70 lines
1.8 KiB
Go
70 lines
1.8 KiB
Go
// Package random holds a few functions for working with random numbers
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package random
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import (
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cryptorand "crypto/rand"
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"encoding/base64"
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"fmt"
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"io"
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)
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// StringFn create a random string for test purposes using the random
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// number generator function passed in.
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//
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// Do not use these for passwords.
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func StringFn(n int, randReader io.Reader) string {
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const (
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vowel = "aeiou"
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consonant = "bcdfghjklmnpqrstvwxyz"
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digit = "0123456789"
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)
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var (
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pattern = []string{consonant, vowel, consonant, vowel, consonant, vowel, consonant, digit}
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out = make([]byte, n)
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p = 0
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)
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_, err := io.ReadFull(randReader, out)
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if err != nil {
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panic(fmt.Sprintf("internal error: failed to read from random reader: %v", err))
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}
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for i := range out {
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source := pattern[p]
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p = (p + 1) % len(pattern)
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// this generation method means the distribution is slightly biased. However these
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// strings are not for passwords so this is deemed OK.
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out[i] = source[out[i]%byte(len(source))]
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}
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return string(out)
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}
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// String create a random string for test purposes.
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//
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// Do not use these for passwords.
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func String(n int) string {
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return StringFn(n, cryptorand.Reader)
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}
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// Password creates a crypto strong password which is just about
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// memorable. The password is composed of printable ASCII characters
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// from the base64 alphabet.
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//
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// Requires password strength in bits.
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// 64 is just about memorable
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// 128 is secure
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func Password(bits int) (password string, err error) {
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bytes := bits / 8
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if bits%8 != 0 {
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bytes++
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}
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var pw = make([]byte, bytes)
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n, err := cryptorand.Read(pw)
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if err != nil {
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return "", fmt.Errorf("password read failed: %w", err)
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}
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if n != bytes {
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return "", fmt.Errorf("password short read: %d", n)
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}
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password = base64.RawURLEncoding.EncodeToString(pw)
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return password, nil
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}
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