We recently had a rainy weekend interrupt our original plans to go geocaching. Instead, I took inspiration from John Baichtel's recent posting - Codes For Kids - to introduce my kids to ciphers.
In 1854, Sir Charles Wheatstone invented the cipher known as "Playfair," named for his friend Lyon Playfair, first Baron Playfair of St. Andrews, who popularized and promoted the cipher. Its ...
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