A crypto-graphical hash is a mathematical process which transforms or maps a set of data (your file) into a fixed set of characters (the hash). What's important to note is that a file or its identical copy will always transform into the same hash value. However, even the slightest change in the file, by a jot or tittle will result in a completely different hash. There are different types of hashing algorithms. HashRepos uses the SHA-256 standard, one of the strongest hash functions available today.
You can hash any type of file you have on your computer, for example a Word document (.doc), Power point presentation (.ppt), a photo (.jpg) or image (.png) file. You can also hash digital media files such as music files (.mp3) or video files (,mp4).
You can use any file hashing utility (online or offline) that uses the SHA-256 algorithm. When using the HashRepos dapp, an integrated hashing utility is included on this site when you are ready to register a hash of your file. We strongly recommend you use this utility to ensure that the right hashing function (SHA-256) is used.
When you hash a file, you would get a 64 readable character set of numbers and letters known as its hash or hash digest.
For example
"8813f390d5fa102fb91bbeba3a18d89ee4ef279c224fcd97455a0f8c1e16b1e1"
A file will always produce exactly the same hash. Thus if you hash a COPY of the file, you can always ascertain if the copy is identical to the original or if has been changed is any way, by comparing the file hashes.
The "Get Started" option in the Top Menu will lead you through the process of selecting your file and submitting its hash to the blockchain.
Check out also, the "Learn" drop down in the Top Menu which has a detailed explanation of the process with screen shots.
Currently, registration of digital assets using hashrepos is free. However 'gas' network transaction fees are payable as in any blockchain transaction.
Please ensure you have sufficient eth or xDai in your connected Metamask Wallet account.
There are no annual or recurring to use HashRepos.
No, there is no additional payment to retrieve information from the HashRepos Smart Contract on the blockchain.
You do however need to have the Metamask Wallet installed as a Chrome Extension. The wallet does not need to be funded.
The HashRepos database of Hashes reside on the Ethereum Blockchain. The blockchain database is stored on several interconnected and synchronized computers on the internet known as nodes.
The nodes are constantly running and updated. Thus the information on the blockchain is decentralised, permanently replicated and perpetually available
The only information stored on the Blockchain using HashRepos is your file hash, a timestamp, a description of the hash and the address of the owner in the Ethereum format.
As with any Smart Contract and Blockchain Dapp, this information is transparent and can be retrieved by anyone. However, this does not pose any threat to the security of your file as the the contents of your file are not stored on the blockchain.
Thus you are able to verify the integrity of your file without having to reveal the contents of the file.
The HashRepos Smart Contract rides on the security features of blockchain technology which is very secure in that transactions are placed in blocks that are interwoven by cryptographical locks.
Furthermore the blockchain is distributed over several nodes which guarantee the integrity of the database making malicious chain tampering and alterations almost impossible.
While the information on the blockchain is very secure, malicioius attacks can happen in a poorly implemented Smart Contract and at the UI level on a compromised computer.
To prevent Smart Contract code vulnerablities, the HashRepos Smart Contract is open sourced and subject to peer review.
To ensure the accuracy of your HashRepos information, you should always check the information by retrieving the data immediately after registration using the utilities provided. You should also exercise good computer virus and malware prevention practice on your computer at all times.
You should also ensure that the zip package which encapsulates your original file with HashRepos registration details in a text file is securely kept.
As regards your tokens and eth held in your Metamask wallet, you should be familiar with the operation of the wallet, safeguarding your private keys and backup.
The Zip file (we call it the zip capsule) is an additional layer of protection provided by HashRepos to link your Hash record on HashRepos to the original file. The file is encapsulated to prevent accidental modification or alteration.
If you need to review the contents of your original file, extract the file from the zip capsule and review the extracted copy. This allows the original file to be retained unmodified in the zip capsule.
Without the zip capsule, you will still be able to ascertain if a copy is authentic by comparing its hash with the hash record on HashRepos. The zip capsule simply provides easy access to the contents of the file while retaining its integrity.
You should keep the Zip file safely and backed up, as with any important files you have on your computer.
The Ethereum address you used to register the hash is of utmost importance. This public address which you used to register the hash can only be signed by the owner of the private keys associated with the public address. You will be able to view and backup the private key (in the form of seed words) from the Metamask Wallet. It is highly important that you keep the private key (or seed words) confidential as it absolutely identifies the owner of the keys as the owner of the hash, and the associated digital asset.
The Mainnet is the Ethereum Blockchain and the longest running blockchain.
The xDai Chain is an alternative to the Ethereum blockchain with much lower fees.
Use the Rinkeby test net only to test your understanding of the HashRepos system without having to incur real tokens.