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Data integrity refers to the accuracy, legitimacy, and consistency of information in a system. When a message is sent, particularly using an untrusted medium, data integrity provides us confidence that the message wasn't tampered with. Checksum solves all three potential data integrity problems listed above. A checksum is a deterministic value derived from the message data and can be transmitted separately. It is common good practice to sign the checksum using a digital signature. The SHA-256 hash function is often used to create checksum digests.