net.rim.device.api.crypto
Class TripleDESDecryptorEngine

java.lang.Object
  extended by net.rim.device.api.crypto.TripleDESDecryptorEngine
All Implemented Interfaces:
BlockDecryptorEngine, SymmetricKeyDecryptorEngine

public final class TripleDESDecryptorEngine
extends Object
implements SymmetricKeyDecryptorEngine

Implements the raw functionality of the TripleDES algorithm.

The TripleDES algorithm proposed by NIST utilizes the standard DES algorithm in an alternating encryption then decryption operation. That is, EDE (Encryption/Decryption/Encryption) performing three DES operations and hence its name. This cipher is also commonly referred to as the DESede cipher.

Our implementation provides two types of TripleDES. Namely, two key and three key TripleDES. That is, two key TripleDES uses two different keys -- one for the encryption operations and one for the decryption operation. Three key TripleDES uses a different key for each operation.

The key length is 128 bits or 192 bits depending on whether you are using two key or three key TripleDES. Note that the effective key length is actually 112 bits or 168 bits after removing the parity bits from the DES operations. The block size is 64 bits.

If possible, three key TripleDES should be used instead of two key TripleDES due to the larger keysize and specific attacks against two key TripleDES.

We implemented TripleDES as it's defined in NIST's FIPS 46-3.

For a code sample using the Triple DES decryptor engine, click here.

See Also:
TripleDESEncryptorEngine, TripleDESKey
Category:
Signed: This element is only accessible by signed applications. If you intend to use this element, please visit http://www.blackberry.com/go/codesigning to obtain a set of code signing keys. Code signing is only required for applications running on BlackBerry smartphones; development on BlackBerry Smartphone Simulators can occur without code signing.
Since:
BlackBerry API 3.6.0

Field Summary
Category: Signed static int BLOCK_LENGTH
          Represents the block length in bytes for the algorithm, namely 8 bytes.
 
Constructor Summary
Category: Signed TripleDESDecryptorEngine(TripleDESKey key)
          Creates a TripleDESDecryptorEngine object based upon a TripleDES key as input, and initializes this key for use with the algorithm.
 
Method Summary
Category: Signed  void decrypt(byte[] ciphertext, int ciphertextOffset, byte[] plaintext, int plaintextOffset)
          Decodes a block of the given ciphertext into a block of plaintext.
Category: Signed  String getAlgorithm()
          Returns the name of the algorithm used.
Category: Signed  int getBlockLength()
          Returns the block length of the block cipher in bytes.
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 



Field Detail

BLOCK_LENGTH

public static final int BLOCK_LENGTH
Represents the block length in bytes for the algorithm, namely 8 bytes.

See Also:
Constant Field Values
Category:
Signed: This element is only accessible by signed applications. If you intend to use this element, please visit http://www.blackberry.com/go/codesigning to obtain a set of code signing keys. Code signing is only required for applications running on BlackBerry smartphones; development on BlackBerry Smartphone Simulators can occur without code signing.
Since:
BlackBerry API 3.6.0


Constructor Detail

TripleDESDecryptorEngine

public TripleDESDecryptorEngine(TripleDESKey key)
                         throws CryptoTokenException,
                                CryptoUnsupportedOperationException
Creates a TripleDESDecryptorEngine object based upon a TripleDES key as input, and initializes this key for use with the algorithm.

Parameters:
key - The TripleDESKey object to use for decryption.
Throws:
CryptoTokenException - Thrown when a problem occurs with the crypto token, or the crypto token is invalid.
CryptoUnsupportedOperationException - Thrown when a call is made to an unsupported operation.
Category:
Signed: This element is only accessible by signed applications. If you intend to use this element, please visit http://www.blackberry.com/go/codesigning to obtain a set of code signing keys. Code signing is only required for applications running on BlackBerry smartphones; development on BlackBerry Smartphone Simulators can occur without code signing.
Since:
BlackBerry API 3.6.0


Method Detail

getAlgorithm

public String getAlgorithm()
Returns the name of the algorithm used.

This method will always return the String "TripleDES"

Specified by:
getAlgorithm in interface BlockDecryptorEngine
Returns:
A String that represents the name of the algorithm.
Category:
Signed: This element is only accessible by signed applications. If you intend to use this element, please visit http://www.blackberry.com/go/codesigning to obtain a set of code signing keys. Code signing is only required for applications running on BlackBerry smartphones; development on BlackBerry Smartphone Simulators can occur without code signing.
Since:
BlackBerry API 3.6.0

getBlockLength

public int getBlockLength()
Description copied from interface: BlockDecryptorEngine
Returns the block length of the block cipher in bytes.

Specified by:
getBlockLength in interface BlockDecryptorEngine
Returns:
An integer that specifies the length of a block of data.
Category:
Signed: This element is only accessible by signed applications. If you intend to use this element, please visit http://www.blackberry.com/go/codesigning to obtain a set of code signing keys. Code signing is only required for applications running on BlackBerry smartphones; development on BlackBerry Smartphone Simulators can occur without code signing.
Since:
BlackBerry API 3.6.0

decrypt

public void decrypt(byte[] ciphertext,
                    int ciphertextOffset,
                    byte[] plaintext,
                    int plaintextOffset)
             throws CryptoTokenException
Description copied from interface: BlockDecryptorEngine
Decodes a block of the given ciphertext into a block of plaintext.

Specified by:
decrypt in interface BlockDecryptorEngine
Parameters:
ciphertext - A byte array containing the input that is to be decrypted.
ciphertextOffset - The starting offset, or initial byte position, of the data within the input array.
plaintext - A byte array containing the output from the method.
plaintextOffset - The starting offset, or initial byte position, of the data within the output array.
Throws:
CryptoTokenException - Thrown when an error occurs with the crypto token or the crypto token is invalid.
Category:
Signed: This element is only accessible by signed applications. If you intend to use this element, please visit http://www.blackberry.com/go/codesigning to obtain a set of code signing keys. Code signing is only required for applications running on BlackBerry smartphones; development on BlackBerry Smartphone Simulators can occur without code signing.
Since:
BlackBerry API 3.6.0





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