOFB(CipherKey key,
                  int bufSize)
Create a new OFB-mode decrypt session with the specified key. A buffer of bufSize bytes is created to hold a pre-calculated xor-stream.

DecryptOFB

public DecryptOFB(int bufSize)
Create a new OFB-mode decrypt session with no key. No encryption can be performed until the setKey() method has been called.

A buffer of bufSize bytes is created to hold a pre-calculated xor-stream.

Method Detail

getKey

public CipherKey getKey()
Return the key used for encryption.
Overrides:
getKey in class DecryptMode

setKey

public void setKey(CipherKey key)
Set the key to use for encryption. The key can only be set once in this version of the library. The 1.1.x and eventually 1.2.x series allows dynamic re-keying.
Overrides:
setKey in class DecryptMode

plainBlockSize

public int plainBlockSize()
Return the size of the blocks of plaintext output by this object.
Overrides:
plainBlockSize in class DecryptMode

decrypt

public byte[] decrypt(byte[] source,
                      int i,
                      int length)
Send bytes to the DecryptOFB object for encryption.

Decrypt length bytes from source, starting at i and return the plaintext.

Overrides:
decrypt in class DecryptMode

close

public void close()
Close files and kill threads owned by the object. This should be called to make sure all resources are freed.
Overrides:
close in class DecryptMode


Copyright 1997-2000 Logi Ragnarsson