remove restrictions on any secured PDF document (you should have the right to do it, for example,
if you forgot the password). Any Acrobat version up to 9 is supported, even with 128-bit AES or
128-bit RC4 encryption. PDF restrictions removal is an instant process. Unlocked
file can be opened in any PDF viewer without any restrictions so you may
remove the PDF open
password. Decryption of the file with password for opening is guaranteed for PDF
files Any Acrobat version up to 9 is supported, even with 128-bit AES or
128-bit RC4 encryption,but you must know the password first.
Upload a PDF and Unlock it(10M Max)
Give a PDF Url and Unlock it(10M Max,also depend on the download speed.)
The standard PDF protection scheme can have two different passwords: a Document Open password and a Permissions password. When a Document Open password (also known as a user password) is set, anyone who tries to open the PDF must type in the password. When a Permissions password (also known as a master or owner password) is set, recipients don't need a password to open the document, but they must type the Permissions password to set or change the restricted features. If the PDF is secured with both types of passwords, it can be opened with either password, but only the Permissions password allows the user to change the restricted features.
Used crypto algorithms were being improved with PDF developing - up to PDF version 1.4 only 40-bit keys have been used, then the 128-bit ones came, and starting from version 1.6, AES encryption is being added. In Acrobat 9, 256-bit AES keys were introduced.
However, PDF security system is implemented so that a file with restrictions may be decrypted instantly, irrespective of the password length, even for 256-bit keys. A document with password for opening, using 40-bit key, can be decrypted on a modern computer in less than a day by using guaranteed decryption. To open a document with 128 or 256-bit key, only PDF brute force software can be used.
What pdfdecrypt can not do
the PDF encrypted with User Password, and you do not know it.
the PDF with 256-bit AES encryption or any third party encryption,such as DRM
the PDF with Certificate encryption(If you want this feature, please contact with me
the PDF is bigger than 10M(for upload)
If you forgot the user password, please try pdfcrack
If you want to desktop version pdfcrypt, please try pdfcrypt
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