The difference between hashing & photoDNA

Hashing and PhotoDNA are related concepts. That being said, they serve different purposes in the context of content matching and identification. Here is the main difference between hashing and PhotoDNA:

Hashing:

•  Hashing is a general concept used to transform data into a fixed-sized string of characters using a hash function.

•  Hashing is a one-way process. It cannot easily be reversed to retrieve the original data. It is often used for password storage and data verification.

•  Good hash functions aim to produce unique hash values for difference inputs, but collisions can be possible.

•   It is used for various things including, data integrity, securing passwords & more.

PhotoDNA:

•  PhotoDNA is a specific technology developed for identifying and tracking CSAM online.

•  PhotoDNA does not directly use traditional hashing. Instead, it creates a unique digital signature or hash of an image, considering the perceptual content of the image.

• PhotoDNA is designed to be resilient to modifications like resizing or compression, making it effective in identifying similar images even if they have undergone alterations.

• PhotoDNA is primarily used by online platforms and service providers to detect and prevent the distribution of illegal and harmful content.

Overall, both PhotoDNA and hashing involve the use of hash values, hashing is a general concept applicable in various context, whereas PhotoDNA is a specific technology developed for content-matching, particularly for identifying and combatting the distribution of illegal content, with a focus on images related to child exploitation. PhotoDNA goes beyond traditional hashing by considering the perceptual content of images to improve accuracy and effectiveness in detecting modified content or content that is similar.