GpgRecvStore.h

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#pragma once
 
#include <cstdint>
#include <cstddef>
 
namespace cdc::mod_gpg {
 
constexpr uint8_t kGpgRecvFlagVerified = 0x01;

#pragma pack(push, 1)
struct gpg_recv_key_t {
    uint8_t  curve;
    char     user_id[64];
    uint8_t  pubkey[64];
    uint8_t  pubkey_len;
    uint32_t created_at;
    uint8_t  fingerprint_v4[20];
    uint8_t  fingerprint_v5[32];
    uint32_t received_at;
    uint8_t  my_signature[64];
    uint8_t  sig_len;
    uint32_t sig_created_at;
    // DEC (RFC 6637 ECDH P-256) encryption subkey and the two signatures the
    // peer produced over it. Cannot be forged locally; replayed verbatim into
    // the armored export. All-zero when absent.
    uint8_t  pubkey_dec[64];
    uint32_t created_at_dec;
    uint8_t  owner_self_sig[64];
    uint8_t  dec_binding_sig[64];
    uint8_t  flags;
};
#pragma pack(pop)
 
static_assert(sizeof(gpg_recv_key_t) ==
              (1 + 64 + 64 + 1 + 4 + 20 + 32 + 4 + 64 + 1 + 4 +
               64 + 4 + 64 + 64 + 1),
              "gpg_recv_key_t layout drift");

struct gpg_recv_index_entry_t {
    char     nvs_key[16];
    uint32_t received_at;
    uint8_t  flags;
};

class GpgRecvStore {
public:
    static constexpr uint8_t kMaxKeys = 128;
 
    static GpgRecvStore& instance();

    bool addKey(const gpg_recv_key_t& key);

    uint8_t count();

    uint8_t listIndex(gpg_recv_index_entry_t* out, uint8_t max);

    bool getKey(uint8_t index, gpg_recv_key_t* out);

    bool deleteKey(uint8_t index);

    bool setSignature(uint8_t index,
                      const uint8_t* sig, uint8_t sig_len,
                      uint32_t sig_created_at,
                      uint8_t flags);
 
private:
    GpgRecvStore() = default;
    GpgRecvStore(const GpgRecvStore&) = delete;
    GpgRecvStore& operator=(const GpgRecvStore&) = delete;

    static void deriveKeyName(const uint8_t fp_v4[20], char out[16]);

    bool readByName(const char* nvs_key, gpg_recv_key_t* out);

    bool writeByName(const char* nvs_key, const gpg_recv_key_t& key);

    bool resolveKeyName(uint8_t index, char out[16]);
};
 
} // namespace cdc::mod_gpg