Provides a basic API for using block cipher Modes of Operation.
See: Description
Interface Summary | |
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IAuthenticatedMode | The interface for encryption modes that also produce a message authentication tag. |
IMode |
The basic visible methods of any block cipher mode. Block ciphers encrypt plaintext in fixed size n-bit blocks. |
Class Summary | |
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BaseMode |
A basic abstract class to facilitate implementing block cipher modes of operations. |
CBC | The Cipher Block Chaining mode. |
CFB | The cipher feedback mode. |
CTR |
The implementation of the Counter Mode. The algorithm steps are formally described as follows: CTR Encryption: O[j] = E(K)(T[j]); for j = 1, 2...n; C[j] = P[j] ^ O[j]; for j = 1, 2...n. |
EAX |
A conventional two-pass authenticated-encrypted mode, EAX. |
ECB |
The implementation of the Electronic Codebook mode. The Electronic Codebook (ECB) mode is a confidentiality mode that is defined as follows:
In ECB encryption, the forward cipher function is applied directly, and independently, to each block of the plaintext. |
ICM |
An implementation of David McGrew Integer Counter Mode (ICM) as an IMode. ICM is a way to define a pseudorandom keystream generator using a block cipher. |
ModeFactory |
A Factory to instantiate block cipher modes of operations. |
OFB |
The Output Feedback (OFB) mode is a confidentiality mode that requires a
unique |
Cipher modes operate on the next level up from the underlying block cipher. They transform the blocks going in and out of the cipher in ways to give them desirable properties in certain circumstances.
The following diagram shows the important classes participating in this package:
The following example encrypts and decrypts a byte array with the AES
in CFB mode. See the gnu.crypto.pad
package for instances
where the input is not a multiple of the cipher or mode's block size.
IMode mode = ModeFactory.getInstance("CFB", "AES", 16); Map attributes = new HashMap(); // These attributes are defined in gnu.crypto.cipher.IBlockCipher. attributes.put(IMode.KEY_MATERIAL, key_bytes); attributes.put(IMode.CIPHER_BLOCK_SIZE, new Integer(16)); // These attributes are defined in IMode. attributes.put(IMode.STATE, new Integer(IMode.ENCRYPTION)); attributes.put(IMode.IV, iv_bytes); mode.init(attributes); int bs = mode.currentBlockSize(); for (int i = 0; i + bs < pt.length; i += bs) { mode.update(pt, i, ct, i); } mode.reset(); attributes.put(IMode.STATE, new Integer(IMode.DECRYPTION); mode.init(attributes); for (int i = 0; i + bs < ct.length; i += bs) { mode.update(ct, i, cpt, i); }