dsp-blockchain/gui/encyption.py

from codecs import encode
import rsa
from create_keys import get_keys, get_private_key, get_symmetric_key
from cryptography.fernet import Fernet
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import hashes, serialization
from cryptography.hazmat.primitives.asymmetric import padding

# encrypt blockstring with name from contract
def encrypt_data(contract, block_string): 

    # create symmetric key for transaction and retrieve pubkey from contract
    symmetric_key = get_symmetric_key(contract)
    pubkey = get_keys(contract)

    # create chiper and encrypt data using symmetric key
    chiper = Fernet(symmetric_key)
    data = str(chiper.encrypt(block_string))[2:-1]

    # encrypt semmetric key with pubkey and cast to string
    encrypted_key = str(rsa.encrypt(symmetric_key,pubkey))[2:-1]
    return data, encrypted_key

# decrypt t form contract name
def decrypt_data(name, t):

    # retrieve private key
    private_key = get_private_key(name)

    # decript symmetric key
    en_key = encode(t.encrypted_key.encode().decode('unicode_escape'),"raw_unicode_escape")
    key = rsa.decrypt(en_key, private_key)

    # decrypt data with decrypted semmetric key
    cipher = Fernet(key)
    decrypted_data = cipher.decrypt(bytes(t.data, 'utf-8'))

    # decode and retrun data
    return decrypted_data.decode('utf8').replace("'", '"')