CuteFTP Professional User s Guide 

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RANSPORT 

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AYER

When you first attempt to connect to an SSH2 site, CuteFTP Professional and the server 

determine whether the transmission should be encrypted or clear, compressed or 

uncompressed, what Method Authentication Code (MAC) to use, and what kind of 

encryption (cipher) to use.  

Once the encryption method is chosen the following happens:  

1.  The server sends a public key to CuteFTP. 

2.  CuteFTP generates a session key, and encrypts it with the server's public key. 

3.  CuteFTP then sends the encrypted session key back to server.  

4.  The server then decrypts the session key with its private key and from that time all 

transmitted data is encrypted with the session key.  

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UTHENTICATION 

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AYER

After the Transport Layer is established, the server attempts to authenticate the client.  

Common methods for establishing user authentication include:  

Public Key Authentication Method: publickey  

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To use this method, you will need your private key and your public key, 

which is passed to the server. The server encrypts a random number with 

your public key and sends it to you. 

2.  If you have not already entered your passphrase in SSH2 security settings, 

CuteFTP asks you for your passphrase to activate the private key. 

3.  The private key decrypts the number and sends it back to the server. 

4.  The server recognizes the number as correct and allows the connection. 

Password Authentication Method: password  

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Using this method, the client sends its password to server. The client does 

not need to explicitly encrypt the password, because it is automatically 

encrypted by the SSH2 Transport Layer. This is the default in CuteFTP. 

With this type of authentication, the connection will fail if the Transport 

Layer cannot encrypt the data.  

After the encryption method is established and authentication is complete, the two systems 

are ready to exchange secure data. CuteFTP Professional sends a secured FTP connection 

along the encrypted data tunnel, the remote system and responds and you can begin 

transferring files securely.  

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RANSPORT 

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AYER SETTINGS

To select Message Authentication Codes (MAC) 

Message Authentication Codes are algorithms used to confirm data has not been altered 

between the client and server. 

1.  From the menu, choose Tools > Global Options.  

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