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Switch to golang's crypto/rand #12

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Switch to golang's crypto/rand #12

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17 changes: 7 additions & 10 deletions utils.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ package gotp

import (
"fmt"
"math/rand"
"crypto/rand"
"net/url"
"strings"
"time"
Expand Down Expand Up @@ -77,14 +77,11 @@ func Itob(integer int) []byte {

// generate a random secret of given length
func RandomSecret(length int) string {
rand.Seed(time.Now().UnixNano())
letterRunes := []rune("ABCDEFGHIJKLMNOPQRSTUVWXYZ234567")

bytes := make([]rune, length)

for i := range bytes {
bytes[i] = letterRunes[rand.Intn(len(letterRunes))]
s := make([]byte, length*10)
_, err := rand.Read(s)
if err != nil {
log.Println("Unable to generate secret; insufficient entropy?",err)
return ""
}

return string(bytes)
return hex.EncodeToString(s[:length])
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random secret should be base32 format according to OTP.secret.

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@codewinch codewinch Jan 5, 2022 •
edited
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16 bytes with that constrained alphabet (base32) is probably not a large enough search space to be secure.

https://datatracker.ietf.org/doc/html/rfc4226#appendix-A.4.1
https://datatracker.ietf.org/doc/html/rfc6238
https://datatracker.ietf.org/doc/html/rfc4086#page-34

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from https://github.com/pquerna/otp/blob/60112ee2a95553a491c22956619ef30260ec93e8/totp/totp.go#L150

var b32NoPadding = base32.StdEncoding.WithPadding(base32.NoPadding)
b32NoPadding(EncodeToString(secret))

Still needs to be 32 bytes though.

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Trying to figure out how to edit this PR in the web UI without actually going to the trouble of cloning it locally haha

}