Crehash

Crehash is a term that generally refers to the process of rehashing or recalculating cryptographic hashes. In computer science and cryptography, a hash function takes an input of any size and produces a fixed-size string of characters, known as a hash value or digest. This hash value is unique to the input data, meaning that even a tiny change in the input will result in a significantly different hash.

Rehashing can occur for several reasons. One common scenario is when a hash function is found to have vulnerabilities or weaknesses. In such cases, developers may decide to update the system to use a more secure and robust hash algorithm, requiring all existing data to be rehashed. Another reason is for data integrity checks. If data has been transmitted or stored, its hash can be recalculated and compared to the original hash to ensure that the data has not been altered.

The process of crehashing itself involves feeding the original data through the chosen hash function again to generate a new hash. This is a computationally intensive process, especially for large datasets. In some contexts, "crehash" might also be used informally to describe the act of re-generating a hash for a specific purpose, such as for a password reset or when verifying the authenticity of a file. The specific implementation and purpose of crehashing will depend on the system and its security requirements.