public CryptoBox(byte[] data, byte[] K) throws IOException { curveType = 0x02CA; // 1. The destination public key is called K. // 2. Generate 16 random bytes using a secure random number generator. Call them IV. initializationVector = cryptography().randomBytes(16); // 3. Generate a new random EC key pair with private key called r and public key called R. byte[] r = cryptography().randomBytes(PRIVATE_KEY_SIZE); R = cryptography().createPublicKey(r); // 4. Do an EC point multiply with public key K and private key r. This gives you public key P. byte[] P = cryptography().multiply(K, r); byte[] X = Points.getX(P); // 5. Use the X component of public key P and calculate the SHA512 hash H. byte[] H = cryptography().sha512(X); // 6. The first 32 bytes of H are called key_e and the last 32 bytes are called key_m. byte[] key_e = Arrays.copyOfRange(H, 0, 32); byte[] key_m = Arrays.copyOfRange(H, 32, 64); // 7. Pad the input text to a multiple of 16 bytes, in accordance to PKCS7. // 8. Encrypt the data with AES-256-CBC, using IV as initialization vector, key_e as encryption key and the padded input text as payload. Call the output cipher text. encrypted = cryptography().crypt(true, data, key_e, initializationVector); // 9. Calculate a 32 byte MAC with HMACSHA256, using key_m as salt and IV + R + cipher text as data. Call the output MAC. mac = calculateMac(key_m); // The resulting data is: IV + R + cipher text + MAC }