Returns a clone if the implementation is cloneable.

  Returns a clone if the implementation is cloneable.
Returns: a clone if the implementation is cloneable.
Throws:
- CloneNotSupportedException - if this is called on an implementation that does not support Cloneable.

  Returns the name of the algorithm for this signature object.

  Returns the name of the algorithm for this signature object.
Returns: the name of the algorithm for this signature object.

  Returns a Signature object that implements the specified signature algorithm.

  Returns a Signature object that implements the specified signature algorithm.

This method traverses the list of registered security Providers, starting with the most preferred Provider. A new Signature object encapsulating the SignatureSpi implementation from the first Provider that supports the specified algorithm is returned.

Note that the list of registered providers may be retrieved via the Security.getProviders() method.
Returns: the new Signature object.
Parameters:
- algorithm - the standard name of the algorithm requested. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard algorithm names.
Throws:
- NoSuchAlgorithmException - if no Provider supports a Signature implementation for the specified algorithm.
See Also: Provider,

  Returns a Signature object that implements the specified signature algorithm.

  Returns a Signature object that implements the specified signature algorithm.

A new Signature object encapsulating the SignatureSpi implementation from the specified Provider object is returned. Note that the specified Provider object does not have to be registered in the provider list.
Returns: the new Signature object.
Parameters:
- algorithm - the name of the algorithm requested. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard algorithm names.
- provider - the provider.
Throws:
- NoSuchAlgorithmException - if a SignatureSpi implementation for the specified algorithm is not available from the specified Provider object.
- IllegalArgumentException - if the provider is null.
Since: 1.4
See Also: Provider,

  Returns a Signature object that implements the specified signature algorithm.

  Returns a Signature object that implements the specified signature algorithm.

A new Signature object encapsulating the SignatureSpi implementation from the specified provider is returned. The specified provider must be registered in the security provider list.

Note that the list of registered providers may be retrieved via the Security.getProviders() method.
Returns: the new Signature object.
Parameters:
- algorithm - the name of the algorithm requested. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard algorithm names.
- provider - the name of the provider.
Throws:
- NoSuchAlgorithmException - if a SignatureSpi implementation for the specified algorithm is not available from the specified provider.
- NoSuchProviderException - if the specified provider is not registered in the security provider list.
- IllegalArgumentException - if the provider name is null or empty.
See Also: Provider,

  Gets the value of the specified algorithm parameter.

  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.
Returns: the object that represents the parameter value, or null if there is none.
Parameters:
- param - the string name of the parameter.
Throws:
- InvalidParameterException - if param is an invalid parameter for this engine, or another exception occurs while trying to get this parameter.
See Also: Signature.setParameter(String, Object),

  Returns the parameters used with this signature object.

  Returns the parameters used with this signature object.

The returned parameters may be the same that were used to initialize this signature, or may contain a combination of default and randomly generated parameter values used by the underlying signature implementation if this signature requires algorithm parameters but was not initialized with any.
Returns: the parameters used with this signature, or null if this signature does not use any parameters.
Since: 1.4
See Also: Signature.setParameter(AlgorithmParameterSpec),

  Returns the provider of this signature object.

  Returns the provider of this signature object.
Returns: the provider of this signature object

  Initialize this object for signing.

  Initialize this object for signing. If this method is called
again with a different argument, it negates the effect
of this call.
Parameters:
- privateKey - the private key of the identity whose signature is going to be generated.
Throws:
- InvalidKeyException - if the key is invalid.

  Initialize this object for signing.

  Initialize this object for signing. If this method is called
again with a different argument, it negates the effect
of this call.
Parameters:
- privateKey - the private key of the identity whose signature is going to be generated.
- random - the source of randomness for this signature.
Throws:
- InvalidKeyException - if the key is invalid.

  Initializes this object for verification, using the public key from the given certificate.

  Initializes this object for verification, using the public key from the given certificate.

If the certificate is of type X.509 and has a key usage extension field marked as critical, and the value of the key usage extension field implies that the public key in the certificate and its corresponding private key are not supposed to be used for digital signatures, an InvalidKeyException is thrown.
Parameters:
- certificate - the certificate of the identity whose signature is going to be verified.
Throws:
- InvalidKeyException - if the public key in the certificate is not encoded properly or does not include required parameter information or cannot be used for digital signature purposes.
Since: 1.3

  Initializes this object for verification.

