Updated with upstream

3 files changed, 242 insertions, 249 deletions

diff --git a/toxencryptsave/defines.h b/toxencryptsave/defines.h
new file mode 100644
index 00000000..e3fca073
--- /dev/null
+++ b/toxencryptsave/defines.h
@@ -0,0 +1,2 @@
+#define TOX_ENC_SAVE_MAGIC_NUMBER "toxEsave"
+#define TOX_ENC_SAVE_MAGIC_LENGTH 8
diff --git a/toxencryptsave/toxencryptsave.c b/toxencryptsave/toxencryptsave.c
index 9172f512..e2f28a58 100644
--- a/toxencryptsave/toxencryptsave.c
+++ b/toxencryptsave/toxencryptsave.c
@@ -26,8 +26,9 @@
 #endif
 
 #include "toxencryptsave.h"
+#include "defines.h"
 #include "../toxcore/crypto_core.h"
-#include "../toxcore/tox.h"
+#define SET_ERROR_PARAMETER(param, x) {if(param) {*param = x;}}
 
 #ifdef VANILLA_NACL
 #include "crypto_pwhash_scryptsalsa208sha256/crypto_pwhash_scryptsalsa208sha256.h"
@@ -35,81 +36,70 @@
 #include <crypto_hash_sha256.h>
 #endif
 
-#define TOX_PASS_ENCRYPTION_EXTRA_LENGTH (crypto_box_MACBYTES + crypto_box_NONCEBYTES \
-           + crypto_pwhash_scryptsalsa208sha256_SALTBYTES + TOX_ENC_SAVE_MAGIC_LENGTH)
-
-#define TOX_PASS_KEY_LENGTH (crypto_pwhash_scryptsalsa208sha256_SALTBYTES + crypto_box_KEYBYTES)
-
-int tox_pass_encryption_extra_length()
-{
-    return TOX_PASS_ENCRYPTION_EXTRA_LENGTH;
-}
+#if TOX_PASS_SALT_LENGTH != crypto_pwhash_scryptsalsa208sha256_SALTBYTES
+#error TOX_PASS_SALT_LENGTH is assumed to be equal to crypto_pwhash_scryptsalsa208sha256_SALTBYTES
+#endif
 
-int tox_pass_key_length()
-{
-    return TOX_PASS_KEY_LENGTH;
-}
+#if TOX_PASS_KEY_LENGTH != crypto_box_KEYBYTES
+#error TOX_PASS_KEY_LENGTH is assumed to be equal to crypto_box_KEYBYTES
+#endif
 
-int tox_pass_salt_length()
-{
-    return crypto_pwhash_scryptsalsa208sha256_SALTBYTES;
-}
+#if TOX_PASS_ENCRYPTION_EXTRA_LENGTH != (crypto_box_MACBYTES + crypto_box_NONCEBYTES + crypto_pwhash_scryptsalsa208sha256_SALTBYTES + TOX_ENC_SAVE_MAGIC_LENGTH)
+#error 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)
+#endif
 
-/* 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
+/* 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.
  */
 
-/*  return size of the messenger data (for encrypted saving). */
-uint32_t tox_encrypted_size(const Tox *tox)
-{
-    return tox_size(tox) + TOX_PASS_ENCRYPTION_EXTRA_LENGTH;
-}
-
 /* This retrieves the salt used to encrypt the given data, which can then be passed to
  * derive_key_with_salt to produce the same key as was previously used. Any encrpyted
  * data with this module can be used as input.
  *
- * returns -1 if the magic number is wrong
- * returns 0 otherwise (no guarantee about validity of data)
+ * returns true if magic number matches
+ * success does not say anything about the validity of the data, only that data of
+ * the appropriate size was copied
  */
-int tox_get_salt(uint8_t *data, uint8_t *salt)
+bool tox_get_salt(const uint8_t *data, uint8_t *salt)
 {
     if (memcmp(data, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH) != 0)
-        return -1;
+        return 0;
 
     data += TOX_ENC_SAVE_MAGIC_LENGTH;
     memcpy(salt, data, crypto_pwhash_scryptsalsa208sha256_SALTBYTES);
-    return 0;
+    return 1;
 }
 
