#oaep 1 post tagged oaep. RSA Is a Trapdoor, Not a Cryptosystem: OAEP, PSS, and the 25-Year Padding-Oracle Lineage Jul 11, 2026 Textbook RSA is a trapdoor, not a cryptosystem. A field guide to OAEP, PSS, PKCS#1 v1.5, and the Bleichenbacher-ROBOT-Marvin padding-oracle lineage, done right.