69 lines
1.8 KiB
Go
69 lines
1.8 KiB
Go
package entropy
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import (
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crip "crypto/rand"
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"encoding/binary"
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"math/rand"
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"time"
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"nullprogram.com/x/rng"
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)
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// RandomStrChoice returns a random item from an input slice of strings.
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func RandomStrChoice(choice []string) string {
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if len(choice) > 0 {
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return choice[RNGUint32()%uint32(len(choice))]
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}
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return choice[0]
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}
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// GetCryptoSeed returns a random int64 derived from crypto/rand.
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// This can be used as a seed for the math/rand package.
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func GetCryptoSeed() int64 {
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var seed int64
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_ = binary.Read(crip.Reader, binary.BigEndian, &seed)
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return seed
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}
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// GetOptimizedRand returns a pointer to a new rand.Rand which uses crypto/rand to seed a splitmix64 rng.
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func GetOptimizedRand() *rand.Rand {
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r := new(rng.SplitMix64)
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r.Seed(GetCryptoSeed())
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return rand.New(r)
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}
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// RNGUint32 returns a random uint32 using crypto/rand and splitmix64.
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func RNGUint32() uint32 {
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r := GetOptimizedRand()
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return r.Uint32()
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}
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// RNG returns integer with a maximum amount of 'n' using crypto/rand and splitmix64.
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func RNG(n int) int {
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r := GetOptimizedRand()
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return r.Intn(n)
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}
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// OneInA generates a random number with a maximum of 'million' (input int).
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// If the resulting random number is equal to 1, then the result is true.
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func OneInA(million int) bool {
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return RNG(million) == 1
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}
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// RandSleepMS sleeps for a random period of time with a maximum of n milliseconds.
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func RandSleepMS(n int) {
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time.Sleep(time.Duration(RNG(n)) * time.Millisecond)
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}
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// characters used for the gerneration of random strings.
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const charset = "abcdefghijklmnopqrstuvwxyz1234567890"
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// RandStr generates a random alphanumeric string with a max length of size. Charset used is all lowercase.
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func RandStr(size int) string {
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buf := make([]byte, size)
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for i := 0; i != size; i++ {
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buf[i] = charset[uint32(RNG(32))%uint32(len(charset))]
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}
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return string(buf)
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}
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