diff options
Diffstat (limited to 'src/lib/pubkey/mce/mceliece.cpp')
| -rw-r--r-- | src/lib/pubkey/mce/mceliece.cpp | 173 |
1 files changed, 68 insertions, 105 deletions
diff --git a/src/lib/pubkey/mce/mceliece.cpp b/src/lib/pubkey/mce/mceliece.cpp index 08b3f13a3..dd05b8212 100644 --- a/src/lib/pubkey/mce/mceliece.cpp +++ b/src/lib/pubkey/mce/mceliece.cpp @@ -9,164 +9,127 @@ * */ +#include <botan/internal/mce_internal.h> #include <botan/mceliece.h> -#include <botan/mceliece_key.h> -#include <botan/internal/code_based_key_gen.h> -#include <botan/polyn_gf2m.h> -#include <botan/code_based_util.h> -#include <botan/goppa_code.h> +#include <botan/internal/code_based_util.h> #include <botan/internal/bit_ops.h> +#include <set> namespace Botan { namespace { -void concat_vectors(byte* x, const byte* a, const byte* b, u32bit dimension, u32bit codimension) +secure_vector<byte> concat_vectors(const secure_vector<byte>& a, const secure_vector<byte>& b, + u32bit dimension, u32bit codimension) { - if(dimension % 8 == 0) + secure_vector<byte> x(bit_size_to_byte_size(dimension) + bit_size_to_byte_size(codimension)); + + const size_t final_bits = dimension % 8; + + if(final_bits == 0) { const size_t dim_bytes = bit_size_to_byte_size(dimension); - copy_mem(x, a, dim_bytes); - copy_mem(x + dim_bytes, b, bit_size_to_byte_size(codimension)); + copy_mem(&x[0], a.data(), dim_bytes); + copy_mem(&x[dim_bytes], b.data(), bit_size_to_byte_size(codimension)); } else { - u32bit i, j, k, l; - i = dimension - 8 * (dimension/ 8); - j = 8 - i; - l = dimension / 8; - copy_mem(x, a, 1 * (dimension / 8)); - x[l] = static_cast<byte>(a[l] & ((1 << i) - 1)); - - for(k = 0; k < codimension / 8; ++k) + copy_mem(&x[0], a.data(), (dimension / 8)); + u32bit l = dimension / 8; + x[l] = static_cast<byte>(a[l] & ((1 << final_bits) - 1)); + + for(u32bit k = 0; k < codimension / 8; ++k) { - x[l] ^= static_cast<byte>(b[k] << i); + x[l] ^= static_cast<byte>(b[k] << final_bits); ++l; - x[l] = static_cast<byte>(b[k] >> j); + x[l] = static_cast<byte>(b[k] >> (8 - final_bits)); } - x[l] ^= static_cast<byte>(b[k] << i); + x[l] ^= static_cast<byte>(b[codimension/8] << final_bits); } + + return x; } -std::vector<byte> mult_by_pubkey(const byte *cleartext, - std::vector<byte> const& public_matrix, - u32bit code_length, u32bit t) +secure_vector<byte> mult_by_pubkey(const secure_vector<byte>& cleartext, + std::vector<byte> const& public_matrix, + u32bit code_length, u32bit t) { - std::vector<byte> ciphertext(code_length); - u32bit i, j; - u32bit ext_deg = ceil_log2(code_length); - u32bit codimension = ext_deg * t; - u32bit dimension = code_length - codimension; - std::vector<byte> cR(bit_size_to_32bit_size(codimension)* sizeof(u32bit)); + const u32bit ext_deg = ceil_log2(code_length); + const u32bit codimension = ext_deg * t; + const u32bit dimension = code_length - codimension; + secure_vector<byte> cR(bit_size_to_32bit_size(codimension) * sizeof(u32bit)); const byte* pt = public_matrix.data(); - for(i = 0; i < dimension / 8; ++i) + for(size_t i = 0; i < dimension / 8; ++i) { - for(j = 0; j < 8; ++j) + for(size_t j = 0; j < 8; ++j) { if(cleartext[i] & (1 << j)) { xor_buf(cR.data(), pt, cR.size()); } - pt += bit_size_to_32bit_size(codimension) * sizeof(u32bit); + pt += cR.size(); } } - for(j = 0; j < dimension % 8 ; ++j) + for(size_t i = 0; i < dimension % 8 ; ++i) { - if(cleartext[i] & (1 << j)) + if(cleartext[dimension/8] & (1 << i)) { - xor_buf(cR.data(), pt, bit_size_to_byte_size(codimension)); + xor_buf(cR.data(), pt, cR.size()); } - pt += bit_size_to_32bit_size(codimension) * sizeof(u32bit); + pt += cR.size(); } - concat_vectors(ciphertext.data(), cleartext, cR.data(), dimension, codimension); + secure_vector<byte> ciphertext = concat_vectors(cleartext, cR, dimension, codimension); + ciphertext.resize((code_length+7)/8); return ciphertext; } -} - -secure_vector<gf2m> create_random_error_positions(unsigned code_length, - unsigned error_weight, - RandomNumberGenerator& rng) - { - secure_vector<gf2m> result(error_weight); - gf2m i; - for(i = 0; i < result.size(); i++) - { - unsigned j; - char try_again = 0; - do - { - try_again = 0; - gf2m new_pos = random_code_element(code_length, rng); - for(j = 0; j < i; j++) - { - if(new_pos == result[j]) - { - try_again = 1; - break; - } - } - result[i] = new_pos; - } while(try_again); - } - return result; - } - -McEliece_Private_Operation::McEliece_Private_Operation(const McEliece_PrivateKey& private_key) - :m_priv_key(private_key) +secure_vector<byte> create_random_error_vector(unsigned code_length, + unsigned error_weight, + RandomNumberGenerator& rng) { - } - -secure_vector<byte> McEliece_Private_Operation::decrypt(const byte msg[], size_t msg_len) - { - secure_vector<gf2m> err_pos; + secure_vector<byte> result((code_length+7)/8); - secure_vector<byte> plaintext = mceliece_decrypt( - err_pos, - msg, msg_len, - m_priv_key - ); + size_t bits_set = 0; - return mceliece_message_parts(err_pos, plaintext, m_priv_key.get_code_length()).get_concat(); - } + while(bits_set < error_weight) + { + gf2m x = random_code_element(code_length, rng); -McEliece_Public_Operation::McEliece_Public_Operation(const McEliece_PublicKey& public_key, u32bit the_code_length) - :m_pub_key(public_key), - m_code_length(the_code_length) - {} + const size_t byte_pos = x / 8, bit_pos = x % 8; -secure_vector<byte> McEliece_Public_Operation::encrypt(const byte msg[], size_t msg_len, RandomNumberGenerator&) - { - mceliece_message_parts parts(msg, msg_len, m_pub_key.get_code_length()); - secure_vector<gf2m> err_pos = parts.get_error_positions(); - secure_vector<byte> message_word = parts.get_message_word(); - secure_vector<byte> ciphertext((m_pub_key.get_code_length()+7)/8); + const byte mask = (1 << bit_pos); + if(result[byte_pos] & mask) + continue; // already set this bit - std::vector<byte> ciphertext_tmp = mceliece_encrypt( message_word, m_pub_key.get_public_matrix(), err_pos, m_code_length); + result[byte_pos] |= mask; + bits_set++; + } - copy_mem(ciphertext.data(), ciphertext_tmp.data(), ciphertext.size()); - return ciphertext; + return result; } -std::vector<byte> mceliece_encrypt(const secure_vector<byte> & cleartext, - std::vector<byte> const& public_matrix, - const secure_vector<gf2m> & err_pos, - u32bit code_length) +} + +void mceliece_encrypt(secure_vector<byte>& ciphertext_out, + secure_vector<byte>& error_mask_out, + const secure_vector<byte>& plaintext, + const McEliece_PublicKey& key, + RandomNumberGenerator& rng) { - std::vector<byte> ciphertext = mult_by_pubkey(cleartext.data(), public_matrix, code_length, err_pos.size()); + secure_vector<byte> error_mask = create_random_error_vector(key.get_code_length(), key.get_t(), rng); - // flip t error positions - for(size_t i = 0; i < err_pos.size(); ++i) - { - ciphertext[err_pos[i] / 8] ^= (1 << (err_pos[i] % 8)); - } + secure_vector<byte> ciphertext = mult_by_pubkey(plaintext, key.get_public_matrix(), + key.get_code_length(), key.get_t()); - return ciphertext; + ciphertext ^= error_mask; + + ciphertext_out.swap(ciphertext); + error_mask_out.swap(error_mask); } } |