The Standard specifies a suite of algorithms that can be used to generate a digital signature. Digital signatures are used to detect unauthorized modifications to data and to authenticate the identity of the signatory. In addition, the recipient of signed data can use a digital signature as evidence in demonstrating to a third party that the signature was, in fact, generated by the claimed signatory. This is known as non-repudiation, since the signatory cannot easily repudiate the signature at a later time. This Standard specifies three techniques for the generation and verification of digital signatures: DSA, ECDSA and RSA. This revision increases the length of the keys allowed for DSA, provides additional requirements for the use of ECDSA and RSA, and includes requirements for obtaining assurances necessary for valid digital signatures.