What does Hash mean, how does it work, where is it used? How does the SHA-256 hash function used in Bitcoin work? Details in our article.
It uses hash algorithms in many areas of technology, especially cryptocurrencies such as Bitcoin (BTC). In this article, we have examined the hash structures used for encryption and sometimes for data integrity control. In the article we prepared, we will explain the terms such as hashing algorithm, SHA-256, MD5, summary function. You will find the details of the hash algorithm used in Bitcoin in our article.
What is Hash?
The mathematical operation that converts the entered data into a fixed-length output is called hash. One of the purposes of this process is to hide the data. For example, passwords written while subscribing to websites are converted to hash and written to the database. In this way, the person who examines the database cannot know the password of the user.
Another purpose of use is to create a secure summary of the data. No matter how long the input data is, the hash code can be stored for summary purposes, as the output will always be the same length.
While creating hash algorithms, the following four elements are given importance:
It should be easy to calculate the input summary
It should be very difficult to find the input from the summary data
The summary should change if the input data changes
The likelihood of the same summary from different inputs should be very low
Hash signature algorithms and summarization functions are frequently used in electronic signature applications.
For example, the hash data of the novel draft, which is hundreds of pages long, would be a short line length. Instead of checking the entire post, it will be sufficient to look at the hash code to see if any changes have been made to the draft.
What is the SHA-256 algorithm used in Bitcoin?
SHA (Secure Hash Algorithm - Secure Hash Algorithm); It is the name of the hash algorithm developed by the US National Security Agency (NSA).
This standard started to be used with SHA-0 in 1993, and its performance was increased with SHA-1 developed in 1995. The SHA-2 standard was developed in 2004 after several vulnerabilities detected. SHA-2 standard; It has subsets like SHA-224, SHA-256, SHA-384 and SHA-512.
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The hash algorithm called SHA-256 is used in the Bitcoin network. SHA-256 standard; Even if the input data consists of a letter, hundreds of pages of novel length always provides 64 characters of output in the hexadecimal number system. You can use the link here to see a working example.
Use of SHA-256 algorithm on blockchain
In the Bitcoin network; Block information, block number, “nonce” value and hash code belonging to the previous block are converted into hash code in accordance with the SHA-256 standard by combining current transactions between users.
For example, while preparing this article, the hash code for 2,684 transfer transactions in the block number 629.334 created in the Bitcoin network was as follows:
"0000000000000000000bfc7df45983354cc12847745459a0e4c834f77ddb4c9b"
As can be seen, more than 2 600 transactions information is converted into 64 character summary output only. Thus, it is possible to check with only this summary data instead of examining all data against any changes in the block.
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Blocks in the Bitcoin network contain hash codes of the block that preceded them. Therefore, since the hash code will be different when the data in the block is made, the backward change will be understood immediately.
Can SHA-256 hash algorithm be hacked?
Although it is easy to produce hash output from input data, finding input from hash data is mathematically impossible.
Using the output, input data cannot be found, but it is possible to find simple data called "brute force" by using each character in order.
There are many websites operating to decode hash codes on the Internet. In these sites, the data that users enter into the system and their equivalents in the hash algorithms are recorded. In this way, millions of data accumulate in the database. If the hash code on hand belongs to a simple data, it is likely to be resolved.
The md5hashing.net website, which comes out with a simple search on Google, allows data to be converted to hash code with various algorithms. If the "Store Result" option is checked, your search is saved in the database. If the hash code obtained is entered in the "Decrypt" field by any user, it will now be found as it is registered in the system.
When we enter the hash code of the “Bitcoin” SHA-256 format, which we have given above, into the system, we see that another user found the equivalent because he previously saved this data in the system.
On the other hand, we cannot find an answer for the word "Cointelegraph" in the SHA-256 format mentioned above, since nobody has searched for it before.
In short, it is possible to find the hash codes of short data consisting of several characters by trial and error methods. In other words, if you make your password as “123456” while signing up on a website, the equivalent of this in SHA-256 format will be:
8d969eef6ecad3c29a3a629280e686cf0c3f5d5a86aff3ca12020c923adc6c92 "
When you search the above code on Google, it is a piece of cake to find that it belongs to “123456” data.
However, as with the Bitcoin network, it is impossible to reject the hash code in which block data containing thousands of transfer transactions is converted. But we cannot know what the future will bring.
