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Top Description Fields Constructors Methods
com.sun.crypto.provider

pack-priv final Class OutputFeedback

extends FeedbackCipher
Class Inheritance
Imports
java.security.InvalidKeyException, .ProviderException, sun.security.util.ArrayUtil
This class represents ciphers in output-feedback (OFB) mode.

This mode is implemented independently of a particular cipher. Ciphers to which this mode should apply (e.g., DES) must be plugged-in using the constructor.

Note

This class does not deal with buffering or padding.

Author
Gigi Ankeny

Field Summary

Modifier and TypeField and Description
private final byte[]
k

private final int
numBytes

private final byte[]
register

private byte[]
registerSave

Inherited from com.sun.crypto.provider.FeedbackCipher:
blockSizeembeddedCipheriv

Constructor Summary

AccessConstructor and Description
pack-priv
OutputFeedback(SymmetricCipher embeddedCipher, int numBytes)

Method Summary

Modifier and TypeMethod and Description
pack-priv int
decrypt(byte[] cipher, int cipherOffset, int cipherLen, byte[] plain, int plainOffset)

Implements abstract com.sun.crypto.provider.FeedbackCipher.decrypt.

Performs decryption operation.

pack-priv int
decryptFinal(byte[] cipher, int cipherOffset, int cipherLen, byte[] plain, int plainOffset)

Overrides com.sun.crypto.provider.FeedbackCipher.decryptFinal.

Performs decryption operation for the last time.

pack-priv int

Returns:

the length of the encrypted data
encrypt(byte[]
the buffer with the input data to be encrypted
plain, int
the offset in plain
plainOffset, int
the length of the input data
plainLen, byte[]
the buffer for the result
cipher, int
the offset in cipher
cipherOffset)

Implements abstract com.sun.crypto.provider.FeedbackCipher.encrypt.

Performs encryption operation.

pack-priv int

Returns:

the length of the encrypted data
encryptFinal(byte[]
the buffer with the input data to be encrypted
plain, int
the offset in plain
plainOffset, int
the length of the input data
plainLen, byte[]
the buffer for the result
cipher, int
the offset in cipher
cipherOffset)

Overrides com.sun.crypto.provider.FeedbackCipher.encryptFinal.

Performs last encryption operation.

pack-priv String

Returns:

the string OFB
getFeedback()

Implements abstract com.sun.crypto.provider.FeedbackCipher.getFeedback.

Gets the name of this feedback mode.

pack-priv void
init(boolean
flag indicating encryption or decryption
decrypting, String
the algorithm name
algorithm, byte[]
the key
key, byte[]
the iv
iv)

Implements abstract com.sun.crypto.provider.FeedbackCipher.init.

Initializes the cipher in the specified mode with the given key and iv.

pack-priv void
reset()

Implements abstract com.sun.crypto.provider.FeedbackCipher.reset.

Resets the iv to its original value.

pack-priv void
restore()

Implements abstract com.sun.crypto.provider.FeedbackCipher.restore.

Restores the content of this cipher to the previous saved one.

pack-priv void
save()

Implements abstract com.sun.crypto.provider.FeedbackCipher.save.

Save the current content of this cipher.

Inherited from com.sun.crypto.provider.FeedbackCipher:
getBlockSizegetEmbeddedCiphergetIV

Field Detail

kback to summary
private final byte[] k
numBytesback to summary
private final int numBytes
registerback to summary
private final byte[] register
registerSaveback to summary
private byte[] registerSave

Constructor Detail

OutputFeedbackback to summary
pack-priv OutputFeedback(SymmetricCipher embeddedCipher, int numBytes)

Method Detail

decryptback to summary
pack-priv int decrypt(byte[] cipher, int cipherOffset, int cipherLen, byte[] plain, int plainOffset)

Implements abstract com.sun.crypto.provider.FeedbackCipher.decrypt.

Doc from com.sun.crypto.provider.FeedbackCipher.decrypt.

Performs decryption operation.

The input cipher, starting at cipherOffset and ending at (cipherOffset+cipherLen-1), is decrypted. The result is stored in plain, starting at plainOffset.

The subclass that implements Cipher should ensure that init has been called before this method is called.

decryptFinalback to summary
pack-priv int decryptFinal(byte[] cipher, int cipherOffset, int cipherLen, byte[] plain, int plainOffset)

Overrides com.sun.crypto.provider.FeedbackCipher.decryptFinal.

Doc from com.sun.crypto.provider.FeedbackCipher.decryptFinal.

Performs decryption operation for the last time.

Note

For cipher feedback modes which does not perform special handling for the last few blocks, this is essentially the same as encrypt(...). Given most modes do not do special handling, the default impl for this method is to simply call decrypt(...).

encryptback to summary
pack-priv int encrypt(byte[] plain, int plainOffset, int plainLen, byte[] cipher, int cipherOffset)

Implements abstract com.sun.crypto.provider.FeedbackCipher.encrypt.

Performs encryption operation.

The input plain text plain, starting at plainOffset and ending at (plainOffset + plainLen - 1), is encrypted. The result is stored in cipher, starting at cipherOffset.

Parameters
plain:byte[]

the buffer with the input data to be encrypted

plainOffset:int

the offset in plain

plainLen:int

the length of the input data

cipher:byte[]

the buffer for the result

cipherOffset:int

the offset in cipher

Returns:int

the length of the encrypted data

Exceptions
ProviderException:
if plainLen is not a multiple of the numBytes
encryptFinalback to summary
pack-priv int encryptFinal(byte[] plain, int plainOffset, int plainLen, byte[] cipher, int cipherOffset)

Overrides com.sun.crypto.provider.FeedbackCipher.encryptFinal.

Performs last encryption operation.

The input plain text plain, starting at plainOffset and ending at (plainOffset + plainLen - 1), is encrypted. The result is stored in cipher, starting at cipherOffset.

Parameters
plain:byte[]

the buffer with the input data to be encrypted

plainOffset:int

the offset in plain

plainLen:int

the length of the input data

cipher:byte[]

the buffer for the result

cipherOffset:int

the offset in cipher

Returns:int

the length of the encrypted data

getFeedbackback to summary
pack-priv String getFeedback()

Implements abstract com.sun.crypto.provider.FeedbackCipher.getFeedback.

Gets the name of this feedback mode.

Returns:String

the string OFB

initback to summary
pack-priv void init(boolean decrypting, String algorithm, byte[] key, byte[] iv) throws InvalidKeyException

Implements abstract com.sun.crypto.provider.FeedbackCipher.init.

Initializes the cipher in the specified mode with the given key and iv.

Parameters
decrypting:boolean

flag indicating encryption or decryption

algorithm:String

the algorithm name

key:byte[]

the key

iv:byte[]

the iv

Exceptions
InvalidKeyException:
if the given key is inappropriate for initializing this cipher
resetback to summary
pack-priv void reset()

Implements abstract com.sun.crypto.provider.FeedbackCipher.reset.

Resets the iv to its original value. This is used when doFinal is called in the Cipher class, so that the cipher can be reused (with its original iv).

restoreback to summary
pack-priv void restore()

Implements abstract com.sun.crypto.provider.FeedbackCipher.restore.

Restores the content of this cipher to the previous saved one.

saveback to summary
pack-priv void save()

Implements abstract com.sun.crypto.provider.FeedbackCipher.save.

Save the current content of this cipher.