/**
 * Web Crypto API implementation of the SDK crypto functions.
 * This is Edge Runtime compatible (works in browsers, Cloudflare Workers, Vercel Edge, etc.)
 *
 * These functions mirror the Node.js crypto implementations in ./crypto.ts
 */
/**
 * Generates a 128-bit key from the API key using HMAC SHA-256.
 * Returns the first half (128 bits) of the HMAC digest as a hex string.
 *
 * This mirrors the Node.js implementation:
 *   crypto.createHmac('sha256', apiKey).digest('hex').slice(0, 32)
 *
 * Note: The Node.js version HMACs an empty message with apiKey as the secret.
 *
 * @param apiKey The API key to derive the encryption key from
 * @returns Promise<string> A 32-character hex string (128 bits)
 */
export declare function generate128BitKey(apiKey: string): Promise<string>;
/**
 * Decrypts an AES-128-CBC encrypted token.
 *
 * The encrypted message format (from the Go backend):
 * - First 16 bytes: IV (Initialization Vector)
 * - Remaining bytes: Ciphertext (PKCS7 padded)
 *
 * @param key A 32-character hex string (128-bit key from generate128BitKey)
 * @param encryptedMessage Hex-encoded encrypted message (IV + ciphertext)
 * @returns Promise<string> The decrypted plaintext
 */
export declare function decryptAES128BitToken(
  key: string,
  encryptedMessage: string,
): Promise<string>;