SHA-1 Digital Signatures

Exacta digitally signs every survey that is built and sent via STARS. While we were building STARS, the land survey industry was still faxing surveys and then delivering the originals.  When we started emailing PDFs through STARS, we would still mail the originals.  Luckily, later that year, we learned from a Florida Survey Laws course provided by the Florida Surveyor and Mapping Society, that there are actually laws on the books that govern Electronic Signatures in land surveys.  So, Exacta immediately invested in a SHA-1 Hash calculator in STARS.

Today, we still have a few clients that prefer to see a raised seal version of the survey at their closing tables, and it is our pleasure to provide those copies when our clients deem it necessary; however, legally the PDF that they receive in their inbox is actually a digitally signed survey fully compliant with the Florida Statutes governing land surveys and electronic commerce.

Many people see our surveys and think that the signature that they see on our survey IS the digital signature.  The signature that you see on our survey map is a graphic representation of the signature of the Florida Professional Land Surveyor in responsible charge of that specific survey, and that graphic signature is only placed onto our survey by the person of whom that specific signature represents; however, THAT picture of their signature is actually NOT the digital signature on that survey PDF.

The digital signature is an embedded code that only exists for that specific survey PDF.  If that PDF is ever manipulated in any way whatsoever, the code becomes different, and that survey PDF would no longer be digitally signed or authentic.
We issue every survey with a separate invoice (even if the balance is zero), and on that separate invoice PDF, there is a box that shows the 40 character SHA-1 Hash code created for and associated with that specific survey PDF.  If any person ever wants to authenticate that PDF, they just need to drop that specific PDF into any of the many available SHA-1 Hash Authentication tools (we call that tool a SHA-1 Black Box.).  If those two 40 character codes are exactly the same, then that document is digitally signed and that survey is authentic.  The SHA-1 Hash authentication code for every survey is also available by logging into STARS.

If the SHA-1 Hash code that is emitted by using an SHA-1 Hash calculator tool is ever different, then it means that somewhere along the way, someone was changed the information contained on that survey PDF; therefore, that survey would no longer be valid.

In the end, any authenticated digitally signed survey PDF that you might be looking at on a computer screen is far more secure than any paper survey.  It is far easier for scoundrels to use an eraser and a pen to change any paper survey with a raised seal than it is attempt to manipulate the encryption code associated with the SHA-1 Hash.

Today, surveys are used to obtain permits for any number of reasons.  In the vast majority of these cases, the permitting offices at the local municipality offices almost always require a raised seal copy of the survey in order to verify its authenticity.  If the survey is recent and the date of the survey is acceptable with the municipality, then our surveyor in charge will print, crimp and mail a raised seal copy for these purposes.