 /* Generates a secret symmetric key from the given passphrase. out_key must be at least
  * TOX_PASS_KEY_LENGTH bytes long.
  * Be sure to not compromise the key! Only keep it in memory, do not write to disk.
- * This function is fairly cheap, but irungentoo insists that you be allowed to
- * cache the result if you want, to minimize computation for repeated encryptions.
  * The password is zeroed after key derivation.
  * The key should only be used with the other functions in this module, as it
  * includes a salt.
+ * 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. See below.
  *
- * returns 0 on success
- * returns -1 on failure
+ * returns true on success
  */
-int tox_derive_key_from_pass(uint8_t *passphrase, uint32_t pplength, uint8_t *out_key)
+bool tox_derive_key_from_pass(uint8_t *passphrase, size_t pplength, TOX_PASS_KEY *out_key,
+                              TOX_ERR_KEY_DERIVATION *error)
 {
     uint8_t salt[crypto_pwhash_scryptsalsa208sha256_SALTBYTES];
     randombytes(salt, sizeof salt);
-    return tox_derive_key_with_salt(passphrase, pplength, salt, out_key);
+    return tox_derive_key_with_salt(passphrase, pplength, salt, out_key, error);
 }
 
 /* Same as above, except with use the given salt for deterministic key derivation.
- * The salt must be tox_salt_length() bytes in length.
+ * The salt must be TOX_PASS_SALT_LENGTH bytes in length.
  */
-int tox_derive_key_with_salt(uint8_t *passphrase, uint32_t pplength, uint8_t *salt, uint8_t *out_key)
+bool tox_derive_key_with_salt(uint8_t *passphrase, size_t pplength, uint8_t *salt, TOX_PASS_KEY *out_key,
+                              TOX_ERR_KEY_DERIVATION *error)
 {
-    if (pplength == 0)
-        return -1;
+    if (pplength == 0 || !passphrase || !salt || !out_key) {
+        SET_ERROR_PARAMETER(error, TOX_ERR_KEY_DERIVATION_NULL);
+        return 0;
+    }
 
     uint8_t passkey[crypto_hash_sha256_BYTES];
     crypto_hash_sha256(passkey, passphrase, pplength);
@@ -125,27 +115,33 @@ int tox_derive_key_with_salt(uint8_t *passphrase, uint32_t pplength, uint8_t *sa
                 crypto_pwhash_scryptsalsa208sha256_OPSLIMIT_INTERACTIVE * 2, /* slightly stronger */
                 crypto_pwhash_scryptsalsa208sha256_MEMLIMIT_INTERACTIVE) != 0) {
         /* out of memory most likely */
-        return -1;
+        SET_ERROR_PARAMETER(error, TOX_ERR_KEY_DERIVATION_FAILED);
+        return 0;
     }
 
     sodium_memzero(passkey, crypto_hash_sha256_BYTES); /* wipe plaintext pw */
-    memcpy(out_key, salt, crypto_pwhash_scryptsalsa208sha256_SALTBYTES);
-    memcpy(out_key + crypto_pwhash_scryptsalsa208sha256_SALTBYTES, key, crypto_box_KEYBYTES);
-    return 0;
+    memcpy(out_key->salt, salt, crypto_pwhash_scryptsalsa208sha256_SALTBYTES);
+    memcpy(out_key->key, key, crypto_box_KEYBYTES);
+    SET_ERROR_PARAMETER(error, TOX_ERR_KEY_DERIVATION_OK);
+    return 1;
 }
 
