D-Link Dis-200G Series Web Ui Reference Manual Download

Page: 108 / 161

DIS-200G Series Industrial Gigabit Ethernet Smart Managed Switch

SSL

Secure Sockets Layer (SSL) is a security feature that will provide a secure communication path between a

host and client through the use of authentication, digital signatures and encryption. These security

functions are implemented through the use of a cipher suite, which is a security string that determines the

exact cryptographic parameters, specific encryption algorithms and key sizes to be used for an

authentication session and consists of three levels:

•

Key Exchange

: The first part of the Cipher suite string specifies the public key algorithm to be

used. This switch utilizes the Rivest Shamir Adleman (RSA) public key algorithm and the Digital

Signature Algorithm (DSA), specified here as the DHE DSS Diffie-Hellman (DHE) public key

algorithm. This is the first authentication process between client and host as they “exchange

keys” in looking for a match and therefore authentication to be accepted to negotiate

encryptions on the following level.

•

Encryption

: The second part of the cipher suite that includes the encryption used for encrypting

the messages sent between client and host. The Switch supports two types of cryptology

algorithms:



Stream Ciphers

– There are two types of stream ciphers on the Switch, RC4 with 40- bit

keys and RC4 with 128-bit keys. These keys are used to encrypt messages and need to

be consistent between client and host for optimal use.



CBC Block Ciphers

– CBC refers to Cipher Block Chaining, which means that a portion of

the previously encrypted block of encrypted text is used in the encryption of the current

block. The Switch supports the 3DES EDE encryption code defined by the Data Encryption

Standard (DES) to create the encrypted text.

•

Hash Algorithm

: This part of the cipher suite allows the user to choose a message digest

function which will determine a Message Authentication Code. This Message Authentication

Code will be encrypted with a sent message to provide integrity and prevent against replay

attacks. The Switch supports two hash algorithms, MD5 (Message Digest 5) and SHA (Secure

Hash Algorithm).

These three parameters are uniquely assembled in four choices on the Switch to create a three- layered

encryption code for secure communication between the server and the host. The user may implement any

one or combination of the cipher suites available, yet different cipher suites will affect the security level

and the performance of the secured connection. The information included in the cipher suites is not

included with the Switch and requires downloading from a third source in a file form called a certificate.

This function of the Switch cannot be executed without the presence and implementation of the certificate

file and can be downloaded to the Switch by utilizing a TFTP server. The Switch supports SSL3.0, TLS1.0,

TLS1.1 and TLS1.2. Other versions of SSL may not be compatible with this Switch and may cause

problems upon authentication and transfer of messages from client to host.
When the SSL function has been enabled, the web will become disabled. To manage the Switch through

the web based management while utilizing the SSL function, the web browser must support
SSL encryption and the header of the URL must begin with https://. (Ex. https://xx.xx.xx.xx) Any other

method will result in an error and no access can be authorized for the web-based management.
Users can download a certificate file for the SSL function on the Switch from a TFTP server. The certificate

file is a data record used for authenticating devices on the network. It contains information on the owner,

keys for authentication and digital signatures. Both the server and the client must have consistent

certificate files for optimal use of the SSL function. Currently, the Switch comes with a certificate pre-

loaded though the user may need to download more, depending on user circumstances.