Our book "Digital Signatures for PDF documents" published in 2013 was one of the most downloaded iText books ever. Its content is still relevant on a conceptual level, but it was time to write a new revision for more than one reason.
In July 2017, ISO 32000-2 was released. In this release several security handlers are now officially deprecated,
In February 2017, it was finally proven that signed documents using SHA-1 as hashing algorithm can be changed without breaking the signature,
In December 2016, iText Group filed a series of three patents that use Blockchain to solve some issues that are inherent to PDF Advanced Electronic Signatures (PAdES),
In May 2016, iText 7 was released. Although the digital signature functionality didn't change that much, it would be nice to have some updated examples.
Important functionality was added based on feedback on the publication (e.g. methods for deferred signing).
Many things have changed on the digital signatures front in the last five years, and rather than writing a revision of the first edition, we have chosen to rewrite the book from scratch.
In the first chapter, we'll look at some basic concepts: what do we want to achieve, and which concepts can help us meet those goals?
In chapter two, we apply those concepts to PDF. We'll learn about the minimum requirements to sign a document in the Portable Document Format.
In the third chapter, we'll look at some best practices, looking at different ways to store a private key, and ensuring the long-term validation of the signature.
In chapter four, we look at different architectures that can be used when creating a real-world application.
Chapter five discusses some advantages and disadvantages of wet ink signatures on paper versus digital signatures in PDF.
In the sixth chapter, we explain what Blockchain is about, and why Blockchain could solve some of the issues we identified when talking about PDF digital signatures.
In the final chapter, we explain the three patents filed by iText Group by means of a series of use cases.
We hope you'll enjoy this book; let's make it as popular as its predecessor.