src/util/auth.cpp

   1 /*
   2 Minetest
   3 Copyright (C) 2015, 2016 est31 <MTest31@outlook.com>
   4
   5 This program is free software; you can redistribute it and/or modify
   6 it under the terms of the GNU Lesser General Public License as published by
   7 the Free Software Foundation; either version 2.1 of the License, or
   8 (at your option) any later version.
   9
  10 This program is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU Lesser General Public License for more details.
  14
  15 You should have received a copy of the GNU Lesser General Public License along
  16 with this program; if not, write to the Free Software Foundation, Inc.,
  17 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18 */
  19
  20 #include <algorithm>
  21 #include <string>
  22 #include "auth.h"
  23 #include "base64.h"
  24 #include "sha1.h"
  25 #include "srp.h"
  26 #include "util/string.h"
  27 #include "debug.h"
  28
  29 // Get an sha-1 hash of the player's name combined with
  30 // the password entered. That's what the server uses as
  31 // their password. (Exception : if the password field is
  32 // blank, we send a blank password - this is for backwards
  33 // compatibility with password-less players).
  34 std::string translate_password(const std::string &name,
  35         const std::string &password)
  36 {
  37         if (password.length() == 0)
  38                 return "";
  39
  40         std::string slt = name + password;
  41         SHA1 sha1;
  42         sha1.addBytes(slt.c_str(), slt.length());
  43         unsigned char *digest = sha1.getDigest();
  44         std::string pwd = base64_encode(digest, 20);
  45         free(digest);
  46         return pwd;
  47 }
  48
  49 // Call lower level SRP code to generate a verifier with the
  50 // given pointers. Contains the preparations, call parameters
  51 // and error checking common to all srp verifier generation code.
  52 // See docs of srp_create_salted_verification_key for more info.
  53 static inline void gen_srp_v(const std::string &name,
  54         const std::string &password, char **salt, size_t *salt_len,
  55         char **bytes_v, size_t *len_v)
  56 {
  57         std::string n_name = lowercase(name);
  58         SRP_Result res = srp_create_salted_verification_key(SRP_SHA256, SRP_NG_2048,
  59                 n_name.c_str(), (const unsigned char *)password.c_str(),
  60                 password.size(), (unsigned char **)salt, salt_len,
  61                 (unsigned char **)bytes_v, len_v, NULL, NULL);
  62         FATAL_ERROR_IF(res != SRP_OK, "Couldn't create salted SRP verifier");
  63 }
  64
  65 /// Creates a verification key with given salt and password.
  66 std::string generate_srp_verifier(const std::string &name,
  67         const std::string &password, const std::string &salt)
  68 {
  69         size_t salt_len = salt.size();
  70         // The API promises us that the salt doesn't
  71         // get modified if &salt_ptr isn't NULL.
  72         char *salt_ptr = (char *)salt.c_str();
  73
  74         char *bytes_v = nullptr;
  75         size_t verifier_len = 0;
  76         gen_srp_v(name, password, &salt_ptr, &salt_len, &bytes_v, &verifier_len);
  77         std::string verifier = std::string(bytes_v, verifier_len);
  78         free(bytes_v);
  79         return verifier;
  80 }
  81
  82 /// Creates a verification key and salt with given password.
  83 void generate_srp_verifier_and_salt(const std::string &name,
  84         const std::string &password, std::string *verifier,
  85         std::string *salt)
  86 {
  87         char *bytes_v = nullptr;
  88         size_t verifier_len;
  89         char *salt_ptr = nullptr;
  90         size_t salt_len;
  91         gen_srp_v(name, password, &salt_ptr, &salt_len, &bytes_v, &verifier_len);
  92         *verifier = std::string(bytes_v, verifier_len);
  93         *salt = std::string(salt_ptr, salt_len);
  94         free(bytes_v);
  95         free(salt_ptr);
  96 }
  97
  98 /// Gets an SRP verifier, generating a salt,
  99 /// and encodes it as DB-ready string.
 100 std::string get_encoded_srp_verifier(const std::string &name,
 101         const std::string &password)
 102 {
 103         std::string verifier;
 104         std::string salt;
 105         generate_srp_verifier_and_salt(name, password, &verifier, &salt);
 106         return encode_srp_verifier(verifier, salt);
 107 }
 108
 109 /// Converts the passed SRP verifier into a DB-ready format.
 110 std::string encode_srp_verifier(const std::string &verifier,
 111         const std::string &salt)
 112 {
 113         std::ostringstream ret_str;
 114         ret_str << "#1#"
 115                 << base64_encode((unsigned char *)salt.c_str(), salt.size()) << "#"
 116                 << base64_encode((unsigned char *)verifier.c_str(), verifier.size());
 117         return ret_str.str();
 118 }
 119
 120 /// Reads the DB-formatted SRP verifier and gets the verifier
 121 /// and salt components.
 122 bool decode_srp_verifier_and_salt(const std::string &encoded,
 123         std::string *verifier, std::string *salt)
 124 {
 125         std::vector<std::string> components = str_split(encoded, '#');
 126
 127         if ((components.size() != 4)
 128                         || (components[1] != "1") // 1 means srp
 129                         || !base64_is_valid(components[2])
 130                         || !base64_is_valid(components[3]))
 131                 return false;
 132
 133         *salt = base64_decode(components[2]);
 134         *verifier = base64_decode(components[3]);
 135         return true;
 136
 137 }