CleartextSignature.h

/*
CleartextSignature.h
OpenPGP Cleartext Signature Framework data structure (RFC 4880 sec 7)

Copyright (c) 2013 - 2018 Jason Lee @ calccrypto at gmail.com

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*/

#ifndef __OPENPGP_CLEARTEXT_SIGNATURE__
#define __OPENPGP_CLEARTEXT_SIGNATURE__

#include "Misc/sigcalc.h"
#include "PGP.h"
#include "DetachedSignature.h"

namespace OpenPGP {
    // 7. Cleartext Signature Framework
    //
    //   It is desirable to be able to sign a textual octet stream without
    //   ASCII armoring the stream itself, so the signed text is still
    //   readable without special software. In order to bind a signature to
    //   such a cleartext, this framework is used. (Note that this framework
    //   is not intended to be reversible. RFC 3156 [RFC3156] defines another
    //   way to sign cleartext messages for environments that support MIME.)
    //
    //   The cleartext signed message consists of:
    //
    //     - The cleartext header ’-----BEGIN PGP SIGNED MESSAGE-----’ on a
    //       single line,
    //
    //     - One or more "Hash" Armor Headers,
    //
    //     - Exactly one empty line not included into the message digest,
    //
    //     - The dash-escaped cleartext that is included into the message
    //       digest,
    //
    //     - The ASCII armored signature(s) including the ’-----BEGIN PGP
    //       SIGNATURE-----’ Armor Header and Armor Tail Lines.
    //
    //   If the "Hash" Armor Header is given, the specified message digest
    //   algorithm(s) are used for the signature. If there are no such
    //   headers, MD5 is used. If MD5 is the only hash used, then an
    //   implementation MAY omit this header for improved V2.x compatibility.
    //   If more than one message digest is used in the signature, the "Hash"
    //   armor header contains a comma-delimited list of used message digests.
    //   Current message digest names are described below with the algorithm
    //   IDs.
    //
    //   An implementation SHOULD add a line break after the cleartext, but
    //   MAY omit it if the cleartext ends with a line break. This is for
    //   visual clarity.

    class CleartextSignature {
        private:
            PGP::Armor_Keys hash_armor_header;
            std::string message;
            DetachedSignature sig;

        public:
            typedef std::shared_ptr <CleartextSignature> Ptr;

            CleartextSignature();
            CleartextSignature(const CleartextSignature & copy);
            CleartextSignature(const std::string & data);
            CleartextSignature(std::istream & stream);

            void read(const std::string & data);
            void read(std::istream & stream);
            std::string show(const std::size_t indents = 0, const std::size_t indent_size = 4) const;
            std::string write(const Packet::Tag::Format header = Packet::Tag::Format::DEFAULT) const;

            PGP::Armor_Keys get_hash_armor_header() const;
            std::string get_message() const;
            DetachedSignature get_sig() const;

            void set_hash_armor_header(const PGP::Armor_Keys & keys);
            void set_message(const std::string & data);
            void set_sig(const DetachedSignature & s);

            static std::string dash_escape(const std::string & text);
            static std::string reverse_dash_escape(const std::string & text);
            std::string data_to_text() const;                            // remove trailing whitespace
            static std::string data_to_text(const std::string & text);   // remove trailing whitespace

            bool meaningful() const;

            CleartextSignature & operator=(const CleartextSignature & copy);
            CleartextSignature::Ptr clone() const;
    };

}

#endif