How does a digital signature ensure the integrity of a transaction?

@mandy 

A digital signature ensures the integrity of a transaction by providing a way to verify that the transaction has not been modified or tampered with during transmission.

The process involves using public-key cryptography, where the sender (signer) of the transaction encrypts a message with their private key. This encrypted message, known as the digital signature, is unique to the transaction and can only be decrypted using the corresponding public key held by the receiver (verifier).

When the receiver receives the transaction, they can use the signer's public key to decrypt the digital signature and obtain the original message. If the decrypted message matches the received transaction data, it proves that the message has not been altered since the digital signature was created.

Any modification to the transaction would result in a different decrypted message, as even a small change in the data would have a significant impact on the resulting decrypted message. Therefore, if the decrypted message does not match the received transaction data, it indicates that the transaction has been tampered with, ensuring the integrity of the transaction.

Additionally, digital signatures also provide non-repudiation, meaning the signer cannot deny their participation in the transaction since their digital signature is uniquely tied to their private key.