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ergo/irc/utils/crypto.go
Shivaram Lingamneni 11076be0ee review fixes
2019-05-12 16:26:23 -04:00

48 lines
1.3 KiB
Go

// Copyright (c) 2018 Shivaram Lingamneni <slingamn@cs.stanford.edu>
// released under the MIT license
package utils
import (
"crypto/rand"
"crypto/subtle"
"encoding/base32"
"encoding/base64"
)
var (
// slingamn's own private b32 alphabet, removing 1, l, o, and 0
B32Encoder = base32.NewEncoding("abcdefghijkmnpqrstuvwxyz23456789").WithPadding(base32.NoPadding)
)
const (
SecretTokenLength = 26
)
// generate a secret token that cannot be brute-forced via online attacks
func GenerateSecretToken() string {
// 128 bits of entropy are enough to resist any online attack:
var buf [16]byte
rand.Read(buf[:])
// 26 ASCII characters, should be fine for most purposes
return B32Encoder.EncodeToString(buf[:])
}
// securely check if a supplied token matches a stored token
func SecretTokensMatch(storedToken string, suppliedToken string) bool {
// XXX fix a potential gotcha: if the stored token is uninitialized,
// then nothing should match it, not even supplying an empty token.
if len(storedToken) == 0 {
return false
}
return subtle.ConstantTimeCompare([]byte(storedToken), []byte(suppliedToken)) == 1
}
// generate a 256-bit secret key that can be written into a config file
func GenerateSecretKey() string {
var buf [32]byte
rand.Read(buf[:])
return base64.RawURLEncoding.EncodeToString(buf[:])
}