Cryptology and Public-Key Encryption

Cryptology

• Cryptology is the study of encryption and cryptanalysis together.
• It involves the process of converting from plaintext to ciphertext.

Public-Key Encryption Scheme

• A public-key encryption scheme is vulnerable to a brute-force attack.

Key Size for Public-Key Method

• For practical encryption and decryption in the public-key method, the key size should be large enough.

Types of Attacks

• In the ciphertext-only attack, the cryptanalyst must know the encryption algorithm.
• In brute-force attacks, on average, half of the possible keys must be tried to achieve results.
• Cryptanalysis attacks exploit the characteristics of the algorithm to attempt to deduce a specific plaintext or to deduce the key being used.

Symmetric Cipher System

• Diffie-Hellman and DSS are not examples of symmetric cipher systems.
• DES is an example of a symmetric cipher system.

Symmetric Key Cryptography

• In symmetric key cryptography, both parties must possess a secret key.

Asymmetric Cipher System

• In an asymmetric cipher system, it is computationally infeasible for an adversary, knowing the public key, to determine the private key.

Secure Use of Private Key Encryption

• One requirement for the secure use of private key encryption is that the encryption algorithm should be strong.
• The pair of keys should be computationally hard to discover.