John D. Cook • 7/28/2026

Cryptographic Keys and Decks of Cards

This article examines the concept of encoding cryptographic keys through the permutation order of playing cards, building on the fact that a 52-card deck can store 225 bits. It calculates the deck sizes needed for various key types: 58 cards for a 256-bit Bitcoin key (using a Zwicker deck), 301 cards for a 2048-bit RSA key (casino shoe of six unique decks), 422 cards for 3072-bit RSA, and 1442 cards for ML-KEM-512 (post-quantum). The piece highlights the challenge of larger key sizes in post-quantum cryptography and includes Python verification code.

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#Bitcoin #Rsa #Cryptographic Keys