## About FNV132 hash

FNV-1 (Fowler-Noll-Vo) is a non-cryptographic hash function designed for fast hashing of data. FNV-1 32-bit (FNV-1a) specifically refers to a variant of the FNV-1 hash function that produces a 32-bit hash value. Here’s an overview of FNV-1a 32-bit:

### Characteristics of FNV-1a 32-bit

**Output Size**:- FNV-1a 32-bit produces a fixed-length output of 32 bits (4 bytes).

**Initialization Values**:- FNV-1a initializes its hash value with a specified starting value. For FNV-1a 32-bit, the initial hash value (
`hash`

) is typically set to`0x811c9dc5`

.

- FNV-1a initializes its hash value with a specified starting value. For FNV-1a 32-bit, the initial hash value (
**Prime and XOR Constants**:- FNV-1a uses a prime number and XOR operation at each step of processing:
- Prime: The prime number used for FNV-1a 32-bit is
`0x01000193`

. - XOR: Each byte of the input data is XORed into the hash value.

- Prime: The prime number used for FNV-1a 32-bit is

- FNV-1a uses a prime number and XOR operation at each step of processing:
**Hash Calculation**:- For each byte
`data[i]`

in the input data:- Update the hash value using the formula:
`hash = (hash ^ data[i]) * Prime`

.

- Update the hash value using the formula:
- After processing all bytes, the hash value is the final 32-bit FNV-1a hash.

- For each byte
**Properties**:- FNV-1a 32-bit is designed for fast hashing of data and is commonly used in applications where speed is prioritized over cryptographic security.
- It is deterministic and produces the same hash value for identical input data.
- FNV-1a is not suitable for cryptographic purposes due to its vulnerability to collision attacks and its predictable nature.

### Usage

**Applications**: FNV-1a 32-bit is used in various applications such as hash tables, checksums, and non-critical hash-based operations where quick computation and distribution of hash values are necessary.**Implementation**: It is straightforward to implement and is often used in combination with other hash functions or checksum algorithms to provide basic data integrity checks.

### Example Calculation

Given a sequence of bytes `data`

, the FNV-1a 32-bit hash `FNV1a_32(data)`

is calculated as follows:

- Initialize the hash value
`hash`

to`0x811c9dc5`

. - For each byte
`data[i]`

in the input data:- XOR
`hash`

with`data[i]`

. - Multiply
`hash`

by the prime number`0x01000193`

.

- XOR
- The final FNV-1a 32-bit hash value after processing all bytes is
`hash`

.

### Security Considerations

- FNV-1a 32-bit is not suitable for cryptographic applications due to its susceptibility to collision attacks and its predictable output.
- It should not be used in scenarios where data security or cryptographic integrity is required.

### Summary

FNV-1a 32-bit (FNV-1 32-bit) is a non-cryptographic hash function designed for fast computation of hash values. It produces a fixed-length 32-bit hash output and is commonly used in applications where speed and simplicity are prioritized over security, such as in hash tables and checksums.