Signature Algorithm

The Signature Algorithm specifies the cryptographic method used by the Certificate Authority to digitally sign the certificate. This algorithm ensures the certificate's integrity and authenticity by creating a digital signature that can be verified using the CA's public key. Common signature algorithms include RSA with SHA-256 (RSA-SHA256), ECDSA with SHA-256 (ECDSA-SHA256), and RSA with SHA-384. The algorithm consists of two parts: the hashing algorithm (like SHA-256) that creates a fixed-size digest of the certificate data, and the encryption algorithm (like RSA or ECDSA) that encrypts this digest using the CA's private key. Modern certificates predominantly use SHA-256 as the hashing function, as older algorithms like SHA-1 have been deprecated due to security vulnerabilities. ECDSA signatures are becoming increasingly popular due to their smaller size and better performance compared to RSA while providing equivalent security levels.