/work/toxencryptsave/toxencryptsave.c

Source (jump to first uncovered line)
/* SPDX-License-Identifier: GPL-3.0-or-later
 * Copyright © 2016-2018 The TokTok team.
 * Copyright © 2013 Tox project.
 */

/**
 * Batch encryption functions.
 */
#include "toxencryptsave.h"

#include <sodium.h>

#include <stdlib.h>
#include <string.h>

#include "../toxcore/ccompat.h"
#include "../toxcore/crypto_core.h"
#include "defines.h"

static_assert(TOX_PASS_SALT_LENGTH == crypto_pwhash_scryptsalsa208sha256_SALTBYTES,
              "TOX_PASS_SALT_LENGTH is assumed to be equal to crypto_pwhash_scryptsalsa208sha256_SALTBYTES");
static_assert(TOX_PASS_KEY_LENGTH == CRYPTO_SHARED_KEY_SIZE,
              "TOX_PASS_KEY_LENGTH is assumed to be equal to CRYPTO_SHARED_KEY_SIZE");
static_assert(TOX_PASS_ENCRYPTION_EXTRA_LENGTH == (crypto_box_MACBYTES + crypto_box_NONCEBYTES +
              crypto_pwhash_scryptsalsa208sha256_SALTBYTES + TOX_ENC_SAVE_MAGIC_LENGTH),
              "TOX_PASS_ENCRYPTION_EXTRA_LENGTH is assumed to be equal to (crypto_box_MACBYTES + crypto_box_NONCEBYTES + crypto_pwhash_scryptsalsa208sha256_SALTBYTES + TOX_ENC_SAVE_MAGIC_LENGTH)");

#define SET_ERROR_PARAMETER(param, x) \
    do {                              \
        if (param != nullptr) {       \
            *param = x;               \
        }                             \
    } while (0)

uint32_t tox_pass_salt_length(void)
{
    return TOX_PASS_SALT_LENGTH;
}
uint32_t tox_pass_key_length(void)
{
    return TOX_PASS_KEY_LENGTH;
}
uint32_t tox_pass_encryption_extra_length(void)
{
    return TOX_PASS_ENCRYPTION_EXTRA_LENGTH;
}

struct Tox_Pass_Key {
    uint8_t salt[TOX_PASS_SALT_LENGTH];
    uint8_t key[TOX_PASS_KEY_LENGTH];
};

void tox_pass_key_free(Tox_Pass_Key *key)
{
    free(key);
}

/* Clients should consider alerting their users that, unlike plain data, if even one bit
 * becomes corrupted, the data will be entirely unrecoverable.
 * Ditto if they forget their password, there is no way to recover the data.
 */

/**
 * Retrieves the salt used to encrypt the given data.
 *
 * The retrieved salt can then be passed to tox_pass_key_derive_with_salt to
 * produce the same key as was previously used. Any data encrypted with this
 * module can be used as input.
 *
 * The cipher text must be at least TOX_PASS_ENCRYPTION_EXTRA_LENGTH bytes in length.
 * The salt must be TOX_PASS_SALT_LENGTH bytes in length.
 * If the passed byte arrays are smaller than required, the behaviour is
 * undefined.
 *
 * If the cipher text pointer or the salt is NULL, this function returns false.
 *
 * Success does not say anything about the validity of the data, only that
 * data of the appropriate size was copied.
 *
 * @return true on success.
 */
bool tox_get_salt(
        const uint8_t ciphertext[TOX_PASS_ENCRYPTION_EXTRA_LENGTH],
        uint8_t salt[TOX_PASS_SALT_LENGTH], Tox_Err_Get_Salt *error)
{
    if (ciphertext == nullptr || salt == nullptr) {
        SET_ERROR_PARAMETER(error, TOX_ERR_GET_SALT_NULL);
        return false;
    }

    if (memcmp(ciphertext, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH) != 0) {
        SET_ERROR_PARAMETER(error, TOX_ERR_GET_SALT_BAD_FORMAT);
        return false;
    }

    ciphertext += TOX_ENC_SAVE_MAGIC_LENGTH;
    memcpy(salt, ciphertext, crypto_pwhash_scryptsalsa208sha256_SALTBYTES);
    SET_ERROR_PARAMETER(error, TOX_ERR_GET_SALT_OK);
    return true;
}

