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Git commit signing is enabled (or disabled) for your entire MettleCI Workbench instance, after which it is made available to those Workbench users who configure their Workbench user profiles appropriately. To enable Git commit signing in your Workbench instance set the commitSigningEnabled to true in your config.yml file. See MettleCI Workbench Configuration Files Explained - gitAuthentication for an example of how to do this.
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