Healex.HL7v2Anonymizer

This console application allows you to anonymize HL7v2 messages. The standard configuration anonymizes all identifiable data in HL7 v2 messages and hashes fields that include an ID.

Motivation

The project was built to enable anyone to share HL7v2 sample messages without identifiable data.

How to use?

1. Download the latest release to a location of your choice.
2. Unzip it.
3. Run the application with at least the -d or --directory option set
   For example on windows run: Healex.HL7v2Anonymizer.exe -d C:\Path\To\Files
   On Linux that would be ./Healex.Hl7v2Anonymizer -d /path/to/files

Warning: This will overwrite the original message if no separate output directory is specified.

Command line arguments

The following arguments or options are supported

Short	Long	Required	Description
-d	--directory	required	The path to the directory containing the files to be anonymized
-o	--output	optional	The path to the directory where anonymized files should be written If not set, files are overwritten in the directory specified with -d
-a	--append	optional	Defines a suffix that is to be appended to the filenames. For example if "_Anonymized is set, all files will be written to {filename}_Anonymized.hl7."
-h	--help	optional	displays the help message

Configuration

This application will use the appsettings.json to read the values that are to be replaced for each segments and their corresponding subsegments. If a value is to be replaced in a repeating field, the same rules are applied to all components of each repetition.

A segment is recognized by its "Segment" property. Each segment contains an array of replacements. A segment's subsegment can be identified by its "Path" property inside the replacements array. Subsegments will also have a value property that contains the value by which a value inside a HL7v2 message is to be replaced.

Say for instance, you want to replace the value that is currently assigned for the given name of an NK1 segment. Navigate to appsettings.json, find the NK1 segment and replace the value for path "Path": "NK1.2.2" like this:

    {
        "Segment": "NK1",
        "Replacements": [
            // ommited
            {
                "Path": "NK1.2.2",
                "Value": "Given name" <---- replace this value
            },
            // omitted
        ]
    }

Ideally, the value corresponds to its semantic - so if you want a date to be replaced, give it a random date like 01.01.2020 as opposed to entering a random value. You may also want to pay attention to any character limits for fields and values specified by the HL7 v2 version you are using. Depending on the HL7 v2 version, replacements could otherwise render the message invalid according to that version. For instance, in version 2.5 the NK1.2.2 field only allows a maximum of 30 characters.

Use the "HASH" keyword to generate persistent, pseudonymized IDs. This function will always generate the same anonymized ID for a given ID in the HL7 v2 message. The hash function is one-way, so there is no way of reversing the pseudonymized ID back to its original ID.

    {
        "Segment": "PID",
        "Replacements": [
            // ommited
            {
                "Path": "PID.1.1",
                "Value": "HASH" <---- The value in PID.1.1 will be hashed, not overwritten
            },
            // omitted
        ]
    }

Adding additional segments works in a similar manner. Simply add a new segment to the appsettings.json after "Segment": "IN2". Make sure to add a comma to the closing brace of this segment so the JSON file remains valid, then use this template to add a new segment.

    {
        "Segment": "SEGMENT_ID",
        "Replacements": [
            {
                "Path": "Path_to_sub_segment1",
                "Value": "Replacement_value1"
            },
            {
                "Path": "Path_to_sub_segment2",
                "Value": "Replacement_value2"
            }
        ]
    }

Save and restart application for the changes to take effect.