diff --git a/pkg/e2ee/manager.go b/pkg/e2ee/manager.go
index 28f8e4e..40b8dc5 100644
--- a/pkg/e2ee/manager.go
+++ b/pkg/e2ee/manager.go
@@ -329,6 +329,24 @@ func (m *Manager) DecryptMessageV2(msg *line.Message) (string, error) {
 	if err != nil {
 		return "", err
 	}
+
+	ver := 2
+	if vStr, ok := msg.ContentMetadata["e2eeVersion"]; ok && vStr == "1" {
+		ver = 1
+	}
+
+	if ver == 1 {
+		cipher, err := assembleCipherV1(msg.Chunks)
+		if err != nil {
+			return "", err
+		}
+		pt, _, err := m.runner.ChannelDecryptV1(chanID, senderKeyID, receiverKeyID, base64.StdEncoding.EncodeToString(cipher))
+		if err != nil {
+			return "", err
+		}
+		return pt, nil
+	}
+
 	pt, _, err := m.runner.ChannelDecryptV2(chanID, msg.To, msg.From, senderKeyID, receiverKeyID, msg.ContentType, base64.StdEncoding.EncodeToString(cipher))
 	if err != nil {
 		return "", err
@@ -336,6 +354,26 @@ func (m *Manager) DecryptMessageV2(msg *line.Message) (string, error) {
 	return pt, nil
 }
 
+func assembleCipherV1(chunks []string) ([]byte, error) {
+	if len(chunks) < 3 {
+		return nil, fmt.Errorf("not enough chunks")
+	}
+	decode := func(s string) ([]byte, error) { return base64.StdEncoding.DecodeString(strings.TrimSpace(s)) }
+	b0, err := decode(chunks[0])
+	if err != nil {
+		return nil, err
+	}
+	b1, err := decode(chunks[1])
+	if err != nil {
+		return nil, err
+	}
+	b2, err := decode(chunks[2])
+	if err != nil {
+		return nil, err
+	}
+	return append(append(b0, b1...), b2...), nil
+}
+
 func (m *Manager) UnwrapGroupSharedKey(chatMid string, sharedKey *line.E2EEGroupSharedKey) (int, error) {
 	m.mu.Lock()
 	defer m.mu.Unlock()
diff --git a/pkg/internal/runner.js b/pkg/internal/runner.js
index 195b6bc..6ef90e5 100644
--- a/pkg/internal/runner.js
+++ b/pkg/internal/runner.js
@@ -398,6 +398,21 @@ async function run() {
 					process.stdout.write(
 						JSON.stringify({ ciphertext: u8ToB64(ct) }) + "\n"
 					);
+				} else if (type === "channel_decrypt_v1") { // messages sent from ios LINE app use v1
+					const {
+						channelId,
+						ciphertext,
+					} = query;
+					const chan = getChannel(toIntStrict("channelId", channelId));
+
+					const u8Cipher = b64ToU8(ciphertext);
+					const pt = chan.decryptV1(
+						u8Cipher
+					);
+					const plaintext = new TextDecoder().decode(Uint8Array.from(pt).buffer);
+					process.stdout.write(
+						JSON.stringify({ plaintext, base64: u8ToB64(pt) }) + "\n"
+					);
 				} else if (type === "channel_decrypt_v2") {
 					const {
 						channelId,
diff --git a/pkg/runner.go b/pkg/runner.go
index 0e4a6bc..0883711 100644
--- a/pkg/runner.go
+++ b/pkg/runner.go
@@ -404,6 +404,28 @@ func (r *Runner) ChannelEncryptV2(channelID int, to, from string, senderKeyID, r
 	return ct, nil
 }
 
+// decrypts ciphertext with channel v1 (ios)
+func (r *Runner) ChannelDecryptV1(channelID, senderKeyID, receiverKeyID int, ciphertext string) (string, string, error) {
+	resp, err := r.call(map[string]any{
+		"type":          "channel_decrypt_v1",
+		"channelId":     channelID,
+		"senderKeyId":   senderKeyID,
+		"receiverKeyId": receiverKeyID,
+		"ciphertext":    ciphertext,
+	})
+	if err != nil {
+		return "", "", err
+	}
+	var plaintext, base64 string
+	if v, ok := resp["plaintext"]; ok {
+		_ = json.Unmarshal(v, &plaintext)
+	}
+	if v, ok := resp["base64"]; ok {
+		_ = json.Unmarshal(v, &base64)
+	}
+	return plaintext, base64, nil
+}
+
 // decrypts ciphertext with channel v2
 func (r *Runner) ChannelDecryptV2(channelID int, to, from string, senderKeyID, receiverKeyID, contentType int, ciphertext string) (string, string, error) {
 	resp, err := r.call(map[string]any{