Cryptographic Keys and Decks of Cards

The previous post looked at the idea of storing a cryptographic key in the order of a deck of cards. A deck of 52 cards can store 225 bits of data because ⌊log2(52!)⌋ = 225. Here ⌊x⌋ is x rounded down to the nearest integer. If we want to store bigger keys, we’re going to need a bigger deck of cards. Bitcoin A Bitcoin key has 256 bits, which would require a deck of 58 cards. There is a card game called Zwicker that uses a deck of 58 cards, the usual 52 cards plus six jokers. So you could store a Bitcoin key in the permutation of a Zwicker deck. RSA RSA key sizes vary, but 2048 and 3072 are common. A 2048-bit key would require a deck of 301 cards. Casinos often use a shoe of 312 cards, combining six decks of 52 cards, to deal Baccarat or Blackjack. However, casinos combine identical decks. If you were to combine six unique decks, you could store a 2048-bit key. Storing a 3072-bit key would require a deck of 422 cards. You could make a deck of 432 cards by combining 8 distinguishable…