net.rim.device.api.crypto
Class OAEPUnformatterEngine

java.lang.Object
  extended by net.rim.device.api.crypto.OAEPUnformatterEngine
All Implemented Interfaces:
BlockUnformatterEngine

public final class OAEPUnformatterEngine
extends Object
implements BlockUnformatterEngine

Referenced from site http://www.rsa.com/.

Optimal Asymmetric Encryption Padding (OAEP) is a method for encoding messages developed by Mihir Bellare and Phil Rogaway [BR94]. The technique of encoding a message with OAEP and then encrypting it with RSA is provably secure in the random oracle model. Informally, this means that if hash functions are truly random, then an adversary who can recover such a message must be able to break RSA.

An OAEP encoded message consists of a ``masked data'' string concatenated with a ``masked random number''. In the simplest form of OAEP, the masked data is formed by taking the XOR of the plaintext message M and the hash G of a random string r. The masked random number is the XOR of r with the hash H of the masked data. The input to the RSA encryption function is then: [M XOR G(r)] || [r XOR H(M XOR G(r))]

Often, OAEP is used to encode small items such as keys. There are other variations on OAEP (differing only slightly from the above) that include a feature called ``plaintext-awareness''. This means that to construct a valid OAEP encoded message, an adversary must know the original plaintext. To accomplish this, the plaintext message M is first padded (for example, with a string of zeroes) before the masked data is formed. OAEP is supported in the ANSI X9.44, IEEE P1363 and SET standards.

For a code sample using the OAEP unformatter engine, click here.

See Also:
OAEPFormatterEngine
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 Summary
Category: Signed OAEPUnformatterEngine(PrivateKeyDecryptorEngine engine)
          Creates an OAEPUnformatterEngine object based upon the given decryptor engine, as well as the SHA-1 digest algorithm.
Category: Signed OAEPUnformatterEngine(PrivateKeyDecryptorEngine engine, byte[] parameters)
          Creates an OAEPUnformatterEngine object based upon the given decryptor engine, as well as the SHA-1 digest algorithm, and the given parameters.
Category: Signed OAEPUnformatterEngine(PrivateKeyDecryptorEngine engine, Digest digest)
          Creates an OAEPUnformatterEngine object based upon the given decryptor engine and digest algorithm.
Category: Signed OAEPUnformatterEngine(PrivateKeyDecryptorEngine engine, Digest digest, byte[] parameters)
          Creates an OAEPUnformatterEngine object based upon the given decryptor engine, digest algorithm and parameters.
 
Method Summary
Category: Signed  int decryptAndUnformat(byte[] input, int inputOffset, byte[] output, int outputOffset)
          Decrypts the input and then "unformats" it into the original plaintext assuming this block is not the last block in the stream.
Category: Signed  int decryptAndUnformat(byte[] input, int inputOffset, byte[] output, int outputOffset, boolean lastBlock)
          Decrypts the input and then "unformats" it into the original plaintext.
Category: Signed  String getAlgorithm()
          Returns the name of the algorithm used, ie PublicKeyEncryptorEngine.getAlgorithm() + "_OAEP".
Category: Signed  int getInputBlockLength()
          Returns the length of an input block in bytes.
Category: Signed  int getOutputBlockLength()
          Returns the length of an output block in bytes.
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 



Constructor Detail

OAEPUnformatterEngine

public OAEPUnformatterEngine(PrivateKeyDecryptorEngine engine)
Creates an OAEPUnformatterEngine object based upon the given decryptor engine, as well as the SHA-1 digest algorithm.

Parameters:
engine - The PrivateKeyDecryptorEngine used to decrypt the formatted message.
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

OAEPUnformatterEngine

public OAEPUnformatterEngine(PrivateKeyDecryptorEngine engine,
                             byte[] parameters)
Creates an OAEPUnformatterEngine object based upon the given decryptor engine, as well as the SHA-1 digest algorithm, and the given parameters.

Parameters:
engine - The PrivateKeyDecryptorEngine used to decrypt the formatted message.
parameters - A byte array containing the parameters to be compared to those found in the formatted message.
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

OAEPUnformatterEngine

public OAEPUnformatterEngine(PrivateKeyDecryptorEngine engine,
                             Digest digest)
Creates an OAEPUnformatterEngine object based upon the given decryptor engine and digest algorithm.

Parameters:
engine - The PrivateKeyDecryptorEngine object used to decrypt the formatted message.
digest - The digest to be used during the unformatting process.
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

OAEPUnformatterEngine

public OAEPUnformatterEngine(PrivateKeyDecryptorEngine engine,
                             Digest digest,
                             byte[] parameters)
Creates an OAEPUnformatterEngine object based upon the given decryptor engine, digest algorithm and parameters.

Parameters:
engine - The PrivateKeyDecryptorEngine object used to decrypt the formatted message.
digest - The digest to be used during the unformatting process.
parameters - A byte array containing teh paramters to be compared to those found in the formatted message.
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, ie PublicKeyEncryptorEngine.getAlgorithm() + "_OAEP".

Specified by:
getAlgorithm in interface BlockUnformatterEngine
Returns:
A String representing the name of the algorithm used.
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

getInputBlockLength

public int getInputBlockLength()
Description copied from interface: BlockUnformatterEngine
Returns the length of an input block in bytes.

Specified by:
getInputBlockLength in interface BlockUnformatterEngine
Returns:
An integer representing the length, in bytes, of an input block.
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

getOutputBlockLength

public int getOutputBlockLength()
Description copied from interface: BlockUnformatterEngine
Returns the length of an output block in bytes.

Specified by:
getOutputBlockLength in interface BlockUnformatterEngine
Returns:
An integer that represents the length, in bytes, of an output block.
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

decryptAndUnformat

public int decryptAndUnformat(byte[] input,
                              int inputOffset,
                              byte[] output,
                              int outputOffset,
                              boolean lastBlock)
                       throws DecodeException,
                              BadPaddingException,
                              CryptoTokenException
Description copied from interface: BlockUnformatterEngine
Decrypts the input and then "unformats" it into the original plaintext.

Specified by:
decryptAndUnformat in interface BlockUnformatterEngine
Parameters:
input - A byte array containing the encoded ciphertext.
inputOffset - The offset, or initial bit position, of the data within the byte array.
output - The byte array that will contain the plaintext.
outputOffset - The offset, or initial bit position, of the data within the byte array.
lastBlock - A boolean flag indicating whether this is the last block in the stream to be decrypted.
Returns:
An integer representing the value of the operation.
Throws:
DecodeException - Thrown if the input cannot be decoded properly.
BadPaddingException - Thrown if the input has improper padding.
CryptoTokenException - Thrown when a problem occurs with a 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

decryptAndUnformat

public int decryptAndUnformat(byte[] input,
                              int inputOffset,
                              byte[] output,
                              int outputOffset)
                       throws DecodeException,
                              BadPaddingException,
                              CryptoTokenException
Description copied from interface: BlockUnformatterEngine
Decrypts the input and then "unformats" it into the original plaintext assuming this block is not the last block in the stream.

Specified by:
decryptAndUnformat in interface BlockUnformatterEngine
Parameters:
input - A byte array containing the encoded ciphertext.
inputOffset - The offset, or initial bit position, of the data within the byte array.
output - The byte array that will contain the plaintext.
outputOffset - The offset, or initial bit position, of the data within the byte array.
Returns:
An integer representing the value of the operation.
Throws:
DecodeException - Thrown if the input cannot be decoded properly.
BadPaddingException - Thrown if the input has improper padding.
CryptoTokenException - Thrown when a problem occurs with a 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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