From CryptoDox, The Online Encyclopedia on Cryptography and Information Security
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 (i.e., 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.
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.
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.