Document verification

Check a letter against its fingerprint

Every letter we prepare is signed electronically, and the last page records a SHA-256 fingerprint of its exact wording. Paste that fingerprint here and we confirm whether it matches a letter we prepared, and when it was signed.

Document hash (SHA-256)

I have the letter but not the hash

Paste the full letter text below instead and we compute the fingerprint here in the same way. Copy from the first line of the sender's name through the closing signature, exactly as it appears, with nothing added or removed. A single changed character produces a different fingerprint, which is the point of the exercise. The letter text

What a match tells you

A match means the wording you hold is byte-for-byte the wording that was signed, on the date shown. It is the same idea as a seal: change one character of the letter and the fingerprint no longer matches, so a document that verifies cannot have been edited after signing.

It does not tell you who signed it, what was demanded, or whose deposit it was. Anyone can hold a fingerprint; nobody should be able to turn one into a person's name and address. If you need those details, they belong to the tenant who signed, and they can produce them.

What a certified letter proves alongside it

The fingerprint proves what was signed, and when. USPS Certified Mail proves it was mailed and arrived, and on what date: the receipt, the tracking history and the delivery signature. A small claims court asks for the delivery proof first; the fingerprint backs up which wording it was. That is why we do both rather than either.

No match?

Most often the text was copied with something missing or added: a header, a page number, a trailing space, or a line the email client rewrapped. Try the hash from the certificate page rather than retyping the letter. A genuine non-match means the wording differs from what was signed, and that is worth knowing.