What is a hash?

A hash is a unique digital fingerprint, or label that identifies a picture of confirmed child sexual abuse. Our hashes are created in various formats (think of them like different languages) including PhotoDNA, SHA1, SHA256 and MD5.

By using our Hash List, tech companies can stop criminals from uploading, downloading, viewing, sharing or hosting known images and videos showing child sexual abuse.

By the end of 2021, we had created 1,004,611 unique hashes to share with technology companies.

Total unique hashes by severity and age

  • Category A: Images involving penetrative sexual activity; images involving sexual activity with an animal or sadism.
  • Category B: Images involving non-penetrative sexual activity.
  • Category C: Other indecent images not falling within categories A or B.
Source: IWF Annual Report 2021

Total unique hashes by severity and sex

Source: IWF Annual Report 2021
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