Plaintext Definition

Plaintext is a term used in cryptography that refers to a message before encryption or after decryption. That is, it is a message in a form that is easily readable by humans.

Encryption is the process of obscuring messages to make them unreadable in the absence special knowledge. It is usually done for secrecy, and typically for confidential communications. It can also be used for authentication (i.e., the process of confirming the identity of an individual or a transmission). Decryption is the opposite, i.e., the conversion of encrypted data into plaintext. Ciphertext is a message after encryption or before decryption.

Plaintext should not be confused with plain text. The latter refers to text consisting entirely of characters (e.g., those of an alphabet) that are used in some written human language, as contrasted with sequences of bits that do not represent human readable characters. Plaintext is written in plain text.

Plain text can consist of plaintext and/or ciphertext. Plaintext, because it consists of human-readable characters, is a type of plain text. Ciphertext can be written as plain text or in any other form.

Cleartext refers to a message or other data that is transferred or stored without cryptographic protection. Cleartext material can be in plain text form, or it can be stored in some binary file (i.e., non-plain text) format, such as those produced by word processing programs (e.g., OpenOffice or Microsoft Word).

Plaintext is encrypted into ciphertext using a cipher algorithm. An algorithm is a set of precise and unambiguous rules that specify how to solve some problem or perform some task. Examples of plaintext information that is usually encrypted prior to transmission over a network are financial transactions and diplomatic messages.

Created February 19, 2006.
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