From e190cdb8fc96be0c571e3cbcc414e2feb7991ece Mon Sep 17 00:00:00 2001
From: Clawd <ai@clawd.bot>
Date: Thu, 19 Feb 2026 20:26:44 -0800
Subject: Rename PLAN to README

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+# secp256k1 from Scratch — Learning Plan
+
+Building ECDSA on secp256k1 in Go, from first principles.
+
+**Goal:** Understand the math deeply, not just copy formulas. End with a working (non-production) implementation.
+
+---
+
+## Progress
+
+### Part 1: Foundations
+- [x] **Modular arithmetic** — clock math, remainders, finite sets
+- [x] **Modular division/inverses** — finding multiplicative inverses
+- [x] **What is an elliptic curve** — y² = x³ + 7, points as (x, y) pairs
+
+### Part 2: Curve Operations
+- [ ] **Point addition** — adding two points geometrically and algebraically
+- [ ] **Point doubling** — special case when adding a point to itself
+- [ ] **The point at infinity** — identity element (like zero for addition)
+- [ ] **Scalar multiplication** — multiplying a point by an integer (repeated addition)
+
+### Part 3: Key Pairs
+- [ ] **Generator point G** — the "starting point" everyone uses
+- [ ] **Private key** — just a random big number
+- [ ] **Public key** — private key × G (scalar multiplication)
+- [ ] **Why it's hard to reverse** — the discrete log problem
+
+### Part 4: ECDSA Signing
+- [ ] **What a signature proves** — "I know the private key for this public key"
+- [ ] **The signing algorithm** — k, r, s explained
+- [ ] **Why random k matters** — reuse = leaked private key
+
+### Part 5: ECDSA Verification
+- [ ] **The verification equation** — checking without knowing the private key
+- [ ] **Putting it together** — sign and verify a message
+
+### Part 6: Implementation
+- [ ] **Field element type** — big.Int wrapper with mod p
+- [ ] **Point type** — x, y coordinates + infinity
+- [ ] **Point addition/doubling** — the core math
+- [ ] **Scalar multiplication** — double-and-add algorithm
+- [ ] **ECDSA sign/verify** — the full flow
+- [ ] **Test against known vectors** — verify correctness
+
+---
+
+## Code Location
+
+`/home/ai/vault/projects/secp256k1-learn/`
+
+We'll build incrementally:
+- `field.go` — modular arithmetic
+- `point.go` — curve points and operations
+- `ecdsa.go` — signing and verification
+- `main.go` — demo/test harness
+
+---
+
+## Resources
+
+- secp256k1 parameters: p, n, G coordinates
+- Test vectors from Bitcoin/Nostr for verification
+- No external crypto libraries (that's the point)
+
+---
+
+## Notes
+
+*Add observations, "aha" moments, or questions here as we go.*
+
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