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/* This example demonstrates how to use the low-level interface to
decrypt a file. */
#define _GNU_SOURCE
#include <assert.h>
/* Roughly glibc compatible error reporting. */
#define error(S, E, F, ...) do { \
fprintf (stderr, (F), __VA_ARGS__); \
int s = (S), e = (E); \
if (e) { fprintf (stderr, ": %s", strerror (e)); } \
fprintf (stderr, "\n"); \
fflush (stderr); \
if (s) { exit (s); } \
} while (0)
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sequoia/openpgp.h>
struct decrypt_cookie {
pgp_cert_t key;
int decrypt_called;
};
static pgp_status_t
get_public_keys_cb (void *cookie_raw,
pgp_keyid_t *keyids, size_t keyids_len,
pgp_cert_t **certs, size_t *cert_len,
void (**our_free)(void *))
{
/* Feed the Certs to the verifier here. */
*certs = NULL;
*cert_len = 0;
*our_free = free;
return PGP_STATUS_SUCCESS;
}
static pgp_status_t
check_cb (void *cookie_opaque, pgp_message_structure_t structure)
{
pgp_message_structure_iter_t iter = pgp_message_structure_iter (structure);
for (pgp_message_layer_t layer = pgp_message_structure_iter_next (iter);
layer;
layer = pgp_message_structure_iter_next (iter)) {
uint8_t algo;
uint8_t aead_algo;
pgp_verification_result_iter_t results;
switch (pgp_message_layer_variant (layer)) {
case PGP_MESSAGE_LAYER_COMPRESSION:
pgp_message_layer_compression (layer, &algo);
fprintf (stderr, "Compressed using %d\n", algo);
break;
case PGP_MESSAGE_LAYER_ENCRYPTION:
pgp_message_layer_encryption (layer, &algo, &aead_algo);
if (aead_algo) {
fprintf (stderr, "Encrypted and protected using %d/%d\n",
algo, aead_algo);
} else {
fprintf (stderr, "Encrypted using %d\n", algo);
}
break;
case PGP_MESSAGE_LAYER_SIGNATURE_GROUP:
pgp_message_layer_signature_group (layer, &results);
for (pgp_verification_result_t result =
pgp_verification_result_iter_next (results);
result;
result = pgp_verification_result_iter_next (results)) {
pgp_signature_t sig = NULL;
pgp_key_t key = NULL;
pgp_keyid_t keyid;
char *keyid_str = NULL;
pgp_error_t err = NULL;
char *err_str = NULL;
switch (pgp_verification_result_variant (result)) {
case PGP_VERIFICATION_RESULT_GOOD_CHECKSUM:
pgp_verification_result_good_checksum (result, NULL, NULL,
&key, NULL, NULL);
keyid = pgp_key_keyid (key);
keyid_str = pgp_keyid_to_string (keyid);
fprintf (stderr, "Good signature from %s\n", keyid_str);
break;
case PGP_VERIFICATION_RESULT_MALFORMED_SIGNATURE:
pgp_verification_result_malformed_signature (result, NULL, &err);
err_str = pgp_error_to_string (err);
fprintf (stderr, "Malformed signature: %s\n", err_str);
break;
case PGP_VERIFICATION_RESULT_MISSING_KEY:
pgp_verification_result_missing_key (result, &sig);
keyid = pgp_signature_issuer (sig);
keyid_str = pgp_keyid_to_string (keyid);
fprintf (stderr, "No key to check signature from %s\n", keyid_str);
break;
case PGP_VERIFICATION_RESULT_UNBOUND_KEY:
pgp_verification_result_unbound_key (result, NULL, NULL, &err);
err_str = pgp_error_to_string (err);
fprintf (stderr, "Signing key not bound: %s\n", err_str);
break;
case PGP_VERIFICATION_RESULT_BAD_KEY:
pgp_verification_result_bad_key (result, NULL, NULL, NULL,
NULL, NULL, &err);
err_str = pgp_error_to_string (err);
fprintf (stderr, "Bad signing key: %s\n", err_str);
break;
case PGP_VERIFICATION_RESULT_BAD_SIGNATURE:
pgp_verification_result_bad_signature (result, NULL, NULL, NULL,
NULL, NULL, &err);
err_str = pgp_error_to_string (err);
fprintf (stderr, "Bad signature: %s\n", err_str);
break;
default:
assert (! "reachable");
}
free (keyid_str);
free (err_str);
pgp_error_free (err);
pgp_signature_free (sig);
pgp_key_free (key);
pgp_verification_result_free (result);
}
pgp_verification_result_iter_free (results);
break;
default:
assert (! "reachable");
}
pgp_message_layer_free (layer);
}
pgp_message_structure_iter_free (iter);
pgp_message_structure_free (structure);
/* Implement your verification policy here. */
return PGP_STATUS_SUCCESS;
}
static pgp_status_t
decrypt_cb (void *cookie_opaque,
pgp_pkesk_t *pkesks, size_t pkesk_count,
pgp_skesk_t *skesks, size_t skesk_count,
uint8_t sym_algo_hint,
pgp_decryptor_do_decrypt_cb_t *decrypt,
void *decrypt_cookie,
pgp_fingerprint_t *identity_out)
{
pgp_status_t rc;
pgp_error_t err;
struct decrypt_cookie *cookie = cookie_opaque;
/* Prevent iterations, we only have one key to offer. */
assert (!cookie->decrypt_called);
cookie->decrypt_called = 1;
for (int i = 0; i < pkesk_count; i++) {
pgp_pkesk_t pkesk = pkesks[i];
pgp_keyid_t keyid = pgp_pkesk_recipient (pkesk);
pgp_cert_key_iter_t key_iter = pgp_cert_key_iter (cookie->key);
pgp_key_amalgamation_t ka;
pgp_key_t key;
while ((ka = pgp_cert_key_iter_next (key_iter))) {
key = pgp_key_amalgamation_key (ka);
pgp_keyid_t this_keyid = pgp_key_keyid (key);
int match = pgp_keyid_equal (this_keyid, keyid);
pgp_keyid_free (this_keyid);
if (match)
break;
pgp_key_free (key);
pgp_key_amalgamation_free (ka);
}
pgp_cert_key_iter_free (key_iter);
pgp_keyid_free (keyid);
if (! key)
continue;
uint8_t algo;
uint8_t session_key[1024];
size_t session_key_len = sizeof session_key;
if (pgp_pkesk_decrypt (&err,
pkesk, key, &algo,
session_key, &session_key_len)) {
error (1, 0, "pgp_pkesk_decrypt: %s", pgp_error_to_string (err));
}
pgp_key_free (key);
pgp_key_amalgamation_free (ka);
pgp_session_key_t sk = pgp_session_key_from_bytes (session_key,
session_key_len);
rc = decrypt (decrypt_cookie, algo, sk);
pgp_session_key_free (sk);
*identity_out = pgp_cert_fingerprint (cookie->key);
return rc;
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