Verisign traces digital signature history as it promotes real-time certificate checks
in plain words
Verisign The company that operates the .com and .net registries. Full definition of Verisign wrote a blog post explaining how digital signatures work and where they came from. Digital signatures are a way computers prove a message really came from someone, using a math trick with two keys, one public and one private. Verisign says old methods of checking if a certificate is still valid can become outdated, so it built a tool called Verisign Informed to check certificate status in real time.
Verisign published a blog post tracing the technical history behind its Verisign Informed service, which checks the real-time validity status of digital certificates. The company argues that cached validation data can become stale, creating gaps between what a system believes about a certificate and its actual current status, a problem it says Verisign Informed is built to close.
The post credits Whitfield Diffie and Martin E. Hellman's 1976 paper “New Directions in Cryptography” with introducing public-key cryptography, where a private key signs data and a corresponding public key lets anyone verify that signature. This sign-and-verify process became the basis for the modern digital signature.
Verisign notes that further cryptographic systems followed, including the RSA algorithm from Ronald L. Rivest, Adi Shamir, and Leonard Adleman, NIST's Digital Signature Algorithm and its elliptic curve variant, and more recently two post-quantum algorithms, SLH-DSA and ML-DSA, developed as quantum computing threatens to undermine older cryptographic assumptions.
The post also credits Loren M. Kohnfelder's 1978 bachelor's thesis with introducing the concept of the digital certificate, a signed statement from a certification authority confirming that a named party controls a particular private key. Kohnfelder proposed that certificates needed ways to signal when they should no longer be trusted, suggesting lists of revoked certificates, expiration The date a domain registration ends unless it is renewed. Full definition of expiration dates, and direct status updates, drawing an analogy to lost credit cards.
Verisign states that digital certificates and the first two of Kohnfelder's proposed mechanisms were later standardized in ITU-T Recommendation X.509, while the third mechanism, real-time status checking, was eventually implemented through the Online Certificate Status Protocol, published in 1999. Verisign frames its Informed product as an extension of that same goal, moving from simple verification of a signature to ongoing trust in a certificate's current status, particularly as artificial intelligence and quantum computing create new security challenges for the systems underlying secure online communication.