feat: add local signup and Kakao verification gate

app/gateway-frontend/src/utils/passwordEnvelope.ts

@@ -0,0 +1,46 @@
+import { trpc } from './trpc';
+
+const pemToBuffer = (pem: string): ArrayBuffer => {
+    const encoded = pem.replace(/-----BEGIN PUBLIC KEY-----|-----END PUBLIC KEY-----|\s/g, '');
+    const binary = window.atob(encoded);
+    const buffer = new ArrayBuffer(binary.length);
+    const bytes = new Uint8Array(buffer);
+    for (let index = 0; index < binary.length; index += 1) {
+        bytes[index] = binary.charCodeAt(index);
+    }
+    return buffer;
+};
+
+const bytesToBase64 = (bytes: Uint8Array): string => {
+    let binary = '';
+    for (const byte of bytes) {
+        binary += String.fromCharCode(byte);
+    }
+    return window.btoa(binary);
+};
+
+export const sealPassword = async (password: string): Promise<{ keyId: string; ciphertext: string }> => {
+    const encoded = new TextEncoder().encode(password);
+    if (Array.from(password).length < 6 || encoded.byteLength > 128) {
+        throw new Error('비밀번호는 6자 이상, UTF-8 기준 128바이트 이하여야 합니다.');
+    }
+    if (!window.crypto?.subtle) {
+        throw new Error('이 브라우저에서는 안전한 비밀번호 전송을 사용할 수 없습니다.');
+    }
+    const keyInfo = await trpc.auth.passwordKey.query();
+    const publicKey = await window.crypto.subtle.importKey(
+        'spki',
+        pemToBuffer(keyInfo.publicKeyPem),
+        {
+            name: 'RSA-OAEP',
+            hash: 'SHA-256',
+        },
+        false,
+        ['encrypt']
+    );
+    const ciphertext = await window.crypto.subtle.encrypt({ name: 'RSA-OAEP' }, publicKey, encoded);
+    return {
+        keyId: keyInfo.keyId,
+        ciphertext: bytesToBase64(new Uint8Array(ciphertext)),
+    };
+};