Cracking Codes with Python

23GENERATING KEYS FOR THE PUBLIC KEY CIPHER

“Use deliberately compromised cryptography, that has a back door that only the ‘good guys’ are supposed to have the keys to, and you have effectively no security. You might as well skywrite it as encrypt it with pre-broken, sabotaged encryption.”—Cory Doctorow, science fiction author, 2015

All the ciphers you’ve learned about in this book so far have one feature in common: the encryption key is the same as the decryption key. This leads to a tricky problem: how do you share encrypted messages with someone you’ve never talked to before? Any eavesdroppers would be able to intercept an encryption key you ...