CSZ EZT-570S, Руководство пользователя

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EZT-570S User Manual
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7.7 Digital Signatures
The Signature screen allows the user to add digital signatures to historical data log files and view any
digital signatures currently associated with the loaded historical log file.
Figure 7-10 Digital Signatures
When a historical data file is loaded, the Signature screen will display any signatures currently
associated with the file. To verify a digital signature and insure that the data file has not been altered,
touch the signature in the list box and press the “Verify” button. The EZT-570S will compare the
signature to the log file to see if any alterations to the data have been made. The EZT-570S will then
indicate if the signature is valid or not.
If the signature is valid, the historical data file is intact and has not been altered. If the signature is
invalid, the data has been altered at some time after the signature was assigned to the file. For data
integrity, the EZT-570S automatically signs a data file when logging is stopped; however, this only
occurs if the “Auto Interval” is selected on the Log screen. If a different logging interval is used, and
the file size becomes greater than 500KB, the EZT-570S will not automatically sign the file, and it
must be signed by a user.
To add a digital signature to the historical log file, touch the “Entry” field at the bottom of the screen
and enter in the comment line for the signature (up to 16 characters maximum). Press the “Save”
button and the signature will be added to the log file. The signature includes the date and time of the
signature, the user name and comment line. If a user is not logged into the system, the default user
name “Device Manager” will be used as the user.
The Signature screen is not available if security is disabled. The EZT-570S security module
must be enabled in order to digitally sign data log files. See Section 6, Security.