List of blog entries

  • 2021-10-10 @Matthias Valvekens
    PDF As She Is Wrote #2: The quirks of PDF public-key encryption

    The previous instalment in this series had to do with digital signing in PDF. This post is about another, lesser known application of PKI in PDF: using PKI to encrypt PDF files. The idea is that this allows you to encrypt a PDF file with key material from one or more X.509 certificates, so that only the designated recipients can decrypt the document using their respective private keys.

    Read »

  • 2021-09-29 @Matthias Valvekens
    FOSDEM 2021 talk: Document security and digital signatures in PDF

    Last February, I gave a talk on PDF’s security features at FOSDEM ’21. The session was recorded, and is embedded below. This was my first talk at a non-maths conference; take that as you will.

    Read »

  • 2021-09-22 @Matthias Valvekens
    PDF As She Is Wrote #1: How are signers identified?

    This is the first installment in PDF as She Is Wrote . With this post, I intend to start a series on the way the PDF standards (mainly ISO 32000-x) are implemented in the “real world”. The focus is on implementation behaviour, not the minutiae of what the standard says (or should say), although I’ll occasionally comment on that as well. Given my area of interest, a significant portion of the content will relate to digital signing in some way.

    Read »