argon2fmt.cpp

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/**
* (C) 2019 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
 
#include <botan/argon2fmt.h>
#include <botan/pwdhash.h>
#include <botan/rng.h>
#include <botan/base64.h>
#include <botan/internal/parsing.h>
#include <botan/internal/fmt.h>
 
namespace Botan {
 
namespace {
 
std::string strip_padding(std::string s)
   {
   while(!s.empty() && s[s.size()-1] == '=')
      s.resize(s.size() - 1);
   return s;
   }
 
std::string argon2_family(uint8_t y)
   {
   if(y == 0)
      return "Argon2d";
   else if(y == 1)
      return "Argon2i";
   else if(y == 2)
      return "Argon2id";
   else
      throw Not_Implemented("Unknown Argon2 family type");
   }
 
}
 
std::string argon2_generate_pwhash(const char* password, size_t password_len,
                                   RandomNumberGenerator& rng,
                                   size_t p, size_t M, size_t t,
                                   uint8_t y, size_t salt_len, size_t output_len)
   {
   std::vector<uint8_t> salt(salt_len);
   rng.randomize(salt.data(), salt.size());
 
   std::vector<uint8_t> output(output_len);
 
   auto pwdhash_fam = PasswordHashFamily::create_or_throw(argon2_family(y));
   auto pwdhash = pwdhash_fam->from_params(M, t, p);
 
   pwdhash->derive_key(output.data(), output.size(),
                       password, password_len,
                       salt.data(), salt.size());
 
   const auto enc_salt = strip_padding(base64_encode(salt));
   const auto enc_output = strip_padding(base64_encode(output));
 
   const std::string argon2_mode = [&]() -> std::string
      {
      if(y == 0)
         return "d";
      else if(y == 1)
         return "i";
      else
         return "id";
      }();
 
   return fmt("$argon2{}$v=19$m={},t={},p={}${}${}",
              argon2_mode, M, t, p,
              enc_salt, enc_output);
   }
 
bool argon2_check_pwhash(const char* password, size_t password_len,
                         std::string_view input_hash)
   {
   const std::vector<std::string> parts = split_on(input_hash, '$');
 
   if(parts.size() != 5)
      return false;
 
   uint8_t family = 0;
 
   if(parts[0] == "argon2d")
      family = 0;
   else if(parts[0] == "argon2i")
      family = 1;
   else if(parts[0] == "argon2id")
      family = 2;
   else
      return false;
 
   if(parts[1] != "v=19")
      return false;
 
   const std::vector<std::string> params = split_on(parts[2], ',');
 
   if(params.size() != 3)
      return false;
 
   size_t M = 0, t = 0, p = 0;
 
   for(const auto& param_str : params)
      {
      const std::vector<std::string> param = split_on(param_str, '=');
 
      if(param.size() != 2)
         return false;
 
      std::string_view key = param[0];
      const size_t val = to_u32bit(param[1]);
      if(key == "m")
         M = val;
      else if(key == "t")
         t = val;
      else if(key == "p")
         p = val;
      else
         return false;
      }
 
   std::vector<uint8_t> salt(base64_decode_max_output(parts[3].size()));
   salt.resize(base64_decode(salt.data(), parts[3], false));
 
   std::vector<uint8_t> hash(base64_decode_max_output(parts[4].size()));
   hash.resize(base64_decode(hash.data(), parts[4], false));
 
   if(hash.size() < 4)
      return false;
 
   std::vector<uint8_t> generated(hash.size());
   auto pwdhash_fam = PasswordHashFamily::create_or_throw(argon2_family(family));
   auto pwdhash = pwdhash_fam->from_params(M, t, p);
 
   pwdhash->derive_key(generated.data(), generated.size(),
                       password, password_len,
                       salt.data(), salt.size());
 
   return constant_time_compare(generated.data(), hash.data(), generated.size());
   }
 
}