Bcrypt timing test

bcrypt.go

package main

import (
	"fmt"
	"time"

	"golang.org/x/crypto/bcrypt"
)

var guesses = []string{
	"4d457b76e5f6d0aef98d7afaf09654869b29cdfda8c673fb871a77d2e48ce945",
	"7382dbaa5833d99439fb2f32f6eab080ad83011c5590d707c43b833fd5d5d111",
	"b79192dd8faa68340a0081df567dfa7bddb8e6576461dbc0077ebbfc9db88e5f",
	"094628eba62f1e625c473524f16a0f7c41c517a06dfb5e1d9fec29f8157f84b8",
	"1d457b76e5f6d0aef98d7afaf09654869b29cdfda8c673fb871a77d2e48ce945",
	"2382dbaa5833d99439fb2f32f6eab080ad83011c5590d707c43b833fd5d5d111",
	"379192dd8faa68340a0081df567dfa7bddb8e6576461dbc0077ebbfc9db88e5f",
	"494628eba62f1e625c473524f16a0f7c41c517a06dfb5e1d9fec29f8157f84b8",
	"5d457b76e5f6d0aef98d7afaf09654869b29cdfda8c673fb871a77d2e48ce945",
	"6382dbaa5833d99439fb2f32f6eab080ad83011c5590d707c43b833fd5d5d111",
	"779192dd8faa68340a0081df567dfa7bddb8e6576461dbc0077ebbfc9db88e5f",
	"894628eba62f1e625c473524f16a0f7c41c517a06dfb5e1d9fec29f8157f84b8",
	"979192dd8faa68340a0081df567dfa7bddb8e6576461dbc0077ebbfc9db88e5f",
	"094628eba62f1e625c473524f16a0f7c41c517a06dfb5e1d9fec29f8157f84b8",
}

var pass = "755aea6445a9251bb6ac9e08c28896c93b08868f860ea2451530c9db83588f77"

var costs = []int{
	8,
	10,
	12,
	14,
	16,
	18,
}
// Aim for a cost in the order of ~250ms on the current server
// Example execution on an Apple M1 Max
// single hash took 16.51353ms using 8 rounds
// single hash took 65.572939ms using 10 rounds
// single hash took 261.835407ms using 12 rounds
// single hash took 1.046684905s using 14 rounds
// single hash took 4.184984836s using 16 rounds
// single hash took 16.708390377s using 18 rounds

func main() {
	for _, c := range costs {
		start := time.Now()
		test(c, 10)
		fmt.Println(time.Since(start))
	}
}

func test(cost, times int) {
	hash, err := bcrypt.GenerateFromPassword([]byte(pass), cost)

	if err != nil {
		panic(err)
	}

	var count = 0
	var start = time.Now()
	for i := 0; i < times; i++ {
		for _, g := range guesses {
			if err = bcrypt.CompareHashAndPassword(hash, []byte(g)); err == nil {
				panic(err)
			}
			count++
		}
	}
	var dur = time.Since(start)
	var single = dur / time.Duration(count)
	fmt.Printf("single hash took %+v using %d rounds (%d executions)\n", single, cost, count)
}