Pure-Ruby framework for parsing, modifying, and creating PDF files, with lazy on-demand parsing: compression filters with predictors, RC4/AES encryption (including Revision 6), digital signatures and usage rights, file attachments, AcroForm/XFA forms, and object streams. Ships CLI tools including `pdfcop` for detecting dangerous PDF content (not a full malware-analysis/forensics suite by the author's own description) plus decompression, decryption, encryption, resource-extraction, and metadata-inspection utilities.