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refactor toxencryptedsave to allow passphrase encryption of arbitrary data

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also a minor API change for clarity
This commit is contained in:
dubslow 2014-10-08 18:14:23 -05:00
parent eee37b5767
commit e6f30694d3
3 changed files with 87 additions and 36 deletions
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2
auto_tests/encryptsave_test.c
View File

@ -65,7 +65,7 @@ START_TEST(test_save_friend)
uint8_t data[size];
test = tox_encrypted_save(tox1, data, "correcthorsebatterystaple", 25);
ck_assert_msg(test == 0, "failed to encrypted save");
ck_assert_msg(tox_is_data_encrypted(data) == 1, "magic number missing");
ck_assert_msg(tox_is_save_encrypted(data) == 1, "magic number missing");
Tox *tox3 = tox_new(0);
test = tox_encrypted_load(tox3, data, size, "correcthorsebatterystaple", 25);
ck_assert_msg(test == 0, "failed to encrypted load");

97
toxencryptsave/toxencryptsave.c
View File

@ -44,17 +44,16 @@
/* return size of the messenger data (for encrypted saving). */
uint32_t tox_encrypted_size(const Tox *tox)
{
return tox_size(tox) + crypto_box_MACBYTES + crypto_box_NONCEBYTES
+ crypto_pwhash_scryptsalsa208sha256_SALTBYTES + TOX_ENC_SAVE_MAGIC_LENGTH;
return tox_size(tox) + TOX_PASS_ENCRYPTION_EXTRA_LENGTH + TOX_ENC_SAVE_MAGIC_LENGTH;
}
/* Save the messenger data encrypted with the given password.
* data must be at least tox_encrypted_size().
/* Encrypts the given data with the given passphrase. The output array must be
* at least data_len + TOX_PASS_ENCRYPTION_EXTRA_LENGTH bytes long.
*
* returns 0 on success
* returns -1 on failure
*/
int tox_encrypted_save(const Tox *tox, uint8_t *data, uint8_t *passphrase, uint32_t pplength)
int tox_pass_encrypt(uint8_t* data, uint32_t data_len, uint8_t* passphrase, uint32_t pplength, uint8_t* out)
{
if (pplength == 0)
return -1;
@ -79,15 +78,10 @@ int tox_encrypted_save(const Tox *tox, uint8_t *data, uint8_t *passphrase, uint3
sodium_memzero(passkey, crypto_hash_sha256_BYTES); /* wipe plaintext pw */
/* next get plain save data */
uint32_t temp_size = tox_size(tox);
uint8_t temp_data[temp_size];
tox_save(tox, temp_data);
/* the output data consists of, in order:
* magic number, salt, nonce, mac, enc_data
* salt, nonce, mac, enc_data
* where the mac is automatically prepended by the encrypt()
* the magic+salt+nonce is called the prefix
* the salt+nonce is called the prefix
* I'm not sure what else I'm supposed to do with the salt and nonce, since we
* need them to decrypt the data
*/
@ -96,40 +90,56 @@ int tox_encrypted_save(const Tox *tox, uint8_t *data, uint8_t *passphrase, uint3
uint8_t nonce[crypto_box_NONCEBYTES];
random_nonce(nonce);
memcpy(data, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH);
data += TOX_ENC_SAVE_MAGIC_LENGTH;
memcpy(data, salt, crypto_pwhash_scryptsalsa208sha256_SALTBYTES);
data += crypto_pwhash_scryptsalsa208sha256_SALTBYTES;
memcpy(data, nonce, crypto_box_NONCEBYTES);
data += crypto_box_NONCEBYTES;
memcpy(out, salt, crypto_pwhash_scryptsalsa208sha256_SALTBYTES);
out += crypto_pwhash_scryptsalsa208sha256_SALTBYTES;
memcpy(out, nonce, crypto_box_NONCEBYTES);
out += crypto_box_NONCEBYTES;
/* now encrypt */
if (encrypt_data_symmetric(key, nonce, temp_data, temp_size, data)
!= temp_size + crypto_box_MACBYTES) {
if (encrypt_data_symmetric(key, nonce, data, data_len, out)
!= data_len + crypto_box_MACBYTES) {
return -1;
}
return 0;
}
/* Load the messenger from encrypted data of size length.
/* Save the messenger data encrypted with the given password.
* data must be at least tox_encrypted_size().
*
* returns 0 on success
* returns -1 on failure
*/
int tox_encrypted_load(Tox *tox, const uint8_t *data, uint32_t length, uint8_t *passphrase, uint32_t pplength)
int tox_encrypted_save(const Tox *tox, uint8_t *data, uint8_t *passphrase, uint32_t pplength)
{
if (length <= crypto_box_MACBYTES + crypto_box_NONCEBYTES + crypto_pwhash_scryptsalsa208sha256_SALTBYTES +
TOX_ENC_SAVE_MAGIC_LENGTH)
return -1;
if (memcmp(data, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH) != 0)
return -1;
/* first get plain save data */
uint32_t temp_size = tox_size(tox);
uint8_t temp_data[temp_size];
tox_save(tox, temp_data);
/* the output data consists of, in order: magic number, enc_data */
/* first add the magic number */
memcpy(data, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH);
data += TOX_ENC_SAVE_MAGIC_LENGTH;
uint32_t decrypt_length = length - crypto_box_MACBYTES - crypto_box_NONCEBYTES
- crypto_pwhash_scryptsalsa208sha256_SALTBYTES - TOX_ENC_SAVE_MAGIC_LENGTH;
/* now encrypt */
return tox_pass_encrypt(temp_data, temp_size, passphrase, pplength, data);
}
/* Decrypts the given data with the given passphrase. The output array must be
* at least data_len - TOX_PASS_ENCRYPTION_EXTRA_LENGTH bytes long.
*
* returns the length of the output data (== data_len - TOX_PASS_ENCRYPTION_EXTRA_LENGTH) on success
* returns -1 on failure
*/
int tox_pass_decrypt(const uint8_t* data, uint32_t length, uint8_t* passphrase, uint32_t pplength, uint8_t* out)
{
if (length <= TOX_PASS_ENCRYPTION_EXTRA_LENGTH)
return -1;
uint32_t decrypt_length = length - TOX_PASS_ENCRYPTION_EXTRA_LENGTH;
uint8_t salt[crypto_pwhash_scryptsalsa208sha256_SALTBYTES];
uint8_t nonce[crypto_box_NONCEBYTES];
@ -155,13 +165,32 @@ int tox_encrypted_load(Tox *tox, const uint8_t *data, uint32_t length, uint8_t *
sodium_memzero(passkey, crypto_hash_sha256_BYTES); /* wipe plaintext pw */
/* decrypt the data */
uint8_t temp_data[decrypt_length];
if (decrypt_data_symmetric(key, nonce, data, decrypt_length + crypto_box_MACBYTES, temp_data)
if (decrypt_data_symmetric(key, nonce, data, decrypt_length + crypto_box_MACBYTES, out)
!= decrypt_length) {
return -1;
}
return decrypt_length;
}
/* Load the messenger from encrypted data of size length.
*
* returns 0 on success
* returns -1 on failure
*/
int tox_encrypted_load(Tox *tox, const uint8_t *data, uint32_t length, uint8_t *passphrase, uint32_t pplength)
{
if (memcmp(data, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH) != 0)
return -1;
data += TOX_ENC_SAVE_MAGIC_LENGTH; length -= TOX_ENC_SAVE_MAGIC_LENGTH;
uint32_t decrypt_length = length - TOX_PASS_ENCRYPTION_EXTRA_LENGTH;
uint8_t temp_data[decrypt_length];
if (tox_pass_decrypt(data, length, passphrase, pplength, temp_data)
!= decrypt_length)
return -1;
return tox_load(tox, temp_data, decrypt_length);
}
@ -170,7 +199,7 @@ int tox_encrypted_load(Tox *tox, const uint8_t *data, uint32_t length, uint8_t *
* returns 1 if it is encrypted
* returns 0 otherwise
*/
int tox_is_data_encrypted(const uint8_t *data)
int tox_is_save_encrypted(const uint8_t *data)
{
if (memcmp(data, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH) == 0)
return 1;

