remove ginext/mongoext (no-dep lib)

totpext/totp.go

@@ -0,0 +1,89 @@
+package totpext
+
+import (
+	"crypto/hmac"
+	"crypto/rand"
+	"crypto/sha1"
+	"encoding/base32"
+	"encoding/binary"
+	"fmt"
+	"hash"
+	"net/url"
+	"strconv"
+	"time"
+)
+
+// https://datatracker.ietf.org/doc/html/rfc6238
+// https://datatracker.ietf.org/doc/html/rfc4226
+// https://datatracker.ietf.org/doc/html/rfc2104
+
+// https://en.wikipedia.org/wiki/Universal_2nd_Factor
+// https://en.wikipedia.org/wiki/HMAC-based_one-time_password
+// https://en.wikipedia.org/wiki/HMAC
+
+func TOTP(key []byte) string {
+	t := time.Now().Unix() / 30
+	return generateTOTP(sha1.New, key, t, 6)
+}
+
+func Validate(key []byte, totp string) bool {
+	t := time.Now().Unix() / 30
+
+	if generateTOTP(sha1.New, key, t, 6) == totp {
+		return true
+	}
+
+	if generateTOTP(sha1.New, key, t-1, 6) == totp {
+		return true
+	}
+
+	if generateTOTP(sha1.New, key, t+1, 6) == totp {
+		return true
+	}
+
+	return false
+}
+
+func GenerateSecret() ([]byte, error) {
+	secret := make([]byte, 20)
+	_, err := rand.Read(secret)
+	if err != nil {
+		return nil, err
+	}
+	return secret, nil
+}
+
+func generateTOTP(algo func() hash.Hash, secret []byte, time int64, returnDigits int) string {
+	msg := make([]byte, 8)
+	binary.BigEndian.PutUint64(msg, uint64(time))
+
+	mac := hmac.New(algo, secret)
+	mac.Write(msg)
+	hmacResult := mac.Sum(nil)
+
+	offsetBits := hmacResult[len(hmacResult)-1] & 0x0F
+
+	p := hmacResult[offsetBits : offsetBits+4]
+
+	truncated := binary.BigEndian.Uint32(p) & 0x7FFFFFFF // Last 31 bits
+
+	val := strconv.Itoa(int(truncated))
+	for len(val) < returnDigits {
+		val = "0" + val
+	}
+	val = val[len(val)-returnDigits:]
+
+	return val
+}
+
+func GenerateOTPAuth(ccn string, key []byte, accountmail string, issuer string) string {
+
+	return fmt.Sprintf("otpauth://totp/%v:%v?secret=%v&issuer=%v&algorithm=%v&period=%v&digits=%v",
+		ccn,
+		url.QueryEscape(accountmail),
+		base32.StdEncoding.EncodeToString(key),
+		issuer,
+		"SHA1",
+		"30",
+		"6")
+}