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feat: custom pairing code #1109

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feat: custom pairing code #1109

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86f392b
feat: custom pairing code
ZhanNexus Mar 29, 2026
e364489
fix: syntax error
ZhanNexus Mar 29, 2026
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29 changes: 23 additions & 6 deletions pair-code.go
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Original file line number Diff line number Diff line change
Expand Up @@ -54,16 +54,23 @@ type phoneLinkingCache struct {
pairingRef string
}

func generateCompanionEphemeralKey() (ephemeralKeyPair *keys.KeyPair, ephemeralKey []byte, encodedLinkingCode string) {
func generateCompanionEphemeralKey(pairingCode string) (ephemeralKeyPair *keys.KeyPair, ephemeralKey []byte, encodedLinkingCode string) {
ephemeralKeyPair = keys.NewKeyPair()
salt := random.Bytes(32)
iv := random.Bytes(16)
linkingCode := random.Bytes(5)
encodedLinkingCode = linkingBase32.EncodeToString(linkingCode)

if pairingCode != "" && len(pairingCode) == 8 {
encodedLinkingCode = pairingCode
} else {
linkingCode := random.Bytes(5)
encodedLinkingCode = linkingBase32.EncodeToString(linkingCode)
}

linkCodeKey := pbkdf2.Key([]byte(encodedLinkingCode), salt, 2<<16, 32, sha256.New)
linkCipherBlock, _ := aes.NewCipher(linkCodeKey)
encryptedPubkey := ephemeralKeyPair.Pub[:]
cipher.NewCTR(linkCipherBlock, iv).XORKeyStream(encryptedPubkey, encryptedPubkey)

ephemeralKey = make([]byte, 80)
copy(ephemeralKey[0:32], salt)
copy(ephemeralKey[32:48], iv)
Expand All @@ -86,12 +93,22 @@ func generateCompanionEphemeralKey() (ephemeralKeyPair *keys.KeyPair, ephemeralK
// The client display name must be formatted as `Browser (OS)`, and only common browsers/OSes are allowed
// (the server will validate it and return 400 if it's wrong).
//
// The optional pairingCode parameter allows specifying a custom 8-character pairing code using valid base32 characters.
// If not provided or invalid, a random code will be generated.
//
// See https://faq.whatsapp.com/1324084875126592 for more info
func (cli *Client) PairPhone(ctx context.Context, phone string, showPushNotification bool, clientType PairClientType, clientDisplayName string) (string, error) {
func (cli *Client) PairPhone(ctx context.Context, phone string, showPushNotification bool, clientType PairClientType, clientDisplayName string, pairingCode ...string) (string, error) {
if cli == nil {
return "", ErrClientIsNil
}
ephemeralKeyPair, ephemeralKey, encodedLinkingCode := generateCompanionEphemeralKey()

var pairCode string
if len(pairingCode) > 0 && pairingCode[0] != "" {
pairCode = pairingCode[0]
}

ephemeralKeyPair, ephemeralKey, encodedLinkingCode := generateCompanionEphemeralKey(pairCode)

phone = notNumbers.ReplaceAllString(phone, "")
if len(phone) <= 6 {
return "", ErrPhoneNumberTooShort
Expand Down Expand Up @@ -182,7 +199,7 @@ func (cli *Client) handleCodePairNotification(ctx context.Context, parentNode *w
keyBundleSalt := random.Bytes(32)
keyBundleNonce := random.Bytes(12)

// Decrypt the primary device's ephemeral public key, which was encrypted with the 8-character pairing code,
// Decrypt the primary device's ephemeral public key, which was encrypted with the pairing code,
// then compute the DH shared secret using our ephemeral private key we generated earlier.
primarySalt := wrappedPrimaryEphemeralPub[0:32]
primaryIV := wrappedPrimaryEphemeralPub[32:48]
Expand Down