ptth/bare_minimum_crypto/cpp/receiver.cpp

127 lines
2.9 KiB
C++

#include "receiver.h"
#include <sodium.h>
#include "json.hpp"
#include "expiring_signature.h"
#include "sodium_helpers.h"
#include "string_helpers.h"
#include "time_helpers.h"
namespace BareMinimumCrypto::Receiver {
using nlohmann::json;
bool is_pubkey_length (const vector <uint8_t> & v) {
return v.size () == crypto_sign_PUBLICKEYBYTES;
}
optional <vector <uint8_t>> try_verify_signed_data (
const vector <uint8_t> & pubkey,
const ExpiringSignature & sig,
Instant now
) {
try_sodium_init ();
if (! is_pubkey_length (pubkey)) {
return nullopt;
}
if (crypto_sign_verify_detached (
sig.sig.data (),
(const uint8_t *)sig.cert_s.data (),
sig.cert_s.size (),
pubkey.data ()
) != 0) {
return nullopt;
}
const json j = json::parse (sig.cert_s);
const TimeRange tr {
j ["not_before"],
j ["not_after"]
};
if (! tr.contains (now)) {
return nullopt;
}
const string payload_b64 = j ["payload_b64"];
const auto payload = std::move (*BareMinimumCrypto::base64_decode (payload_b64));
return payload;
}
optional <vector <uint8_t>> verify_signed_data (
const vector <uint8_t> & pubkey,
const ExpiringSignature & sig,
Instant now
) {
try {
return try_verify_signed_data (pubkey, sig, now);
}
catch (json::exception &) {
return nullopt;
}
}
optional <vector <uint8_t>> verify_cert_and_data (
const vector <uint8_t> & root_pubkey,
const ExpiringSignature & signed_cert,
const ExpiringSignature & signed_data,
Instant now
) {
auto subkey_opt = verify_signed_data (root_pubkey, signed_cert, now);
if (! subkey_opt) {
return nullopt;
}
const auto subkey = std::move (*subkey_opt);
return verify_signed_data (subkey, signed_data, now);
}
optional <vector <uint8_t>> verify_cert_and_data (
const vector <uint8_t> & root_pubkey,
const ExpiringSignature & signed_cert,
const ExpiringSignature & signed_data
) {
return verify_cert_and_data (root_pubkey, signed_cert, signed_data, Instant::now ());
}
optional <vector <uint8_t>> try_verify_cert_and_data (
const vector <uint8_t> & root_pubkey,
const string & json_string,
Instant now
) {
const json j = json::parse (json_string);
ExpiringSignature cert;
cert.sig = *base64_decode (j ["cert"]["sig_b64"]);
cert.cert_s = j ["cert"]["payload_s"];
auto subkey_opt = verify_signed_data (root_pubkey, cert, now);
const auto subkey = std::move (*subkey_opt);
ExpiringSignature data;
data.sig = *base64_decode (j ["data"]["sig_b64"]);
data.cert_s = j ["data"]["payload_s"];
return verify_signed_data (subkey, data, now);
}
optional <vector <uint8_t>> verify_cert_and_data (
const vector <uint8_t> & root_pubkey,
const string & json_string
) {
try {
return try_verify_cert_and_data (root_pubkey, json_string, Instant::now ());
}
catch (json::exception &) {
return nullopt;
}
}
}