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java.lang.Object | +--net.rim.device.api.crypto.OAEPFormatterEngine
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 formatter engine, click here.
For information on cryptographic algorithms, see Crypto Algorithms.
OAEPUnformatterEngine| Constructor Summary | ||
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OAEPFormatterEngine(PublicKeyEncryptorEngine engine)
Creates an OAEPFormatterEngine object based on the given encryptor engine, as well as the
SHA-1 digest algorithm. |
|
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OAEPFormatterEngine(PublicKeyEncryptorEngine engine,
byte[] parameters)
Creates an OAEPFormatterEngine object based on the given encryptor engine, as well as the
SHA-1 digest algorithm, and the given parameters. |
|
|
OAEPFormatterEngine(PublicKeyEncryptorEngine engine,
Digest digest)
Creates an OAEPFormatterEngine object based on the given encryptor engine and digest
algorithm. |
|
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OAEPFormatterEngine(PublicKeyEncryptorEngine engine,
Digest digest,
byte[] parameters)
Creates an OAEPFormatterEngine object based on the given encryptor engine, digest
algorithm and parameters. |
|
| Method Summary | ||
|
int |
formatAndEncrypt(byte[] input,
int inputOffset,
int inputLength,
byte[] output,
int outputOffset)
Formats the input into the proper format and then encrypts it, assuming this is not the last block to be encrypted. |
|
int |
formatAndEncrypt(byte[] input,
int inputOffset,
int inputLength,
byte[] output,
int outputOffset,
boolean lastBlock)
Formats the input into the proper format and then encrypts it. |
|
String |
getAlgorithm()
Returns the name of the algorithm used, ie PublicKeyEncryptorEngine.getAlgorithm() + "_OAEP". |
|
int |
getInputBlockLength()
Returns the length of an input block in bytes. |
|
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 |
public OAEPFormatterEngine(PublicKeyEncryptorEngine engine)
OAEPFormatterEngine object based on the given encryptor engine, as well as the
SHA-1 digest algorithm.
engine - The PublicKeyEncryptorEngine object used to encrypt the formatted message.public OAEPFormatterEngine(PublicKeyEncryptorEngine engine, byte[] parameters)
OAEPFormatterEngine object based on the given encryptor engine, as well as the
SHA-1 digest algorithm, and the given parameters.
engine - The PublicKeyEncryptorEngine used to encrypt the formatted message.parameters - A byte array containing the parameters to be incorporated into the formatted message.public OAEPFormatterEngine(PublicKeyEncryptorEngine engine, Digest digest)
OAEPFormatterEngine object based on the given encryptor engine and digest
algorithm.
engine - The PublicKeyEncryptorEngine object used to encrypt the formatted message.digest - The digest to be used during the formatting process.public OAEPFormatterEngine(PublicKeyEncryptorEngine engine, Digest digest, byte[] parameters)
OAEPFormatterEngine object based on the given encryptor engine, digest
algorithm and parameters.
engine - The PublicKeyEncryptorEngine object used to encrypt the formatted message.digest - The digest to be used during the formatting process.parameters - A byte array containing the parameters to be incorporated into the formatted message.| Method Detail |
public int formatAndEncrypt(byte[] input,
int inputOffset,
int inputLength,
byte[] output,
int outputOffset)
throws MessageTooLongException,
CryptoTokenException
BlockFormatterEngine
BlockFormatterEngineinput - A byte array containing the data to be encrypted.inputOffset - The offset, or initial bit position, of the data within the byte array.inputLength - The amount of data to encrypt.output - A byte array to hold the encoded and encrypted data.outputOffset - The offset, or initial bit position, of the data within the byte array.MessageTooLongException - Thrown if the input is too long to be encoded
with the given encoding scheme.CryptoTokenException - Thrown when a problem occurs with a crypto token or the crypto token is invalid.
public int formatAndEncrypt(byte[] input,
int inputOffset,
int inputLength,
byte[] output,
int outputOffset,
boolean lastBlock)
throws MessageTooLongException,
CryptoTokenException
BlockFormatterEngine
BlockFormatterEngineinput - A byte array containing the data to be encrypted.inputOffset - The offset, or initial bit position, of the data within the byte array.inputLength - The amount of data to encrypt.output - A byte array to hold the encoded and encrypted data.outputOffset - The offset, or initial bit position, of the data within the byte array.lastBlock - A boolean that indicates the last block
to be encrypted.MessageTooLongException - Thrown if the input is too long to be encoded
with the given encoding scheme.CryptoTokenException - Thrown when a problem occurs with a crypto token or the crypto token is invalid.public String getAlgorithm()
PublicKeyEncryptorEngine.getAlgorithm() + "_OAEP".
BlockFormatterEnginepublic int getInputBlockLength()
BlockFormatterEngine
BlockFormatterEnginepublic int getOutputBlockLength()
BlockFormatterEngine
BlockFormatterEngine
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