-/* Encrypt arbitrary with a key produced by tox_derive_key_from_pass. The output
+/* Encrypt arbitrary with a key produced by tox_derive_key_*. The output
  * array must be at least data_len + TOX_PASS_ENCRYPTION_EXTRA_LENGTH bytes long.
  * key must be TOX_PASS_KEY_LENGTH bytes.
  * If you already have a symmetric key from somewhere besides this module, simply
  * call encrypt_data_symmetric in toxcore/crypto_core directly.
  *
- *
- * returns 0 on success
- * returns -1 on failure
+ * returns true on success
  */
-int tox_pass_key_encrypt(const uint8_t *data, uint32_t data_len, const uint8_t *key, uint8_t *out)
+bool tox_pass_key_encrypt(const uint8_t *data, size_t data_len, const TOX_PASS_KEY *key, uint8_t *out,
+                          TOX_ERR_ENCRYPTION *error)
 {
+    if (data_len == 0 || !data || !key || !out) {
+        SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_NULL);
+        return 0;
+    }
+
     /* the output data consists of, in order:
      * salt, nonce, mac, enc_data
      * where the mac is automatically prepended by the encrypt()
@@ -159,8 +155,7 @@ int tox_pass_key_encrypt(const uint8_t *data, uint32_t data_len, const uint8_t *
     out += TOX_ENC_SAVE_MAGIC_LENGTH;
 
     /* then add the rest prefix */
-    memcpy(out, key, crypto_pwhash_scryptsalsa208sha256_SALTBYTES);
-    key += crypto_pwhash_scryptsalsa208sha256_SALTBYTES;
+    memcpy(out, key->salt, crypto_pwhash_scryptsalsa208sha256_SALTBYTES);
     out += crypto_pwhash_scryptsalsa208sha256_SALTBYTES;
 
     uint8_t nonce[crypto_box_NONCEBYTES];
@@ -169,177 +164,133 @@ int tox_pass_key_encrypt(const uint8_t *data, uint32_t data_len, const uint8_t *
     out += crypto_box_NONCEBYTES;
 
     /* now encrypt */
-    if (encrypt_data_symmetric(key, nonce, data, data_len, out)
+    if (encrypt_data_symmetric(key->key, nonce, data, data_len, out)
             != data_len + crypto_box_MACBYTES) {
-        return -1;
+        SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_FAILED);
+        return 0;
     }
 
-    return 0;
+    SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_OK);
+    return 1;
 }
 
 /* Encrypts the given data with the given passphrase. The output array must be
  * at least data_len + TOX_PASS_ENCRYPTION_EXTRA_LENGTH bytes long. This delegates
  * to tox_derive_key_from_pass and tox_pass_key_encrypt.
  *
- * returns 0 on success
- * returns -1 on failure
+ * returns true on success
  */
-int tox_pass_encrypt(const uint8_t *data, uint32_t data_len, uint8_t *passphrase, uint32_t pplength, uint8_t *out)
+bool tox_pass_encrypt(const uint8_t *data, size_t data_len, uint8_t *passphrase, size_t pplength, uint8_t *out,
+                      TOX_ERR_ENCRYPTION *error)
 {
-    uint8_t key[TOX_PASS_KEY_LENGTH];
-
-    if (tox_derive_key_from_pass(passphrase, pplength, key) == -1)
-        return -1;
+    TOX_PASS_KEY key;
+    TOX_ERR_KEY_DERIVATION _error;
 
-    return tox_pass_key_encrypt(data, data_len, key, out);
-}
-
-/* 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_save(const Tox *tox, uint8_t *data, uint8_t *passphrase, uint32_t pplength)
-{
-    /* first get plain save data */
-    uint32_t temp_size = tox_size(tox);
-    uint8_t temp_data[temp_size];
-    tox_save(tox, temp_data);
-
-    /* now encrypt */
-    return tox_pass_encrypt(temp_data, temp_size, passphrase, pplength, data);
-}
+    if (!tox_derive_key_from_pass(passphrase, pplength, &key, &_error)) {
+        if (_error == TOX_ERR_KEY_DERIVATION_NULL) {
+            SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_NULL);
+        } else if (_error == TOX_ERR_KEY_DERIVATION_FAILED) {
+            SET_ERROR_PARAMETER(error, TOX_ERR_ENCRYPTION_KEY_DERIVATION_FAILED);
+        }
 
