Private and public keys are used when creating digital signatures for authenticating the identity of an electronic document sender. These keys are used in two main encryption systems: Symmetric and Asymmetric.
This system uses only private keys, which can be anything from a numerical symbol to a string of random letters. These private keys are used to encode a message, so that only the sender and the recipient of the message who know what the secret key is can “unlock” it and decrypt it. The system works pretty much like two best friends using a decoder ring to send secret messages to each other. The symmetric system’s only downside is the potentially unsafe private key transmission via the Internet, where other people can “crack” it and decode the message.
As a solution for the not completely safe Symmetric Encryption, there is the Asymmetric Encryption system that uses a pair of keys for added security: a private and a public key. The private key is for yourself and the public key is published online for others to see.
The public key is used to access the encryption code that corresponds to your private key. So, if you are sending an encrypted message to Susan which you do not want others to see, you would use her public key to encrypt it. She will be able to decrypt it with her own corresponding private key. Likewise, if she sends a message to you, she uses your public key to encrypt the message and you would use your private key to decrypt it.
Digital IDs are packages of information that allow for a more electronically secured communication line because they enable users to make use of these encryption systems. They are used to verify the real sender of an email, hide the encrypted message’s content, show whether the message has been tampered with during the transit, etc. They are ideal because they can't be easily forged. By applying them to your PDF files after the PDF creation process, you are ensuring your document’s security.