Final answer:
The primary problem of symmetric cryptography is key management, which involves securely exchanging and updating keys between the sender and receiver. This becomes challenging in large-scale systems where multiple users need to share secret keys.
Step-by-step explanation:
The primary problem of symmetric cryptography is key management. In symmetric cryptography, the same key is used for both encryption and decryption of data. This means that the sender and the receiver must somehow exchange the same key securely in order to ensure the confidentiality of the communication. Key management becomes a challenge, especially in large-scale systems where multiple users need to share secret keys.
For example, in a network where multiple users want to communicate securely using symmetric cryptography, each pair of users would need their own unique key. This can quickly become unmanageable as the number of users increases, making it difficult to securely distribute and update all the necessary keys.
Therefore, key management is the primary problem of symmetric cryptography.