Cryptography Tutorials - Herong's Tutorial Examples - Version 5.33, by Dr. Herong Yang
java.security.Signature - The Data Signing Class
This section describes the data signing and verification Java class, java.security.Signature, and its major methods like update(), sign() and verify().
The java.security.Signature class is an abstract class providing a link to implementation classes of digital signature algorithms provided by various security package providers. Major methods in the KeyPairGenerator class:
getInstance() - Returns a Signature object of the specified algorithm from the implementation of the specified provider. If provider is not specified, the default implementation is used. This is a static method.
initSign() - Initializes the current Signature object with the specified private key to be ready to take input data for generating a new signature.
initVerify() - Initializes the current Signature object with the specified public key to be ready to take input data for verifying an existing signature.
update() - Adds more data to the current Signature object for signature generation or signature verification.
sign() - Generates a new signature for the input data received so far in the current Signature object, and returns the signature as a byte array. It also removes the input data.
verify() - Verifies the input data received so far in the current Signature object against the specified signature, and returns true or false. It also removes the input data.
getAlgorithm() - Returns the algorithm name of the current Signature object.
getProvider() - Returns the provider as a Provider object of the current Signature object.
See the next section on how to write a sample program.
Last update: 2013.
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