Initial commit - 611 cybersecurity skills across all subdomains

skills/implementing-zero-knowledge-proof-for-authentication/references/workflows.md

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+# Workflows - Zero-Knowledge Proof for Authentication
+
+## Workflow 1: Schnorr Interactive ZKP
+
+```
+Prover (knows secret x)              Verifier (knows y = g^x mod p)
+      |                                      |
+      |-- Commitment: t = g^r mod p -------->|
+      |                                      |
+      |<-- Challenge: c (random) ------------|
+      |                                      |
+      |-- Response: s = (r + c*x) mod q ---->|
+      |                                      |
+      |                              [Verify: g^s == t * y^c mod p]
+      |                              [Accept or Reject]
+```
+
+## Workflow 2: Non-Interactive ZKP (Fiat-Shamir)
+
+```
+Prover:
+  1. Choose random r
+  2. Compute t = g^r mod p
+  3. Compute c = H(g || y || t)  (Fiat-Shamir)
+  4. Compute s = (r + c*x) mod q
+  5. Send proof (t, s) to verifier
+
+Verifier:
+  1. Compute c = H(g || y || t)
+  2. Check g^s == t * y^c mod p
+```
+
+## Workflow 3: Registration and Authentication
+
+```
+[Registration]:
+  User --> [Choose password/secret x]
+       --> [Compute y = g^x mod p]
+       --> [Send y to server]
+  Server --> [Store y (public key only)]
+
+[Authentication]:
+  User <--> Server: [Run Schnorr protocol]
+  Server: [Verifies proof without learning x]
+  Server: [Grants session token on success]
+```