/**
 * Generates a secret symmetric key from the given passphrase.
 *
 * Be sure to not compromise the key! Only keep it in memory, do not write
 * it to disk.
 *
 * Note that this function is not deterministic; to derive the same key from
 * a password, you also must know the random salt that was used. A
 * deterministic version of this function is `tox_pass_key_derive_with_salt`.
 *
 * @param passphrase The user-provided password. Can be empty.
 * @param passphrase_len The length of the password.
 *
 * @return new symmetric key on success, NULL on failure.
 */
Tox_Pass_Key *tox_pass_key_derive(
        const uint8_t passphrase[], size_t passphrase_len,
        Tox_Err_Key_Derivation *error)
{
    const Random *rng = os_random();

    if (rng == nullptr) {
        SET_ERROR_PARAMETER(error, TOX_ERR_KEY_DERIVATION_FAILED);
        return nullptr;
    }

    uint8_t salt[crypto_pwhash_scryptsalsa208sha256_SALTBYTES];
    random_bytes(rng, salt, sizeof(salt));
    return tox_pass_key_derive_with_salt(passphrase, passphrase_len, salt, error);
}

/**
 * Same as above, except use the given salt for deterministic key derivation.
 *
 * @param passphrase The user-provided password. Can be empty.
 * @param passphrase_len The length of the password.
 * @param salt An array of at least TOX_PASS_SALT_LENGTH bytes.
 *
 * @return new symmetric key on success, NULL on failure.
 */
Tox_Pass_Key *tox_pass_key_derive_with_salt(
        const uint8_t passphrase[], size_t passphrase_len,
        const uint8_t salt[TOX_PASS_SALT_LENGTH], Tox_Err_Key_Derivation *error)
{
    if (salt == nullptr || (passphrase == nullptr && passphrase_len != 0)) {
        SET_ERROR_PARAMETER(error, TOX_ERR_KEY_DERIVATION_NULL);
        return nullptr;
    }

    uint8_t passkey[crypto_hash_sha256_BYTES];
    crypto_hash_sha256(passkey, passphrase, passphrase_len);

    uint8_t key[CRYPTO_SHARED_KEY_SIZE];

    // Derive a key from the password
    // http://doc.libsodium.org/key_derivation/README.html
    // note that, according to the documentation, a generic pwhash interface will be created
    // once the pwhash competition (https://password-hashing.net/) is over */
    if (crypto_pwhash_scryptsalsa208sha256(
                key, sizeof(key), (char *)passkey, sizeof(passkey), salt,
                crypto_pwhash_scryptsalsa208sha256_OPSLIMIT_INTERACTIVE * 2, /* slightly stronger */
                crypto_pwhash_scryptsalsa208sha256_MEMLIMIT_INTERACTIVE) != 0) {
        /* out of memory most likely */
        SET_ERROR_PARAMETER(error, TOX_ERR_KEY_DERIVATION_FAILED);
        return nullptr;
    }

    crypto_memzero(passkey, crypto_hash_sha256_BYTES); /* wipe plaintext pw */

    Tox_Pass_Key *out_key = (Tox_Pass_Key *)calloc(1, sizeof(Tox_Pass_Key));

    if (out_key == nullptr) {
        SET_ERROR_PARAMETER(error, TOX_ERR_KEY_DERIVATION_FAILED);
        return nullptr;
    }

    memcpy(out_key->salt, salt, crypto_pwhash_scryptsalsa208sha256_SALTBYTES);
    memcpy(out_key->key, key, CRYPTO_SHARED_KEY_SIZE);
    SET_ERROR_PARAMETER(error, TOX_ERR_KEY_DERIVATION_OK);
    return out_key;
}

/**
 * Encrypt a plain text with a key produced by tox_pass_key_derive or tox_pass_key_derive_with_salt.
 *
 * The output array must be at least `plaintext_len + TOX_PASS_ENCRYPTION_EXTRA_LENGTH`
 * bytes long.
 *
 * @param plaintext A byte array of length `plaintext_len`.
 * @param plaintext_len The length of the plain text array. Bigger than 0.
 * @param ciphertext The cipher text array to write the encrypted data to.
 *
 * @return true on success.
 */
bool tox_pass_key_encrypt(const Tox_Pass_Key *key, const uint8_t plaintext[], size_t plaintext_len,
                          uint8_t ciphertext[], Tox_Err_Encryption *error)
{
    const Random *rng = os_random();

    if (rng == nullptr) {
        SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_FAILED);
        return false;
    }

    if (plaintext_len == 0 || plaintext == nullptr || key == nullptr || ciphertext == nullptr) {
        SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_NULL);
        return false;
    }

