If only owner password is set, decryption is being done instantly; decrypted file can be opened in any PDF viewer (e.g. Adobe Acrobat Reader) without any restrictions, i.e. with edit/copy/print/annotate functions enabled. Alternatively, owner password can be recovered using brute-force or dictionary attacks.

Additionally, PDF Password Cracker Pro supports "key search" attack that allows to decrypt PDF files with 40-bit security regardless the password length.