Botan 2.1.0 Crypto and TLS for C++11

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tss.cpp
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1 /*
2 * RTSS (threshold secret sharing)
3 * (C) 2009 Jack Lloyd
4 *
5 * Botan is released under the Simplified BSD License (see license.txt)
6 */
7
8 #include <botan/tss.h>
9 #include <botan/loadstor.h>
10 #include <botan/hex.h>
11 #include <botan/sha2_32.h>
12 #include <botan/sha160.h>
13
14 namespace Botan {
15
16 namespace {
17
18 /**
19 Table for GF(2^8) arithmetic (exponentials)
20 */
21 const uint8_t RTSS_EXP[256] = {
22 0x01, 0x03, 0x05, 0x0F, 0x11, 0x33, 0x55, 0xFF, 0x1A, 0x2E, 0x72,
23 0x96, 0xA1, 0xF8, 0x13, 0x35, 0x5F, 0xE1, 0x38, 0x48, 0xD8, 0x73,
24 0x95, 0xA4, 0xF7, 0x02, 0x06, 0x0A, 0x1E, 0x22, 0x66, 0xAA, 0xE5,
25 0x34, 0x5C, 0xE4, 0x37, 0x59, 0xEB, 0x26, 0x6A, 0xBE, 0xD9, 0x70,
26 0x90, 0xAB, 0xE6, 0x31, 0x53, 0xF5, 0x04, 0x0C, 0x14, 0x3C, 0x44,
27 0xCC, 0x4F, 0xD1, 0x68, 0xB8, 0xD3, 0x6E, 0xB2, 0xCD, 0x4C, 0xD4,
28 0x67, 0xA9, 0xE0, 0x3B, 0x4D, 0xD7, 0x62, 0xA6, 0xF1, 0x08, 0x18,
29 0x28, 0x78, 0x88, 0x83, 0x9E, 0xB9, 0xD0, 0x6B, 0xBD, 0xDC, 0x7F,
30 0x81, 0x98, 0xB3, 0xCE, 0x49, 0xDB, 0x76, 0x9A, 0xB5, 0xC4, 0x57,
31 0xF9, 0x10, 0x30, 0x50, 0xF0, 0x0B, 0x1D, 0x27, 0x69, 0xBB, 0xD6,
32 0x61, 0xA3, 0xFE, 0x19, 0x2B, 0x7D, 0x87, 0x92, 0xAD, 0xEC, 0x2F,
33 0x71, 0x93, 0xAE, 0xE9, 0x20, 0x60, 0xA0, 0xFB, 0x16, 0x3A, 0x4E,
34 0xD2, 0x6D, 0xB7, 0xC2, 0x5D, 0xE7, 0x32, 0x56, 0xFA, 0x15, 0x3F,
35 0x41, 0xC3, 0x5E, 0xE2, 0x3D, 0x47, 0xC9, 0x40, 0xC0, 0x5B, 0xED,
36 0x2C, 0x74, 0x9C, 0xBF, 0xDA, 0x75, 0x9F, 0xBA, 0xD5, 0x64, 0xAC,
37 0xEF, 0x2A, 0x7E, 0x82, 0x9D, 0xBC, 0xDF, 0x7A, 0x8E, 0x89, 0x80,
38 0x9B, 0xB6, 0xC1, 0x58, 0xE8, 0x23, 0x65, 0xAF, 0xEA, 0x25, 0x6F,
39 0xB1, 0xC8, 0x43, 0xC5, 0x54, 0xFC, 0x1F, 0x21, 0x63, 0xA5, 0xF4,
40 0x07, 0x09, 0x1B, 0x2D, 0x77, 0x99, 0xB0, 0xCB, 0x46, 0xCA, 0x45,
41 0xCF, 0x4A, 0xDE, 0x79, 0x8B, 0x86, 0x91, 0xA8, 0xE3, 0x3E, 0x42,
42 0xC6, 0x51, 0xF3, 0x0E, 0x12, 0x36, 0x5A, 0xEE, 0x29, 0x7B, 0x8D,
43 0x8C, 0x8F, 0x8A, 0x85, 0x94, 0xA7, 0xF2, 0x0D, 0x17, 0x39, 0x4B,
44 0xDD, 0x7C, 0x84, 0x97, 0xA2, 0xFD, 0x1C, 0x24, 0x6C, 0xB4, 0xC7,
45 0x52, 0xF6, 0x01 };
46
47 /**
48 Table for GF(2^8) arithmetic (logarithms)
49 */
50 const uint8_t RTSS_LOG[] = {
51 0x90, 0x00, 0x19, 0x01, 0x32, 0x02, 0x1A, 0xC6, 0x4B, 0xC7, 0x1B,
52 0x68, 0x33, 0xEE, 0xDF, 0x03, 0x64, 0x04, 0xE0, 0x0E, 0x34, 0x8D,
53 0x81, 0xEF, 0x4C, 0x71, 0x08, 0xC8, 0xF8, 0x69, 0x1C, 0xC1, 0x7D,
54 0xC2, 0x1D, 0xB5, 0xF9, 0xB9, 0x27, 0x6A, 0x4D, 0xE4, 0xA6, 0x72,
55 0x9A, 0xC9, 0x09, 0x78, 0x65, 0x2F, 0x8A, 0x05, 0x21, 0x0F, 0xE1,
56 0x24, 0x12, 0xF0, 0x82, 0x45, 0x35, 0x93, 0xDA, 0x8E, 0x96, 0x8F,
