No, since you are required to compute the hash offline. All SHA256 hashes result in a 64 characters string, whether it comes from a short sentence or a database dump of several terabytes, so the size of the original document/data to notarize is not a concern.

No. The SHA256 algorithm treats your data as a continuous finite stream of bytes and ignores the content. Just remember that the document shall never be changed once it’s notarized. Changing a single bit in the file would void the entire notarisation process. Some software (spreadsheets, word processors) might change the file if you open it (autosave, updates, statistics, metadata etc). Keep the original file you used for the hash in a safe place and never overwrite it. If you need to make changes, we suggest to work on copies. In general, zip files and PDFs are the most suitable for this purpouse.

Yes. Since this is a free service, the access to this resource is reguated to discourage inappropruiate use. Currently each registered user can perform a maximum of one notarisation per day.

Sure! You can encrypt the document and then calculate the hash of its’ encrypted version, since the content of the file does not affect the SHA256 algorithm. Just note that this might be unnecessary, since it is impossible to revert the hash procedure and retrieve the content of the original file from the hash. On the other hand it is advisable to encrypt the document if it contains sensitive data and/or if you plan to store it into an online/cloud service (like Dropbox, Amazon S3, etc).

No. Quadrans Notarisation is a free service and we cannot keep a copy of every document/data we notarize, plus it’s insecure. The user of the service shall keep the original copy of the notarized data in a safe place along with the documents received that prove the notarisation took place. These elements can be used to prove data integrity, timestamp and ownership.

Exactly. In order to deal with a great amount of data in total security and privacy, Quadrans Notarisation makes extensive use of Merkle Trees and hashes. What gets written on the Quadrans Blockchain is the root of the Merkle Tree, and the tree is composed pairing the ‘evidences’ of the submitted hashes. In other words: your hash and email address are used to derive a unique ‘evidence’, then ‘evidences’ of many other documents are collected in a Merkle Tree and the root of that Merkle Tree is written in the Blockchain.

Quadrans Notarisation service notarizes the hash you submitted, as well as the fact that it actually was sent from your email address. Firstly we compute the hash of the sender’s email address (a string) using SHA256. Then the hash submitted and the hash of the email address are concatenated to form a 512-binary array. That binary array gets hashed twice with SHA256 to form the evidence. This way, Quadrans records that the document/data was sent from that email address, without revealing the contents of the document/data nor the sender’s email address.

Legal aspects and implications of a blockchain notarisation may vary according to legislation of the country you operate in. Some countries consider the timestamp obtained via the blockchain notarisation legally valid, others don’t. Please seek professional advice to clarify any aspect that may concern legal implication an validity. Also, if you are using this notarisation for a cross-border business, you might need to check on both countries as ther legislation is likely to have different approaches.