"Burdens of Proof: Cryptographic Culture and Evidence Law in the Age of Electronic Documents" by Jean-François Blanchette is underappreciated by cryptographers. Go read it: mitpress.mit.edu/978026201751...

Burdens of Proof

An examination of the challenges of establishing the authenticity of electronic documents—in particular the design of a cryptographic equivalent to handwri...

yeah yeah yeah, the author has a thing for steganography, but there's so much gold in this book, especially Chapter 4. If you take my "advanced topics in cryptography" module in autumn, you'll hear about it.