Advanced Placement (AP) Computer Science 2025 – 400 Free Practice Questions to Pass the Exam

A hash function is primarily used in cryptology to verify the integrity of a message. When a message is hashed, it produces a fixed-size string of characters that is unique to the original data. This hash can be used to ensure that the message has not been altered in any way. If even a single character in the original message changes, the resulting hash will be drastically different, allowing recipients to detect any tampering.

In scenarios where secure communication is required, hashes are often used in conjunction with other cryptographic methods, such as digital signatures. By hashing a message and then signing the hash with a private key, it creates a signature that can later be verified by anyone with the corresponding public key, thus confirming both the identity of the sender and the integrity of the message.

The other functions like encrypting messages, generating key pairs, or decoding messages relate to different aspects of cryptography but do not specifically represent the primary role of hash functions.