Messing with crypto/rand generating uint64's

salt_test.go

package main

import (
	"bytes"
	"crypto/rand"
	"encoding/binary"
	"fmt"
	. "github.com/ghthor/gospec/src/gospec"
	"github.com/ghthor/gospec/src/gospec"
	"log"
	"math"
	"math/big"
)

func NewMaxUint64() *big.Int {
	var i big.Int

	buf := bytes.NewBuffer(make([]byte, 0, 8))
	err := binary.Write(buf, binary.BigEndian, uint64(math.MaxUint64))
	if err != nil {
		log.Fatal(err)
	}
	i.SetBytes(buf.Bytes())

	return &i
}

func DescribePasswordHashing(c gospec.Context) {
	c.Specify("create a big.Int with math.MaxUint64", func() {
		maxUint64 := NewMaxUint64()

		c.Expect(maxUint64.String(), Equals, fmt.Sprintf("%d", uint64(math.MaxUint64)))

		var i uint64
		err := binary.Read(bytes.NewReader(maxUint64.Bytes()), binary.BigEndian, &i)
		c.Expect(err, IsNil)
		c.Expect(i, Equals, uint64(math.MaxUint64))
	})

	c.Specify("generate a cryptography safe number in range [0, math.MaxUint64)", func() {
		maxUint64 := NewMaxUint64()

		for i := uint64(0); i < uint64(1e10); i++ {
			num, err := rand.Int(rand.Reader, maxUint64)
			c.Expect(err, IsNil)
			// Check that num < maxUint64
			c.Expect(num.Cmp(maxUint64), Equals, -1)
		}
	})

	c.Specify("passwords are salted with 8 bytes", func() {
		//i, err := rand.Int(rand.Reader, )
	})
}