摘要 |
Field devices used to measure process parameters can also function as a data historian by storing process data and associated time stamps. In response to a request for stored process data, the field device uses a cipher and a secret method to generate an encrypted validation string that is provided along with unencrypted information including the process data and time stamps. A validation service that maintains a secure database of field devices and their associated ciphers and secret methods can validate the unencrypted information by using the validation string.
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