57 0xDB, 0xBD, 0x36, 0xD0, 0xCE, 0x94, 0x13, 0x5C, 0xD2, 0xF1, 0x40,
58 0x46, 0x83, 0x38, 0x66, 0xDD, 0xFD, 0x30, 0xBF, 0x06, 0x8B, 0x62,
59 0xB3, 0x25, 0xE2, 0x98, 0x22, 0x88, 0x91, 0x10, 0x7E, 0x6E, 0x48,
60 0xC3, 0xA3, 0xB6, 0x1E, 0x42, 0x3A, 0x6B, 0x28, 0x54, 0xFA, 0x85,
61 0x3D, 0xBA, 0x2B, 0x79, 0x0A, 0x15, 0x9B, 0x9F, 0x5E, 0xCA, 0x4E,
62 0xD4, 0xAC, 0xE5, 0xF3, 0x73, 0xA7, 0x57, 0xAF, 0x58, 0xA8, 0x50,
63 0xF4, 0xEA, 0xD6, 0x74, 0x4F, 0xAE, 0xE9, 0xD5, 0xE7, 0xE6, 0xAD,
64 0xE8, 0x2C, 0xD7, 0x75, 0x7A, 0xEB, 0x16, 0x0B, 0xF5, 0x59, 0xCB,
65 0x5F, 0xB0, 0x9C, 0xA9, 0x51, 0xA0, 0x7F, 0x0C, 0xF6, 0x6F, 0x17,
66 0xC4, 0x49, 0xEC, 0xD8, 0x43, 0x1F, 0x2D, 0xA4, 0x76, 0x7B, 0xB7,
67 0xCC, 0xBB, 0x3E, 0x5A, 0xFB, 0x60, 0xB1, 0x86, 0x3B, 0x52, 0xA1,
68 0x6C, 0xAA, 0x55, 0x29, 0x9D, 0x97, 0xB2, 0x87, 0x90, 0x61, 0xBE,
69 0xDC, 0xFC, 0xBC, 0x95, 0xCF, 0xCD, 0x37, 0x3F, 0x5B, 0xD1, 0x53,
70 0x39, 0x84, 0x3C, 0x41, 0xA2, 0x6D, 0x47, 0x14, 0x2A, 0x9E, 0x5D,
71 0x56, 0xF2, 0xD3, 0xAB, 0x44, 0x11, 0x92, 0xD9, 0x23, 0x20, 0x2E,
72 0x89, 0xB4, 0x7C, 0xB8, 0x26, 0x77, 0x99, 0xE3, 0xA5, 0x67, 0x4A,
73 0xED, 0xDE, 0xC5, 0x31, 0xFE, 0x18, 0x0D, 0x63, 0x8C, 0x80, 0xC0,
74 0xF7, 0x70, 0x07 };
75
76 uint8_t gfp_mul(uint8_t x, uint8_t y)
77 {
78 if(x == 0 || y == 0)
79 return 0;
80 return RTSS_EXP[(RTSS_LOG[x] + RTSS_LOG[y]) % 255];
81 }
82
83 uint8_t rtss_hash_id(const std::string& hash_name)
84 {
85 if(hash_name == "SHA-160")
86 return 1;
87 else if(hash_name == "SHA-256")
88 return 2;
89 else
90 throw Invalid_Argument("RTSS only supports SHA-1 and SHA-256");
91 }
92
93 HashFunction* get_rtss_hash_by_id(uint8_t id)
94 {
95 if(id == 1)
96 return new SHA_160;
97 else if(id == 2)
98 return new SHA_256;
99 else
100 throw Decoding_Error("Bad RTSS hash identifier");
101 }
102
103 }
104
105 RTSS_Share::RTSS_Share(const std::string& hex_input)
106 {
107 m_contents = hex_decode_locked(hex_input);
108 }
109
110 uint8_t RTSS_Share::share_id() const
111 {
112 if(!initialized())
113 throw Invalid_State("RTSS_Share::share_id not initialized");
114
115 return m_contents[20];
116 }
117
118 std::string RTSS_Share::to_string() const
119 {
120 return hex_encode(m_contents.data(), m_contents.size());
121 }
122
123 std::vector<RTSS_Share>
124 RTSS_Share::split(uint8_t M, uint8_t N,
125 const uint8_t S[], uint16_t S_len,
126 const uint8_t identifier[16],
127 RandomNumberGenerator& rng)
128 {
129 if(M == 0 || N == 0 || M > N)
130 throw Encoding_Error("RTSS_Share::split: M == 0 or N == 0 or M > N");
131
132 SHA_256 hash; // always use SHA-256 when generating shares
133
134 std::vector<RTSS_Share> shares(N);
135
136 // Create RTSS header in each share
137 for(uint8_t i = 0; i != N; ++i)
138 {
139 shares[i].m_contents += std::make_pair(identifier, 16);
