HMAC is a hash based message authentication code. This assures the receiver, that not only the message hasn’t been modified, but also who sent it, is the one you expect it from.
WIRESHARK USE CERTIFICATE MAC
This is achieved, because MAC uses a private key as the seed to the hash function it uses. Data integrityĪ MAC is used to make sure that nobody has tempered with the data in transit and also provides authentication.
In RSA, if an attacker gets hold of server’s private key, it can derive the symmetric keys and decrypt the exchanged data. In DH, if an attacker intercepts the traffic during the handshake, it does not have enough information to compute the master secret and thus derive the keys, even if it has the server’s private key. The pre-master key is used with other values to generate the encryption and MAC keys (one for each direction - total 4) The components are not transmitted across the network, but remain on each side. Each side adds components that must remain private. key generation (DH, ECDH): The client and server independently generate a pre-master secret, after an initial exchange of components, that are required for the process, all of which can be public and therefore do not require encryption.The master secret is used in a Pseudo Random Function to generate the actual session keys. Both sides use this key and parameters exchanged during the handshake process to generate the master secret. key exchange (RSA,DSA): the client generates a pre-master secret and sends it to the server, encrypted with the server’s public key.The components used to generate the session keys are passed between the client and the server in one of two ways. Session keys are computed on each side of the connection. The truth is that the session keys are never exchanged, but they are generated independently on each side, based on other data they have exchanged. The server decrypts it with its private key, and then uses this decrypted key for encryption and decryption of data. I have read many times that the client generates a session key, encrypts it with the public key from the server and sends it to the server. Of course if you encrypt with the private key, then anyone can decrypt it, so the usual case is that the public key is used for encryption, while the secret key is used for signing (more on this later). Although this is the common case, the truth is you can do both: encrypt with private and decypt with public, OR, encrypt with public and decrypt with private. Some people think that the public key can be used only for encyption and the private only for decryption. One key is distributed and is called public, and the other is kept confidential and called private. Public Key Infrastructure uses asymmetric algorithms.The same key cannot be used for encryption and decryption.Whatever is encrypted with one key, can be decrypted with the other.Asymmetric algorithms like RSA, DH, use two separate keys.(actually if the session takes long, they can be regenerated) Symmetric keys are known also as session keys, because they are used for a single session and then discarded.They are always used for the encryption of data, because they are more cpu efficient.Symmetric algorithms like AES, use a single key for encryption and decryption.There are two main categories of encryption algorigthms. When using https, all http data are transfered in the record layer.Ĭonfidentiality is achieved through encryption. A total of four keys are used (MAC + encryption in one direction, MAC + Encryption in the other direction).
Each block is decrypted, decompressed, MAC verified and reassembled. On the incoming side, it does the opposite things. Its functions are breaking all outgoing messages into blocks, compressing them, adding a MAC and encrypting them.
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