The selection and use of safety/security measures are typically based on an evaluation of the threats and - not the least - legal implications. This may result in the implementation of various safety measures, which are all independent of the UN/EDIFACT message structure, but nevertheless may contribute to the legal confidence arising from the records.
Trading partners utilizing UN/EDIFACT may select among a variety of security procedures and services, some of which are available within UN/EDIFACT and others which are generally available.
Security Services in UN/EDIFACT. Trading partners may elect security services which consist of some of the security services available within UN/EDIFACT, as listed below, in order to meet the legal requirements or thwart the identified threats. Each of these security services requires the use of cryptographic techniques. Thus any message (which is nothing but a sequence of digits) transferred from one computer to another can be protected by calculating digital mathematical functions (known as cryptographic techniques) on the message, before and after the transmission. This provides the tools to detect any unintended change not only during transit, but also during storage at either end, thus achieving the desired security service.
The UN/EDIFACT documents identified in the listing following this Technical Annex Checklist include specific materials explaining the security services and key management techniques mentioned below in detail, and should be consulted by a user searching for information.
Message content integrity protects against the modification of data in a message of any kind. This may further be extended to message sequence integrity, which establishes the order in which the messages appeared. Message integrity in itself is typically not achieved unless some key is involved to generate what is known as a Message Authentication Code (MAC). This is a cryptographic fingerprint of the message, which is created by means of a secret key. Normally, anyone in possession of that secret key may generate the MAC-value, unless specially protected hardware is used.
If there is a further need to distinguish between the sender of the message and the recipient (e.g. for legal purposes), the correct security service to apply is non-repudiation of origin, which requires appending time stamps for timeliness and subsequently the calculation of digital signatures based on public key algorithms.
Thus non-repudiation of origin implies message authentication, which in turn implies message integrity.
Corresponding to non-repudiation of origin, the recipient may return a message, secured by a digital signature, which provides non-repudiation of receipt. Of a different nature is the service confidentiality, which protects against disclosure of the content of a message during transit over some network.
UN/EDIFACT security is concerned with the protection of the EDIFACT messages only, and not the internal security related to the end-user applications, where the messages are being generated or processed. In conclusion, the use of security in UN/EDIFACT requires the use of cryptographic techniques, which in turn require the use of cryptographic keys. Thus key management is implied by the use of security in UN/EDIFACT.
For all security purposes, keys (which in fact are large numbers) must be treated with care. Algorithms are in general public knowledge, and only give the desired security if combined with keys. The users may have a common key which is used for cryptographic purposes, or they may each have a pair of matching keys (one private and one public key). Common to all systems are that keys must be distributed in a secure manner. This may either be handled on a bilateral basis, or by involving a third party. The third party is trusted to handle certain procedures regarding registration, certification and distribution of keys. These third parties are often called Trusted Third Parties (TTPs). Under all circumstances there must be agreed rules and procedures for key management between the involved parties.
