EntityQ829915· pop 26· linked from 91 articlesPlayfair cipherSign in to saveearly block substitution cipherConnectionsencryptionEntitysymmetric-key algorithmEntityWilliam Frederick FriedmanEntitycodeEntitytwo-square cipherEntitySecure channelEntityJoseph MauborgneEntityoutline of cryptographyEntityNew ZealandCountryWorld War IIConceptWorld War IConceptInternational Standard Book NumberEntitycryptocurrencyEntitycryptographyEntitydigital object identifierEntityThe TimesEntitytelegraphyEntityChatham IslandsEntityJ. J. AbramsEntitySecond Boer WarEntityCategoriesClassical ciphersEnglish inventions