The Encryption Process
Confidentiality, integrity, authenticity. Formal E/D definitions, threat models, CIA mapping.
Open → 02Cryptographic Primitives
Encryption, hash, MAC, signatures. Birthday bound, HMAC formula, 6-step signing flow.
Open → 03Kerckhoffs's Principle
"The enemy knows the system." Shannon's maxim, open design, historic failures.
Open →Simple Substitution
Monoalphabetic permutation, 26! keyspace, full frequency-analysis walkthrough.
Open → 05Vigenère Cipher
Polyalphabetic shifts, worked LEMON example, Kasiski + Friedman key-length math.
Open → 06Playfair Cipher
5×5 digraph matrix, 3 rules + decryption, full HELLO trace.
Open →AES — Full Round Math
FIPS-197 vector, SubBytes→ShiftRows→MixColumns→AddRoundKey + GF(2⁸), S-box, full structure.
Open → 07BAES Round 1 Every Step
S-box coordinates, ShiftRows map, MixColumns binary + intermediates, AddRoundKey per byte.
Open → 08DES / Feistel
Feistel proof, F-function, E/P tables, shift table, full K1 from 133457799BBCDFF1.
Open → 08BDES Key Expansion Every Bit
PC-1 pick-by-pick, shifts every round, PC-2 pick-by-pick to K₁ + all K₁–K₁₆.
Open →RSA — The Math
Keygen, Euclid for d, square-and-multiply traces, padding & attacks.
Open → 10Diffie-Hellman
Shared secret without sending it, exponentiation trace, discrete-log hardness.
Open → 11Man-in-the-Middle
Why anonymous DH falls, K1 vs K2 algebra, STS/TLS fixes.
Open →SPS Protocol
Customer/Merchant/PG dual envelope, sequence diagram, property table.
Open → 13Access Control Models
DAC/MAC/RBAC/ABAC, Bell–LaPadula, Biba, decision logic.
Open → 14ABAC
Attribute policies, XACML PEP/PDP/PIP/PAP flow, combining rules.
Open →