Lamport Signature
The Lamport signature is a one-time signature scheme built from one-way hash functions, signing each bit with an independent key pair.
Purpose
To provide hash-based quantum-safe signatures and illustrate one-time signature principles.
Mechanism
Keys: for each bit i, generate random x_i^0 and x_i^1; the public key is y_i^b=H(x_i^b). To sign message m, reveal x_i^{b_i} for each bit b_i. Verification checks H(x_i^{b_i})=y_i^{b_i}. Each key is used only once.
Use cases
- Post-quantum signatures
- Hash-based cryptography
- One-time signatures