The reasons for digitally signing documents are largely the same as for signing paper documents. Digital signatures are verified through the use of computer encryption (Authentication: The process of verifying that people and products are who they say they are. For example, confirming the source and integrity of a software publisher's code by verifying the digital signature used to sign the code.) Digital information, such as documents, emails, and macros. Digital signatures help ensure:

Authenticity Digital signatures help ensure that the signer is who he claims to be.

Integrity Digital signatures help ensure that content has not been altered or tampered with after it has been digitally signed.

Non-repudiation Digital signatures help prove to all parties that the signed content is valid. "Repudiation" means that the signer denies any behavior related to the signed content.

To ensure the above, the content must be digitally signed by the content creator using a signature that meets the following conditions:

The digital signature is valid (valid: a certificate status, according to A certificate is checked against the certification authority's database and found to be legitimate, up-to-date, and not expired or revoked. A document is considered valid if it is signed by a valid certificate and has not been changed since signing.)

The certificate associated with this digital signature (Certificate: A digital method of proving identity and authenticity. Certificates are issued by a certification authority and, like driver's licenses, may expire or be revoked.) Valid (not expired).

The signer or company as the issuer is trusted (Trust: Indicates whether you trust the recipient (person or group) to whom the certificate was issued. The default setting is "Inherit the trust relationship from the issuer", which is because Trust the certificate by trusting the issuer (usually the certificate authority).

The certificate associated with the digital signature is issued by a reputable Certificate Authority (CA) (Certificate Authority (CA): A commercial organization that issues digital certificates, tracks the person to whom the certificate is issued, and signs the certificate to verify their validity and track revoked or expired certificates issued to signing issuers.