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Signature
cryptix.provider.elgamal.Any_ElGamal_PKCS1Signature
public abstract class Any_ElGamal_PKCS1Signature
extends Signature
java.security.interfaces.ElGamalKey
, ElGamalCipher
, java.security.Signature
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protected Object |
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protected void |
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protected byte[] |
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protected void |
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protected boolean |
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protected abstract byte[] |
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protected Any_ElGamal_PKCS1Signature(String mdAlgorithm)
Constructor for an Any_ElGamal_PKCS1Signature.
- Parameters:
mdAlgorithm
- the standard JCA algorithm name of the message digest to be used.
protected Object engineGetParameter(String param)
SPI: Returns an algorithm-specific parameter. ElGamal has one algorithm-specific parameter called "random", as described above. It is guaranteed to be a subclass of java.util.Random. Calling this method with a param string other than "random" will return null.
- Parameters:
param
- the string name of the parameter.
- Returns:
- the object that represents the parameter value, or null if there is none.
protected void engineInitSign(PrivateKey key) throws InvalidKeyException
SPI: Initializes the cipher for signing, using the given private key. The key object must implement java.security.interfaces.ElGamalPrivateKey. The input to this algorithm will be padded on the left with random bits, up to the size of a block, before signing.
- Parameters:
key
- the private key
protected void engineInitVerify(PublicKey key) throws InvalidKeyException
SPI: Initializes the cipher for verification, using the given public key. The key object must implement java.security.interfaces.ElGamalPublicKey.
- Parameters:
key
- the public key
protected void engineSetParameter(String param, Object value)
SPI: Sets an algorithm-specific parameter. ElGamal has one algorithm-specific parameter called "random", of type java.util.Random. It specifies the source of random bits used for generating the k values needed for signing. If this parameter is not set wheninitSign
is called, the result ofnew SecureRandom()
will be used. You can set the "random" parameter using the following code:try { elgamal.setParameter("random", random_number_generator); } catch (InvalidParameterException e) { ... }This is not useful if the Signature object will only be used for verification.
- Parameters:
param
- the string identifier of the parameter.value
- the parameter value.
protected byte[] engineSign() throws SignatureException
Terminates the update process and returns the signature bytes of all the data signed so far. NOTES: Sun's documentation talks about the bytes returned being X.509-encoded. For this ElGamal/PKCS#1 implementation, they conform to PKCS#1 section 10. Practically, the return value will be formed by concatenating a leading NULL byte, a block type BT, a padding block PS, another NULLbyte, and finally a data block D; ie:return = 0x00 || BT || PS || 0x00 || D.For signing, PKCS#1 block type 01 encryption-block formatting scheme is employed. The block type BT is a single byte valued 0x01 and the padding block PS is enough 0xFF bytes to make the length of the complete Multi Precision Integer equal to the length of the public modulus. The data block D consists of the MIC -- Message Integrity Check, or message digest value-- and the MIC algorithm ASN.1 encoded identifier. The formal syntax in ASN.1 notation is:SEQUENCE { digestAlgorithm AlgorithmIdentifier, digest OCTET STRING } AlgorithmIdentifier ::= SEQUENCE { algorithm OBJECT IDENTIFIER, parameters ANY DEFINED BY algorithm OPTIONAL }
- Returns:
- the bytes of the signing operation's result.
protected void engineUpdate(byte b) throws SignatureException
Updates the data to be signed or verified, using one byte.
- Parameters:
b
- the byte to use for the update process.
protected void engineUpdate(byte[] in, int offset, int length) throws SignatureException
Updates the data to be signed or verified, using the specified sub-array of bytes, starting at the specified offset.
- Parameters:
in
- the array of bytes.offset
- the offset to start from in in.length
- the number of bytes to use, starting at offset.
protected boolean engineVerify(byte[] signature) throws SignatureException
Terminates the update process and verifies that the passed signature equals that of a generated one based on the updated data so far. NOTES: Sun's documentation talks about the bytes received being X.509-encoded. For this ElGamal/PKCS#1 implementation, the bytes received are assumed to conform to PKCS#1 section 10, or have been generated by a previous invocation of theengineSign
method.
- Parameters:
signature
- the signature bytes to be verified.
- Returns:
- true if the signature was verified successfully, false otherwise.
protected abstract byte[] getAlgorithmEncoding()
Returns the ASN.1 bytes of the AlgorithmIdentifier token described inengineSign()
method above.
- Returns:
- the AlgorithmIdentifier bytes.