140 shares[i].m_contents += rtss_hash_id(hash.name());
141 shares[i].m_contents += M;
142 shares[i].m_contents += get_byte(0, S_len);
143 shares[i].m_contents += get_byte(1, S_len);
144 }
145
146 // Choose sequential values for X starting from 1
147 for(uint8_t i = 0; i != N; ++i)
148 shares[i].m_contents.push_back(i+1);
149
150 // secret = S || H(S)
151 secure_vector<uint8_t> secret(S, S + S_len);
152 secret += hash.process(S, S_len);
153
154 for(size_t i = 0; i != secret.size(); ++i)
155 {
156 std::vector<uint8_t> coefficients(M-1);
157 rng.randomize(coefficients.data(), coefficients.size());
158
159 for(uint8_t j = 0; j != N; ++j)
160 {
161 const uint8_t X = j + 1;
162
163 uint8_t sum = secret[i];
164 uint8_t X_i = X;
165
166 for(size_t k = 0; k != coefficients.size(); ++k)
167 {
168 sum ^= gfp_mul(X_i, coefficients[k]);
169 X_i = gfp_mul(X_i, X);
170 }
171
172 shares[j].m_contents.push_back(sum);
173 }
174 }
175
176 return shares;
177 }
178
179 secure_vector<uint8_t>
180 RTSS_Share::reconstruct(const std::vector<RTSS_Share>& shares)
181 {
182 const size_t RTSS_HEADER_SIZE = 20;
183
184 for(size_t i = 0; i != shares.size(); ++i)
185 {
186 if(shares[i].size() != shares[0].size())
187 throw Decoding_Error("Different sized RTSS shares detected");
188 if(shares[i].share_id() == 0)
189 throw Decoding_Error("Invalid (id = 0) RTSS share detected");
190 if(shares[i].size() < RTSS_HEADER_SIZE)
191 throw Decoding_Error("Missing or malformed RTSS header");
192
193 if(!same_mem(&shares[0].m_contents[0],
194 &shares[i].m_contents[0], RTSS_HEADER_SIZE))
195 throw Decoding_Error("Different RTSS headers detected");
196 }
197
198 if(shares.size() < shares[0].m_contents[17])
199 throw Decoding_Error("Insufficient shares to do TSS reconstruction");
200
201 uint16_t secret_len = make_uint16(shares[0].m_contents[18],
202 shares[0].m_contents[19]);
203
204 uint8_t hash_id = shares[0].m_contents[16];
205
206 std::unique_ptr<HashFunction> hash(get_rtss_hash_by_id(hash_id));
207
208 if(shares[0].size() != secret_len + hash->output_length() + RTSS_HEADER_SIZE + 1)
209 throw Decoding_Error("Bad RTSS length field in header");
210
211 std::vector<uint8_t> V(shares.size());
212 secure_vector<uint8_t> secret;
213
214 for(size_t i = RTSS_HEADER_SIZE + 1; i != shares[0].size(); ++i)
215 {
216 for(size_t j = 0; j != V.size(); ++j)
217 V[j] = shares[j].m_contents[i];
218
219 uint8_t r = 0;
220 for(size_t k = 0; k != shares.size(); ++k)
221 {
222 // L_i function:
223 uint8_t r2 = 1;
224 for(size_t l = 0; l != shares.size(); ++l)
225 {
226 if(k == l)
227 continue;
228
229 uint8_t share_k = shares[k].share_id();
230 uint8_t share_l = shares[l].share_id();
231
232 if(share_k == share_l)
