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java.lang.Objectnet.rim.device.api.crypto.DESDecryptorEngine
public final class DESDecryptorEngine
The DESDecryptorEngine
implements the decryption functionality
of the DES block cipher. DES is the Data Encryption Standard
which in actuality uses the DEA Data Encryption Algorithm to
compute the plaintext from the ciphertext. DES is defined in FIPS 46-3.
DES operates on 64 bit blocks and has an effective key length of 56 bits. In reality, the key is 64 bits but there are 8 bits of parity used which means that the effective key length is only 56 bits. Every eighth bit is used for parity and it is the least significant bit that is used for parity. The algorithm is uses the basic principles of data confusion and diffusion.
For a code sample using the DES decryptor engine, click here.
DESEncryptorEngine
Field Summary | ||
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static int |
BLOCK_LENGTH
Represents the block length of the cipher in bytes, namely 8 bytes. |
Constructor Summary | ||
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DESDecryptorEngine(DESKey key)
Creates a DESDecryptorEngine object based on a given DES key. |
Method Summary | ||
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void |
decrypt(byte[] ciphertext,
int ciphertextOffset,
byte[] plaintext,
int plaintextOffset)
Decodes a block of the given ciphertext into a block of plaintext. |
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String |
getAlgorithm()
Returns the name of the algorithm used, ie "DES". |
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int |
getBlockLength()
Returns the block length of the block cipher in bytes. |
Methods inherited from class java.lang.Object |
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equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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public static final int BLOCK_LENGTH
Constructor Detail |
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public DESDecryptorEngine(DESKey key) throws CryptoTokenException, CryptoUnsupportedOperationException
DESDecryptorEngine
object based on a given DES key.
key
- A DES key containing the key material that will be used for decryption.
CryptoTokenException
- Thrown when a problem occurs with a crypto
token or the crypto token is invalid.
CryptoUnsupportedOperationException
- Thrown if a call is made to
an unsupported operation.Method Detail |
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public String getAlgorithm()
This method will always return the string "DES".
getAlgorithm
in interface BlockDecryptorEngine
public int getBlockLength()
BlockDecryptorEngine
getBlockLength
in interface BlockDecryptorEngine
public void decrypt(byte[] ciphertext, int ciphertextOffset, byte[] plaintext, int plaintextOffset) throws CryptoTokenException
BlockDecryptorEngine
decrypt
in interface BlockDecryptorEngine
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.
CryptoTokenException
- Thrown when an error occurs with the crypto
token or the crypto token is invalid.
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