Introduction to Signatures in C#

An electronic signature is used to authenticate the identity of a PDF document in digital form; it’s the digital equivalent of a handwritten signature or seal. Signatures are widely used in various industries — including finance, healthcare, and government — to provide a secure and reliable way of exchanging information electronically.

Electronic signature is a collective term for signing and authenticating digital documents. There are many types of authentications offering different security levels. The most popular are the following:

  • Electronic signature — A simple physical signature placed in a PDF. It can take many forms, including a scanned image of a handwritten signature, a click of an I Agree button on a website, or a biometric signature captured by a touchscreen device.

  • Certificate — A digital certificate used to authenticate the identity of the signer. It contains information about the identity of the certificate holder, including their name, email address, and public key. Certificates are issued by trusted, third-party institutes, known as a certificate authority (CA).

  • Digital signature — An electronic signature backed up with a certificate.

Using a signature in a PDF document assures its integrity. After signing, any form of modification is noted and is visually available.