File Hash calculation

The File Hash acts as a digital fingerprint that uniquely identifies each file. During processing, by default, Epiq Discover calculates the File Hash using one of the following methods and populates the field.

  • When email or ICS (Calendar) information is available, Epiq Discover calculates the File Hash using the following properties:

    • Date

    • To (count only)

    • From

    • CC (count only)

    • BCC (count only)

    • Subject

    • Body Text

    • Attachments (count only; includes both embedded and linked modern attachments, if retrieved during processing, or represented with placeholder native)

  • When email or ICS information is not available, Epiq Discover calculates the binary hash. For Microsoft Teams chat MSG files, the system calculates the binary hash.

  • When a File Hash is not provided in the DAT file during document loading through Desktop Client, the system calculates the File Hash using the raw file bytes. However, when you reprocess these files, the system recalculates the File Hash using the methods described above. As a result, the File Hash value may differ between the loading and reprocessing stages.

  • For projects created in Epiq Discover release 4.4 (October 21, 2025) or later, the system calculates File Hash using SHA256. For projects created before Epiq Discover release 4.4, the system calculates File Hash using SHA1.

Custom File Hash calculation

For ICS files and email files, such as MSG and EML, you can specify the fields used for File Hash calculation. This feature enables the deduplication of identical emails collected and processed from multiple platforms, such as an email archive and an active email server. The system does not support Custom File Hash calculation for the following documents.

  • Parent ICS files that are collected using >

  • Bloomberg email files

  • Microsoft Teams chat MSG files

By default, this feature is disabled. You can enable it in Project Settings. When you apply Custom File Hash calculation, the system populates the and fields. Then, the field displays the Custom File Hash value, and the field displays the default File Hash value. When you do not apply Custom File Hash calculation, the system populates only the field.

The following list provides related topics.