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1. #Can photograv be used with a mac verification
2. #Can photograv be used with a mac code
3. #Can photograv be used with a mac mac

To communicate with assymentric encryption, exchange public keys. Best thing to do in that case is generate a new pair of keys. If the owner of the pairs of keys has his private key compromised, then anyone can know what messages he received. The private key, as the name suggests, must be kept a secret. The public key, as the name suggests, is not a secret, the owner of the pairs of keys can post his public key on his website or whatever for anyone to pick, and in fact he has to in order to receive encrypted messages that can only be decrypted with his private key. A public key can only be decrypted by it's matching private key. The encryption key is the public key while the decryption key is the private key. It uses 4 keys, each user has 2 keys, one for encryption and one for decryption, these 2 keys are mathmatically linked. The assymentric is slower but more secure. The risky part in the symmetric encryption is sending the key from one to another, because there is only one key and if compromised the whole conversation is compromised. Both the sender and the receiver need to know the key and keep it a secret. It uses only 1 key for encryption and decryption. There are 2 types of encryption: symmetric and assymentric. This means that an encryption assures the secrecy of a message. If you combine the key with the encrypted message you get the original message.

This means that a hash assures the integrity of the message.Įncryption (you didn't ask but it's important in the context) = You replace the text of a message in a way that is impossible or at least very difficult to decrypt, unless you have the key. The important thing about a hash is that a minor change to the message makes a huge difference to the hash code. If the 2 hashes match it means the message is the original one, if not, the message has been tampered with. So if you receive a message along with a hash. But the same message will always give the same hash.

With a hash: You cannot revert back to the original message.

#Can photograv be used with a mac code

The length of MD5 code is 128 bits, the length of SHA1 code is 160 bits. 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.

#Can photograv be used with a mac mac

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. 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.

#Can photograv be used with a mac 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.