Hash is a cryptographic type function by which data of an arbitrary size is reduced to a fixed size in a bit array. The result that is obtained as a result of applying a mathematical algorithm is called a sum, and the input data is called a message. A valid Hash function performs under the following conditions: determinism, fast computation for any message, and no two different messages with the same hash value.

Basic properties

Thanks to the cryptographic Hash function, a high level of security is achieved against all known types of cryptanalytic attacks. The following properties confirm the theoretical level of safety:

• resistance to finding a prototype;
• collision;
• resistance to finding a second preimage.

A collision occurs when different inputs produce the same hash result. Stability is ensured until a pair of messages with the same output is identified. It is impossible to completely eliminate such a system's vulnerability since the number of inputs is infinite, but the number of outputs is finite. Therefore, a Hash function will be stable if obtaining a pair of messages with the same output is possible only after extremely complex calculations that would take several million years.

Pre-image resistance determines the stability of the pre-image resistance. An algorithm is considered secure if the probability of finding messages generated by a given hash is extremely low. This property is of great importance from the point of view of data protection since authenticity is proven through Hash messages. There is no need to disclose information.

As a rule, attacks aimed at identifying the second prototype also involve searching for a collision. Therefore, every Hash function that is highly resistant to collision will also be resistant to the second preimage.

In simple words, high performance in all parameters is a guarantee that attackers will not be able to replace or adjust the input data without changing the hash.

Application of Hash

The main purpose of Hash functions involves the following capabilities:

• file/message integrity analysis;
• checking passwords;
• creation of digital signatures.

All this maintains the proper level of security and allows participants in the crypto community to maintain anonymity.