rand

Documentation

Overview

Package rand implements a cryptographically secure pseudorandom number generator.

Index

• Variables
• func Int(rand io.Reader, max *big.Int) (n *big.Int, err error)
• func Prime(rand io.Reader, bits int) (p *big.Int, err error)
• func Read(b []byte) (n int, err error)

Examples

• Read

Variables

var Reader io.Reader

Reader is a global, shared instance of a cryptographically strong pseudo-random generator. On Unix-like systems, Reader reads from /dev/urandom. On Windows systems, Reader uses the CryptGenRandom API.

Functions

func Int

func Int(rand io.Reader, max *big.Int) (n *big.Int, err error)

Int returns a uniform random value in [0, max). It panics if max <= 0.

func Prime

func Prime(rand io.Reader, bits int) (p *big.Int, err error)

Prime returns a number, p, of the given size, such that p is prime with high probability.

func Read

func Read(b []byte) (n int, err error)

Read is a helper function that calls Reader.Read.

Example

This example reads 10 cryptographically secure pseudorandom numbers from rand.Reader and writes them to a byte slice.

package main

import (
	"bytes"
	"crypto/rand"
	"fmt"
	"io"
)

func main() {
	c := 10
	b := make([]byte, c)
	n, err := io.ReadFull(rand.Reader, b)
	if n != len(b) || err != nil {
		fmt.Println("error:", err)
		return
	}
	// The slice should now contain random bytes instead of only zeroes.
	fmt.Println(bytes.Equal(b, make([]byte, c)))

}

Output:

false