-/* Save the messenger data encrypted with the given key from tox_derive_key.
- * data must be at least tox_encrypted_size().
- *
- * returns 0 on success
- * returns -1 on failure
- */
-int tox_encrypted_key_save(const Tox *tox, uint8_t *data, uint8_t *key)
-{
-    /* first get plain save data */
-    uint32_t temp_size = tox_size(tox);
-    uint8_t temp_data[temp_size];
-    tox_save(tox, temp_data);
+        return 0;
+    }
 
-    /* encrypt */
-    return tox_pass_key_encrypt(temp_data, temp_size, key, data);
+    return tox_pass_key_encrypt(data, data_len, &key, out, error);
 }
 
 /* This is the inverse of tox_pass_key_encrypt, also using only keys produced by
  * tox_derive_key_from_pass.
  *
- * returns the length of the output data (== data_len - TOX_PASS_ENCRYPTION_EXTRA_LENGTH) on success
- * returns -1 on failure
+ * the output data has size data_length - TOX_PASS_ENCRYPTION_EXTRA_LENGTH
+ *
+ * returns true on success
  */
-int tox_pass_key_decrypt(const uint8_t *data, uint32_t length, const uint8_t *key, uint8_t *out)
+bool tox_pass_key_decrypt(const uint8_t *data, size_t length, const TOX_PASS_KEY *key, uint8_t *out,
+                          TOX_ERR_DECRYPTION *error)
 {
-    if (length <= TOX_PASS_ENCRYPTION_EXTRA_LENGTH
-            || 0 != memcmp(data, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH))
-        return -1;
+    if (length <= TOX_PASS_ENCRYPTION_EXTRA_LENGTH) {
+        SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_INVALID_LENGTH);
+        return 0;
+    }
+
+    if (!data || !key || !out) {
+        SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_NULL);
+        return 0;
+    }
+
+    if (memcmp(data, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH) != 0) {
+        SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_BAD_FORMAT);
+        return 0;
+    }
 
     data += TOX_ENC_SAVE_MAGIC_LENGTH;
+    data += crypto_pwhash_scryptsalsa208sha256_SALTBYTES; // salt only affects key derivation
 
-    uint32_t decrypt_length = length - TOX_PASS_ENCRYPTION_EXTRA_LENGTH;
-    //uint8_t salt[crypto_pwhash_scryptsalsa208sha256_SALTBYTES];
-    uint8_t nonce[crypto_box_NONCEBYTES];
+    size_t decrypt_length = length - TOX_PASS_ENCRYPTION_EXTRA_LENGTH;
 
-    //memcpy(salt, data, crypto_pwhash_scryptsalsa208sha256_SALTBYTES);
-    key += crypto_pwhash_scryptsalsa208sha256_SALTBYTES; // ignore the salt, which is only needed for kdf
-    data += crypto_pwhash_scryptsalsa208sha256_SALTBYTES;
+    uint8_t nonce[crypto_box_NONCEBYTES];
     memcpy(nonce, data, crypto_box_NONCEBYTES);
     data += crypto_box_NONCEBYTES;
 
     /* decrypt the data */
-    if (decrypt_data_symmetric(key, nonce, data, decrypt_length + crypto_box_MACBYTES, out)
+    if (decrypt_data_symmetric(key->key, nonce, data, decrypt_length + crypto_box_MACBYTES, out)
             != decrypt_length) {
-        return -1;
+        SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_FAILED);
+        return 0;
     }
 
-    return decrypt_length;
+    SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_OK);
+    return 1;
 }
 
