Two locks on one PDF: who can open it, and what they can do.
An open password encrypts the whole file, so nobody reads it without the password. A permissions password lets people read but stops printing, copying or editing. Set either or both, and preview what the recipient will see.
Nobody attacks AES-256 itself; they guess passwords, billions per second on a gaming graphics card. Length matters far more than symbols. Build a password below and see how long a determined guesser would need.
iu7hHtrBlo2pPDF’s Standard security handler turns your passwords into two 32-byte values, /O and /U, using MD5 and RC4. A reader checks a typed password by redoing the same maths and comparing with /U, so the file can tell right from wrong without ever storing the password. These values are computed live from the passwords you set above, with the algorithms in ISO 32000.
/Filter/StandardThe built-in password handler./V /R4 · 4Version 4 uses crypt filters; revision 4 is the AES-128 handler (PDF 1.6)./P-4 (0xFFFFFFFC)Permission flags as a signed 32-bit integer: see the bit table below./O<70c45827b7bb12a982e75dafb143a0c2309bfc0143cfb77294c7e4620a7fc486>RC4 of the padded open password, keyed by MD5×51 of the open password, 20 passes./U<134e1fc5b2b6cdeb02bf5ec17e9be5d500000000000000000000000000000000>RC4 of MD5(padding + /ID), keyed by the file key, 20 passes; last 16 bytes are filler./ID[0]<26dc702722829369eacb5d8b27debd86>Random per file, so the same password gives different /O and /U in different PDFs.file key55f24d565163e5020c38a88a236cd981MD5×51 of (padded password + /O + /P + /ID). Never stored: readers recompute it.object key666b492fa4e571423dd443f77455fcb3 (obj 4)MD5 of file key + object and generation number + “sAlT”. Each object gets its own key.password bytes54756c69702d486172626f75… + paddingPasswords are padded to 32 bytes with a fixed string from the spec; longer ones are cut at 32.The steps appear here as you type.42 54 20 2f 46 31 20 32 30 20 54 66 20 37 32 20 37 36 30 20 54 64 20 28 50 61 79 72 6f 6c 6c 20 73 75 6d 6d 61 72 79 20 2d 20 51 33 29 20 54 6aas stored in the file07 07 07 07 07 07 07 07 07 07 07 07 07 07 07 07 03 42 b4 0a 51 37 78 01 1c 92 4d fc 8c df 75 e8 69 ec 4a 69 b9 ff 4e 01 74 10 d9 ea 97 d6 dd 5bAn open password truly encrypts the content. "No printing" and "no copying" only work because PDF readers agree to honour them; the text itself isn't hidden. Useful to stop casual copying, not a determined person.
If both arrive in the same email, anyone who gets the email gets everything. Pick how you'll send the PDF to see a safer channel for the password.
Each revision of the Standard handler fixed a weakness in the one before. The rows marked “this page” are what the download above produces; R6 needs SHA-384 and SHA-512 key hashing, which this in-browser demo doesn’t implement.
bit 3Printallowedbit 4Modify contentsallowedbit 5Copy text and graphicsallowedbit 6Add annotations, fill formsallowedbit 9Fill forms (even if 6 is off)allowedbit 10Extract for accessibilityallowedbit 11Assemble: insert, rotate, delete pagesallowedbit 12High-quality printallowedPDF tools people use alongside this one.