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63 lines
1.2 KiB
63 lines
1.2 KiB
package common
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import (
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crand "crypto/rand"
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"encoding/hex"
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"math/rand"
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)
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const (
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strChars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz" // 62 characters
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)
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func init() {
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// Seed math/rand with "secure" int64
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b := RandBytes(8)
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var seed uint64
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for i := 0; i < 8; i++ {
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seed |= uint64(b[i])
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seed <<= 8
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}
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rand.Seed(int64(seed))
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}
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// Constructs an alphanumeric string of given length.
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// Not crypto safe
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func RandStr(length int) string {
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chars := []byte{}
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MAIN_LOOP:
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for {
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val := rand.Int63()
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for i := 0; i < 10; i++ {
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v := int(val & 0x3f) // rightmost 6 bits
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if v >= 62 { // only 62 characters in strChars
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val >>= 6
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continue
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} else {
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chars = append(chars, strChars[v])
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if len(chars) == length {
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break MAIN_LOOP
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}
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val >>= 6
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}
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}
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}
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return string(chars)
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}
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// Crypto safe
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func RandBytes(numBytes int) []byte {
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b := make([]byte, numBytes)
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_, err := crand.Read(b)
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if err != nil {
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panic(err)
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}
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return b
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}
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// Crypto safe
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// RandHex(24) gives 96 bits of randomness, strong enough for most purposes.
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func RandHex(numDigits int) string {
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return hex.EncodeToString(RandBytes(numDigits / 2))
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}
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