CompTIA: Advanced Security Practitioner (CASP) Exam Prep

Answer: D - Symmetrical key encryptions are single-key systems that are entirely dependent on the privacy of the key.

Key Takeaway: Symmetric-key algorithms are a class of algorithms for cryptography that use trivially-related, often identical, cryptographic keys for both decryption and encryption. The encryption key is trivially related to the decryption key in that they may be identical or there may be a simple transformation to go between the two keys. In practice, the keys represent a shared secret between two or more parties that can be used to maintain a private information link.