Key Management

Abstract

Managing cryptographic keys is one of the most difficult parts of a cryptographic system. It is particularly difficult if only symmetric key cryptography is available. The advent of asymmetric key cryptography greatly simplified key management and makes it much more secure. Public Key Infrastructure addresses only management of public keys. Private keys must be managed and protected with other mechanisms. A particularly thorny issue is providing escrow of private keys (in the event of a key being lost or the key owner leaving the organization). This can easily be abused by the cryptographic system owner (or the government). Some systems, such as TLS and S/MIME, provide very secure mechanisms for exchange of a symmetric session key (one used only for a single session). With S/MIME it is important to provide a central shared address book with all participant’s digital certificates, since anyone sending an encrypted message must have the recipient’s certificate at the time they send the message.