srand

README

srand

😄 Initialize random seed in Golang.

Usage

import (
    "math/rand"
    "moul.io/srand"
)

func init() {
    rand.Seed(srand.MustSecure())
}

Alternative seeds

// simple seed initializer
rand.Seed(srand.Fast())

// thread-safe simple seed initializer
go func() { rng := rand.New(rand.NewSource(srand.SafeFast())); fmt.Println(rng.Intn(42)) }()
go func() { rng := rand.New(rand.NewSource(srand.SafeFast())); fmt.Println(rng.Intn(42)) }()

// simple seed initializer overridable by the $SRAND env var
rand.Seed(srand.Overridable("SRAND"))

// cryptographically secure initializer
rand.Seed(srand.MustSecure())

Install

$ go get -u moul.io/srand

License

© 2019-2020 Manfred Touron

Licensed under the Apache License, Version 2.0 (LICENSE-APACHE) or the MIT license (LICENSE-MIT), at your option. See the COPYRIGHT file for more details.

SPDX-License-Identifier: (Apache-2.0 OR MIT)

Documentation

Overview

message from the author:

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|   +++       |      |       project or contact me on       |  |
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|/  |       |  \    \ /                    /  ' \/ _ \/ // / / |
||  |       |  |    | |                   /_/_/_/\___/\_,_/_/  |
+--------------------------------------------------------------+

Index

• func Fast() int64
• func MustOverridable(key string) int64
• func MustSecure() int64
• func Overridable(key string) (int64, error)
• func SafeFast() int64
• func Secure() (int64, error)

Examples

• Fast
• MustOverridable
• MustSecure
• SafeFast

Functions

func Fast

func Fast() int64

Fast returns value that can be used to initialize random seed. That value is not cryptographically secure.

Example

package main

import (
	"math/rand"

	"moul.io/srand"
)

func main() {
	rand.Seed(srand.Fast())
}

func MustOverridable

func MustOverridable(key string) int64

Example

package main

import (
	"math/rand"
	"os"

	"moul.io/srand"
)

func main() {
	rand.Seed(srand.MustOverridable("SRAND")) // seed with Fast

	os.Setenv("SRAND", "42")
	rand.Seed(srand.MustOverridable("SRAND")) // seed with 42
}

func MustSecure

func MustSecure() int64

Example

package main

import (
	"math/rand"

	"moul.io/srand"
)

func main() {
	rand.Seed(srand.MustSecure())
}

func Overridable

func Overridable(key string) (int64, error)

Overridable will check if the "key" var is configured, else it will return a Fast random seed.

If $SRAND is not parseable, panic is raised.

func SafeFast

func SafeFast() int64

SafeFast is a thread-safe version of Fast.

Example

package main

import (
	"fmt"
	"math/rand"

	"moul.io/srand"
)

func main() {
	go func() { rng := rand.New(rand.NewSource(srand.SafeFast())); fmt.Println(rng.Intn(42)) }()
	go func() { rng := rand.New(rand.NewSource(srand.SafeFast())); fmt.Println(rng.Intn(42)) }()
	go func() { rng := rand.New(rand.NewSource(srand.SafeFast())); fmt.Println(rng.Intn(42)) }()
	go func() { rng := rand.New(rand.NewSource(srand.SafeFast())); fmt.Println(rng.Intn(42)) }()
	go func() { rng := rand.New(rand.NewSource(srand.SafeFast())); fmt.Println(rng.Intn(42)) }()
}

func Secure

func Secure() (int64, error)

Secure returns a cryptographically secure random seed.

Based on https://stackoverflow.com/a/54491783