(Breaking PDF Encryption and PDF Signatures)
PDF is the most widely used standard for office documents. Supported by many desktop applications, email gateways and web services solutions, are used in all sectors, including government, business and private fields. For protecting sensitive information, PDFs can be encrypted and digitally signed. Assumed to be secure for 15 years, our talk reveals how to break PDF Encryption and how to break PDF Signatures. We elaborated novel attacks leading to critical vulnerabilities in all PDF viewers, most notably in Adobe, Foxit, and Okular. As a result, an attacker can retrieve the plaintext of encrypted PDFs without knowing the password and manipulate the content of digitally signed PDFs arbitrarily while a victim is unable to detect this.
