What is a digital fingerprint or hash file?
Often described as a digital fingerprint, a hash is simply a “summary” generated from a digital document using a mathematical rule or algorithm. It is designed so that a small change in the document would produce a big change in the hash. Hashing algorithms are “one-way”: you can create a hash from a document, but you cannot recreate the document from a hash. A hash is not an encryption of the document. Most importantly, it’s very difficult to find two documents that have the same hash. The Authentic Document Service uses hash files because a small (but important) change in a document (like changing US$100,000 to US$1,000,000) would produce a completely different hash.
Related Questions
- I wish to use an image in a scholarly journal but it is an on-line journal, or the image will be used on the journal’s website. Can I download a digital file and obtain the academic discount?
- How much file space does a digital picture take up? How many pictures can be put on a high density diskette?
- What is a digital fingerprint or hash file?
