Implementing-cryptography-using-python

Chapter 9 ■ Mastering Cryptography Using Python 259
fd = open("client_public_key.pem", "wb")
fd.write(public_key)
fd.close()
# decrypt using RSA
def decrypt_rsa(ciphertext):
key = RSA.importKey(open('client_private_key.pem').read())
cipher = PKCS1_OAEP.new(key)
plaintext = cipher.decrypt(ciphertext)
return plaintext
# encrypt using RSA
def encrypt_rsa(message):
key = RSA.importKey(open('client_public_key.pem').read())
cipher = PKCS1_OAEP.new(key)
ciphertext = cipher.encrypt(message)
plaintext = decrypt_rsa(ciphertext)
return ciphertext
# check client commands
def check_client_command(data):
if data == b'addPKI':
gen_rsa_certs()
return 11
elif data == b'removePKI':
usePKI = False
return 10
return 1
# check server commands
def check_server_command(data):
if data == b'addPKI':
return 11
if data == b'removePKI':
useDH = False
return 10
return 1
Execution
The execution of the PKI solution will appear to work just as the original version
did. Once you type addPKI, the client sends the message to the server unencrypted
and then modifies the data to state “PKI Encryption enabled!” This
should pop up in the command window for the server, as shown in Figure 9.5.