diff options
Diffstat (limited to 'comm/third_party/botan/src/lib/misc/tss/tss.cpp')
| -rw-r--r-- | comm/third_party/botan/src/lib/misc/tss/tss.cpp | 333 |
1 files changed, 333 insertions, 0 deletions
diff --git a/comm/third_party/botan/src/lib/misc/tss/tss.cpp b/comm/third_party/botan/src/lib/misc/tss/tss.cpp new file mode 100644 index 0000000000..dd3a294f8a --- /dev/null +++ b/comm/third_party/botan/src/lib/misc/tss/tss.cpp @@ -0,0 +1,333 @@ +/* +* RTSS (threshold secret sharing) +* (C) 2009,2018 Jack Lloyd +* +* Botan is released under the Simplified BSD License (see license.txt) +*/ + +#include <botan/tss.h> +#include <botan/rng.h> +#include <botan/hash.h> +#include <botan/loadstor.h> +#include <botan/hex.h> + +namespace Botan { + +namespace { + +const size_t RTSS_HEADER_SIZE = 20; + +/** +Table for GF(2^8) arithmetic (exponentials) +*/ +const uint8_t RTSS_EXP[256] = { +0x01, 0x03, 0x05, 0x0F, 0x11, 0x33, 0x55, 0xFF, 0x1A, 0x2E, 0x72, +0x96, 0xA1, 0xF8, 0x13, 0x35, 0x5F, 0xE1, 0x38, 0x48, 0xD8, 0x73, +0x95, 0xA4, 0xF7, 0x02, 0x06, 0x0A, 0x1E, 0x22, 0x66, 0xAA, 0xE5, +0x34, 0x5C, 0xE4, 0x37, 0x59, 0xEB, 0x26, 0x6A, 0xBE, 0xD9, 0x70, +0x90, 0xAB, 0xE6, 0x31, 0x53, 0xF5, 0x04, 0x0C, 0x14, 0x3C, 0x44, +0xCC, 0x4F, 0xD1, 0x68, 0xB8, 0xD3, 0x6E, 0xB2, 0xCD, 0x4C, 0xD4, +0x67, 0xA9, 0xE0, 0x3B, 0x4D, 0xD7, 0x62, 0xA6, 0xF1, 0x08, 0x18, +0x28, 0x78, 0x88, 0x83, 0x9E, 0xB9, 0xD0, 0x6B, 0xBD, 0xDC, 0x7F, +0x81, 0x98, 0xB3, 0xCE, 0x49, 0xDB, 0x76, 0x9A, 0xB5, 0xC4, 0x57, +0xF9, 0x10, 0x30, 0x50, 0xF0, 0x0B, 0x1D, 0x27, 0x69, 0xBB, 0xD6, +0x61, 0xA3, 0xFE, 0x19, 0x2B, 0x7D, 0x87, 0x92, 0xAD, 0xEC, 0x2F, +0x71, 0x93, 0xAE, 0xE9, 0x20, 0x60, 0xA0, 0xFB, 0x16, 0x3A, 0x4E, +0xD2, 0x6D, 0xB7, 0xC2, 0x5D, 0xE7, 0x32, 0x56, 0xFA, 0x15, 0x3F, +0x41, 0xC3, 0x5E, 0xE2, 0x3D, 0x47, 0xC9, 0x40, 0xC0, 0x5B, 0xED, +0x2C, 0x74, 0x9C, 0xBF, 0xDA, 0x75, 0x9F, 0xBA, 0xD5, 0x64, 0xAC, +0xEF, 0x2A, 0x7E, 0x82, 0x9D, 0xBC, 0xDF, 0x7A, 0x8E, 0x89, 0x80, +0x9B, 0xB6, 0xC1, 0x58, 0xE8, 0x23, 0x65, 0xAF, 0xEA, 0x25, 0x6F, +0xB1, 0xC8, 0x43, 0xC5, 0x54, 0xFC, 0x1F, 0x21, 0x63, 0xA5, 0xF4, +0x07, 0x09, 0x1B, 0x2D, 0x77, 0x99, 0xB0, 0xCB, 0x46, 0xCA, 0x45, +0xCF, 0x4A, 0xDE, 0x79, 0x8B, 0x86, 0x91, 0xA8, 0xE3, 0x3E, 0x42, +0xC6, 0x51, 0xF3, 0x0E, 0x12, 0x36, 0x5A, 0xEE, 0x29, 0x7B, 0x8D, +0x8C, 0x8F, 0x8A, 0x85, 0x94, 0xA7, 0xF2, 0x0D, 0x17, 0x39, 0x4B, +0xDD, 0x7C, 0x84, 0x97, 0xA2, 0xFD, 0x1C, 0x24, 0x6C, 0xB4, 0xC7, +0x52, 0xF6, 0x01 }; + +/** +Table for GF(2^8) arithmetic (logarithms) +*/ +const uint8_t RTSS_LOG[] = { +0x90, 0x00, 0x19, 0x01, 0x32, 0x02, 0x1A, 0xC6, 0x4B, 0xC7, 0x1B, +0x68, 0x33, 0xEE, 0xDF, 0x03, 0x64, 0x04, 0xE0, 0x0E, 0x34, 0x8D, +0x81, 