The Record signature feature uses Password-based Encryption (PBE) to create a secret key from a user specified password and randomly generated salt (8 bytes). The secret key is used with a cryptographic hashing function to create a (HMAC) message authentication code. The random salt bytes are then appended to the end of the HMAC and the whole thing is Base64 encoded to achieve the Record signature.

Configuration in MQTT Transmission

Configuration for the digital signature is detailed here MT: Configuration#RecordsRecordsSignature

MQTT Modules for Ignition 8.1 > MR: How to use and validate the Record Signature > history-4 (1).png

Manual validation using MQTT Recorder tags

Use the MQTT Recorder tags MR: Tags to validate the records in the database

Request Hashing Algorithm	String	A writeable tag that sets the requested hashing algorithm to compare database data against
Request Index End	Long	The last record index to use in the comparison
Request Index Start	Long	The first record index to use in the comparison
Request Password	String	The password for the database
Request Table Name	String	The table name containing the records
Result	Dataset	An array containing a set of validation results for each record
Result value > index	Long Array	The record index
Result value > signature	String Array	The record signature
Result value > validated	Boolean Array	The result indicating that the record signature matches the request signature
Result value > error	String Array	A message detailing any errors that occurred when performing the validation
Status	String	A message to indicate the success or failure of the database query. If this status returns Success, the Result dataset will contain the validation result for each record.
Validate	Boolean	A writeable tag that triggers the validation to occur

These tags allow you to confirm that the data in the database has been written using the appropriate hashing algorithm using the steps below:

Set the Request Hashing Algorithm to match the hashing algorithm configured at MQTT Transmission
Set the Request Index End and Request Index Start to define the record index's to use in the comparison
Set the Request Password to the password required for the Datasource configure in the MQTT Recorder
Set the Request Table Name to the table name containing the records for comparison
Set the Validate tag to True to trigger the validation

The response will be contained in the Status and Result tags.

Status will return either Success or Failure for the database query.

Result will return an array containing the validation result for the record if the Status is Success. The array includes:

The record index
The record signature
The result indicating that the record signature matches the request signature
A message detailing any errors that occurred when performing the validation