What property ensures that a hash function always generates the same output given the same input?

The property that ensures a hash function always generates the same output given the same input is known as stability. Stability means that for a given input value, the hash function will consistently produce the same hash value, which is critical for various applications like data integrity checks, password storage, and digital signatures.

When a hash function is stable, it allows for reliable comparisons and lookups since users can confidently expect that the same input will yield the same hash output, regardless of when or where the hashing is done. This makes it essential for scenarios where the integrity of data needs to be maintained and verified over time.

In contrast, uniformity, security, and inversion describe other aspects and characteristics of hash functions but do not specifically relate to the concept of producing a consistent output for the same input. Uniformity relates to how evenly the hash values are distributed across the output space. Security generally refers to the resilience of the hash against attacks or vulnerabilities. Inversion relates to the difficulty of reversing the hash function to find the original input from its hash value.