    // the output data consists of, in order:
    // salt, nonce, mac, enc_data
    // where the mac is automatically prepended by the encrypt()
    // 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

    /* first add the magic number */
    memcpy(ciphertext, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH);
    ciphertext += TOX_ENC_SAVE_MAGIC_LENGTH;

    /* then add the rest prefix */
    memcpy(ciphertext, key->salt, crypto_pwhash_scryptsalsa208sha256_SALTBYTES);
    ciphertext += crypto_pwhash_scryptsalsa208sha256_SALTBYTES;

    uint8_t nonce[crypto_box_NONCEBYTES];
    random_nonce(rng, nonce);
    memcpy(ciphertext, nonce, crypto_box_NONCEBYTES);
    ciphertext += crypto_box_NONCEBYTES;

    /* now encrypt */
    if (encrypt_data_symmetric(key->key, nonce, plaintext, plaintext_len, ciphertext)
            != plaintext_len + crypto_box_MACBYTES) {
        SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_FAILED);
        return false;
    }

    SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_OK);
    return true;
}

/**
 * Encrypts the given data with the given passphrase.
 *
 * The output array must be at least `plaintext_len + TOX_PASS_ENCRYPTION_EXTRA_LENGTH`
 * bytes long. This delegates to tox_pass_key_derive and
 * tox_pass_key_encrypt.
 *
 * @param plaintext A byte array of length `plaintext_len`.
 * @param plaintext_len The length of the plain text array. Bigger than 0.
 * @param passphrase The user-provided password. Can be empty.
 * @param passphrase_len The length of the password.
 * @param ciphertext The cipher text array to write the encrypted data to.
 *
 * @return true on success.
 */
bool tox_pass_encrypt(const uint8_t plaintext[], size_t plaintext_len, const uint8_t passphrase[], size_t passphrase_len,
                      uint8_t ciphertext[/*! plaintext_len + TOX_PASS_ENCRYPTION_EXTRA_LENGTH */], Tox_Err_Encryption *error)
{
    Tox_Err_Key_Derivation err;
    Tox_Pass_Key *key = tox_pass_key_derive(passphrase, passphrase_len, &err);

    if (key == nullptr) {
        if (err == TOX_ERR_KEY_DERIVATION_NULL) {
            SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_NULL);
        } else if (err == TOX_ERR_KEY_DERIVATION_FAILED) {
            SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_KEY_DERIVATION_FAILED);
        }

        return false;
    }

    const bool result = tox_pass_key_encrypt(key, plaintext, plaintext_len, ciphertext, error);
    tox_pass_key_free(key);
    return result;
}

/**
 * This is the inverse of tox_pass_key_encrypt, also using only keys produced by
 * tox_pass_key_derive or tox_pass_key_derive_with_salt.
 *
 * @param ciphertext A byte array of length `ciphertext_len`.
 * @param ciphertext_len The length of the cipher text array. At least TOX_PASS_ENCRYPTION_EXTRA_LENGTH.
 * @param plaintext The plain text array to write the decrypted data to.
 *
 * @return true on success.
 */
bool tox_pass_key_decrypt(const Tox_Pass_Key *key, const uint8_t ciphertext[], size_t ciphertext_len,
                          uint8_t plaintext[], Tox_Err_Decryption *error)
{
    if (ciphertext_len <= TOX_PASS_ENCRYPTION_EXTRA_LENGTH) {
        SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_INVALID_LENGTH);
        return false;
    }

    if (ciphertext == nullptr || key == nullptr || plaintext == nullptr) {
        SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_NULL);
        return false;
    }

    if (memcmp(ciphertext, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH) != 0) {
        SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_BAD_FORMAT);
        return false;
    }

    ciphertext += TOX_ENC_SAVE_MAGIC_LENGTH;
    ciphertext += crypto_pwhash_scryptsalsa208sha256_SALTBYTES; // salt only affects key derivation

    const size_t decrypt_length = ciphertext_len - TOX_PASS_ENCRYPTION_EXTRA_LENGTH;

    uint8_t nonce[crypto_box_NONCEBYTES];
    memcpy(nonce, ciphertext, crypto_box_NONCEBYTES);
    ciphertext += crypto_box_NONCEBYTES;

