A Public Key Cryptography Story

secret_love_message.py

from Crypto.PublicKey import RSA

# Ross created a public-private key pair himself
ross_key = RSA.generate(2048)
# He seperated his public key from the pair
ross_pubkey = ross_key.publickey()

# A key pair for Rachel, NORMALY THIS MUST BE CREATED BY HER!
rachel_key = RSA.generate(2048)
# Rachel's public key
rachel_pubkey = rachel_key.publickey()

# We will assume Ross only knows "rachel_pubkey", he does not know "rachel_key" (Rachel's Key Pair)
# Because "rachel_key" object has the private key information, you can confirm it like this;
# rachel_key.has_private()    --> True
# rachel_pubkey.has_private() --> False

# Ross's message
message = "I love you Rachel!"

# He encrypts it with Rachel's public key
encrypted_message = rachel_pubkey.encrypt(message, '')
print "How everybody sees the message: ", encrypted_message

# Rachel can decrypt the message using her private key, 
# Remember: "rachel_key" object has the private key information
decrypted_message = rachel_key.decrypt(encrypted_message)
print "How Rachel sees the message: ", decrypted_message