 /* Decrypts the given data with the given passphrase. The output array must be
- * at least data_len - TOX_PASS_ENCRYPTION_EXTRA_LENGTH bytes long.
+ * at least data_len - TOX_PASS_ENCRYPTION_EXTRA_LENGTH bytes long. This delegates
+ * to tox_pass_key_decrypt.
+ *
+ * the output data has size data_length - TOX_PASS_ENCRYPTION_EXTRA_LENGTH
  *
- * returns the length of the output data (== data_len - TOX_PASS_ENCRYPTION_EXTRA_LENGTH) on success
- * returns -1 on failure
+ * returns true on success
  */
-int tox_pass_decrypt(const uint8_t *data, uint32_t length, uint8_t *passphrase, uint32_t pplength, uint8_t *out)
+bool tox_pass_decrypt(const uint8_t *data, size_t length, uint8_t *passphrase, size_t pplength, uint8_t *out,
+                      TOX_ERR_DECRYPTION *error)
 {
-    uint8_t passkey[crypto_hash_sha256_BYTES];
-    crypto_hash_sha256(passkey, passphrase, pplength);
+    if (length <= TOX_PASS_ENCRYPTION_EXTRA_LENGTH || pplength == 0) {
+        SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_INVALID_LENGTH);
+        return 0;
+    }
+
+    if (!data || !passphrase || !out) {
+        SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_NULL);
+        return 0;
+    }
+
+    if (memcmp(data, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH) != 0) {
+        SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_BAD_FORMAT);
+        return 0;
+    }
 
     uint8_t salt[crypto_pwhash_scryptsalsa208sha256_SALTBYTES];
     memcpy(salt, data + TOX_ENC_SAVE_MAGIC_LENGTH, crypto_pwhash_scryptsalsa208sha256_SALTBYTES);
 
     /* derive the key */
-    uint8_t key[crypto_box_KEYBYTES + crypto_pwhash_scryptsalsa208sha256_SALTBYTES];
+    TOX_PASS_KEY key;
 
-    if (crypto_pwhash_scryptsalsa208sha256(
-                key + crypto_pwhash_scryptsalsa208sha256_SALTBYTES,
-                crypto_box_KEYBYTES, (char *)passkey, sizeof(passkey), salt,
-                crypto_pwhash_scryptsalsa208sha256_OPSLIMIT_INTERACTIVE * 2, /* slightly stronger */
-                crypto_pwhash_scryptsalsa208sha256_MEMLIMIT_INTERACTIVE) != 0) {
+    if (!tox_derive_key_with_salt(passphrase, pplength, salt, &key, NULL)) {
         /* out of memory most likely */
-        return -1;
+        SET_ERROR_PARAMETER(error, TOX_ERR_DECRYPTION_KEY_DERIVATION_FAILED);
+        return 0;
     }
 
-    sodium_memzero(passkey, crypto_hash_sha256_BYTES); /* wipe plaintext pw */
-
-    return tox_pass_key_decrypt(data, length, key, out);
-}
-
-/* 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)
-{
-    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);
-}
-
-/* Load the messenger from encrypted data of size length, with key from tox_derive_key.
- *
- * returns 0 on success
- * returns -1 on failure
- */
-int tox_encrypted_key_load(Tox *tox, const uint8_t *data, uint32_t length, uint8_t *key)
-{
-    uint32_t decrypt_length = length - TOX_PASS_ENCRYPTION_EXTRA_LENGTH;
-    uint8_t temp_data[decrypt_length];
-
-    if (tox_pass_key_decrypt(data, length, key, temp_data)
-            != decrypt_length)
-        return -1;
-
-    return tox_load(tox, temp_data, decrypt_length);
+    return tox_pass_key_decrypt(data, length, &key, out, error);
 }
 
 /* Determines whether or not the given data is encrypted (by checking the magic number)
- *
- * returns 1 if it is encrypted
- * returns 0 otherwise
  */
-int tox_is_data_encrypted(const uint8_t *data)
+bool tox_is_data_encrypted(const uint8_t *data)
 {
     if (memcmp(data, TOX_ENC_SAVE_MAGIC_NUMBER, TOX_ENC_SAVE_MAGIC_LENGTH) == 0)
         return 1;
     else
         return 0;
 }
-
-int tox_is_save_encrypted(const uint8_t *data)
-{
-    return tox_is_data_encrypted(data);
-}
diff --git a/toxencryptsave/toxencryptsave.h b/toxencryptsave/toxencryptsave.h
index 169f736c..c077d899 100644
--- a/toxencryptsave/toxencryptsave.h
+++ b/toxencryptsave/toxencryptsave.h
@@ -29,27 +29,20 @@ extern "C" {
 #endif
 
