The result of applying hash to a text is a long code. Hash = A result of a mathmatical function that is difficult to reverse engineer.
Also, they are usually slower than MACs, and as such used normally only when there is not yet a shared secret, or the non-repudiation property is important. Most signature schemes actually are implemented with the help of a hash function. So this provides all of integrity, authentication, and non-repudiation. There is the special case of designated verifier signature, which only ones with knowledge of another key can verify, but this is not normally meant when saying "signature". Digital signatures don't prevent the replay attack mentioned previously. Only the holder of the private key can create this signature, and normally anyone knowing the public key can verify it. with the HMAC construction), or created directly as MAC algorithms.Ī (digital) signature is created with a private key, and verified with the corresponding public key of an asymmetric key-pair. MACs can be created from unkeyed hashes (e.g. (Also, in case of a two-sided conversation, make sure that either both sides have different keys, or by another way make sure that messages from one side can't sent back by an attacker to this side.) by including message numbers or timestamps). This means that the receiver can forge any message – thus we have both integrity and authentication (as long as the receiver doesn't have a split personality), but not non-repudiation.Īlso an attacker could replay earlier messages authenticated with the same key, so a protocol should take measures against this (e.g.
MAC DRAW DIGITAL SIGNUTRE CODE
This is sometimes be used with hashes of very big files (like ISO-images), where the hash itself is delivered over HTTPS, while the big file can be transmitted over an insecure channel.Ī message authentication code (MAC) (sometimes also known as keyed hash) protects against message forgery by anyone who doesn't know the secret key (shared by sender and receiver). If the hash is transmitted over a different, protected channel, it can also protect the message against modifications. For MACs, a recipient must be confident that the shared symmetric key has only been shared with the sender.Ī (unkeyed) hash of the message, if appended to the message itself, only protects against accidental changes to the message (or the hash itself), as an attacker who modifies the message can simply calculate a new hash and use it instead of the original one.
MAC DRAW DIGITAL SIGNUTRE VERIFICATION
For digital signatures, a recipient must be confident that the verification key actually belongs to the sender. Please remember that authentication without confidence in the keys used is useless.
0 kommentar(er)
