Ricoh Remote Communication Gate S Uživatelský manuál stáhnout pdf (Strana 19)

Appendix 4. Cryptographic algorithms of HTTPS

Figure 1 shows SSL negotiation with mutual authentication: client authentication and server authentication.

(1) The first step in the process is for the client to send the server “Client Hello” message. This hello message

contains the SSL version and the cipher suites the client can talk and seed of random number. The client

sends its maximum key length details at this time.

(2) The server returns the hello message with one of its own in which it nominates the version of SSL and the

ciphers and key lengths to be used in the conversation, chosen from the choice offered in the client hello.

(3) The server sends its digital certificate to the client for inspection.

(4) The server sends client certificate request after sending its own certificate.

(5) The client verifies server certificate.

(6) The client sends its certificate.

(7) The client generates a pre master secret and encrypts it using the server's public key.

(8) The client sends pre master secret to the server.

(9) The client signs to data using client secret key.

(10) The client sends a Certificate verify message in which it encrypts a known piece of plaintext using its private

key. The server uses the client certificate to decrypt; therefore ascertaining the client has the private key.

(11) The client generates session key with two seeds and pre master secret.

(12) The server verifies client certificate. The server decrypts pre master secret using server private key, and

generates session key.

(13) The client now sends a “Finished” message using the new key to determine if the server is able to decrypt the

message and the negotiation was successful.

(14) The server sends its own “Finished” message encrypted using the key. If the client can read this message then

the negotiation is successfully completed.

Remote Communication Gate and Communication Server have 512 bits certificate; therefore RSA 512 bits cipher

suite is used. AES (Advanced Encryption Standard) with 256 bits key is used for encryption. When HTTPS

method is selected, session key, i.e. encryption key for HTTPS, is created each and every time.

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Ricoh Remote Communication Gate S Uživatelský manuál Strana 19