 #include <stdint.h>
+#include <stddef.h>
+#include <stdbool.h>
 
-#ifndef __TOX_DEFINED__
-#define __TOX_DEFINED__
+#ifndef TOX_DEFINED
+#define TOX_DEFINED
 typedef struct Tox Tox;
+struct Tox_Options;
 #endif
 
-// these functions provide access to these defines in toxencryptsave.c, which
-// otherwise aren't actually available in clients...
-int tox_pass_encryption_extra_length();
+#define TOX_PASS_SALT_LENGTH 32
+#define TOX_PASS_KEY_LENGTH 32
+#define TOX_PASS_ENCRYPTION_EXTRA_LENGTH 80
 
-int tox_pass_key_length();
-
-int tox_pass_salt_length();
-
-/*  return size of the messenger data (for encrypted Messenger saving). */
-uint32_t tox_encrypted_size(const Tox *tox);
-
-/* This "module" provides functions analogous to tox_load and tox_save in toxcore,
- * as well as functions for encryption of arbitrary client data (e.g. chat logs).
- *
- * It is conceptually organized into two parts. The first part are the functions
+/* This module is conceptually organized into two parts. The first part are the functions
  * with "key" in the name. To use these functions, first derive an encryption key
  * from a password with tox_derive_key_from_pass, and use the returned key to
  * encrypt the data. The second part takes the password itself instead of the key,
@@ -59,13 +52,83 @@ uint32_t tox_encrypted_size(const Tox *tox);
  * favor using the first part intead of the second part.
  *
  * The encrypted data is prepended with a magic number, to aid validity checking
- * (no guarantees are made of course).
+ * (no guarantees are made of course). Any data to be decrypted must start with
+ * the magic number.
  *
  * 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.
  */
 
+/* Since apparently no one actually bothered to learn about the module previously,
+ * the recently removed functions tox_encrypted_new and tox_get_encrypted_savedata
+ * may be trivially replaced by calls to tox_pass_decrypt -> tox_new or
+ * tox_get_savedata -> tox_pass_encrypt as appropriate. The removed functions
+ * were never more than 5 line wrappers of the other public API functions anyways.
+ * (As has always been, tox_pass_decrypt and tox_pass_encrypt are interchangeable
+ *  with tox_pass_key_decrypt and tox_pass_key_encrypt, as the client program requires.)
+ */
+
+typedef enum TOX_ERR_KEY_DERIVATION {
+    TOX_ERR_KEY_DERIVATION_OK,
+    /**
+     * Some input data, or maybe the output pointer, was null.
+     */
+    TOX_ERR_KEY_DERIVATION_NULL,
+    /**
+     * The crypto lib was unable to derive a key from the given passphrase,
+     * which is usually a lack of memory issue. The functions accepting keys
+     * do not produce this error.
+     */
+    TOX_ERR_KEY_DERIVATION_FAILED
+} TOX_ERR_KEY_DERIVATION;
+
+typedef enum TOX_ERR_ENCRYPTION {
+    TOX_ERR_ENCRYPTION_OK,
+    /**
+     * Some input data, or maybe the output pointer, was null.
+     */
+    TOX_ERR_ENCRYPTION_NULL,
+    /**
+     * The crypto lib was unable to derive a key from the given passphrase,
+     * which is usually a lack of memory issue. The functions accepting keys
+     * do not produce this error.
+     */
+    TOX_ERR_ENCRYPTION_KEY_DERIVATION_FAILED,
+    /**
+     * The encryption itself failed.
+     */
+    TOX_ERR_ENCRYPTION_FAILED
+} TOX_ERR_ENCRYPTION;
+
+typedef enum TOX_ERR_DECRYPTION {
+    TOX_ERR_DECRYPTION_OK,
+    /**
+     * Some input data, or maybe the output pointer, was null.
+     */
+    TOX_ERR_DECRYPTION_NULL,
+    /**
+     * The input data was shorter than TOX_PASS_ENCRYPTION_EXTRA_LENGTH bytes
+     */
+    TOX_ERR_DECRYPTION_INVALID_LENGTH,
+    /**
+     * The input data is missing the magic number (i.e. wasn't created by this
+     * module, or is corrupted)
+     */
+    TOX_ERR_DECRYPTION_BAD_FORMAT,
+    /**
+     * The crypto lib was unable to derive a key from the given passphrase,
+     * which is usually a lack of memory issue. The functions accepting keys
+     * do not produce this error.
+     */
+    TOX_ERR_DECRYPTION_KEY_DERIVATION_FAILED,
+    /**
+     * The encrypted byte array could not be decrypted. Either the data was
+     * corrupt or the password/key was incorrect.
+     */
+    TOX_ERR_DECRYPTION_FAILED
+} TOX_ERR_DECRYPTION;
+
 
