Generate a secure numeric hash from string in Node

Question

I would like to generate a secure digit code of fixed length from a string in Node. The interface would look something like:

hashStringToNumericCode("arandomhash", 6) => "041558"

The idea would be to use the generated code as a type of password. So it doesn't need to be unique, but it should be randomly distributed. Assume that the input string is the output of a SHA-1 hash function. In other words, assume that the input string is randomly distributed.

How could that be implemented?

Answer 1

function hashStringToNumericCode (word, length) {
  let num = 1
  for (let i = 0; i < word.length; i++) {
    const bufferValue = Buffer.from(word[i])
    const intValue = parseInt(bufferValue.toString('hex'), 16)
    num *= intValue
  }
  let modulusNumber = ''
  for (let i = 0; i < length; i++) {
    modulusNumber += '9'
  }
  modulusNumber = parseInt(modulusNumber)
  num %= modulusNumber
  console.log(num)
}