What is the primary weakness of symmetric-key encryption?

The primary weakness of symmetric-key encryption lies in the challenge of securely distributing the keys. In symmetric-key encryption, both the sender and the receiver use the same key for both encryption and decryption. This means that the key must be shared between parties before secure communication can occur. If the key is intercepted or compromised during this process, the entire security of the encryption is undermined, since anyone with the key can decrypt the data.

This vulnerability is particularly significant in scenarios where multiple users need access to the key or in larger networks where securely exchanging keys can become complicated. Unlike asymmetric encryption, which uses a pair of keys (one public and one private) to mitigate this issue, symmetric encryption relies on the secure management of a single shared key. Therefore, the difficulty in distributing keys securely is a critical weakness that organizations must address to maintain secure communications.