    /* decrypt the ciphertext */
    if (decrypt_data_symmetric(key->key, nonce, ciphertext, decrypt_length + crypto_box_MACBYTES, plaintext)
            != decrypt_length) {
        SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_FAILED);
        return false;
    }

    SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_OK);
    return true;
}

/**
 * Decrypts the given data with the given passphrase.
 *
 * The output array must be at least `ciphertext_len - TOX_PASS_ENCRYPTION_EXTRA_LENGTH`
 * bytes long. This delegates to tox_pass_key_decrypt.
 *
 * @param ciphertext A byte array of length `ciphertext_len`.
 * @param ciphertext_len The length of the cipher text array. At least TOX_PASS_ENCRYPTION_EXTRA_LENGTH.
 * @param passphrase The user-provided password. Can be empty.
 * @param passphrase_len The length of the password.
 * @param plaintext The plain text array to write the decrypted data to.
 *
 * @return true on success.
 */
bool tox_pass_decrypt(const uint8_t ciphertext[], size_t ciphertext_len, const uint8_t passphrase[],
                      size_t passphrase_len, uint8_t plaintext[/*! ciphertext_len - TOX_PASS_ENCRYPTION_EXTRA_LENGTH */], Tox_Err_Decryption *error)
{
    if (ciphertext_len <= TOX_PASS_ENCRYPTION_EXTRA_LENGTH) {
        SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_INVALID_LENGTH);
        return false;
    }

    if (ciphertext == nullptr || passphrase == nullptr || plaintext == nullptr) {
        SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_NULL);
        return false;
    }

    if (memcmp(ciphertext, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH) != 0) {
        SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_BAD_FORMAT);
        return false;
    }

    uint8_t salt[crypto_pwhash_scryptsalsa208sha256_SALTBYTES];
    memcpy(salt, ciphertext + TOX_ENC_SAVE_MAGIC_LENGTH, crypto_pwhash_scryptsalsa208sha256_SALTBYTES);

    /* derive the key */
    Tox_Pass_Key *key = tox_pass_key_derive_with_salt(passphrase, passphrase_len, salt, nullptr);

    if (key == nullptr) {
        /* out of memory most likely */
        SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_KEY_DERIVATION_FAILED);
        return false;
    }

    const bool result = tox_pass_key_decrypt(key, ciphertext, ciphertext_len, plaintext, error);
    tox_pass_key_free(key);
    return result;
}

/**
 * Determines whether or not the given data is encrypted by this module.
 *
 * It does this check by verifying that the magic number is the one put in
 * place by the encryption functions.
 *
 * The data must be at least TOX_PASS_ENCRYPTION_EXTRA_LENGTH bytes in length.
 * If the passed byte array is smaller than required, the behaviour is
 * undefined.
 *
 * If the data pointer is NULL, the behaviour is undefined
 *
 * @return true if the data is encrypted by this module.
 */
bool tox_is_data_encrypted(const uint8_t data[TOX_PASS_ENCRYPTION_EXTRA_LENGTH])
{
    return memcmp(data, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH) == 0;
}

