8 References

#peer_kpub is 32 bytes

#self_kpri is 32 bytes

#secret is 30 bytes

secret = ecdh(peer_kpub, self_Kpvt)

#Sample python code from openssi

#Salt is random number that is read from gauge

#length is 16 bytes for AES-128

#iterations is 128

#key is AES-128 key

from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2HMAC
kdf = PBKDF2HMAC(
    aglorithm = hashes.SHA256( ), 
    length = 16,
    salt=bytes(salt),
    iterations = 128,
    backed=backend
)
aeskey = bytearray(kdf.derive(bytes(secret)))

#iv is read from gauge

Encrypted ProdKpvt CProdKpve is 32 bytes

from Crypto.Cipher import AES
cipher = AES.new(aeskey, AES.MODE_CTR, nonce=bytes(iv[0:8]), initial_value=bytes(iv[8:16]))
    CProdKpvt = cipher.encrypt(ProdKpvt)