No definition in earlier IP projects. ITrust definition not yet developed.
- Diffie & Landau 2007 (†848 p.13): a transformation of a message that makes the message incomprehensible to anyone who is not in possession of secret information that is needed to restore the message to its normal plaintext or cleartext form.
- de Leeuw et al. (eds) 2007 (†850 p.567): The basic idea in cryptography is to apply a complex transformation to the information to be protected. (†2379)
- DuPont 2016 (†854 p.294): Cryptography is a complex phenomenon that shifts in composition and use across history, but is essentially notational symbols that are activated through encryption, to produce ciphertext. Usually (but not always), cryptography refers to a process of establishing and maintaining secrecy (†2382)
- Kahn 1967 (†849 n.p.): cryptography, on the other hand, do not conceal the presence of a secret message but render it unintelligible to outsiders by various transformations of the plaintext. (†2378)
- Shannon 1945 (†851 p.657): A secrecy system is defined abstractly as a set of transformations of one space (the set of possible messages) into a second space (the set of possible cryptograms). Each particular transformation of the set corresponds to enciphering with a particular key. The transformations are supposed reversible (non-singular) so that unique deciphering is possible when the key is known. (†2381)