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Previously you learned about asymmetric key algorithms and you should understand that asymmetric encryption requires two keys: public and private. As a review, using the flashcards define asymmetric key encryption, public key, private key, and digital certificate. Then read the section on asymmetric encryption.
Unlike symmetric encryption methods, asymmetric encryption methods use two separate keys for the encryption and decryption process. Asymmetric encryption is also referred to as public key encryption. A public key is used during the encryption process to encrypt the plaintext message and a private key is used during the decryption process to decrypt ciphertext.
| Advantages | Disadvantages |
|---|---|
| Easier to deal with key distribution and ensure integrity of message | Slower due to multiple keys |
Watch the video, Encryption Part I: Introduction to Encryption 2 (6:23) which discusses asymmetric encryption and hashing.
If Alice wants to send a message that only Bob can read, Alice will use Bob's public key to encrypt the message. The only way the message can be decrypted is when Bob uses his private key.
Figure 2 – Asymmetric encryption
The most popular asymmetric algorithm is RSA which can provide key exchange, encryption, and digital signatures. The strength of this algorithm lies in the difficulty of calculating the prime factors of very large numbers. Other asymmetric algorithms include ElGamal, ECC, and Knapsack. Read the article, Asymmetric Encryption Algorithms, Diffie-Hellman, RSA, ECC, ElGamal, DSA, for a comparison of these algorithms.