233 throw Decoding_Error("Duplicate shares found in RTSS recovery");
234
235 uint8_t div = RTSS_EXP[(255 +
236 RTSS_LOG[share_l] -
237 RTSS_LOG[share_k ^ share_l]) % 255];
238
239 r2 = gfp_mul(r2, div);
240 }
241
242 r ^= gfp_mul(V[k], r2);
243 }
244 secret.push_back(r);
245 }
246
247 if(secret.size() != secret_len + hash->output_length())
248 throw Decoding_Error("Bad length in RTSS output");
249
250 hash->update(secret.data(), secret_len);
251 secure_vector<uint8_t> hash_check = hash->final();
252
253 if(!same_mem(hash_check.data(),
254 &secret[secret_len], hash->output_length()))
255 throw Decoding_Error("RTSS hash check failed");
256
257 return secure_vector<uint8_t>(secret.cbegin(), secret.cbegin() + secret_len);
258 }
259
260 }
Botan::RTSS_Share::size
size_t size() const
Definition: tss.h:64
Botan::RTSS_Share::reconstruct
static secure_vector< uint8_t > reconstruct(const std::vector< RTSS_Share > &shares)
Definition: tss.cpp:180
Botan::same_mem
bool same_mem(const T *p1, const T *p2, size_t n)
Definition: mem_ops.h:98
Botan::RTSS_Share::RTSS_Share
RTSS_Share()=default
Botan::RTSS_Share::to_string
std::string to_string() const
Definition: tss.cpp:118
Botan::RandomNumberGenerator
Definition: rng.h:25
Botan::RandomNumberGenerator::randomize
virtual void randomize(uint8_t output[], size_t length)=0
Botan::RTSS_Share::initialized
bool initialized() const
Definition: tss.h:69
Botan::SHA_256::name
std::string name() const override
Definition: sha2_32.h:43
Botan::Invalid_State
Definition: exceptn.h:61
Botan::secure_vector
std::vector< T, secure_allocator< T >> secure_vector
Definition: secmem.h:121
Botan::Buffered_Computation::process
secure_vector< uint8_t > process(const uint8_t in[], size_t length)
Definition: buf_comp.h:124
Botan::Decoding_Error
Definition: exceptn.h:189
Botan::hex_decode_locked
secure_vector< uint8_t > hex_decode_locked(const char input[], size_t input_length, bool ignore_ws)
Definition: hex.cpp:162
Botan
Definition: alg_id.cpp:13
Botan::RTSS_Share::split
static std::vector< RTSS_Share > split(uint8_t M, uint8_t N, const uint8_t secret[], uint16_t secret_len, const uint8_t identifier[16], RandomNumberGenerator &rng)
Definition: tss.cpp:124
Botan::make_uint16
uint16_t make_uint16(uint8_t i0, uint8_t i1)
Definition: loadstor.h:60
Botan::get_byte
uint8_t get_byte(size_t byte_num, T input)
Definition: loadstor.h:47
Botan::hex_encode
void hex_encode(char output[], const uint8_t input[], size_t input_length, bool uppercase)
Definition: hex.cpp:14
Botan::Encoding_Error
Definition: exceptn.h:180
hash
MechanismType hash
Definition: p11_mechanism.cpp:63
Botan::SHA_256
Definition: sha2_32.h:40
Botan::RTSS_Share::share_id
uint8_t share_id() const
Definition: tss.cpp:110