How to encrypt PDF document protection

The first encryption is password encryption, as long as the user enters the correct password to open or document permissions password can open the document. This encryption method is easy to use, the limitation is that his protection relies on a simple string of passwords, the password is compromised can not protect the effect.

The second method of encryption is certificate encryption. The PKI asymmetric encryption algorithm is used to encrypt the public key certificate, and the private key certificate can be used to open the decryption. If the document is compromised, it also represents the user's private key certificate being compromised. In order to facilitate the safekeeping of use, there are also users to the private key certificate into the U-key, the use of the need to insert U-key.

Small series of warm hint: Two encryption methods are in the off-line state of encryption, but also the application of the most 2 kinds of document protection measures, at the same time, these 2 encryption methods have their own limitations, or there is the risk of information leakage, need to be combined with other document security measures.