Explain what is meant by a non-cryptographically secure hash function and how it differs from secure cryptographic hashes.

A non-cryptographic hash function is a function that transforms input data into a fixed-size hash but does not possess the properties necessary for cryptographic security. Main differences from cryptographic hash functions:

• Lack of collision resistance: it is easy to find two different inputs with the same hash.
• Lack of preimage resistance: it is possible to recover or find an input based on the hash.
• Vulnerability to attacks: such functions do not protect against forgery or data modification.

An example of a non-cryptographic hash function is a simple checksum or CRC, which is used for error checking but not for security. Cryptographic hashes (e.g., SHA-256) are used where data protection and tamper-proofing are important.