From 9f7df0f13bd3e50425429c2e7cde11defda050e7 Mon Sep 17 00:00:00 2001
From: Paul Miller <paul@paulmillr.com>
Date: Sun, 8 Jan 2023 17:46:55 +0000
Subject: [PATCH] ECDSA adjustments

---
 src/abstract/weierstrass.ts | 23 +++++++++++++++++------
 test/basic.test.js          |  7 ++++++-
 2 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/src/abstract/weierstrass.ts b/src/abstract/weierstrass.ts
index 27cf50c..4fdfb59 100644
--- a/src/abstract/weierstrass.ts
+++ b/src/abstract/weierstrass.ts
@@ -922,16 +922,16 @@ export function weierstrass(curveDef: CurveType): CurveFn {
 
   function bits2int_2(bytes: Uint8Array): bigint {
     const delta = bytes.length * 8 - CURVE.nBitLength;
-    const big = bytesToNumberBE(bytes);
-    return delta > 0 ? big >> BigInt(delta) : big;
+    const num = bytesToNumberBE(bytes);
+    return delta > 0 ? num >> BigInt(delta) : num;
   }
 
   // Ensures ECDSA message hashes are 32 bytes and < curve order
   function _truncateHash(hash: Uint8Array, truncateOnly = false): bigint {
-    let h = bits2int_2(hash);
+    const h = bits2int_2(hash);
+    if (truncateOnly) return h;
     const { n } = CURVE;
-    if (!truncateOnly && h >= n) h -= n;
-    return h;
+    return h >= n ? h - n : h;
   }
   const truncateHash = CURVE.truncateHash || _truncateHash;
 
@@ -1134,8 +1134,19 @@ export function weierstrass(curveDef: CurveType): CurveFn {
   // RFC6979 methods
   function bits2int(bytes: Uint8Array): bigint {
     const { nByteLength } = CURVE;
+    if (!(bytes instanceof Uint8Array)) throw new Error('Expected Uint8Array');
     const slice = bytes.length > nByteLength ? bytes.slice(0, nByteLength) : bytes;
-    return bytesToNumberBE(slice);
+    // const slice = bytes; nByteLength; nBitLength;
+    let num = bytesToNumberBE(slice);
+    // const { nBitLength } = CURVE;
+    // const delta = (bytes.length * 8) - nBitLength;
+    // if (delta > 0) {
+    //   // console.log('bits=', bytes.length*8, 'CURVE n=', nBitLength, 'delta=', delta);
+    //   // console.log(bytes.length, nBitLength, delta);
+    //   // console.log(bytes, new Error().stack);
+    //   num >>= BigInt(delta);
+    // }
+    return num;
   }
   function bits2octets(bytes: Uint8Array): Uint8Array {
     const z1 = bits2int(bytes);
diff --git a/test/basic.test.js b/test/basic.test.js
index c653fb1..636e5db 100644
--- a/test/basic.test.js
+++ b/test/basic.test.js
@@ -2,6 +2,7 @@ import { deepStrictEqual, throws } from 'assert';
 import { should } from 'micro-should';
 import * as fc from 'fast-check';
 import * as mod from '../lib/esm/abstract/modular.js';
+import { bytesToHex as toHex } from '../lib/esm/abstract/utils.js';
 // Generic tests for all curves in package
 import { secp192r1 } from '../lib/esm/p192.js';
 import { secp224r1 } from '../lib/esm/p224.js';
@@ -497,7 +498,11 @@ for (const name in CURVES) {
         const priv = C.utils.randomPrivateKey();
         const pub = C.getPublicKey(priv);
         const sig = C.sign(msg, priv);
-        deepStrictEqual(C.verify(sig, msg, pub), true);
+        deepStrictEqual(
+          C.verify(sig, msg, pub),
+          true,
+          `priv=${toHex(priv)},pub=${toHex(pub)},msg=${msg}`
+        );
       }),
       { numRuns: NUM_RUNS }
     )