Standard PDF security-filter cryptography is implemented from scratch in JavaScript: MD5, SHA-256/384/512, RC4 and AES-128/256.
Unlock support: revision 2 / 3 (RC4), revision 4 (RC4 or AES-128, incl. EncryptMetadata=false), revision 5 (AES-256, PDF 1.7) and revision 6 (AES-256, PDF 2.0). Owner and user passwords are both recognized. The output is rewritten with a fresh classic xref table; object/string encryption is undone byte-for-byte.
Encrypt support: writes RC4-128 (R=3, V=2) or AES-128 (R=4, V=4) with a /StdCF crypt filter, a random document ID and your chosen permission flags.
PDFs that embed most objects inside compressed object streams (ObjStm) are handled at the stream level; if the document catalog is inside such a stream, it is recovered automatically when the browser’s built-in decompressor is available.
Everything runs locally. Nothing is uploaded, stored or logged.