1. The length is shorter than the original.

2. Avalanche, that is, even if only one bit of the source file changes, the digital signature will completely change beyond recognition.

3. One-way function: You can deduce the digital signature from the file, but you cannot deduce the content of the file from the digital signature.

The third-party electronic contract platform uses digital signature to sign electronic contracts, which makes the signed contracts tamper-proof.