Botan  2.13.0
Crypto and TLS for C++11
skein_512.cpp
Go to the documentation of this file.
1 /*
2 * The Skein-512 hash function
3 * (C) 2009,2010,2014 Jack Lloyd
4 *
5 * Botan is released under the Simplified BSD License (see license.txt)
6 */
7 
8 #include <botan/skein_512.h>
9 #include <botan/loadstor.h>
10 #include <botan/exceptn.h>
11 #include <algorithm>
12 
13 namespace Botan {
14 
15 Skein_512::Skein_512(size_t arg_output_bits,
16  const std::string& arg_personalization) :
17  m_personalization(arg_personalization),
18  m_output_bits(arg_output_bits),
19  m_threefish(new Threefish_512),
20  m_T(2), m_buffer(64), m_buf_pos(0)
21  {
22  if(m_output_bits == 0 || m_output_bits % 8 != 0 || m_output_bits > 512)
23  throw Invalid_Argument("Bad output bits size for Skein-512");
24 
25  initial_block();
26  }
27 
28 std::string Skein_512::name() const
29  {
30  if(m_personalization != "")
31  return "Skein-512(" + std::to_string(m_output_bits) + "," +
32  m_personalization + ")";
33  return "Skein-512(" + std::to_string(m_output_bits) + ")";
34  }
35 
37  {
38  return new Skein_512(m_output_bits, m_personalization);
39  }
40 
41 std::unique_ptr<HashFunction> Skein_512::copy_state() const
42  {
43  std::unique_ptr<Skein_512> copy(new Skein_512(m_output_bits, m_personalization));
44 
45  copy->m_threefish->m_K = this->m_threefish->m_K;
46  copy->m_T = this->m_T;
47  copy->m_buffer = this->m_buffer;
48  copy->m_buf_pos = this->m_buf_pos;
49 
50  // work around GCC 4.8 bug
51  return std::unique_ptr<HashFunction>(copy.release());
52  }
53 
55  {
56  zeroise(m_buffer);
57  m_buf_pos = 0;
58 
59  initial_block();
60  }
61 
62 void Skein_512::reset_tweak(type_code type, bool is_final)
63  {
64  m_T[0] = 0;
65 
66  m_T[1] = (static_cast<uint64_t>(type) << 56) |
67  (static_cast<uint64_t>(1) << 62) |
68  (static_cast<uint64_t>(is_final) << 63);
69  }
70 
71 void Skein_512::initial_block()
72  {
73  const uint8_t zeros[64] = { 0 };
74 
75  m_threefish->set_key(zeros, sizeof(zeros));
76 
77  // ASCII("SHA3") followed by version (0x0001) code
78  uint8_t config_str[32] = { 0x53, 0x48, 0x41, 0x33, 0x01, 0x00, 0 };
79  store_le(uint32_t(m_output_bits), config_str + 8);
80 
81  reset_tweak(SKEIN_CONFIG, true);
82  ubi_512(config_str, sizeof(config_str));
83 
84  if(m_personalization != "")
85  {
86  /*
87  This is a limitation of this implementation, and not of the
88  algorithm specification. Could be fixed relatively easily, but
89  doesn't seem worth the trouble.
90  */
91  if(m_personalization.length() > 64)
92  throw Invalid_Argument("Skein personalization must be less than 64 bytes");
93 
94  const uint8_t* bits = cast_char_ptr_to_uint8(m_personalization.data());
95  reset_tweak(SKEIN_PERSONALIZATION, true);
96  ubi_512(bits, m_personalization.length());
97  }
98 
99  reset_tweak(SKEIN_MSG, false);
100  }
101 
102 void Skein_512::ubi_512(const uint8_t msg[], size_t msg_len)
103  {
104  secure_vector<uint64_t> M(8);
105 
106  do
107  {
108  const size_t to_proc = std::min<size_t>(msg_len, 64);
109  m_T[0] += to_proc;
110 
111  load_le(M.data(), msg, to_proc / 8);
112 
113  if(to_proc % 8)
114  {
115  for(size_t j = 0; j != to_proc % 8; ++j)
116  M[to_proc/8] |= static_cast<uint64_t>(msg[8*(to_proc/8)+j]) << (8*j);
117  }
118 
119  m_threefish->skein_feedfwd(M, m_T);
120 
121  // clear first flag if set
122  m_T[1] &= ~(static_cast<uint64_t>(1) << 62);
123 
124  msg_len -= to_proc;
125  msg += to_proc;
126  } while(msg_len);
127  }
128 
129 void Skein_512::add_data(const uint8_t input[], size_t length)
130  {
131  if(length == 0)
132  return;
133 
134  if(m_buf_pos)
135  {
136  buffer_insert(m_buffer, m_buf_pos, input, length);
137  if(m_buf_pos + length > 64)
138  {
139  ubi_512(m_buffer.data(), m_buffer.size());
140 
141  input += (64 - m_buf_pos);
142  length -= (64 - m_buf_pos);
143  m_buf_pos = 0;
144  }
145  }
146 
147  const size_t full_blocks = (length - 1) / 64;
148 
149  if(full_blocks)
150  ubi_512(input, 64*full_blocks);
151 
152  length -= full_blocks * 64;
153 
154  buffer_insert(m_buffer, m_buf_pos, input + full_blocks * 64, length);
155  m_buf_pos += length;
156  }
157 
158 void Skein_512::final_result(uint8_t out[])
159  {
160  m_T[1] |= (static_cast<uint64_t>(1) << 63); // final block flag
161 
162  for(size_t i = m_buf_pos; i != m_buffer.size(); ++i)
163  m_buffer[i] = 0;
164 
165  ubi_512(m_buffer.data(), m_buf_pos);
166 
167  const uint8_t counter[8] = { 0 };
168 
169  reset_tweak(SKEIN_OUTPUT, true);
170  ubi_512(counter, sizeof(counter));
171 
172  copy_out_vec_le(out, m_output_bits / 8, m_threefish->m_K);
173 
174  m_buf_pos = 0;
175  initial_block();
176  }
177 
178 }
std::unique_ptr< HashFunction > copy_state() const override
Definition: skein_512.cpp:41
void clear() override
Definition: skein_512.cpp:54
const uint8_t * cast_char_ptr_to_uint8(const char *s)
Definition: mem_ops.h:189
std::string to_string(const BER_Object &obj)
Definition: asn1_obj.cpp:213
MechanismType type
T load_le(const uint8_t in[], size_t off)
Definition: loadstor.h:123
Definition: alg_id.cpp:13
Skein_512(size_t output_bits=512, const std::string &personalization="")
Definition: skein_512.cpp:15
size_t buffer_insert(std::vector< T, Alloc > &buf, size_t buf_offset, const T input[], size_t input_length)
Definition: secmem.h:80
HashFunction * clone() const override
Definition: skein_512.cpp:36
void store_le(uint16_t in, uint8_t out[2])
Definition: loadstor.h:454
void zeroise(std::vector< T, Alloc > &vec)
Definition: secmem.h:160
void copy_out_vec_le(uint8_t out[], size_t out_bytes, const std::vector< T, Alloc > &in)
Definition: loadstor.h:694
std::string name() const override
Definition: skein_512.cpp:28