0xEF, 0x4C, 0x71, 0x08, 0xC8, 0xF8, 0x69, 0x1C, 0xC1, 0x7D, +0xC2, 0x1D, 0xB5, 0xF9, 0xB9, 0x27, 0x6A, 0x4D, 0xE4, 0xA6, 0x72, +0x9A, 0xC9, 0x09, 0x78, 0x65, 0x2F, 0x8A, 0x05, 0x21, 0x0F, 0xE1, +0x24, 0x12, 0xF0, 0x82, 0x45, 0x35, 0x93, 0xDA, 0x8E, 0x96, 0x8F, +0xDB, 0xBD, 0x36, 0xD0, 0xCE, 0x94, 0x13, 0x5C, 0xD2, 0xF1, 0x40, +0x46, 0x83, 0x38, 0x66, 0xDD, 0xFD, 0x30, 0xBF, 0x06, 0x8B, 0x62, +0xB3, 0x25, 0xE2, 0x98, 0x22, 0x88, 0x91, 0x10, 0x7E, 0x6E, 0x48, +0xC3, 0xA3, 0xB6, 0x1E, 0x42, 0x3A, 0x6B, 0x28, 0x54, 0xFA, 0x85, +0x3D, 0xBA, 0x2B, 0x79, 0x0A, 0x15, 0x9B, 0x9F, 0x5E, 0xCA, 0x4E, +0xD4, 0xAC, 0xE5, 0xF3, 0x73, 0xA7, 0x57, 0xAF, 0x58, 0xA8, 0x50, +0xF4, 0xEA, 0xD6, 0x74, 0x4F, 0xAE, 0xE9, 0xD5, 0xE7, 0xE6, 0xAD, +0xE8, 0x2C, 0xD7, 0x75, 0x7A, 0xEB, 0x16, 0x0B, 0xF5, 0x59, 0xCB, +0x5F, 0xB0, 0x9C, 0xA9, 0x51, 0xA0, 0x7F, 0x0C, 0xF6, 0x6F, 0x17, +0xC4, 0x49, 0xEC, 0xD8, 0x43, 0x1F, 0x2D, 0xA4, 0x76, 0x7B, 0xB7, +0xCC, 0xBB, 0x3E, 0x5A, 0xFB, 0x60, 0xB1, 0x86, 0x3B, 0x52, 0xA1, +0x6C, 0xAA, 0x55, 0x29, 0x9D, 0x97, 0xB2, 0x87, 0x90, 0x61, 0xBE, +0xDC, 0xFC, 0xBC, 0x95, 0xCF, 0xCD, 0x37, 0x3F, 0x5B, 0xD1, 0x53, +0x39, 0x84, 0x3C, 0x41, 0xA2, 0x6D, 0x47, 0x14, 0x2A, 0x9E, 0x5D, +0x56, 0xF2, 0xD3, 0xAB, 0x44, 0x11, 0x92, 0xD9, 0x23, 0x20, 0x2E, +0x89, 0xB4, 0x7C, 0xB8, 0x26, 0x77, 0x99, 0xE3, 0xA5, 0x67, 0x4A, +0xED, 0xDE, 0xC5, 0x31, 0xFE, 0x18, 0x0D, 0x63, 0x8C, 0x80, 0xC0, +0xF7, 0x70, 0x07 }; + +uint8_t gfp_mul(uint8_t x, uint8_t y) + { + if(x == 0 || y == 0) + return 0; + return RTSS_EXP[(RTSS_LOG[x] + RTSS_LOG[y]) % 255]; + } + +uint8_t rtss_hash_id(const std::string& hash_name) + { + if(hash_name == "None") + return 0; + else if(hash_name == "SHA-160" || hash_name == "SHA-1" || hash_name == "SHA1") + return 1; + else if(hash_name == "SHA-256") + return 2; + else + throw Invalid_Argument("RTSS only supports SHA-1 and SHA-256"); + } + +std::unique_ptr<HashFunction> get_rtss_hash_by_id(uint8_t id) + { + if(id == 0) + return std::unique_ptr<HashFunction>(); + if(id == 1) + return HashFunction::create_or_throw("SHA-1"); + else if(id == 2) + return HashFunction::create_or_throw("SHA-256"); + else + throw Decoding_Error("Unknown RTSS hash identifier"); + } + +} + +RTSS_Share::RTSS_Share(const std::string& hex_input) + { + m_contents = hex_decode_locked(hex_input); + } + +RTSS_Share::RTSS_Share(const uint8_t bin[], size_t len) + { + m_contents.assign(bin, bin + len); + } + +uint8_t RTSS_Share::share_id() const + { + if(!initialized()) + throw Invalid_State("RTSS_Share::share_id not initialized"); + + if(m_contents.size() < RTSS_HEADER_SIZE + 1) + throw Decoding_Error("RTSS_Share::share_id invalid share data"); + + return