/usr/include/digidocpp/ is in libdigidocpp-dev 0.3.0-0ubuntu11.
This file is owned by root:root, with mode 0o755.
..
/usr/include/digidocpp/ADoc.h
/usr/include/digidocpp/BDoc.h
/usr/include/digidocpp/BDocException.h
/usr/include/digidocpp/Conf.h
/usr/include/digidocpp/DDoc.h
/usr/include/digidocpp/Document.h
/usr/include/digidocpp/Exception.h
/usr/include/digidocpp/Exports.h
/usr/include/digidocpp/Signature.h
/usr/include/digidocpp/SignatureAttributes.h
/usr/include/digidocpp/SignatureBES.h
/usr/include/digidocpp/SignatureException.h
/usr/include/digidocpp/SignatureMobile.h
/usr/include/digidocpp/SignatureTM.h
/usr/include/digidocpp/WDoc.h
/usr/include/digidocpp/XmlConf.h
/usr/include/digidocpp/crypto/
/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
/usr/include/digidocpp/io/
/usr/include/digidocpp/io/IOException.h
/usr/include/digidocpp/io/ISerialize.h
/usr/include/digidocpp/io/ZipSerialize.h
/usr/include/digidocpp/util/
/usr/include/digidocpp/util/String.h
/usr/include/digidocpp/xml/
/usr/include/digidocpp/xml/XAdES.hxx
/usr/include/digidocpp/xml/conf.hxx
/usr/include/digidocpp/xml/xmldsig-core-schema.hxx