Certified Bitcoin Professional Practice Exam

How does a digital signature ensure data integrity?

1. By encrypting the entire message

2. By proving that the message was sent by a verified user

3. By hashing the data before transmission

4. By confirming the correct private key was used

The correct answer is: By confirming the correct private key was used

A digital signature is a cryptographic mechanism that ensures data integrity and authenticity by using a private key to create a unique hash of the message. When a sender creates a digital signature, the message is hashed, and this hash is then encrypted with the sender's private key. The resulting digital signature is sent along with the message. Using the correct private key is crucial here because it verifies the origin of the message. If someone else tried to forge the signature, they would not have access to the correct private key, and therefore, the signature would not match when decrypted with the sender's public key. This mismatch would indicate that the message has either been tampered with or was not sent by the verified user. By confirming that the correct private key was used, recipients can trust that the message is intact and that it truly comes from the claimed sender, which is fundamental to ensuring the integrity of the data. This process allows users to verify both the authenticity of the sender and the integrity of the communication without revealing the message content itself, distinguishing it from other methods like simple encryption or hashing alone.