feat: add pointNegate() (see issue #61)

Author: motorina0

src/lib.rs

@@ -418,6 +418,20 @@ pub extern "C" fn private_sub() -> i32 {
     }
 }
 
+#[allow(clippy::missing_panics_doc)]
+#[no_mangle]
+#[export_name = "privateNegate"]
+pub extern "C" fn private_key_negate() -> i32 {
+    unsafe {
+        if secp256k1_ec_seckey_negate(secp256k1_context_no_precomp, PRIVATE_INPUT.as_mut_ptr()) == 1
+        {
+            1
+        } else {
+            0
+        }
+    }
+}
+
 #[allow(clippy::missing_panics_doc)]
 #[no_mangle]
 pub extern "C" fn sign(extra_data: i32) {

src_ts/index.ts

@@ -244,6 +244,19 @@ export function privateSub(
   }
 }
 
+export function privateNegate(d: Uint8Array): Uint8Array | null {
+  validate.validatePrivate(d);
+
+  try {
+    PRIVATE_KEY_INPUT.set(d);
+    return wasm.privateNegate() === 1
+      ? PRIVATE_KEY_INPUT.slice(0, validate.PRIVATE_KEY_SIZE)
+      : null;
+  } finally {
+    PRIVATE_KEY_INPUT.fill(0);
+  }
+}
+
 export interface XOnlyPointAddTweakResult {
   parity: 1 | 0;
   xOnlyPubkey: Uint8Array;

src_ts/wasm_loader.ts

@@ -48,6 +48,7 @@ interface Secp256k1WASM {
   pointMultiply: (p: number, outputlen: number) => number;
   privateAdd: () => number;
   privateSub: () => number;
+  privateNegate: () => number;
   sign: (e: number) => void;
   signRecoverable: (e: number) => 0 | 1 | 2 | 3;
   signSchnorr: (e: number) => void;

tests/fixtures/points.json

@@ -10207,6 +10207,78 @@
         "d": "0000000000000000000000000000000000000000000000000000000000000001",
         "expected": "02e493dbf1c10d80f3581e4904930b1404cc6c13900ee0758474fa94abe8c4cd13"
       }
+    ],
+    "pointNegate": [
+      {
+        "d": "0000000000000000000000000000000000000000000000000000000000000001",
+        "expected": "fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364140",
+        "description": "== 1"
+      },
+      {
+        "d": "0000000000000000000000000000000000000000000000000000000000000002",
+        "expected": "fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd036413f",
+        "description": "== 2"
+      },
+      {
+        "d": "0000000000000000000000000000000000000000000000000000000000000003",
+        "expected": "fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd036413e",
+        "description": "== 3"
+      },
+      {
+        "d": "fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364140",
+        "expected": "0000000000000000000000000000000000000000000000000000000000000001",
+        "description": "== -1"
+      },
+      {
+        "d": "fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd036413f",
+        "expected": "0000000000000000000000000000000000000000000000000000000000000002",
+        "description": "== -2"
+      },
+      {
+        "d": "fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd036413e",
+        "expected": "0000000000000000000000000000000000000000000000000000000000000003",
+        "description": "== -3"
+      },
+      {
+        "d": "b1121e4088a66a28f5b6b0f5844943ecd9f610196d7bb83b25214b60452c09af",
+        "expected": "4eede1bf775995d70a494f0a7bb6bc11e0b8cccd41cce8009ab1132c8b0a3792"
+      },
+      {
+        "d": "0705e4b49ea25478d60ba7287cf2cc020c074dd97d478c7f84a3cfbab8c376e6",
+        "expected": "f8fa1b4b615dab8729f458d7830d33fcaea78f0d320113bc3b2e8ed21772ca5b"
+      },
+      {
+        "d": "bd66074dae0276b29dd5d1136f53293e68eac94ceb82a2d2266411b22ec0f59c",
+        "expected": "4299f8b251fd894d622a2eec90acd6c051c41399c3c5fd69996e4cdaa1754ba5"
+      },
+      {
+        "d": "b5aa6da19452b8c9bb92b784fb6d47ab74bb066c2a879733b19ec8b1135c6a0b",
+        "expected": "4a55925e6bad4736446d487b0492b85345f3d67a84c109080e3395dbbcd9d736"
+      },
+      {
+        "d": "dc8c84fef13612bc12677f9d7300fce12fb2ce47340e28d9e478d5dabec4e813",
+        "expected": "23737b010ec9ed43ed9880628cff031d8afc0e9f7b3a7761db5988b21171592e"
+      },
+      {
+        "d": "348c8f3e7b11be8629ecaa28c8ef9fa6ee2d400cece1d49ea30e3b5653f01bf5",
+        "expected": "cb7370c184ee4179d61355d737106057cc819cd9c266cb9d1cc423367c46254c"
+      },
+      {
+        "d": "c29d155bad7e29720784de6783c4c7c7c5135597b390b256d19aa8cb9e493cc2",
+        "expected": "3d62eaa45281d68df87b21987c3b3836f59b874efbb7ede4ee37b5c131ed047f"
+      },
+      {
+        "d": "ebdddef7704d4ef7322074d84fd087ce73eafac8d3170e8a122aa9cf0486e42f",
+        "expected": "142221088fb2b108cddf8b27b02f783046c3e21ddc3191b1ada7b4bdcbaf5d12"
+      },
+      {
+        "d": "4f9694abc84c0d804bbff0f0609ee078a1284772b26efabf25c25ccf85dc272c",
+        "expected": "b0696b5437b3f27fb4400f0f9f611f8619869573fcd9a57c9a1001bd4a5a1a15"
+      },
+      {
+        "d": "c20f4427017ea5f9f7fedcf5a9d9f9f7e37933769efcba600e3494f010e00048",
+        "expected": "3df0bbd8fe815a060801230a56260606d735a970104be5dbb19dc99cbf5640f9"
+      }
     ]
   },
   "invalid": {

tests/points.js

@@ -213,4 +213,30 @@ export default function (secp256k1) {
 
     t.end();
   });
+
+  test("pointNegate", (t) => {
+    for (const f of fpoints.valid.pointNegate) {
+      const d = fromHex(f.d);
+      const expected = fromHex(f.expected);
+      let description = `-${f.d} = ${f.expected}`;
+      if (f.description) description += ` (${f.description})`;
+      t.same(secp256k1.privateNegate(d), expected, description);
+
+      t.equal(secp256k1.privateAdd(d, expected), null, description);
+    }
+
+    // using the same data as point from scalar
+    for (const f of fpoints.invalid.pointFromScalar) {
+      const d = fromHex(f.d);
+      t.throws(
+        () => {
+          secp256k1.privateNegate(d);
+        },
+        new RegExp(f.exception),
+        `${f.description} throws ${f.exception}`
+      );
+    }
+
+    t.end();
+  });
 }