  Initializes this object for verification. If this method is called
again with a different argument, it negates the effect
of this call.
Parameters:
- publicKey - the public key of the identity whose signature is going to be verified.
Throws:
- InvalidKeyException - if the key is invalid.

  Initializes this signature engine with the specified parameter set.

  Initializes this signature engine with the specified parameter set.
Parameters:
- params - the parameters
Throws:
- InvalidAlgorithmParameterException - if the given parameters are inappropriate for this signature engine
See Also: Signature.getParameters(),

  Sets the specified algorithm parameter to the specified value.

  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.
Throws:
- InvalidParameterException - if param is an invalid parameter for this signature algorithm engine, the parameter is already set and cannot be set again, a security exception occurs, and so on.
See Also: Signature.getParameter(java.lang.String),

  Returns the signature bytes of all the data updated.

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

A call to this method resets this signature object to the state it was in when previously initialized for signing via a call to initSign(PrivateKey). That is, the object is reset and available to generate another signature from the same signer, if desired, via new calls to update and sign.
Returns: the signature bytes of the signing operation's result.
Throws:
- SignatureException - if this signature object is not initialized properly or if this signature algorithm is unable to process the input data provided.

  Finishes the signature operation and stores the resulting signature bytes in the provided buffer outbuf, starting at offset.

  Finishes the 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.

This signature object is reset to its initial state (the state it was in after a call to one of the initSign methods) and can be reused to generate further signatures with the same private key.
Returns: the number of bytes placed into outbuf.
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.
Throws:
- SignatureException - if this signature object is not initialized properly, if this signature algorithm is unable to process the input data provided, or if len is less than the actual signature length.
Since: 1.2

  Returns a string representation of this signature object, providing information that includes the state of the object and the name of the algorithm used.

  Returns a string representation of this signature object,
providing information that includes the state of the object
and the name of the algorithm used.
Returns: a string representation of this signature object.

  Updates the data to be signed or verified by a byte.

  Updates the data to be signed or verified by a byte.
Parameters:
- b - the byte to use for the update.
Throws:
- SignatureException - if this signature object is not initialized properly.

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

  Updates the data to be signed or verified, using the specified
array of bytes.
Parameters:
- data - the byte array to use for the update.
Throws:
- SignatureException - if this signature object is not initialized properly.

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

  Updates the data to be signed or verified, using the specified
array of bytes, starting at the specified offset.
Parameters:
- data - 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.
Throws:
- SignatureException - if this signature object is not initialized properly.

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

  Updates the data to be signed or verified using the specified
ByteBuffer. Processes the data.remaining() bytes
starting at at data.position().
Upon return, the buffer's position will be equal to its limit;
its limit will not have changed.
Parameters:
- data - the ByteBuffer
Throws:
- SignatureException - if this signature object is not initialized properly.
Since: 1.5

  Verifies the passed-in signature.

  Verifies the passed-in signature.

A call to this method resets this signature object to the state it was in when previously initialized for verification via a call to initVerify(PublicKey). That is, the object is reset and available to verify another signature from the identity whose public key was specified in the call to initVerify.
Returns: true if the signature was verified, false if not.
Parameters:
- signature - the signature bytes to be verified.
Throws:
- SignatureException - if this signature object is not initialized properly, the passed-in signature is improperly encoded or of the wrong type, if this signature algorithm is unable to process the input data provided, etc.

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

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

A call to this method resets this signature object to the state it was in when previously initialized for verification via a call to initVerify(PublicKey). That is, the object is reset and available to verify another signature from the identity whose public key was specified in the call to initVerify.
Returns: true if the signature was verified, false if not.
Parameters:
- signature - 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.
Throws:
- SignatureException - if this signature object is not initialized properly, the passed-in signature is improperly encoded or of the wrong type, if this signature algorithm is unable to process the input data provided, etc.
- IllegalArgumentException - if the signature byte array is null, or the offset or length is less than 0, or the sum of the offset and length is greater than the length of the signature byte array.
Since: 1.4