Dear Maintainer, This issue was fixed in cryptodrome [1] and I can build successfully your package in a sid chroot environment for amd64 architecture. I guess the failure still persists on armel and mips64el [2] (not verified).
∙ ∙ missing build on armel ∙ ∙ missing build on mips64el [1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1052336 [2] https://tracker.debian.org/pkg/pycryptodome