Digital signatures are used to detect unauthorized changes to data and to authenticate the identity of the person or system that signed it. In practice, a private key creates the signature and a matching public key verifies it, so anyone can check authenticity without learning the signer’s secret key.
When properly implemented, a digital signature provides origin authentication, data integrity, and support for signer non-repudiation—evidence that the claimed signatory produced the signature and cannot easily deny it later. NIST’s Digital Signature Standard (FIPS 186-5) specifies approved algorithms for generating and verifying these signatures on stored or transmitted data.
Source: FIPS 186-5, Digital Signature Standard (DSS) — NIST CSRC