Coverage Report

Created: 2024-01-26 01:52

Line	Count	Source (jump to first uncovered line)
1		/* SPDX-License-Identifier: GPL-3.0-or-later
2		* Copyright © 2016-2018 The TokTok team.
3		* Copyright © 2013 Tox project.
4		*/
5
6		/**
7		* Batch encryption functions.
8		*/
9		#include "toxencryptsave.h"
10
11		#include <sodium.h>
12
13		#include <stdlib.h>
14		#include <string.h>
15
16		#include "../toxcore/ccompat.h"
17		#include "../toxcore/crypto_core.h"
18		#include "defines.h"
19
20		static_assert(TOX_PASS_SALT_LENGTH == crypto_pwhash_scryptsalsa208sha256_SALTBYTES,
21		"TOX_PASS_SALT_LENGTH is assumed to be equal to crypto_pwhash_scryptsalsa208sha256_SALTBYTES");
22		static_assert(TOX_PASS_KEY_LENGTH == CRYPTO_SHARED_KEY_SIZE,
23		"TOX_PASS_KEY_LENGTH is assumed to be equal to CRYPTO_SHARED_KEY_SIZE");
24		static_assert(TOX_PASS_ENCRYPTION_EXTRA_LENGTH == (crypto_box_MACBYTES + crypto_box_NONCEBYTES +
25		crypto_pwhash_scryptsalsa208sha256_SALTBYTES + TOX_ENC_SAVE_MAGIC_LENGTH),
26		"TOX_PASS_ENCRYPTION_EXTRA_LENGTH is assumed to be equal to (crypto_box_MACBYTES + crypto_box_NONCEBYTES + crypto_pwhash_scryptsalsa208sha256_SALTBYTES + TOX_ENC_SAVE_MAGIC_LENGTH)");
27
28		#define SET_ERROR_PARAMETER(param, x) \
29	175	do { \
30	175	if (param != nullptr) { \
31	135	*param = x; \
32	135	} \
33	175	} while (0)
34
35		uint32_t tox_pass_salt_length(void)
36	0	{
37	0	return TOX_PASS_SALT_LENGTH;
38	0	}
39		uint32_t tox_pass_key_length(void)
40	0	{
41	0	return TOX_PASS_KEY_LENGTH;
42	0	}
43		uint32_t tox_pass_encryption_extra_length(void)
44	0	{
45	0	return TOX_PASS_ENCRYPTION_EXTRA_LENGTH;
46	0	}
47
48		struct Tox_Pass_Key {
49		uint8_t salt[TOX_PASS_SALT_LENGTH];
50		uint8_t key[TOX_PASS_KEY_LENGTH];
51		};
52
53		void tox_pass_key_free(Tox_Pass_Key *key)
54	84	{
55	84	free(key);
56	84	}
57
58		/* Clients should consider alerting their users that, unlike plain data, if even one bit
59		* becomes corrupted, the data will be entirely unrecoverable.
60		* Ditto if they forget their password, there is no way to recover the data.
61		*/
62
63		/**
64		* Retrieves the salt used to encrypt the given data.
65		*
66		* The retrieved salt can then be passed to tox_pass_key_derive_with_salt to
67		* produce the same key as was previously used. Any data encrypted with this
68		* module can be used as input.
69		*
70		* The cipher text must be at least TOX_PASS_ENCRYPTION_EXTRA_LENGTH bytes in length.
71		* The salt must be TOX_PASS_SALT_LENGTH bytes in length.
72		* If the passed byte arrays are smaller than required, the behaviour is
73		* undefined.
74		*
75		* If the cipher text pointer or the salt is NULL, this function returns false.
76		*
77		* Success does not say anything about the validity of the data, only that
78		* data of the appropriate size was copied.
79		*
80		* @return true on success.
81		*/
82		bool tox_get_salt(
83		const uint8_t ciphertext[TOX_PASS_ENCRYPTION_EXTRA_LENGTH],
84		uint8_t salt[TOX_PASS_SALT_LENGTH], Tox_Err_Get_Salt *error)
85	1	{
86	1	if (ciphertext == nullptr \|\| salt == nullptr) {
87	0	SET_ERROR_PARAMETER(error, TOX_ERR_GET_SALT_NULL);
88	0	return false;
89	0	}
90
91	1	if (memcmp(ciphertext, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH) != 0) {
92	0	SET_ERROR_PARAMETER(error, TOX_ERR_GET_SALT_BAD_FORMAT);
93	0	return false;
94	0	}
95
96	1	ciphertext += TOX_ENC_SAVE_MAGIC_LENGTH;
97	1	memcpy(salt, ciphertext, crypto_pwhash_scryptsalsa208sha256_SALTBYTES);
98	1	SET_ERROR_PARAMETER(error, TOX_ERR_GET_SALT_OK);
99	1	return true;
100	1	}
101
102		/**
103		* Generates a secret symmetric key from the given passphrase.
104		*
105		* Be sure to not compromise the key! Only keep it in memory, do not write
106		* it to disk.
107		*
108		* Note that this function is not deterministic; to derive the same key from
109		* a password, you also must know the random salt that was used. A
