mirror of
https://github.com/octoleo/syncthing.git
synced 2024-11-14 09:14:10 +00:00
273cc9cef8
crypto/rand output is cryptographically secure by the Go library documentation's promise. That, rather than strength (= passes randomness tests) is the property that Syncthing needs).
69 lines
2.0 KiB
Go
69 lines
2.0 KiB
Go
// Copyright (C) 2014 The Syncthing Authors.
|
|
//
|
|
// This Source Code Form is subject to the terms of the Mozilla Public
|
|
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
|
|
// You can obtain one at https://mozilla.org/MPL/2.0/.
|
|
|
|
// Package rand implements functions similar to math/rand in the standard
|
|
// library, but on top of a secure random number generator.
|
|
package rand
|
|
|
|
import (
|
|
cryptoRand "crypto/rand"
|
|
mathRand "math/rand"
|
|
"reflect"
|
|
)
|
|
|
|
// Reader is the standard crypto/rand.Reader, re-exported for convenience
|
|
var Reader = cryptoRand.Reader
|
|
|
|
// randomCharset contains the characters that can make up a rand.String().
|
|
const randomCharset = "2345679abcdefghijkmnopqrstuvwxyzACDEFGHJKLMNPQRSTUVWXYZ"
|
|
|
|
var (
|
|
// defaultSecureSource is a concurrency-safe, cryptographically secure
|
|
// math/rand.Source.
|
|
defaultSecureSource = newSecureSource()
|
|
|
|
// defaultSecureRand is a math/rand.Rand based on the secure source.
|
|
defaultSecureRand = mathRand.New(defaultSecureSource)
|
|
)
|
|
|
|
// String returns a cryptographically secure random string of characters
|
|
// (taken from randomCharset) of the specified length. The returned string
|
|
// contains ~5.8 bits of entropy per character, due to the character set used.
|
|
func String(l int) string {
|
|
bs := make([]byte, l)
|
|
for i := range bs {
|
|
bs[i] = randomCharset[defaultSecureRand.Intn(len(randomCharset))]
|
|
}
|
|
return string(bs)
|
|
}
|
|
|
|
// Int63 returns a cryptographically secure random int63.
|
|
func Int63() int64 {
|
|
return defaultSecureSource.Int63()
|
|
}
|
|
|
|
// Uint64 returns a cryptographically secure strongly random uint64.
|
|
func Uint64() uint64 {
|
|
return defaultSecureSource.Uint64()
|
|
}
|
|
|
|
// Intn returns, as an int, a cryptographically secure non-negative
|
|
// random number in [0,n). It panics if n <= 0.
|
|
func Intn(n int) int {
|
|
return defaultSecureRand.Intn(n)
|
|
}
|
|
|
|
// Shuffle the order of elements in slice.
|
|
func Shuffle(slice interface{}) {
|
|
rv := reflect.ValueOf(slice)
|
|
swap := reflect.Swapper(slice)
|
|
length := rv.Len()
|
|
if length < 2 {
|
|
return
|
|
}
|
|
defaultSecureRand.Shuffle(length, swap)
|
|
}
|