Answer:
The pitfall that is NOT associated with encryption is "Implementing a reliable and proven cryptography." This is actually a positive aspect of encryption, as using reliable and proven cryptographic algorithms and protocols enhances security.
The other options are all pitfalls:
1. Relying on algorithms being secret: Security through obscurity is generally considered a pitfall because it relies on the secrecy of the algorithm rather than its strength.
2. Missing encryption of data and communications: Not encrypting data or communications when it's necessary can lead to security breaches.
3. Using hardcoded/predictable weak keys: Weak keys can easily be guessed or brute-forced, compromising the security of the encryption.
Hope this helps :)