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package kauth
import (
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"encoding/base64"
"encoding/hex"
"errors"
"os"
"github.com/martinlehoux/kagamigo/kcore"
"golang.org/x/exp/slog"
)
var (
ErrEncryptedTooShort = errors.New("encrypted text is too short")
ErrCookieBadLength = errors.New("cookie secret must be 32 bytes")
)
// Generate a random 32-byte secret for cookies
func GenerateCookieSecret() []byte {
secret := make([]byte, 32)
_, err := rand.Read(secret)
kcore.Expect(err, "failed to generate random bytes")
return secret
}
func LoadCookieSecret(cookieSecretString string) []byte {
cookiesSecret, err := hex.DecodeString(cookieSecretString)
if err != nil {
err = kcore.Wrap(err, "error decoding cookie secret")
slog.Error(err.Error())
os.Exit(1)
}
if len(cookiesSecret) != 32 {
slog.Error(ErrCookieBadLength.Error())
os.Exit(1)
}
slog.Info("cookie secret loaded")
return cookiesSecret
}
func encrypt(secret []byte, plainText string) string {
block, err := aes.NewCipher(secret)
kcore.Expect(err, "error creating AES cipher")
aead, err := cipher.NewGCM(block)
kcore.Expect(err, "error creating AEAD")
nonce := make([]byte, aead.NonceSize())
_, err = rand.Read(nonce)
kcore.Expect(err, "error generating nonce")
return base64.URLEncoding.EncodeToString(aead.Seal(nonce, nonce, []byte(plainText), nil))
}
func decrypt(secret []byte, encryptedText string) (string, error) {
encryptedBytes, err := base64.URLEncoding.DecodeString(encryptedText)
if err != nil {
err = kcore.Wrap(err, "error decoding base64")
return "", err
}
block, err := aes.NewCipher(secret)
kcore.Expect(err, "error creating AES cipher")
aead, err := cipher.NewGCM(block)
kcore.Expect(err, "error creating AEAD")
nonceSize := aead.NonceSize()
if len(encryptedBytes) < nonceSize {
return "", ErrEncryptedTooShort
}
nonce, cipherText := encryptedBytes[:nonceSize], encryptedBytes[nonceSize:]
plainBytes, err := aead.Open(nil, nonce, cipherText, nil) // #nosec G407
if err != nil {
err = kcore.Wrap(err, "error decrypting")
return "", err
}
return string(plainBytes), nil
}
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