What is Digital Signature Algorithm (DSA)?

The term Digital Signature Algorithm (DSA) is used to describe a type of signature algorithm that was introduced in 1991 by the National Institute of Standards and Technology (NIST) in the United States. It was developed until it eventually reached the stage where it was able to be implemented as a part of the Federal Information Processing Standards (FIPS) in 1994.

DSA is based on the difficulty of discrete logarithm problems and public key cryptography (asymmetric cryptography) on a public key algorithm. It’s usually combined with other security protocols such as the Secure Sockets Layer (SSL) or Pretty Good Privacy (PGC) protocols.

Before we dive even further into this term, you must know the definition of a digital signature.

What is a digital signature? It’s a mathematical mechanism developed for the purpose of determining whether a digital document is authentic or not. It can also be described as a tool based on a signature algorithm that allows users to check if the message has been modified after signature. 

Firstly, a digital signature proves that a document has been sent by an authenticated party. Secondly, it establishes the fact that the document hasn’t been tampered with.

Why are digital signatures important in the first place? They’re one of the pillars upholding the security of computers today.

The digital signature algorithm is what enables the creation of digital signatures. 

They’re generally used for digital documents but have also been applied for authenticating messages. For example, it can add another layer of security for sending and receiving emails that hold extremely sensitive information. 

The digital signature algorithm consists of three stages:

1. Key pair generation;
2. Signing a document;
3. Verifying whether the signature of the document is correct.

As mentioned above, the first stage is generating a DSA key pair. Its two main elements are a public key and a private key. The public key, just as the name implies, is public, meaning it can be accessed and shared between multiple parties. The private key, on the other hand, remains confidential. However, it’s always randomly generated. 

Whoever is generating the signature must know the private key so they can complete the second stage of signing the document.

The public key is needed in order to verify the authenticity of the DSA signature on a document. Keep in mind that this public key must correspond to the private key which was used to generate the DSA signature.

DSA secures virtual communication efforts by using mathematical functions and conjunction of public and private keys.

Additionally, DSA is occasionally utilized for key exchange protocols and cryptographic nonce schemes. 

The main advantages of using a digital signature algorithm include:

• Saves space unlike many other alternative algorithms;
• Already uses asymmetric key cryptography which makes it substantially faster;
• Provides protection against forgery and other criminal activities.