java.security
Class SignatureSpi

java.lang.Object
 |
 +--java.security.SignatureSpi

Direct Known Subclasses:

Signature

public abstract class SignatureSpi

extends Object

Untamed: This class defines the Service Provider Interface (SPI) for the Signature class, which is used to provide the functionality of a digital signature algorithm. Digital signatures are used for authentication and integrity assurance of digital data. .

All the abstract methods in this class must be implemented by each cryptographic service provider who wishes to supply the implementation of a particular signature algorithm.

Version:

1.19, 12/03/01

Author:

Benjamin Renaud

See Also:

Signature

appRandom

protected SecureRandom appRandom

Application-specified source of randomness.

SignatureSpi

public SignatureSpi()

Enabled:

engineInitVerify

protected abstract void engineInitVerify(PublicKey publicKey)
 throws InvalidKeyException

Initializes this signature object with the specified public key for verification operations.

Parameters:

publicKey - the public key of the identity whose signature is going to be verified.

InvalidKeyException

engineInitSign

protected abstract void engineInitSign(PrivateKey privateKey)
 throws InvalidKeyException

Initializes this signature object with the specified private key for signing operations.

Parameters:

privateKey - the private key of the identity whose signature will be generated.

InvalidKeyException

engineInitSign

protected void engineInitSign(PrivateKey privateKey,
 SecureRandom random)
 throws InvalidKeyException

Initializes this signature object with the specified private key and source of randomness for signing operations.

This concrete method has been added to this previously-defined abstract class. (For backwards compatibility, it cannot be abstract.)

Parameters:

privateKey - the private key of the identity whose signature will be generated.

random - the source of randomness

InvalidKeyException

engineUpdate

protected abstract void engineUpdate(byte b)
 throws SignatureException

Updates the data to be signed or verified using the specified byte.

Parameters:

b - the byte to use for the update.

SignatureException

engineUpdate

protected abstract void engineUpdate(byte[] b,
 int off,
 int len)
 throws SignatureException

Updates the data to be signed or verified, using the specified array of bytes, starting at the specified offset.

Parameters:

b - the array of bytes

off - the offset to start from in the array of bytes

len - the number of bytes to use, starting at offset

SignatureException

engineSign

protected abstract byte[] engineSign()
 throws SignatureException

Returns the signature bytes of all the data updated so far. The format of the signature depends on the underlying signature scheme.

Returns:

the signature bytes of the signing operation's result.

SignatureException

engineSign

protected int engineSign(byte[] outbuf,
 int offset,
 int len)
 throws SignatureException

Finishes this signature operation and stores the resulting signature bytes in the provided buffer outbuf, starting at offset. The format of the signature depends on the underlying signature scheme.

The signature implementation is reset to its initial state (the state it was in after a call to one of the engineInitSign methods) and can be reused to generate further signatures with the same private key. This method should be abstract, but we leave it concrete for binary compatibility. Knowledgeable providers should override this method.

Parameters:

outbuf - buffer for the signature result.

offset - offset into outbuf where the signature is stored.

len - number of bytes within outbuf allotted for the signature. Both this default implementation and the SUN provider do not return partial digests. If the value of this parameter is less than the actual signature length, this method will throw a SignatureException. This parameter is ignored if its value is greater than or equal to the actual signature length.

Returns:

the number of bytes placed into outbuf

SignatureException

Since:

1.2

engineVerify

protected abstract boolean engineVerify(byte[] sigBytes)
 throws SignatureException

Verifies the passed-in signature.

Parameters:

sigBytes - the signature bytes to be verified.

Returns:

true if the signature was verified, false if not.

SignatureException

engineVerify

protected boolean engineVerify(byte[] sigBytes,
 int offset,
 int length)
 throws SignatureException

Verifies the passed-in signature in the specified array of bytes, starting at the specified offset.

Note: Subclasses should overwrite the default implementation.

Parameters:

sigBytes - the signature bytes to be verified.

offset - the offset to start from in the array of bytes.

length - the number of bytes to use, starting at offset.

Returns:

true if the signature was verified, false if not.

SignatureException

engineSetParameter

protected abstract void engineSetParameter(String param,
 Object value)
 throws InvalidParameterException

Deprecated. Replaced by engineSetParameter.

Sets the specified algorithm parameter to the specified value. This method supplies a general-purpose mechanism through which it is possible to set the various parameters of this object. A parameter may be any settable parameter for the algorithm, such as a parameter size, or a source of random bits for signature generation (if appropriate), or an indication of whether or not to perform a specific but optional computation. A uniform algorithm-specific naming scheme for each parameter is desirable but left unspecified at this time.

Parameters:

param - the string identifier of the parameter.

value - the parameter value.

InvalidParameterException

engineSetParameter

protected void engineSetParameter(AlgorithmParameterSpec params)
 throws InvalidAlgorithmParameterException

This method is overridden by providers to initialize this signature engine with the specified parameter set.

Parameters:

params - the parameters

InvalidAlgorithmParameterException

engineGetParameters

protected AlgorithmParameters engineGetParameters()

This method is overridden by providers to return the parameters used with this signature engine, or null if this signature engine does not use any parameters.

The returned parameters may be the same that were used to initialize this signature engine, or may contain a combination of default and randomly generated parameter values used by the underlying signature implementation if this signature engine requires algorithm parameters but was not initialized with any.

Returns:

the parameters used with this signature engine, or null if this signature engine does not use any parameters

engineGetParameter

protected abstract Object engineGetParameter(String param)
 throws InvalidParameterException

Deprecated.

Gets the value of the specified algorithm parameter. This method supplies a general-purpose mechanism through which it is possible to get the various parameters of this object. A parameter may be any settable parameter for the algorithm, such as a parameter size, or a source of random bits for signature generation (if appropriate), or an indication of whether or not to perform a specific but optional computation. A uniform algorithm-specific naming scheme for each parameter is desirable but left unspecified at this time.

Parameters:

param - the string name of the parameter.

Returns:

the object that represents the parameter value, or null if there is none.

InvalidParameterException

clone

public Object clone()
 throws CloneNotSupportedException

Suppressed: Returns a clone if the implementation is cloneable.

Overrides:

clone in class Object

Returns:

a clone if the implementation is cloneable.

CloneNotSupportedException

See Also:

java.lang.Cloneable