1. Cryptography, for Fun and Profit

2. Synopsis What is Cryptography? Some simple cryptographic systems and a modern application. An unbreakable cipher. Some modern algorithms (survey) Practical use of cryptography Some uses of cryptography.

3. What is Cryptography?

4. Worst case conditions. The cryptanalyst has complete knowledge of the cipher system The cryptanalyst has a considerable amount of ciphertext The cryptanalyst knows the plaintext equivalent of a certain amount of some ciphertext.

5. Some simple cryptographic systems and a modern application. Caesar cipher. A modern application: rot13. Vigenere ciphers Scrambling/transposition Steganography Main concept: modular arithmetic

6. An unbreakable cipher. One-time-pad Perfect secrecy

7. Some modern algorithms (survey) Bit strings Blocks DES AES Diffie-Hellman RSA

8. Practical use of cryptography Be realistic

9. Some uses of Cryptography Confidentiality Integrity Entity authentication Source authentication Non-repudiation Certification Authorities Data safeguarding and hijacking.