/usr/include/digidocpp/crypto/ is in libdigidocpp-dev 0.3.0-0ubuntu4.
This file is owned by root:root, with mode 0o755.
..
/usr/include/digidocpp/crypto/Digest.h
/usr/include/digidocpp/crypto/OpenSSLHelpers.h
/usr/include/digidocpp/crypto/cert/
/usr/include/digidocpp/crypto/cert/DirectoryX509CertStore.h
/usr/include/digidocpp/crypto/cert/X509Cert.h
/usr/include/digidocpp/crypto/cert/X509CertStore.h
/usr/include/digidocpp/crypto/crypt/
/usr/include/digidocpp/crypto/crypt/RSACrypt.h
/usr/include/digidocpp/crypto/ocsp/
/usr/include/digidocpp/crypto/ocsp/OCSP.h
/usr/include/digidocpp/crypto/ocsp/OCSPException.h
/usr/include/digidocpp/crypto/signer/
/usr/include/digidocpp/crypto/signer/EstEIDSigner.h
/usr/include/digidocpp/crypto/signer/PKCS11Signer.h
/usr/include/digidocpp/crypto/signer/RSASigner.h
/usr/include/digidocpp/crypto/signer/SignException.h
/usr/include/digidocpp/crypto/signer/Signer.h