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Diffstat (limited to 'comm/third_party/botan/src/lib/pubkey/mce/gf2m_small_m.h')
| -rw-r--r-- | comm/third_party/botan/src/lib/pubkey/mce/gf2m_small_m.h | 221 |
1 files changed, 221 insertions, 0 deletions
diff --git a/comm/third_party/botan/src/lib/pubkey/mce/gf2m_small_m.h b/comm/third_party/botan/src/lib/pubkey/mce/gf2m_small_m.h new file mode 100644 index 0000000000..ae3eab2264 --- /dev/null +++ b/comm/third_party/botan/src/lib/pubkey/mce/gf2m_small_m.h @@ -0,0 +1,221 @@ +/* + * (C) Copyright Projet SECRET, INRIA, Rocquencourt + * (C) Bhaskar Biswas and Nicolas Sendrier + * + * (C) 2014 cryptosource GmbH + * (C) 2014 Falko Strenzke fstrenzke@cryptosource.de + * + * Botan is released under the Simplified BSD License (see license.txt) + * + */ + +#ifndef BOTAN_GF2M_SMALL_M_H_ +#define BOTAN_GF2M_SMALL_M_H_ + +#include <botan/types.h> +#include <vector> + +BOTAN_FUTURE_INTERNAL_HEADER(gf2m_small_m.h) + +namespace Botan { + +typedef uint16_t gf2m; + +/** +* GF(2^m) field for m = [2...16] +*/ +class BOTAN_PUBLIC_API(2,0) GF2m_Field + { + public: + explicit GF2m_Field(size_t extdeg); + + gf2m gf_mul(gf2m x, gf2m y) const + { + return ((x) ? gf_mul_fast(x, y) : 0); + } + + gf2m gf_square(gf2m x) const + { + return ((x) ? gf_exp(_gf_modq_1(gf_log(x) << 1)) : 0); + } + + gf2m square_rr(gf2m x) const + { + return _gf_modq_1(x << 1); + } + + gf2m gf_mul_fast(gf2m x, gf2m y) const + { + return ((y) ? gf_exp(_gf_modq_1(gf_log(x) + gf_log(y))) : 0); + } + + /* + naming convention of GF(2^m) field operations: + l logarithmic, unreduced + r logarithmic, reduced + n normal, non-zero + z normal, might be zero + */ + + gf2m gf_mul_lll(gf2m a, gf2m b) const + { + return (a + b); + } + + gf2m gf_mul_rrr(gf2m a, gf2m b) const + { + return (_gf_modq_1(gf_mul_lll(a, b))); + } + + gf2m gf_mul_nrr(gf2m a, gf2m b) const + { + return (gf_exp(gf_mul_rrr(a, b))); + } + + gf2m gf_mul_rrn(gf2m a, gf2m y) const + { + return _gf_modq_1(gf_mul_lll(a, gf_log(y))); + } + + gf2m gf_mul_rnr(gf2m y, gf2m a) const + { + return gf_mul_rrn(a, y); + } + + gf2m gf_mul_lnn(gf2m x, gf2m y) const + { + return (gf_log(x) + gf_log(y)); + } + + gf2m gf_mul_rnn(gf2m x, gf2m y) const + { + return _gf_modq_1(gf_mul_lnn(x, y)); + } + + gf2m gf_mul_nrn(gf2m a, gf2m y) const + { + return gf_exp(_gf_modq_1((a) + gf_log(y))); + } + + /** + * zero operand allowed + */ + gf2m gf_mul_zrz(gf2m a, gf2m y) const + { + return ( (y == 0) ? 0 : gf_mul_nrn(a, y) ); + } + + gf2m gf_mul_zzr(gf2m a, gf2m y) const + { + return gf_mul_zrz(y, a); + } + + /** + * non-zero operand + */ + gf2m gf_mul_nnr(gf2m y, gf2m a) const + { + return gf_mul_nrn(a, y); + } + + gf2m gf_sqrt(gf2m x) const + { + return ((x) ? gf_exp(_gf_modq_1(gf_log(x) << (get_extension_degree()-1))) : 0); + } + + gf2m gf_div_rnn(gf2m x, gf2m y) const + { + return _gf_modq_1(gf_log(x) - gf_log(y)); + } + + gf2m gf_div_rnr(gf2m x, gf2m b) const + { + return _gf_modq_1(gf_log(x) - b); + } + + gf2m gf_div_nrr(gf2m a, gf2m b) const + { + return gf_exp(_gf_modq_1(a - b)); + } + + gf2m gf_div_zzr(gf2m x, gf2m b) const + { + return ((x) ? gf_exp(_gf_modq_1(gf_log(x) - b)) : 0); + } + + gf2m gf_inv(gf2m x) const + { + return gf_exp(gf_ord() - gf_log(x)); + } + + gf2m gf_inv_rn(gf2m x) const + { + return (gf_ord() - gf_log(x)); + } + + gf2m gf_square_ln(gf2m x) const + { + return gf_log(x) << 1; + } + + gf2m gf_square_rr(gf2m a) const + { + return a << 1; + } + + gf2m gf_l_from_n(gf2m x) const + { + return gf_log(x); + } + + gf2m gf_div(gf2m x, gf2m y) const; + + gf2m gf_exp(gf2m i) const + { + return m_gf_exp_table.at(i); /* alpha^i */ + } + + gf2m gf_log(gf2m i) const + { + return m_gf_log_table.at(i); /* return i when x=alpha^i */ + } + + gf2m gf_ord() const + { + return m_gf_multiplicative_order; + } + + size_t get_extension_degree() const + { + return m_gf_extension_degree; + } + + gf2m get_cardinality() const + { + return static_cast<gf2m>(1 << get_extension_degree()); + } + + private: + gf2m _gf_modq_1(int32_t d) const + { + /* residual modulo q-1 + when -q < d < 0, we get (q-1+d) + when 0 <= d < q, we get (d) + when q <= d < 2q-1, we get (d-q+1) + */ + return static_cast<gf2m>(((d) & gf_ord()) + ((d) >> get_extension_degree())); + } + + const size_t m_gf_extension_degree; + const gf2m m_gf_multiplicative_order; + const std::vector<gf2m>& m_gf_log_table; + const std::vector<gf2m>& m_gf_exp_table; + }; + +uint32_t encode_gf2m(gf2m to_enc, uint8_t* mem); + +gf2m decode_gf2m(const uint8_t* mem); + +} + +#endif |