110		* deterministic version of this function is `tox_pass_key_derive_with_salt`.
111		*
112		* @param passphrase The user-provided password. Can be empty.
113		* @param passphrase_len The length of the password.
114		*
115		* @return new symmetric key on success, NULL on failure.
116		*/
117		Tox_Pass_Key *tox_pass_key_derive(
118		const uint8_t passphrase[], size_t passphrase_len,
119		Tox_Err_Key_Derivation *error)
120	45	{
121	45	const Random *rng = os_random();
122
123	45	if (rng == nullptr) {
124	0	SET_ERROR_PARAMETER(error, TOX_ERR_KEY_DERIVATION_FAILED);
125	0	return nullptr;
126	0	}
127
128	45	uint8_t salt[crypto_pwhash_scryptsalsa208sha256_SALTBYTES];
129	45	random_bytes(rng, salt, sizeof(salt));
130	45	return tox_pass_key_derive_with_salt(passphrase, passphrase_len, salt, error);
131	45	}
132
133		/**
134		* Same as above, except use the given salt for deterministic key derivation.
135		*
136		* @param passphrase The user-provided password. Can be empty.
137		* @param passphrase_len The length of the password.
138		* @param salt An array of at least TOX_PASS_SALT_LENGTH bytes.
139		*
140		* @return new symmetric key on success, NULL on failure.
141		*/
142		Tox_Pass_Key *tox_pass_key_derive_with_salt(
143		const uint8_t passphrase[], size_t passphrase_len,
144		const uint8_t salt[TOX_PASS_SALT_LENGTH], Tox_Err_Key_Derivation *error)
145	86	{
146	86	if (salt == nullptr \|\| (passphrase == nullptr && passphrase_len != 0)) {
147	0	SET_ERROR_PARAMETER(error, TOX_ERR_KEY_DERIVATION_NULL);
148	0	return nullptr;
149	0	}
150
151	86	uint8_t passkey[crypto_hash_sha256_BYTES];
152	86	crypto_hash_sha256(passkey, passphrase, passphrase_len);
153
154	86	uint8_t key[CRYPTO_SHARED_KEY_SIZE];
155
156		// Derive a key from the password
157		// http://doc.libsodium.org/key_derivation/README.html
158		// note that, according to the documentation, a generic pwhash interface will be created
159		// once the pwhash competition (https://password-hashing.net/) is over */
160	86	if (crypto_pwhash_scryptsalsa208sha256(
161	86	key, sizeof(key), (char *)passkey, sizeof(passkey), salt,
162	86	crypto_pwhash_scryptsalsa208sha256_OPSLIMIT_INTERACTIVE * 2, /* slightly stronger */
163	86	crypto_pwhash_scryptsalsa208sha256_MEMLIMIT_INTERACTIVE) != 0) {
164		/* out of memory most likely */
165	0	SET_ERROR_PARAMETER(error, TOX_ERR_KEY_DERIVATION_FAILED);
166	0	return nullptr;
167	0	}
168
169	86	crypto_memzero(passkey, crypto_hash_sha256_BYTES); /* wipe plaintext pw */
170
171	86	Tox_Pass_Key out_key = (Tox_Pass_Key )calloc(1, sizeof(Tox_Pass_Key));
172
173	86	if (out_key == nullptr) {
174	2	SET_ERROR_PARAMETER(error, TOX_ERR_KEY_DERIVATION_FAILED);
175	2	return nullptr;
176	2	}
177
178	84	memcpy(out_key->salt, salt, crypto_pwhash_scryptsalsa208sha256_SALTBYTES);
179	84	memcpy(out_key->key, key, CRYPTO_SHARED_KEY_SIZE);
180	84	SET_ERROR_PARAMETER(error, TOX_ERR_KEY_DERIVATION_OK);
181	84	return out_key;
182	86	}
183
184		/**
185		* Encrypt a plain text with a key produced by tox_pass_key_derive or tox_pass_key_derive_with_salt.
186		*
187		* The output array must be at least `plaintext_len + TOX_PASS_ENCRYPTION_EXTRA_LENGTH`
188		* bytes long.
189		*
190		* @param plaintext A byte array of length `plaintext_len`.
191		* @param plaintext_len The length of the plain text array. Bigger than 0.
192		* @param ciphertext The cipher text array to write the encrypted data to.
193		*
194		* @return true on success.
195		*/
196		bool tox_pass_key_encrypt(const Tox_Pass_Key *key, const uint8_t plaintext[], size_t plaintext_len,
197		uint8_t ciphertext[], Tox_Err_Encryption *error)
198	44	{
199	44	const Random *rng = os_random();
200
201	44	if (rng == nullptr) {
202	0	SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_FAILED);
203	0	return false;
204	0	}
205
