1. message confidentiality 2. message integrity 3. message authentication 4. non
ID: 661937 • Letter: 1
Question
1. message confidentiality
2. message integrity
3. message authentication
4. non-repudiation The 4 services are related in the sense that one services often implies/provides another. Indicate for each service which of the three other services are also provided?
Message integrity means that message has been send and received without any manipulation or modification in the message content, while message confidentiality means that cannot be seen by any unauthorized parties, so confidentiality implies integrity and vice versa. Message authentication is guaranteeing the identity of the end user which by implementing it we provide confidentiality. Non-repudiation implies authentication as the sender and receiver cannot deny a transmitted message.
Explanation / Answer
Integrity: the message is guaranteed to be the same, unaltered, that it was at a previous time.
Authentication: you have some guarantee as to the identity of the source of a given message. This makes sense only if you also have some guarantee that the message was not altered afterwards, so if you have authentication then you should have integrity as well.
Non-repudiation: that's authentication where the guarantee can be shown to third parties and be convincing as well. Basic authentication is when you are the verifier; non-repudiation is when the whole World is the verifier. Thus, successful non-repudiation implies authentication (and thus integrity).
(Note that non-repudiation is a mostly legal concept which cannot be entirely provided by cryptographic tools.)
Confidentiality has no relationship whatsoever with any of the other three. A message can be made confidential through encryption, which in no way protects it against alterations. Conversely, integrity and authentication will commonly be provided by MAC or digital signatures, which don't ensure any confidentiality at all.
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