javascriptjavasha256

Convert SHA-256 string to number - Java

The code below in JS converts a Hash to a number, but I tried to write a similar code in Java and both return different results.

What's the best way to get the same result shown in JS using Java?

JS

const hash = "806abe48226985c5fb0e878792232204d74643e190e25a4c20a97748d52b191c"
console.log(parseInt(hash, 16) % 11);

Result:
2

Java

String hash = "806abe48226985c5fb0e878792232204d74643e190e25a4c20a97748d52b191c";
BigInteger bigInt = new BigInteger(hash, 16);
System.out.println(bigInt.mod(BigInteger.valueOf(11)).intValue());

Result:
4

Solution

  • The correct value is 4. The result from the JavaScript snippet is incorrect, as the number is too large to be represented accurately. Use BigInt instead.

    const hash = "806abe48226985c5fb0e878792232204d74643e190e25a4c20a97748d52b191c"
console.log(Number.isSafeInteger(parseInt(hash, 16))); // do not use this!
console.log((BigInt('0x' + hash) % 11n).toString());