In cryptography, key management includes all of the provisions made in a cryptosystem design, in cryptographic protocols in that design, in user procedures, and so on, which are related to generation, exchange, storage, safeguarding, use, vetting, and replacement of keys. There is a distinction between key management, which concerns keys at the users' level (ie, passed between systems or users or both), and key scheduling which is usually taken to apply to the handling of key material within the operation of a cipher. See also: Topics in cryptography The security of all practical encryption schemes remains unproven, both for symmetric and asymmetric schemes. ... A cryptosystem (or cryptographic system) is the package of all procedures, protocols, cryptographic algorithms and instructions used for encoding and decoding messages using cryptography. ... A cryptographic protocol is an abstract or concrete protocol that performs a security-related function and applies cryptographic methods. ... A key is a piece of information that controls the operation of a cryptography algorithm. ... The key-schedule of DES In cryptography, the algorithm for computing the subkeys for each round in a product cipher from the encryption (or decryption) key is called the key schedule. ... This article is about algorithms for encryption and decryption. ...

Appropriate and successful key management is critical to the secure use of every crypto system without exception. It is, in actual practice, the most difficult aspect of cryptography generally, for it involves system policy, user training, organizational and departmental interactions in many cases, coordination between end users, etc. See also: Topics in cryptography The security of all practical encryption schemes remains unproven, both for symmetric and asymmetric schemes. ...

Many of these concerns are not limited to cryptographic engineering and so are outside a strictly cryptographic brief, though of critical importance. As a result, some aspects of key management fall between two stools as the cryptographers may assume this or that aspect is the responsibility of the using department or upper management or some such, while said department or upper management regard it all as being outside their concerns because 'technical', and so within the purview of the cryptographers. This article is an overview of cryptographic engineering which notes at least some of the differences between ordinary engineering and the cryptographic sort. ...

See also:

• NSA's Electronic Key Management System (EKMS)
• List of cryptographic key types