ssize_t
pwbox_encoded_parse(pwbox_encoded_t **output, const uint8_t *input, const size_t len_in)
{
ssize_t result;
*output = pwbox_encoded_new();
if (NULL == *output)
return -1;
result = pwbox_encoded_parse_into(*output, input, len_in);
if (result < 0) {
pwbox_encoded_free(*output);
*output = NULL;
}
return result;
}
/**
* Make an authenticated passphrase-encrypted blob to encode the
* <b>input_len</b> bytes in <b>input</b> using the passphrase
* <b>secret</b> of <b>secret_len</b> bytes. Allocate a new chunk of memory
* to hold the encrypted data, and store a pointer to that memory in
* *<b>out</b>, and its size in <b>outlen_out</b>. Use <b>s2k_flags</b> as an
* argument to the passphrase-hashing function.
*/
int
crypto_pwbox(uint8_t **out, size_t *outlen_out,
const uint8_t *input, size_t input_len,
const char *secret, size_t secret_len,
unsigned s2k_flags)
{
uint8_t *result = NULL, *encrypted_portion;
size_t encrypted_len = 128 * CEIL_DIV(input_len+4, 128);
ssize_t result_len;
int spec_len;
uint8_t keys[CIPHER_KEY_LEN + DIGEST256_LEN];
pwbox_encoded_t *enc = NULL;
ssize_t enc_len;
crypto_cipher_t *cipher;
int rv;
enc = pwbox_encoded_new();
pwbox_encoded_setlen_skey_header(enc, S2K_MAXLEN);
spec_len = secret_to_key_make_specifier(
pwbox_encoded_getarray_skey_header(enc),
S2K_MAXLEN,
s2k_flags);
if (BUG(spec_len < 0 || spec_len > S2K_MAXLEN))
goto err;
pwbox_encoded_setlen_skey_header(enc, spec_len);
enc->header_len = spec_len;
crypto_rand((char*)enc->iv, sizeof(enc->iv));
pwbox_encoded_setlen_data(enc, encrypted_len);
encrypted_portion = pwbox_encoded_getarray_data(enc);
set_uint32(encrypted_portion, htonl((uint32_t)input_len));
memcpy(encrypted_portion+4, input, input_len);
/* Now that all the data is in position, derive some keys, encrypt, and
* digest */
const int s2k_rv = secret_to_key_derivekey(keys, sizeof(keys),
pwbox_encoded_getarray_skey_header(enc),
spec_len,
secret, secret_len);
if (BUG(s2k_rv < 0))
goto err;
cipher = crypto_cipher_new_with_iv((char*)keys, (char*)enc->iv);
crypto_cipher_crypt_inplace(cipher, (char*)encrypted_portion, encrypted_len);
crypto_cipher_free(cipher);
result_len = pwbox_encoded_encoded_len(enc);
if (BUG(result_len < 0))
goto err;
result = tor_malloc(result_len);
enc_len = pwbox_encoded_encode(result, result_len, enc);
if (BUG(enc_len < 0))
goto err;
tor_assert(enc_len == result_len);
crypto_hmac_sha256((char*) result + result_len - 32,
(const char*)keys + CIPHER_KEY_LEN,
DIGEST256_LEN,
(const char*)result,
result_len - 32);
*out = result;
*outlen_out = result_len;
rv = 0;
goto out;
err:
/* LCOV_EXCL_START
This error case is often unreachable if we're correctly coded, unless
somebody adds a new error case somewhere, or unless you're building
without scrypto support.
- make_specifier can't fail, unless S2K_MAX_LEN is too short.
- secret_to_key_derivekey can't really fail unless we're missing
scrypt, or the underlying function fails, or we pass it a bogus
algorithm or parameters.
- pwbox_encoded_encoded_len can't fail unless we're using trunnel
incorrectly.
- pwbox_encoded_encode can't fail unless we're using trunnel wrong,
or it's buggy.
*/
tor_free(result);
rv = -1;
/* LCOV_EXCL_STOP */
out:
pwbox_encoded_free(enc);
memwipe(keys, 0, sizeof(keys));
return rv;
}
