Card Hiding Game: Perfect Secrecy Through Shuffling
Bob must hide a selected card from Eve using only locks, boxes, and a deck of cards, with all materials remaining in the room, creating a game that illustrates perfect secrecy principles.
One-Time Pad Key Length Limitation Problem
Perfect secrecy’s requirement for long random keys matching message length creates the fundamental practical limitation forcing cryptographers to develop pseudorandom alternatives.
Message, Key, and Ciphertext Space Equality
Shannon’s framework conceptualizes encryption through three equal-sized spaces: all possible messages, all possible keys, and all possible ciphertexts, with perfect secrecy emerging when these spaces have identical size.
Perfect Secrecy: Security Against Unlimited Computation
Claude Shannon defined perfect secrecy as a security property where adversaries with unlimited computational power cannot improve beyond blind guessing when attempting to determine encrypted content from ciphertext alone.
Shannon's 1945 Mathematical Proof of Perfect Secrecy
Twenty-nine-year-old Claude Shannon published a classified paper on September 1, 1945, providing the first rigorous mathematical proof explaining how and why the one-time pad achieves perfect secrecy.
Uniform Message Probability from Ciphertext Observation
Perfect secrecy guarantees that eavesdroppers observing ciphertext alone find every possible plaintext message equally likely, preventing any statistical advantage in guessing attempts.