Which cryptographic system employs a pair of keys, one enabling encryption and the other enabling decryption, often used for secure data transmission?

• A. RSA Cryptosystem
• B. AES
• C. DES
• D. ElGamal

Answer: (A)

Public-key cryptography relies on a pair of keys: one used to encrypt and a different one used to decrypt. This arrangement lets anyone send you a secured message by encrypting with your public key, while only you can read it with your private key. Among the options, RSA cryptosystem is the classic and widely adopted example of such a system, designed so encryption and decryption use separate keys, enabling secure data transmission over networks like the internet. In contrast, AES and DES are symmetric ciphers that use the same key for both directions, so they don’t fit the description. ElGamal is another public-key scheme, but RSA is the most commonly used standard for securing data in transit today, which is why it fits best.