m_contents[20]; + } + +std::string RTSS_Share::to_string() const + { + return hex_encode(m_contents.data(), m_contents.size()); + } + +std::vector<RTSS_Share> +RTSS_Share::split(uint8_t M, uint8_t N, + const uint8_t S[], uint16_t S_len, + const uint8_t identifier[16], + RandomNumberGenerator& rng) + { + return RTSS_Share::split(M, N, S, S_len, + std::vector<uint8_t>(identifier, identifier + 16), + "SHA-256", + rng); + } + +std::vector<RTSS_Share> +RTSS_Share::split(uint8_t M, uint8_t N, + const uint8_t S[], uint16_t S_len, + const std::vector<uint8_t>& identifier, + const std::string& hash_fn, + RandomNumberGenerator& rng) + { + if(M <= 1 || N <= 1 || M > N || N >= 255) + throw Invalid_Argument("RTSS_Share::split: Invalid N or M"); + + if(identifier.size() > 16) + throw Invalid_Argument("RTSS_Share::split Invalid identifier size"); + + const uint8_t hash_id = rtss_hash_id(hash_fn); + + std::unique_ptr<HashFunction> hash; + if(hash_id > 0) + hash = HashFunction::create_or_throw(hash_fn); + + // secret = S || H(S) + secure_vector<uint8_t> secret(S, S + S_len); + if(hash) + secret += hash->process(S, S_len); + + if(secret.size() >= 0xFFFE) + throw Encoding_Error("RTSS_Share::split secret too large for TSS format"); + + // +1 byte for the share ID + const uint16_t share_len = static_cast<uint16_t>(secret.size() + 1); + + secure_vector<uint8_t> share_header(RTSS_HEADER_SIZE); + copy_mem(&share_header[0], identifier.data(), identifier.size()); + share_header[16] = hash_id; + share_header[17] = M; + share_header[18] = get_byte(0, share_len); + share_header[19] = get_byte(1, share_len); + + // Create RTSS header in each share + std::vector<RTSS_Share> shares(N); + + for(uint8_t i = 0; i != N; ++i) + { + shares[i].m_contents.reserve(share_header.size() + share_len); + shares[i].m_contents = share_header; + } + + // Choose sequential values for X starting from 1 + for(uint8_t i = 0; i != N; ++i) + shares[i].m_contents.push_back(i+1); + + for(size_t i = 0; i != secret.size(); ++i) + { + std::vector<uint8_t> coefficients(M-1); + rng.randomize(coefficients.data(), coefficients.size()); + + for(uint8_t j = 0; j != N; ++j) + { + const uint8_t X = j + 1; + + uint8_t sum = secret[i]; + uint8_t X_i = X; + + for(size_t k = 0; k != coefficients.size(); ++k) + { + sum ^= gfp_mul(X_i, coefficients[k]); + X_i = gfp_mul(X_i, X); + } + + shares[j].m_contents.push_back(sum); + } + } + + return shares; + } + +secure_vector<uint8_t> +RTSS_Share::reconstruct(const std::vector<RTSS_Share>& shares) + { + if(shares.size() <= 1) + throw Decoding_Error("Insufficient shares to do TSS reconstruction"); + + for(size_t i = 0; i != shares.size(); ++i) + { + if(shares[i].size() < RTSS_HEADER_SIZE + 1) + throw Decoding_Error("Missing or malformed RTSS header"); + + if(shares[i].share_id() == 0) + throw Decoding_Error("Invalid (id = 0) RTSS share detected"); + + if(i > 0) + { + if(shares[i].size() != shares[0].size()) + throw Decoding_Error("Different sized RTSS shares detected"); + + if(!same_mem(&shares[0].m_contents[0], + &shares[i].m_contents[0], RTSS_HEADER_SIZE)) + throw Decoding_Error("Different RTSS headers detected"); + } + } + + const uint8_t N = shares[0].m_contents[17]; + + if(shares.size() < N) + throw Decoding_Error("Insufficient shares to do TSS reconstruction"); + + const uint16_t share_len = make_uint16(shares[0].m_contents[18], + shares[0].m_contents[19]); + + const uint8_t hash_id = shares[0].m_contents[16]; + std::unique_ptr<HashFunction> hash(get_rtss_hash_by_id(hash_id)); + const size_t hash_len = (hash ? hash->output_length() : 0); + + if(shares[0].size() != RTSS_HEADER_SIZE + share_len) + { + /* + * This second (laxer) check accomodates a bug in TSS that was + * fixed in 2.9.0 - previous versions used the length of the + * *secret* here, instead of the length of the *share*, which is + * precisely 1 + hash_len longer. + */ + if(shares[0].size() <= RTSS_HEADER_SIZE + 1 + hash_len) + throw Decoding_Error("Bad RTSS length field in header"); + } + + std::vector<uint8_t> V(shares.size()); + secure_vector<uint8_t> recovered; + + for(size_t i = RTSS_HEADER_SIZE + 1; i != shares[0].size(); ++i) + { + for(size_t j = 0; j != V.size(); ++j) + V[j] = shares[j].m_contents[i]; + + uint8_t r = 0; + for(size_t k = 0; k != shares.size(); ++k) + { + // L_i function: + uint8_t r2 = 1; + for(size_t l = 0; l != shares.size(); ++l) + { + if(k == l) + continue; + + uint8_t share_k = shares[k].share_id(); + uint8_t share_l = shares[l].share_id(); + + if(share_k == share_l) + throw Decoding_Error("Duplicate shares found in RTSS recovery"); + + uint8_t div = RTSS_EXP[(255 + + RTSS_LOG[share_l] - + RTSS_LOG[share_k ^ share_l]) % 255]; + + r2 = gfp_mul(r2, div); + } + + r ^= gfp_mul(V[k], r2); + } + recovered.push_back(r); + } + + if(hash) + { + if(recovered.size() < hash->output_length()) + throw Decoding_Error("RTSS recovered value too short to be valid"); + + const size_t secret_len = recovered.size() - hash->output_length(); + + hash->update(recovered.data(), secret_len); + secure_vector<uint8_t> hash_check = hash->final(); + + if(!constant_time_compare(hash_check.data(), + &recovered[secret_len], + hash->output_length())) + { + throw Decoding_Error("RTSS hash check failed"); + } + + // remove the trailing hash value + recovered.resize(secret_len); + } + + return recovered; + } + +} |