Padding the hex strings being hashed to 32 bytes

src/index.ts

@@ -93,8 +93,8 @@ export function blind(m: BigInteger, signerR: Point): { mBlinded: BigInteger, us
     const ainvrx = ainv.multiply(rx)
 
     const mHex = m.toString(16)
-    const hHex = keccak256('0x' + mHex)
-    const h = BigInteger.fromHex(hHex.slice(2))
+    const hHex = keccak256('0x' + zeroPad(mHex, 32)).substr(2)
+    const h = BigInteger.fromHex(hHex)
     const mBlinded = ainvrx.multiply(h)
 
     return { mBlinded: mBlinded.mod(n), userSecretData: u }
@@ -121,8 +121,8 @@ export function verify(m: BigInteger, s: UnblindedSignature, q: Point) {
     const sG = G.multiply(s.s)
 
     const mHex = m.toString(16)
-    const hHex = keccak256('0x' + mHex)
-    const h = BigInteger.fromHex(hHex.slice(2))
+    const hHex = keccak256('0x' + zeroPad(mHex, 32)).substr(2)
+    const h = BigInteger.fromHex(hHex)
 
     const rx = s.f.affineX.mod(n)
     const right = s.f.add(
@@ -147,3 +147,11 @@ function random(bytes: number) {
     } while (k.toString() == '0' && k.gcd(n).toString() != '1')
     return k
 }
+
+function zeroPad(hexString: string, byteLength: number) {
+    if (hexString.length > (byteLength * 2)) throw new Error("Out of bounds")
+    while (hexString.length < (byteLength * 2)) {
+        hexString = "0" + hexString
+    }
+    return hexString
+}