24
toxencryptsave/toxencryptsave.h
View File

@ -35,6 +35,8 @@ extern "C" {
typedef struct Tox Tox;
#endif
#define TOX_PASS_ENCRYPTION_EXTRA_LENGTH (crypto_box_MACBYTES + crypto_box_NONCEBYTES \
+ crypto_pwhash_scryptsalsa208sha256_SALTBYTES)
/* This "module" provides functions analogous to tox_load and tox_save in toxcore
* Clients should consider alerting their users that, unlike plain data, if even one bit
@ -45,6 +47,16 @@ typedef struct Tox Tox;
/* return size of the messenger data (for encrypted saving). */
uint32_t tox_encrypted_size(const Tox *tox);
/* Encrypts the given data with the given passphrase. The output array must be
* at least data_len + TOX_PASS_ENCRYPTION_EXTRA_LENGTH bytes long.
*
* tox_encrypted_save() is a good example of how to use this function.
*
* returns 0 on success
* returns -1 on failure
*/
int tox_pass_encrypt(uint8_t* data, uint32_t data_len, uint8_t* passphrase, uint32_t pplength, uint8_t* out);
/* Save the messenger data encrypted with the given password.
* data must be at least tox_encrypted_size().
*
@ -53,6 +65,16 @@ uint32_t tox_encrypted_size(const Tox *tox);
*/
int tox_encrypted_save(const Tox *tox, uint8_t *data, uint8_t *passphrase, uint32_t pplength);
/* Decrypts the given data with the given passphrase. The output array must be
* at least data_len - TOX_PASS_ENCRYPTION_EXTRA_LENGTH bytes long.
*
* tox_encrypted_load() is a good example of how to use this function.
*
* returns the length of the output data (== data_len - TOX_PASS_ENCRYPTION_EXTRA_LENGTH) on success
* returns -1 on failure
*/
int tox_pass_decrypt(const uint8_t* data, uint32_t length, uint8_t* passphrase, uint32_t pplength, uint8_t* out);
/* Load the messenger from encrypted data of size length.
*
* returns 0 on success
@ -65,7 +87,7 @@ int tox_encrypted_load(Tox *tox, const uint8_t *data, uint32_t length, uint8_t *
* returns 1 if it is encrypted
* returns 0 otherwise
*/
int tox_is_data_encrypted(const uint8_t *data);
int tox_is_save_encrypted(const uint8_t *data);
#ifdef __cplusplus
}