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Working version of libexim-encrypt-dlfunc-decrypt-secretbox

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This commit is contained in:
Heiko Reese
2021-09-11 02:06:19 +02:00
parent 41e7c43ab8
commit ad3437f5df
2 changed files with 47 additions and 21 deletions
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57
src/libexim-encrypt-dlfunc-decrypt-secretbox.c
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@ -30,11 +30,11 @@ typedef enum {
} seen_args;
int main(int argc, char *argv[]) {
char* prog_basename = basename(argv[0]);
char *prog_basename = basename(argv[0]);
int opt;
char *cipherstring;
size_t pwlen;
char *b64password;
size_t password_len;
char *password;
char *password_env;
seen_args mode = NONE;
@ -57,9 +57,9 @@ int main(int argc, char *argv[]) {
// check environment for LIBEXIM_PASSWORD
password_env = getenv(ENVVAR_PASSWORD_NAME);
if (password_env != NULL && strlen(password_env) > 0) {
pwlen = strlen(password_env);
b64password = malloc(pwlen + 1);
strncpy(b64password, password_env, pwlen);
password_len = strlen((const char *) password_env);
password = malloc(password_len + 1);
strncpy(password, password_env, password_len);
mode |= PASSENV;
}
@ -69,9 +69,9 @@ int main(int argc, char *argv[]) {
long_options, &long_index)) != -1) {
switch (opt) {
case 'p':
pwlen = strlen(optarg);
b64password = malloc(pwlen + 1);
strncpy(b64password, optarg, pwlen);
password_len = strlen((const char *) optarg);
password = malloc(password_len + 1);
strncpy(password, optarg, password_len);
mode |= PASSARG;
break;
case 'f':
@ -96,16 +96,45 @@ int main(int argc, char *argv[]) {
exit(EXIT_FAILURE);
}
// fail if neither argument nor filename is present
// fail if neither argument nor filename for ciphertext is present
if (input == NONE) {
fprintf(stderr, "[ERROR] Please specify a ciphertext source.\n\n");
print_usage(prog_basename);
exit(EXIT_FAILURE);
}
// base64-decode password
Password p;
p = base64_decode_string(b64password);
// Derive key from the password.
unsigned char keybytes[crypto_secretbox_KEYBYTES];
sodium_memzero(keybytes, crypto_secretbox_KEYBYTES);
crypto_generichash(keybytes, crypto_secretbox_KEYBYTES,
(unsigned char *) password, password_len, NULL, 0);
printf("»%s« [%zu]\n", p.string, p.length);
// base64-decode input
unsigned char *ciphertext;
size_t ciphertext_len;
base64_decode_string(cipherstring, &ciphertext, &ciphertext_len);
// extract nonce
unsigned char nonce[crypto_secretbox_NONCEBYTES];
memcpy(nonce, ciphertext, crypto_secretbox_NONCEBYTES);
// prepare buffer for cleartext
if (ciphertext_len < crypto_secretbox_NONCEBYTES + crypto_secretbox_MACBYTES) {
fprintf(stderr, "[ERROR] Ciphertext is too small to contain any data.\n\n");
exit(EXIT_FAILURE);
}
size_t cleartext_len = ciphertext_len - crypto_secretbox_NONCEBYTES - crypto_secretbox_MACBYTES;
unsigned char *cleartext = (unsigned char *) malloc(cleartext_len + 1);
sodium_memzero(cleartext, cleartext_len + 1);
// decrypt
if (crypto_secretbox_open_easy(cleartext, &ciphertext[crypto_secretbox_NONCEBYTES],
ciphertext_len - crypto_secretbox_NONCEBYTES, nonce, keybytes) == 0) {
} else {
fprintf(stderr, "[ERROR] Unable to decrypt message.\n\n");
exit(EXIT_FAILURE);
}
// print cleartext to stdout
fprintf(stdout, "%s", (const char *) cleartext);
}