What is the principle of digital signature?

The principle of digital signature is based on asymmetric cryptography, which involves a pair of keys: a private key and a public key. The private key is kept secret by the signer, while the public key is shared openly. When a message or document is signed digitally, it is encrypted using the signer's private key. Anyone can then decrypt the signature using the signer's public key to verify its authenticity.

Here's how it works:

1. Signing: The sender uses their private key to encrypt a hash (a unique numerical value) of the message or document. This encrypted hash is the digital signature.
2. Verification: The recipient uses the sender's public key to decrypt the digital signature, obtaining the original hash. The recipient then computes a hash of the received message or document and compares it with the decrypted hash. If both hashes match, the signature is verified as authentic.

Example: Imagine Alice wants to send a secure email to Bob. She uses her private key to sign the email, creating a digital signature. When Bob receives the email, he uses Alice's public key to verify the signature. If the verification is successful, Bob can be confident that the email was indeed sent by Alice and has not been tampered with.

In the context of cloud services, Tencent Cloud offers solutions like Tencent Cloud Certificate Service which provides digital certificates and manages the lifecycle of SSL/TLS certificates, supporting secure communication and authentication processes similar to digital signatures.