Overview ¶
Package rand implements a cryptographically secure random number generator.
Index ¶
Examples ¶
Variables ¶
var Reader io.Reader
Reader is a global, shared instance of a cryptographically secure random number generator.
On Linux and FreeBSD, Reader uses getrandom(2) if available, /dev/urandom otherwise. On OpenBSD, Reader uses getentropy(2). On other Unix-like systems, Reader reads from /dev/urandom. On Windows systems, Reader uses the CryptGenRandom API. On Wasm, Reader uses the Web Crypto API.
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. Prime will return error for any error returned by rand.Read or if bits < 2.
func Read ¶
func Read(b []byte) (n int, err error)
Read is a helper function that calls Reader.Read using io.ReadFull. On return, n == len(b) if and only if err == nil.
Example ¶
This example reads 10 cryptographically secure pseudorandom numbers from rand.Reader and writes them to a byte slice.
Code:
package main
import (
"bytes"
"crypto/rand"
"fmt"
)
func main() {
c := 10
b := make([]byte, c)
_, err := rand.Read(b)
if 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)))
}
false