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Cryptology Academy · Lesson

RSA-PSS for Digital Signatures

Learn PSS encoding, salt, and why it replaced PKCS#1 v1.5 for signing.

Welcome

RSA-PSS (Probabilistic Signature Scheme) is the secure replacement for PKCS#1 v1.5 signatures. It uses randomized encoding for provably secure signatures.

PKCS#1 v1.5 Signature Weaknesses

PKCS#1 v1.5 signatures use a deterministic DigestInfo encoding. Known forgery attacks exploit loose verification implementations. Bleichenbacher (2006) showed signature forgeries against certain verifiers.

All lessons in this course

  1. Textbook RSA & Why It Is Insecure
  2. PKCS#1 v1.5 Padding & Bleichenbacher
  3. OAEP: Optimal Asymmetric Encryption Padding
  4. RSA-PSS for Digital Signatures
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