Page 52 - DCAP516_COMPUTER_SECURITY

Computer Security

Notes RSA algorithm was discovered by three researchers—Rivest, Shamir, Adleman—at MIT.
This method is based on some principles from number theory.

4.8 Keywords

Ciphertext: This is the encrypted message generated by applying the algorithm to the plaintext
message using the secret key.
Decryption: It is the reverse process of converting encoded data to its original un-encoded form,
plaintext.
Encryption: It is a process of coding information which could either be a file or mail message in
into cipher text a form unreadable without a decoding key in order to prevent anyone except the
intended recipient from reading that data.
Plaintext: It is the text message to be transmitted on which an algorithm is applied.
Private Key: The key of a key pair, which is used to create a digital signature. It can be used to
sign a message that only the corresponding public key can verify.
Public Key: It is the key of a key pair that is used to verify a digital signature. Key pair consists
of private and public key.
Secret Key: They constitute a part of algorithm for encryption and decryption of the message.

4.9 Review Questions

1. Define the following:
(a) Crypatanalysis

(b) Cryptology
(c) Cipher
(d) Null cipher

(e) Substitution cipher
(f) Transposition cipher
2. How do you determine the authenticity of the documents? Explain with the help of a
diagram.
3. What is DES? What are its limitations?
4. Explain the uses of encryption.
5. What do you understand by AES algorithm? Explain in detail.
6. What is public key encryption? How many keys are used in such type of encryption.

Answers: Self Assessment

1. cryptograph 2. cryptanalysis
3. cryptology 4. two
5. substitution 6. Transposition
7. True 8. False

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