Practice question · Multiple choice
RSA encryption relies on multiplying two large primes being easy while factoring the product is hard. Why is that asymmetry the whole security model?
Hints
- Ask what you need to encrypt a message, and what you need to read one.
- The product is published deliberately. Why is that safe?
Show the answer
B. Because the public key is the product and the private key the factors
Why
The product is public and the factors are the secret, so a one-way gap becomes an asymmetry between sending and reading. Option 4 overstates it dangerously: factoring is not proved hard, merely not known to be easy, and Shor's algorithm factors efficiently on a quantum computer, which is why post-quantum cryptography exists.
Practise Primes and the Fundamental Theorem of Arithmetic
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