SHOW Signed

net.rim.device.api.crypto
Class CFBDecryptor

java.lang.Object
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  +--java.io.InputStream
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        +--net.rim.device.api.crypto.CryptoInputStream
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              +--net.rim.device.api.crypto.DecryptorInputStream
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                    +--net.rim.device.api.crypto.StreamDecryptor
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                          +--net.rim.device.api.crypto.CFBDecryptor

public final class CFBDecryptor

extends StreamDecryptor

CFBDecryptor is the class used to iterate a given block cipher in 8 or 64-bit Cipher Feedback (CFB) mode. CFB mode is defined in FIPS 81.

Note: CFB mode uses encryption for both the encryption and decryption of the block cipher and hence should only be used with symmetric cryptography and not with asymmetric cryptography.

For a code sample using the CFB decryptor, click here.

Category:

Signed: This element is only accessible by signed clients. If you intend to use this element, please contact RIM to establish the necessary agreements that will allow you to have your COD files signed. Signing is only required for use on the device, development under the JDE can occur without signing the CODs.

See Also:

InitializationVector, CFBEncryptor

Fields inherited from class net.rim.device.api.crypto.CryptoInputStream

_inputStream

Constructor Summary

CFBDecryptor(SymmetricKeyEncryptorEngine engine, InitializationVector iv, InputStream input, boolean eightBitCFB) Creates the CFB cipher with the given encryptor engine and initialization vector.

Method Summary

	protected void	decrypt(byte[] data, int dataOffset, int dataLength) Decrypts data according to the specific implementation of the chosen stream cipher.
	String	getAlgorithm() Returns the name of the encryption algorithm used, ie SymmetricKeyEncryptorEngine.getAlgorithm() + "/CFB".
	InitializationVector	getIV() Returns the initialization vector.

Methods inherited from class net.rim.device.api.crypto.StreamDecryptor

read

Methods inherited from class net.rim.device.api.crypto.CryptoInputStream

available, close, getInputStream, markSupported, read, read

Methods inherited from class java.io.InputStream

mark, reset, skip

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CFBDecryptor

public CFBDecryptor(SymmetricKeyEncryptorEngine engine,
                    InitializationVector iv,
                    InputStream input,
                    boolean eightBitCFB)

Creates the CFB cipher with the given encryptor engine and initialization vector. It is imperative that the initialization vector is always unique for each key used or a cryptanalyst can retrieve the plaintext.

Parameters:

engine - The SymmetricKeyEncryptorEngine object to use for decryption.

iv - The initialization vector. This must have the same length as the block length of the engine.

input - The underlying InputStream object used to read in data for decryption.

eightBitCFB - A boolean to indicate the amount of cipher feedback. If set, then 8 bits of cipher feedback are used, otherwise, the encryptor engine's block size determines the amount of cipher feedback.

Category:

Signed: This element is only accessible by signed clients. If you intend to use this element, please contact RIM to establish the necessary agreements that will allow you to have your COD files signed. Signing is only required for use on the device, development under the JDE can occur without signing the CODs.

Method Detail

getAlgorithm

public String getAlgorithm()

Returns the name of the encryption algorithm used, ie SymmetricKeyEncryptorEngine.getAlgorithm() + "/CFB".

Overrides:

getAlgorithm in class CryptoInputStream

Returns:

The name of the algorithm.

Category:

Signed: This element is only accessible by signed clients. If you intend to use this element, please contact RIM to establish the necessary agreements that will allow you to have your COD files signed. Signing is only required for use on the device, development under the JDE can occur without signing the CODs.

getIV

public InitializationVector getIV()

Returns the initialization vector.

Returns:

The initialization vector.

Category:

Signed: This element is only accessible by signed clients. If you intend to use this element, please contact RIM to establish the necessary agreements that will allow you to have your COD files signed. Signing is only required for use on the device, development under the JDE can occur without signing the CODs.

decrypt

protected void decrypt(byte[] data,
                       int dataOffset,
                       int dataLength)
                throws CryptoTokenException

Description copied from class: StreamDecryptor

Decrypts data according to the specific implementation of the chosen stream cipher. The data should be decrypted in place.

Overrides:

decrypt in class StreamDecryptor

Since:

JDE 3.6

Category:

Signed: This element is only accessible by signed clients. If you intend to use this element, please contact RIM to establish the necessary agreements that will allow you to have your COD files signed. Signing is only required for use on the device, development under the JDE can occur without signing the CODs.