Lecture "On safety and security of information systems: Asymmetric ciphers" provide students with knowledge about: principles of public-Key cryptosystems; RSA algorithm; . Please refer to the detailed content of the lecture! | ASYMMETRIC CIPHERS Contents 1 Principles Of Public-Key Cryptosystems 2 RSA Algorithm 1. Principles Of Public-Key Cryptosystems 1. Principles Of Public-Key Cryptosystems Commonly know as public key cryptography Invented by Whitfield Diffie and Martin Hellman in 1976 Uses a pair of key A private key that is kept secret A public key that can be sent to anyone Public-Key Cryptosystems Asymmetric algorithms rely on one key for encryption and a different but related key for decryption. These algorithms have the following important characteristic. It is computationally infeasible to determine the decryption key given only knowledge of the cryptographic algorithm and the encryption key. Either of the two related keys can be used for encryption with the other used for decryption. Encryption with public key Encryption with private key Authentication and confidentiality possible to provide both the authentication function and confidentiality by a double use of the public-key. Z E PUb E PRa X X D PUa D PRb Z Applications for Public-Key Cryptosystems Encryption decryption The sender encrypts a message with the recipient s public key. Digital signature The sender signs a message with its private key. Key exchange Two sides cooperate to exchange a session key. Requirements for Public-Key Cryptography It is computationally easy for a party B to generate a pair. It is computationally easy for a sender A knowing the public key and the message to be encrypted M to generate the corresponding ciphertext. C E PUb M It is computationally easy for the receiver B to decrypt the resulting ciphertext using the private key to recover the original message Requirements for Public-Key Cryptography It is computationally infeasible for an adversary knowing the public key PUb to determine the private key PRb. It is computationally infeasible for an adversary knowing the public key PUb and a ciphertext C to recover the original message M. 2. RSA ALGORITHM RSA Algorithm Developed in 1977 by Ron .
