How to Build Digital Signatures From Hash Functions
summary
Recap of hash‑based construction shows Lamport one‑time signatures plus Merkle tree aggregation turn impractical one‑time keys into reusable public keys, producing signatures on the order of kilobytes; concrete deployment uses hash‑linked ledgers (Guardtime KSI) that run in production since 2008 and publish periodic anchors (monthly FT ad) to notarize history. Claim: hash‑based schemes retain exponential post‑quantum security and the newer design converts MACs into public signatures by time‑bound MAC→signature (timestamp + inclusion proof) so forged signatures are infeasible.
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chapters (13)
- 0:00Start
- 1:03ABOUT GUARDTIME
- 3:29ASYMMETRIC ENCRYPTION
- 11:26DIGITAL SIGNATURES: WHAT ARE THEY
- 17:28DIGITAL SIGNATURES: MATHEMATICAL MODEL
- 19:19DIGITAL SIGNATURES: SECURITY MODEL
- 22:02DIGITAL SIGNATURES. SIGNER IDENTITY
- 28:54DIGITAL SIGNATURES. SIGNING TIME
- 32:03DIGITAL SIGNATURES IN PRACTICE
- 36:21PROPERTIES OF HASH FUNCTIONS
- 48:37COLLISION RESISTANCE
- 51:26MESSAGE AUTHENTICATION CODES
- 55:44LAMPORT SIGNATURES
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