206	44	if (plaintext_len == 0 \|\| plaintext == nullptr \|\| key == nullptr \|\| ciphertext == nullptr) {
207	0	SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_NULL);
208	0	return false;
209	0	}
210
211		// the output data consists of, in order:
212		// salt, nonce, mac, enc_data
213		// where the mac is automatically prepended by the encrypt()
214		// the salt+nonce is called the prefix
215		// I'm not sure what else I'm supposed to do with the salt and nonce, since we
216		// need them to decrypt the data
217
218		/* first add the magic number */
219	44	memcpy(ciphertext, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH);
220	44	ciphertext += TOX_ENC_SAVE_MAGIC_LENGTH;
221
222		/* then add the rest prefix */
223	44	memcpy(ciphertext, key->salt, crypto_pwhash_scryptsalsa208sha256_SALTBYTES);
224	44	ciphertext += crypto_pwhash_scryptsalsa208sha256_SALTBYTES;
225
226	44	uint8_t nonce[crypto_box_NONCEBYTES];
227	44	random_nonce(rng, nonce);
228	44	memcpy(ciphertext, nonce, crypto_box_NONCEBYTES);
229	44	ciphertext += crypto_box_NONCEBYTES;
230
231		/* now encrypt */
232	44	if (encrypt_data_symmetric(key->key, nonce, plaintext, plaintext_len, ciphertext)
233	44	!= plaintext_len + crypto_box_MACBYTES) {
234	1	SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_FAILED);
235	1	return false;
236	1	}
237
238	43	SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_OK);
239	43	return true;
240	44	}
241
242		/**
243		* Encrypts the given data with the given passphrase.
244		*
245		* The output array must be at least `plaintext_len + TOX_PASS_ENCRYPTION_EXTRA_LENGTH`
246		* bytes long. This delegates to tox_pass_key_derive and
247		* tox_pass_key_encrypt.
248		*
249		* @param plaintext A byte array of length `plaintext_len`.
250		* @param plaintext_len The length of the plain text array. Bigger than 0.
251		* @param passphrase The user-provided password. Can be empty.
252		* @param passphrase_len The length of the password.
253		* @param ciphertext The cipher text array to write the encrypted data to.
254		*
255		* @return true on success.
256		*/
257		bool tox_pass_encrypt(const uint8_t plaintext[], size_t plaintext_len, const uint8_t passphrase[], size_t passphrase_len,
258		uint8_t ciphertext[/! plaintext_len + TOX_PASS_ENCRYPTION_EXTRA_LENGTH /], Tox_Err_Encryption *error)
259	43	{
260	43	Tox_Err_Key_Derivation err;
261	43	Tox_Pass_Key *key = tox_pass_key_derive(passphrase, passphrase_len, &err);
262
263	43	if (key == nullptr) {
264	1	if (err == TOX_ERR_KEY_DERIVATION_NULL) {
265	0	SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_NULL);
266	1	} else if (err == TOX_ERR_KEY_DERIVATION_FAILED) {
267	1	SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_KEY_DERIVATION_FAILED);
268	1	}
269
270	1	return false;
271	1	}
272
273	42	const bool result = tox_pass_key_encrypt(key, plaintext, plaintext_len, ciphertext, error);
274	42	tox_pass_key_free(key);
275	42	return result;
276	43	}
277
278		/**
279		* This is the inverse of tox_pass_key_encrypt, also using only keys produced by
280		* tox_pass_key_derive or tox_pass_key_derive_with_salt.
281		*
282		* @param ciphertext A byte array of length `ciphertext_len`.
283		* @param ciphertext_len The length of the cipher text array. At least TOX_PASS_ENCRYPTION_EXTRA_LENGTH.
284		* @param plaintext The plain text array to write the decrypted data to.
285		*
286		* @return true on success.
287		*/
288		bool tox_pass_key_decrypt(const Tox_Pass_Key *key, const uint8_t ciphertext[], size_t ciphertext_len,
289		uint8_t plaintext[], Tox_Err_Decryption *error)
290	41	{
291	41	if (ciphertext_len <= TOX_PASS_ENCRYPTION_EXTRA_LENGTH) {
292	0	SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_INVALID_LENGTH);
293	0	return false;
294	0	}
295
296	41	if (ciphertext == nullptr \|\| key == nullptr \|\| plaintext == nullptr) {
297	0	SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_NULL);
