Digital Signature Algorithm

What Does Digital Signature Algorithm Mean?

A digital signature algorithm (DSA) refers to a standard for digital signatures. It was introduced in 1991 by the National Institute of Standards and Technology (NIST) as a better method of creating digital signatures. Along with RSA, DSA is considered one of the most preferred digital signature algorithms used today.


Techopedia Explains Digital Signature Algorithm

Unlike DSA, most digital signature types are generated by signing message digests with the private key of the originator. This creates a digital thumbprint of the data. Since just the message digest is signed, the signature is generally much smaller compared to the data that was signed. As a result, digital signatures impose less load on processors at the time of signing execution, use small volumes of bandwidth, and generate small volumes of ciphertext intended for cryptanalysis.

DSA, on the other hand, does not encrypt message digests using private key or decrypt message digests using public key. Instead, it uses unique mathematical functions to create a digital signature consisting of two 160-bit numbers, which are originated from the message digests and the private key. DSAs make use of the public key for authenticating the signature, but the authentication process is more complicated when compared with RSA.

The digital signature procedures for RSA and DSA are usually regarded as being equal in strength. Because DSAs are exclusively used for digital signatures and make no provisions for encrypting data, it is typically not subject to import or export restrictions, which are often enforced on RSA cryptography.


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Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.