What is "cryptography"

Cryptography (from the Greek kryptós, "hidden", and gravy, "written") is the study of the principles and techniques by which information can be transformed from its original form to another illegible, so that it can be known only to its recipient (holder of the "secret key"), which makes it difficult for an unauthorized person to read.

The term is commonly used to refer to the area of study comprehensively, such as cryptology ("the study of secrets"). Other related terms are: Cryptanalysis, Steganography, Esteganalysis, Code, and Cryptology.

Use this tag in questions about:

  • The transformation of the information in its original form into an illegible form, except by(s) the holder(s) of a second confidential information, called key. Also called or .

  • The creation of a fixed-size string from an arbitrary set of data, in an irreversible process, in order to ensure its integrity. Known as scattering or .

    • The use of a hash for the purpose of protecting access passwords in a permanent storage ("hashing password").
    • The creation of a hash from a secret key, with the purpose of ensuring the authenticity of an information and in some cases its irretractability. Also known as MAC (Message Authentication Code - "Message Authentication Code"). In the context of public key encryption, it can be called.

  • The act of hiding secret information inside other seemingly innocuous information. Known as .

Do not use this tag in questions about:

  • Information security in general. If your question does not refer to the use of cryptographic systems, but rather to the security of general systems (e.g., server security, network security, etc.) use the tag instead of this.