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/*
* Passhash9 Password Hashing
* (C) 2010 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/passhash9.h>
#include <botan/loadstor.h>
#include <botan/lookup.h>
#include <botan/pbkdf2.h>
#include <botan/base64.h>
namespace Botan {
namespace {
const std::string MAGIC_PREFIX = "$9$";
const size_t WORKFACTOR_BYTES = 2;
const size_t ALGID_BYTES = 1;
const size_t SALT_BYTES = 12; // 96 bits of salt
const size_t PASSHASH9_PBKDF_OUTPUT_LEN = 24; // 192 bits output
const size_t WORK_FACTOR_SCALE = 10000;
MessageAuthenticationCode* get_pbkdf_prf(byte alg_id)
{
if(alg_id == 0)
return get_mac("HMAC(SHA-1)");
else if(alg_id == 1)
return get_mac("HMAC(SHA-256)");
else if(alg_id == 2)
return get_mac("CMAC(Blowfish)");
else if(alg_id == 3)
return get_mac("HMAC(SHA-384)");
else if(alg_id == 4)
return get_mac("HMAC(SHA-512)");
return nullptr;
}
}
std::string generate_passhash9(const std::string& pass,
RandomNumberGenerator& rng,
u16bit work_factor,
byte alg_id)
{
MessageAuthenticationCode* prf = get_pbkdf_prf(alg_id);
if(!prf)
throw Invalid_Argument("Passhash9: Algorithm id " +
std::to_string(alg_id) +
" is not defined");
PKCS5_PBKDF2 kdf(prf); // takes ownership of pointer
secure_vector<byte> salt(SALT_BYTES);
rng.randomize(&salt[0], salt.size());
const size_t kdf_iterations = WORK_FACTOR_SCALE * work_factor;
secure_vector<byte> blob;
blob.push_back(alg_id);
blob.push_back(get_byte(0, work_factor));
blob.push_back(get_byte(1, work_factor));
blob += salt;
blob += kdf.derive_key(PASSHASH9_PBKDF_OUTPUT_LEN,
pass,
&salt[0], salt.size(),
kdf_iterations).bits_of();
return MAGIC_PREFIX + base64_encode(blob);
}
bool check_passhash9(const std::string& pass, const std::string& hash)
{
const size_t BINARY_LENGTH =
ALGID_BYTES +
WORKFACTOR_BYTES +
PASSHASH9_PBKDF_OUTPUT_LEN +
SALT_BYTES;
const size_t BASE64_LENGTH =
MAGIC_PREFIX.size() + (BINARY_LENGTH * 8) / 6;
if(hash.size() != BASE64_LENGTH)
return false;
for(size_t i = 0; i != MAGIC_PREFIX.size(); ++i)
if(hash[i] != MAGIC_PREFIX[i])
return false;
secure_vector<byte> bin = base64_decode(hash.c_str() + MAGIC_PREFIX.size());
if(bin.size() != BINARY_LENGTH)
return false;
byte alg_id = bin[0];
const size_t work_factor = load_be<u16bit>(&bin[ALGID_BYTES], 0);
// Bug in the format, bad states shouldn't be representable, but are...
if(work_factor == 0)
return false;
if(work_factor > 512)
throw std::invalid_argument("Requested Bcrypt work factor " +
std::to_string(work_factor) + " too large");
const size_t kdf_iterations = WORK_FACTOR_SCALE * work_factor;
MessageAuthenticationCode* pbkdf_prf = get_pbkdf_prf(alg_id);
if(!pbkdf_prf)
return false; // unknown algorithm, reject
PKCS5_PBKDF2 kdf(pbkdf_prf); // takes ownership of pointer
secure_vector<byte> cmp = kdf.derive_key(
PASSHASH9_PBKDF_OUTPUT_LEN,
pass,
&bin[ALGID_BYTES + WORKFACTOR_BYTES], SALT_BYTES,
kdf_iterations).bits_of();
return same_mem(&cmp[0],
&bin[ALGID_BYTES + WORKFACTOR_BYTES + SALT_BYTES],
PASSHASH9_PBKDF_OUTPUT_LEN);
}
}
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