The Digital Signature Algorithm (DSA) is an algorithm used for creating digital signatures in public key cryptography. It was developed as part of the U.S. Government’s Capstone project, an initiative started in the mid-90s to develop secure digital signature systems.
It is based on the difficulty of computing discrete logarithms over finite fields, and provides a means of authenticating a message or other digital asset by attaching a signature to it. DSA essentially refers to the way the algorithm creates a signature by combining the signer’s private key with the message’s hash to produce a unique signature.
This signature is then verified using the signer’s public key, which is publicly available. If the signature is valid, it proves that the message was emitted from the signer, and that it hasn’t been altered since it was signed (known as verification). From a technical standpoint, DSA involves two operations: signing and verifying.
When signing, the algorithm combines the signer’s private key with the message hash to generate a signature. To verify, the algorithm uses the signer’s public key to decrypt the signature and then compares it to the message’s hash to ensure that no alteration has occurred since it was signed.
Overall, DSA enables secure authentication of digital assets and provides a secure means of confirming that they have not been tampered with since they were signed. It is used in many different applications, including digital certificates and authentication systems.