Question

Explain the process of Asymmetric Encryption using public and private keys.

Hint:

{Public Key = Lock (shared with everyone)}
{Private Key = Key (kept secret)}
Encrypt with public key, decrypt with private key.

Answer 1

Concept: Asymmetric encryption, also known as public-key cryptography, is a method of secure communication that uses two mathematically related keys: a public key and a private key. Unlike symmetric encryption, the keys are not identical, which enhances security and enables secure data exchange over insecure networks. Step 1: {\color{red}Key Pair Generation}
A user generates two keys:

• Public Key — shared openly with others
• Private Key — kept secret by the owner

These keys are mathematically linked such that data encrypted with one can only be decrypted with the other.
Step 2: {\color{red}Encryption Using Public Key}
When a sender wants to send a secure message:

• The sender obtains the receiver’s public key
• The message is encrypted using this public key

Once encrypted, the message becomes unreadable to anyone without the corresponding private key.
Step 3: {\color{red}Transmission Over Insecure Channel}
The encrypted data can be safely transmitted over insecure networks such as the internet because:

• The public key does not reveal the private key
• Even if intercepted, the message remains secure

Step 4: {\color{red}Decryption Using Private Key}
Upon receiving the encrypted message:

• The receiver uses their private key
• The original plaintext message is recovered

Only the private key holder can decrypt the message, ensuring confidentiality. Step 5: {\color{red}Additional Use — Digital Signatures}
Asymmetric encryption can also provide authentication:

• A sender can encrypt a hash with their private key (digital signature)
• Anyone can verify it using the sender’s public key