Botan  2.1.0
Crypto and TLS for C++11
skein_512.cpp
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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/parsing.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 
42  {
43  zeroise(m_buffer);
44  m_buf_pos = 0;
45 
46  initial_block();
47  }
48 
49 void Skein_512::reset_tweak(type_code type, bool is_final)
50  {
51  m_T[0] = 0;
52 
53  m_T[1] = (static_cast<uint64_t>(type) << 56) |
54  (static_cast<uint64_t>(1) << 62) |
55  (static_cast<uint64_t>(is_final) << 63);
56  }
57 
58 void Skein_512::initial_block()
59  {
60  const uint8_t zeros[64] = { 0 };
61 
62  m_threefish->set_key(zeros, sizeof(zeros));
63 
64  // ASCII("SHA3") followed by version (0x0001) code
65  uint8_t config_str[32] = { 0x53, 0x48, 0x41, 0x33, 0x01, 0x00, 0 };
66  store_le(uint32_t(m_output_bits), config_str + 8);
67 
68  reset_tweak(SKEIN_CONFIG, true);
69  ubi_512(config_str, sizeof(config_str));
70 
71  if(m_personalization != "")
72  {
73  /*
74  This is a limitation of this implementation, and not of the
75  algorithm specification. Could be fixed relatively easily, but
76  doesn't seem worth the trouble.
77  */
78  if(m_personalization.length() > 64)
79  throw Invalid_Argument("Skein personalization must be less than 64 bytes");
80 
81  const uint8_t* bits = reinterpret_cast<const uint8_t*>(m_personalization.data());
82  reset_tweak(SKEIN_PERSONALIZATION, true);
83  ubi_512(bits, m_personalization.length());
84  }
85 
86  reset_tweak(SKEIN_MSG, false);
87  }
88 
89 void Skein_512::ubi_512(const uint8_t msg[], size_t msg_len)
90  {
91  secure_vector<uint64_t> M(8);
92 
93  do
94  {
95  const size_t to_proc = std::min<size_t>(msg_len, 64);
96  m_T[0] += to_proc;
97 
98  load_le(M.data(), msg, to_proc / 8);
99 
100  if(to_proc % 8)
101  {
102  for(size_t j = 0; j != to_proc % 8; ++j)
103  M[to_proc/8] |= static_cast<uint64_t>(msg[8*(to_proc/8)+j]) << (8*j);
104  }
105 
106  m_threefish->skein_feedfwd(M, m_T);
107 
108  // clear first flag if set
109  m_T[1] &= ~(static_cast<uint64_t>(1) << 62);
110 
111  msg_len -= to_proc;
112  msg += to_proc;
113  } while(msg_len);
114  }
115 
116 void Skein_512::add_data(const uint8_t input[], size_t length)
117  {
118  if(length == 0)
119  return;
120 
121  if(m_buf_pos)
122  {
123  buffer_insert(m_buffer, m_buf_pos, input, length);
124  if(m_buf_pos + length > 64)
125  {
126  ubi_512(m_buffer.data(), m_buffer.size());
127 
128  input += (64 - m_buf_pos);
129  length -= (64 - m_buf_pos);
130  m_buf_pos = 0;
131  }
132  }
133 
134  const size_t full_blocks = (length - 1) / 64;
135 
136  if(full_blocks)
137  ubi_512(input, 64*full_blocks);
138 
139  length -= full_blocks * 64;
140 
141  buffer_insert(m_buffer, m_buf_pos, input + full_blocks * 64, length);
142  m_buf_pos += length;
143  }
144 
145 void Skein_512::final_result(uint8_t out[])
146  {
147  m_T[1] |= (static_cast<uint64_t>(1) << 63); // final block flag
148 
149  for(size_t i = m_buf_pos; i != m_buffer.size(); ++i)
150  m_buffer[i] = 0;
151 
152  ubi_512(m_buffer.data(), m_buf_pos);
153 
154  const uint8_t counter[8] = { 0 };
155 
156  reset_tweak(SKEIN_OUTPUT, true);
157  ubi_512(counter, sizeof(counter));
158 
159  copy_out_vec_le(out, m_output_bits / 8, m_threefish->m_K);
160 
161  m_buf_pos = 0;
162  initial_block();
163  }
164 
165 }
void clear() override
Definition: skein_512.cpp:41
std::string to_string(const BER_Object &obj)
Definition: asn1_obj.cpp:47
MechanismType type
T load_le(const uint8_t in[], size_t off)
Definition: loadstor.h:129
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:133
HashFunction * clone() const override
Definition: skein_512.cpp:36
void store_le(uint16_t in, uint8_t out[2])
Definition: loadstor.h:457
void zeroise(std::vector< T, Alloc > &vec)
Definition: secmem.h:211
void copy_out_vec_le(uint8_t out[], size_t out_bytes, const std::vector< T, Alloc > &in)
Definition: loadstor.h:697
std::string name() const override
Definition: skein_512.cpp:28