The Signature class is used to provide applications the functionality of a digital signature algorithm. Digital signatures are used for authentication and integrity assurance of digital data.
The signature algorithm can be, among others, the NIST standard DSA, using DSA and SHA-256. The DSA algorithm using the SHA-256 message digest algorithm can be specified as
SHA256withDSA. In the case of RSA the signing algorithm could be specified as, for example,
SHA256withRSA. The algorithm name must be specified, as there is no default.
A Signature object can be used to generate and verify digital signatures.
There are three phases to the use of a Signature object for either signing data or verifying a signature:
- Initialization, with either
Depending on the type of initialization, this will update the bytes to be signed or verified. See the
- Signing or Verifying a signature on all updated bytes. See the
sign methods and the
Note that this class is abstract and extends from
SignatureSpi for historical reasons. Application developers should only take notice of the methods defined in this
Signature class; all the methods in the superclass are intended for cryptographic service providers who wish to supply their own implementations of digital signature algorithms.
Every implementation of the Java platform is required to support the following standard
These algorithms are described in the Signature section
of the Java Security Standard Algorithm Names Specification. Consult the release documentation for your implementation to see if any other algorithms are supported.