50 lines
1.1 KiB
Go
50 lines
1.1 KiB
Go
// Package rand contains utilities for interacting with math/rand, including
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// seeding from a random sed.
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package rand
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import (
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"crypto/rand"
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"encoding/binary"
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mrand "math/rand"
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)
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// CryptoUint64 generates a cryptographically-secure 64-bit integer.
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func CryptoUint64() (uint64, error) {
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bs := make([]byte, 8)
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_, err := rand.Read(bs)
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if err != nil {
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return 0, err
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}
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return binary.BigEndian.Uint64(bs), nil
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}
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// Seed initialises the non-cryptographic PRNG with a random,
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// cryptographically secure value. This is done just as a good
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// way to make this random. The returned 64-bit value is the seed.
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func Seed() (uint64, error) {
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seed, err := CryptoUint64()
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if err != nil {
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return 0, err
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}
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// NB: this is permitted.
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mrand.Seed(int64(seed))
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return seed, nil
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}
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// Int is a wrapper for math.Int so only one package needs to be imported.
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func Int() int {
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return mrand.Int()
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}
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// Intn is a wrapper for math.Intn so only one package needs to be imported.
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func Intn(max int) int {
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return mrand.Intn(max)
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}
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// Intn2 returns a random value between min and max, inclusive.
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func Intn2(min, max int) int {
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return Intn(max-min) + min
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}
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