 /******************************* BEGIN PART 2 *******************************
  * For simplicty, the second part of the module is presented first. The API for
@@ -75,41 +138,25 @@ 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. This delegates
+ * at least data_len + TOX_PASS_ENCRYPTION_EXTRA_LENGTH bytes long. This delegates
  * to tox_derive_key_from_pass and tox_pass_key_encrypt.
  *
- * tox_encrypted_save() is a good example of how to use this function.
- *
- * returns 0 on success
- * returns -1 on failure
+ * returns true on success
  */
-int tox_pass_encrypt(const uint8_t *data, uint32_t data_len, uint8_t *passphrase, uint32_t pplength, uint8_t *out);
+bool tox_pass_encrypt(const uint8_t *data, size_t data_len, uint8_t *passphrase, size_t pplength, uint8_t *out,
+                      TOX_ERR_ENCRYPTION *error);
 
-/* 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_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. This delegates
+ * at least data_len - TOX_PASS_ENCRYPTION_EXTRA_LENGTH bytes long. This delegates
  * to tox_pass_key_decrypt.
  *
- * tox_encrypted_load() is a good example of how to use this function.
+ * the output data has size data_length - TOX_PASS_ENCRYPTION_EXTRA_LENGTH
  *
- * returns the length of the output data (== data_len - tox_pass_encryption_extra_length()) on success
- * returns -1 on failure
+ * returns true on success
  */
-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
- * returns -1 on failure
- */
-int tox_encrypted_load(Tox *tox, const uint8_t *data, uint32_t length, uint8_t *passphrase, uint32_t pplength);
+bool tox_pass_decrypt(const uint8_t *data, size_t length, uint8_t *passphrase, size_t pplength, uint8_t *out,
+                      TOX_ERR_DECRYPTION *error);
 
 
 /******************************* BEGIN PART 1 *******************************
@@ -117,8 +164,16 @@ int tox_encrypted_load(Tox *tox, const uint8_t *data, uint32_t length, uint8_t *
  * intensive than part one. The first 3 functions are for key handling.
  */
 
+/* This key structure's internals should not be used by any client program, even
+ * if they are straightforward here.
+ */
+typedef struct {
+    uint8_t salt[TOX_PASS_SALT_LENGTH];
+    uint8_t key[TOX_PASS_KEY_LENGTH];
+} TOX_PASS_KEY;
+
 /* Generates a secret symmetric key from the given passphrase. out_key must be at least
- * tox_pass_key_length() bytes long.
+ * TOX_PASS_KEY_LENGTH bytes long.
  * Be sure to not compromise the key! Only keep it in memory, do not write to disk.
  * The password is zeroed after key derivation.
  * The key should only be used with the other functions in this module, as it
@@ -126,68 +181,53 @@ int tox_encrypted_load(Tox *tox, const uint8_t *data, uint32_t length, uint8_t *
  * 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. See below.
  *
- * returns 0 on success
- * returns -1 on failure
+ * returns true on success
  */
-int tox_derive_key_from_pass(uint8_t *passphrase, uint32_t pplength, uint8_t *out_key);
+bool tox_derive_key_from_pass(uint8_t *passphrase, size_t pplength, TOX_PASS_KEY *out_key,
+                              TOX_ERR_KEY_DERIVATION *error);
 
