README

Password transmission exists in various scenarios. For example, when formatting the hard disk, enter the current password for secondary authentication, set user password, set email password, etc.

(1) The procedure for the client to use the PBKDF2_SHA256 encrypted password for secondary authentication is: salt = base64_decode(key); outlen = 32; enc = PBKDF2(salt, pwd, iter, outlen); --------> openssl PKCS5_PBKDF2_HMAC , and EVP_sha256() cipher = base64_encode(enc);

(2) The client adopts X25519 to encrypt and transmit the password process as follows: Encryption Algorithm: aes_256_gcm The source of Key and iv: the secret is calculated through X25519, and then the key and iv are obtained through hkdf expand

    evp_pkey = (my_pri, my_pub) = generate_X25519_key;
    key_1 = remove "0" from key;
    device_peer_key = base64_decode(key_1);
    secret = X25519_derive(device_peer_key, evp_pkey);
    aes_256_gcm_key = hkdf_expand(secret, label = "expand key", out_len = 16);
    aes_256_gcm_iv = hkdf_expand(secret, label = "expand iv", out_len = 12);

Output:

peer_key = "0" + base64(EVP_PKEY_get_raw_public_key (evp_pkey))  //Here is passing your own public key to the device.
cipher = base64( aes_256_gcm(password, key, iv) + aes_256_gcm_iv + tag )
// tag_len = 16, key_len = 16, iv_len = 12

The following is the web page for calculating cipher provided by us:

1. Calculate the cipher for the secondary authentication pbkdf2.html
2. Calculate the cipher of the password encrypted field x25519.html These pages are to assist you to judge whether the cipher calculation is correct.

Gadget Instructions:

1. pbkdf2.html
Open the widget webpage, input word, salt, and iter values in sequence, and click commit to start running. Among them, word is the password to be encrypted, salt is the random string used to disturb the real password, and iter is the number of iterations. The final result of the operation will be printed in result, and the encrypted value is the calculated ciphertext.
2. x25519.html
Open the widget webpage, input the values of word and peer public in turn, and click commit to start running. Among them, word is the password to be encrypted, and peer public is the public key obtained from nvr. The final result of the run will be printed in result. In encrypted, the value of public is the public key generated by the client, which will be sent to nvr for decryption, and the value of encrypted is the calculated ciphertext.

See Appendixes A.2 for development guidelines for specific scenarios of secondary authentication
See Appendixes A.3 for the development guide of specific scenarios of password encryption