How secure is pdf encryption?
40 bit encryption is definitely not safe. Modern tools can decrypt those files within seconds, independent of the used passwords. 128 or 256 bit encryption is safer as long as both passwords are set and if long passwords were used. Most available decryption tools are only able to decrypt a file by applying a brute force attack. This takes considerable processing time if long and cryptic passwords are used, but it is still not impossible to decrypt those files. If you need more security, then use additional encryption software.