-/* Same as above, except with use the given salt for deterministic key derivation.
- * The salt must be tox_salt_length() bytes in length.
+/* Same as above, except use the given salt for deterministic key derivation.
+ * The salt must be TOX_PASS_SALT_LENGTH bytes in length.
  */
-int tox_derive_key_with_salt(uint8_t *passphrase, uint32_t pplength, uint8_t *salt, uint8_t *out_key);
+bool tox_derive_key_with_salt(uint8_t *passphrase, size_t pplength, uint8_t *salt, TOX_PASS_KEY *out_key,
+                              TOX_ERR_KEY_DERIVATION *error);
 
 /* This retrieves the salt used to encrypt the given data, which can then be passed to
  * derive_key_with_salt to produce the same key as was previously used. Any encrpyted
  * data with this module can be used as input.
  *
- * returns -1 if the magic number is wrong
- * returns 0 otherwise (no guarantee about validity of data)
+ * returns true if magic number matches
+ * success does not say anything about the validity of the data, only that data of
+ * the appropriate size was copied
  */
-int tox_get_salt(uint8_t *data, uint8_t *salt);
+bool tox_get_salt(const uint8_t *data, uint8_t *salt);
 
 /* Now come the functions that are analogous to the part 2 functions. */
 
-/* Encrypt arbitrary with a key produced by tox_derive_key_. The output
- * array must be at least data_len + tox_pass_encryption_extra_length() bytes long.
- * key must be tox_pass_key_length() bytes.
+/* Encrypt arbitrary with a key produced by tox_derive_key_*. The output
+ * array must be at least data_len + TOX_PASS_ENCRYPTION_EXTRA_LENGTH bytes long.
+ * key must be TOX_PASS_KEY_LENGTH bytes.
  * If you already have a symmetric key from somewhere besides this module, simply
  * call encrypt_data_symmetric in toxcore/crypto_core directly.
  *
- * returns 0 on success
- * returns -1 on failure
+ * returns true on success
  */
-int tox_pass_key_encrypt(const uint8_t *data, uint32_t data_len, const uint8_t *key, uint8_t *out);
-
-/* Save the messenger data encrypted with the given key from tox_derive_key.
- * data must be at least tox_encrypted_size().
- *
- * returns 0 on success
- * returns -1 on failure
- */
-int tox_encrypted_key_save(const Tox *tox, uint8_t *data, uint8_t *key);
+bool tox_pass_key_encrypt(const uint8_t *data, size_t data_len, const TOX_PASS_KEY *key, uint8_t *out,
+                          TOX_ERR_ENCRYPTION *error);
 
 /* This is the inverse of tox_pass_key_encrypt, also using only keys produced by
  * tox_derive_key_from_pass.
  *
- * returns the length of the output data (== data_len - tox_pass_encryption_extra_length()) on success
- * returns -1 on failure
- */
-int tox_pass_key_decrypt(const uint8_t *data, uint32_t length, const uint8_t *key, uint8_t *out);
-
-/* Load the messenger from encrypted data of size length, with key from tox_derive_key.
+ * the output data has size data_length - TOX_PASS_ENCRYPTION_EXTRA_LENGTH
  *
- * returns 0 on success
- * returns -1 on failure
+ * returns true on success
  */
-int tox_encrypted_key_load(Tox *tox, const uint8_t *data, uint32_t length, uint8_t *key);
+bool tox_pass_key_decrypt(const uint8_t *data, size_t length, const TOX_PASS_KEY *key, uint8_t *out,
+                          TOX_ERR_DECRYPTION *error);
 
 /* Determines whether or not the given data is encrypted (by checking the magic number)
- *
- * 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); // poorly-named alias for backwards compat (oh irony...)
+bool tox_is_data_encrypted(const uint8_t *data);
 
 #ifdef __cplusplus
 }