298	0	return false;
299	0	}
300
301	41	if (memcmp(ciphertext, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH) != 0) {
302	0	SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_BAD_FORMAT);
303	0	return false;
304	0	}
305
306	41	ciphertext += TOX_ENC_SAVE_MAGIC_LENGTH;
307	41	ciphertext += crypto_pwhash_scryptsalsa208sha256_SALTBYTES; // salt only affects key derivation
308
309	41	const size_t decrypt_length = ciphertext_len - TOX_PASS_ENCRYPTION_EXTRA_LENGTH;
310
311	41	uint8_t nonce[crypto_box_NONCEBYTES];
312	41	memcpy(nonce, ciphertext, crypto_box_NONCEBYTES);
313	41	ciphertext += crypto_box_NONCEBYTES;
314
315		/* decrypt the ciphertext */
316	41	if (decrypt_data_symmetric(key->key, nonce, ciphertext, decrypt_length + crypto_box_MACBYTES, plaintext)
317	41	!= decrypt_length) {
318	1	SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_FAILED);
319	1	return false;
320	1	}
321
322	40	SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_OK);
323	40	return true;
324	41	}
325
326		/**
327		* Decrypts the given data with the given passphrase.
328		*
329		* The output array must be at least `ciphertext_len - TOX_PASS_ENCRYPTION_EXTRA_LENGTH`
330		* bytes long. This delegates to tox_pass_key_decrypt.
331		*
332		* @param ciphertext A byte array of length `ciphertext_len`.
333		* @param ciphertext_len The length of the cipher text array. At least TOX_PASS_ENCRYPTION_EXTRA_LENGTH.
334		* @param passphrase The user-provided password. Can be empty.
335		* @param passphrase_len The length of the password.
336		* @param plaintext The plain text array to write the decrypted data to.
337		*
338		* @return true on success.
339		*/
340		bool tox_pass_decrypt(const uint8_t ciphertext[], size_t ciphertext_len, const uint8_t passphrase[],
341		size_t passphrase_len, uint8_t plaintext[/! ciphertext_len - TOX_PASS_ENCRYPTION_EXTRA_LENGTH /], Tox_Err_Decryption *error)
342	41	{
343	41	if (ciphertext_len <= TOX_PASS_ENCRYPTION_EXTRA_LENGTH) {
344	0	SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_INVALID_LENGTH);
345	0	return false;
346	0	}
347
348	41	if (ciphertext == nullptr \|\| passphrase == nullptr \|\| plaintext == nullptr) {
349	1	SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_NULL);
350	1	return false;
351	1	}
352
353	40	if (memcmp(ciphertext, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH) != 0) {
354	0	SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_BAD_FORMAT);
355	0	return false;
356	0	}
357
358	40	uint8_t salt[crypto_pwhash_scryptsalsa208sha256_SALTBYTES];
359	40	memcpy(salt, ciphertext + TOX_ENC_SAVE_MAGIC_LENGTH, crypto_pwhash_scryptsalsa208sha256_SALTBYTES);
360
361		/* derive the key */
362	40	Tox_Pass_Key *key = tox_pass_key_derive_with_salt(passphrase, passphrase_len, salt, nullptr);
363
364	40	if (key == nullptr) {
365		/* out of memory most likely */
366	1	SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_KEY_DERIVATION_FAILED);
367	1	return false;
368	1	}
369
370	39	const bool result = tox_pass_key_decrypt(key, ciphertext, ciphertext_len, plaintext, error);
371	39	tox_pass_key_free(key);
372	39	return result;
373	40	}
374
375		/**
376		* Determines whether or not the given data is encrypted by this module.
377		*
378		* It does this check by verifying that the magic number is the one put in
379		* place by the encryption functions.
380		*
381		* The data must be at least TOX_PASS_ENCRYPTION_EXTRA_LENGTH bytes in length.
382		* If the passed byte array is smaller than required, the behaviour is
383		* undefined.
384		*
385		* If the data pointer is NULL, the behaviour is undefined
386		*
387		* @return true if the data is encrypted by this module.
388		*/
389		bool tox_is_data_encrypted(const uint8_t data[TOX_PASS_ENCRYPTION_EXTRA_LENGTH])
390	2	{
391	2	return memcmp(data, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH) == 0;
392	2	}