What is the primary security feature of hashing?

The primary security feature of hashing is that it provides data integrity by generating a unique hash value for each unique input. Hashing algorithms take an input (or 'message') and produce a fixed-size string of bytes, typically a digest that uniquely represents the input data. This unique hash value enables verification processes to ensure that the data has not been altered; if even a single bit of the input changes, the resulting hash will be completely different. This characteristic makes hashing a vital component in data integrity checks, digital signatures, and verifying the authenticity of messages.

The other options do not accurately capture the main feature of hashing. Retrieving the original data is not possible with hashing since it is a one-way function; thus, hashing does not facilitate data retrieval. While hashes can play a role in secure transmission by verifying data integrity, they do not encrypt data; encryption and hashing serve different purposes. Lastly, hashing does not compress data; rather, it generates a fixed-length output from variable-length inputs, which can sometimes result in increased data size rather than efficiency in storage.