Botan  2.1.0
Crypto and TLS for C++11
passhash9.cpp
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1 /*
2 * Passhash9 Password Hashing
3 * (C) 2010 Jack Lloyd
4 *
5 * Botan is released under the Simplified BSD License (see license.txt)
6 */
7 
8 #include <botan/passhash9.h>
9 #include <botan/loadstor.h>
10 #include <botan/pbkdf2.h>
11 #include <botan/base64.h>
12 
13 namespace Botan {
14 
15 namespace {
16 
17 const std::string MAGIC_PREFIX = "$9$";
18 
19 const size_t WORKFACTOR_BYTES = 2;
20 const size_t ALGID_BYTES = 1;
21 const size_t SALT_BYTES = 12; // 96 bits of salt
22 const size_t PASSHASH9_PBKDF_OUTPUT_LEN = 24; // 192 bits output
23 
24 const size_t WORK_FACTOR_SCALE = 10000;
25 
26 std::unique_ptr<MessageAuthenticationCode> get_pbkdf_prf(uint8_t alg_id)
27  {
28  if(alg_id == 0)
29  return MessageAuthenticationCode::create("HMAC(SHA-1)");
30  else if(alg_id == 1)
31  return MessageAuthenticationCode::create("HMAC(SHA-256)");
32  else if(alg_id == 2)
33  return MessageAuthenticationCode::create("CMAC(Blowfish)");
34  else if(alg_id == 3)
35  return MessageAuthenticationCode::create("HMAC(SHA-384)");
36  else if(alg_id == 4)
37  return MessageAuthenticationCode::create("HMAC(SHA-512)");
38  return nullptr;
39  }
40 
41 }
42 
43 std::string generate_passhash9(const std::string& pass,
45  uint16_t work_factor,
46  uint8_t alg_id)
47  {
48  std::unique_ptr<MessageAuthenticationCode> prf = get_pbkdf_prf(alg_id);
49 
50  if(!prf)
51  throw Invalid_Argument("Passhash9: Algorithm id " +
52  std::to_string(alg_id) +
53  " is not defined");
54 
55  PKCS5_PBKDF2 kdf(prf.release()); // takes ownership of pointer
56 
57  secure_vector<uint8_t> salt(SALT_BYTES);
58  rng.randomize(salt.data(), salt.size());
59 
60  const size_t kdf_iterations = WORK_FACTOR_SCALE * work_factor;
61 
63  blob.push_back(alg_id);
64  blob.push_back(get_byte(0, work_factor));
65  blob.push_back(get_byte(1, work_factor));
66  blob += salt;
67  blob += kdf.derive_key(PASSHASH9_PBKDF_OUTPUT_LEN,
68  pass,
69  salt.data(), salt.size(),
70  kdf_iterations).bits_of();
71 
72  return MAGIC_PREFIX + base64_encode(blob);
73  }
74 
75 bool check_passhash9(const std::string& pass, const std::string& hash)
76  {
77  const size_t BINARY_LENGTH =
78  ALGID_BYTES +
79  WORKFACTOR_BYTES +
80  PASSHASH9_PBKDF_OUTPUT_LEN +
81  SALT_BYTES;
82 
83  const size_t BASE64_LENGTH =
84  MAGIC_PREFIX.size() + (BINARY_LENGTH * 8) / 6;
85 
86  if(hash.size() != BASE64_LENGTH)
87  return false;
88 
89  for(size_t i = 0; i != MAGIC_PREFIX.size(); ++i)
90  if(hash[i] != MAGIC_PREFIX[i])
91  return false;
92 
93  secure_vector<uint8_t> bin = base64_decode(hash.c_str() + MAGIC_PREFIX.size());
94 
95  if(bin.size() != BINARY_LENGTH)
96  return false;
97 
98  uint8_t alg_id = bin[0];
99 
100  const size_t work_factor = load_be<uint16_t>(&bin[ALGID_BYTES], 0);
101 
102  // Bug in the format, bad states shouldn't be representable, but are...
103  if(work_factor == 0)
104  return false;
105 
106  if(work_factor > 512)
107  throw Invalid_Argument("Requested Bcrypt work factor " +
108  std::to_string(work_factor) + " too large");
109 
110  const size_t kdf_iterations = WORK_FACTOR_SCALE * work_factor;
111 
112  std::unique_ptr<MessageAuthenticationCode> pbkdf_prf = get_pbkdf_prf(alg_id);
113 
114  if(!pbkdf_prf)
115  return false; // unknown algorithm, reject
116 
117  PKCS5_PBKDF2 kdf(pbkdf_prf.release()); // takes ownership of pointer
118 
120  PASSHASH9_PBKDF_OUTPUT_LEN,
121  pass,
122  &bin[ALGID_BYTES + WORKFACTOR_BYTES], SALT_BYTES,
123  kdf_iterations).bits_of();
124 
125  return same_mem(cmp.data(),
126  &bin[ALGID_BYTES + WORKFACTOR_BYTES + SALT_BYTES],
127  PASSHASH9_PBKDF_OUTPUT_LEN);
128  }
129 
130 }
secure_vector< uint8_t > bits_of() const
Definition: symkey.h:31
static std::unique_ptr< MessageAuthenticationCode > create(const std::string &algo_spec, const std::string &provider="")
Definition: mac.cpp:43
bool same_mem(const T *p1, const T *p2, size_t n)
Definition: mem_ops.h:98
virtual void randomize(uint8_t output[], size_t length)=0
size_t base64_decode(uint8_t output[], const char input[], size_t input_length, size_t &input_consumed, bool final_inputs, bool ignore_ws)
Definition: base64.cpp:100
uint16_t load_be< uint16_t >(const uint8_t in[], size_t off)
Definition: loadstor.h:145
OctetString derive_key(size_t out_len, const std::string &passphrase, const uint8_t salt[], size_t salt_len, size_t iterations) const
Definition: pbkdf.h:149
bool check_passhash9(const std::string &pass, const std::string &hash)
Definition: passhash9.cpp:75
std::string to_string(const BER_Object &obj)
Definition: asn1_obj.cpp:47
std::vector< T, secure_allocator< T >> secure_vector
Definition: secmem.h:121
Definition: alg_id.cpp:13
size_t base64_encode(char out[], const uint8_t in[], size_t input_length, size_t &input_consumed, bool final_inputs)
Definition: base64.cpp:35
uint8_t get_byte(size_t byte_num, T input)
Definition: loadstor.h:47
std::string generate_passhash9(const std::string &pass, RandomNumberGenerator &rng, uint16_t work_factor, uint8_t alg_id)
Definition: passhash9.cpp:43
MechanismType hash