## About SNEFRU hash

Snefru is a cryptographic hash function that was developed by Ralph Merkle in 1990. It was named after the ancient Egyptian Pharaoh Sneferu, known for his role in architectural innovation. Snefru operates by processing input data in blocks and iteratively applying a series of mixing and transformation steps to produce a fixed-length hash output.

### Characteristics of Snefru

**Variable-Length Output**:- Snefru can produce hash outputs of varying lengths, depending on the version used. The original Snefru can generate hash values of up to 128 bits, while Snefru-256 extends this to 256 bits.

**Input Padding**:- Snefru pads the input message to fit into blocks of a fixed size. The padding scheme involves appending a single '1' bit followed by '0' bits until the total length of the padded message is congruent to a multiple of the block size.

**Processing in Blocks**:- Snefru processes the input message in fixed-size blocks, typically 512 bits (64 bytes).

**Compression Function**:- The core of Snefru's operation is its compression function, which applies a series of bitwise operations, rotations, and modular additions across multiple rounds to mix and transform the data within each block.

**Iterations**:- Snefru iteratively applies its compression function to each block of the input message. The number of iterations depends on the desired output length and the specific version of Snefru being used.

### Security and Usage

**Security**:- Snefru was initially considered to have good cryptographic properties and resistance against known attacks at the time of its development. However, as with many older hash functions, its security has been re-evaluated over the years, and more modern hash functions like SHA-2 and SHA-3 are generally preferred today due to their stronger security guarantees.

**Usage**:- Snefru has historically been used in various applications requiring hash functions, such as data integrity verification and digital signatures. However, its adoption has declined over time in favor of more widely accepted and standardized hash functions.

### Summary

Snefru is a historical cryptographic hash function known for its variable-length output capability and its iterative processing approach. While it has been used in practical applications, its adoption has waned with the emergence of more secure and efficient hash functions like SHA-2 and SHA-3.