Q13Information System Security
Question
4 marks
What are the differences between symmetric and asymmetric key cryptography?
Answer
A definitive architectural comparison between Symmetric and Asymmetric Cryptography. Violently contrasts the explosive processing speed of single-key systems against the massive key-distribution superiority of public/private key pairs.
The entire field of cryptographic architecture is mathematically divided into two absolute paradigms based strictly on how cryptographic keys are managed and applied to plaintext.
Also known as Secret-Key Cryptography (e.g., AES, DES).
- Mechanism: It utilizes exactly ONE absolute mathematical key to both violently encrypt the plaintext and decrypt the ciphertext.
- Merit (Speed): The mathematical operations (like XOR and bit-shifting) are incredibly simple. It is explosively fast, capable of encrypting 10 Gigabytes of video data in seconds.
- Demerit (Key Distribution): A catastrophic architectural flaw. If Alice wants to talk to Bob, she must physically or securely hand Bob the single secret key. If a hacker intercepts the key during transit, the entire system is destroyed. Furthermore, a network of 1000 users requires 499,500 unique keys to communicate securely.
Also known as Public-Key Cryptography (e.g., RSA, Elliptic Curve).
- Mechanism: It utilizes a mathematically linked PAIR of keys. A Public Key (shared with the entire world) used exclusively to Encrypt. A highly guarded Private Key used exclusively to Decrypt.
- Merit (Key Distribution): It completely annihilates the key-distribution crisis. Alice simply broadcasts her Public Key on the internet. Anyone can encrypt a message to her, but ONLY Alice can mathematically decrypt it.
- Demerit (Speed): The mathematics involve massive prime number modular exponentiation. It is catastrophically slow—up to 1,000 times slower than AES. Therefore, it is never used to encrypt massive files; it is only used to encrypt small symmetric session keys.