diff options
Diffstat (limited to 'src/lib/pubkey/mce/gf2m_small_m.h')
| -rw-r--r-- | src/lib/pubkey/mce/gf2m_small_m.h | 236 |
1 files changed, 236 insertions, 0 deletions
diff --git a/src/lib/pubkey/mce/gf2m_small_m.h b/src/lib/pubkey/mce/gf2m_small_m.h new file mode 100644 index 000000000..9fc42f1fc --- /dev/null +++ b/src/lib/pubkey/mce/gf2m_small_m.h @@ -0,0 +1,236 @@ +/** + * (C) Copyright Projet SECRET, INRIA, Rocquencourt + * (C) Bhaskar Biswas and Nicolas Sendrier + * + * (C) 2014 cryptosource GmbH + * (C) 2014 Falko Strenzke [email protected] + * + * Distributed under the terms of the Botan license + * + */ + +#ifndef BOTAN_GF2M_SMALL_M_H__ +#define BOTAN_GF2M_SMALL_M_H__ + +#include <vector> +#include <botan/types.h> + +namespace Botan { + +namespace gf2m_small_m { + +typedef u16bit gf2m; + +class Gf2m_Field + { + public: + Gf2m_Field(size_t extdeg); + + gf2m gf_mul(gf2m x, gf2m y) + { + return ((x) ? gf_mul_fast(x, y) : 0); + } + + gf2m gf_square(gf2m x) + { + return ((x) ? m_gf_exp_table[_gf_modq_1(m_gf_log_table[x] << 1)] : 0); + } + + gf2m square_rr(gf2m x) + { + return _gf_modq_1(x << 1); + } + + // naming convention of GF(2^m) field operations: + // l logarithmic, unreduced + // r logarithmic, reduced + // n normal, non-zero + // z normal, might be zero + // + inline gf2m gf_mul_lll(gf2m a, gf2m b); + inline gf2m gf_mul_rrr(gf2m a, gf2m b); + inline gf2m gf_mul_nrr(gf2m a, gf2m b); + inline gf2m gf_mul_rrn(gf2m a, gf2m y); + inline gf2m gf_mul_lnn(gf2m x, gf2m y); + inline gf2m gf_mul_rnn(gf2m x, gf2m y); + inline gf2m gf_mul_nrn(gf2m a, gf2m y); + inline gf2m gf_mul_rnr(gf2m y, gf2m a); + inline gf2m gf_mul_zrz(gf2m a, gf2m y); + inline gf2m gf_mul_zzr(gf2m a, gf2m y); + inline gf2m gf_mul_nnr(gf2m y, gf2m a); + inline gf2m gf_sqrt(gf2m x) ; + gf2m gf_div(gf2m x, gf2m y); + inline gf2m gf_div_rnn(gf2m x, gf2m y); + inline gf2m gf_div_rnr(gf2m x, gf2m b); + inline gf2m gf_div_nrr(gf2m a, gf2m b); + inline gf2m gf_div_zzr(gf2m x, gf2m b); + inline gf2m gf_inv(gf2m x); + inline gf2m gf_inv_rn(gf2m x); + inline gf2m gf_square_ln(gf2m x); + inline gf2m gf_square_rr(gf2m a) ; + inline gf2m gf_l_from_n(gf2m x); + + inline gf2m gf_mul_fast(gf2m a, gf2m b); + + gf2m gf_exp(gf2m i) + { + return m_gf_exp_table[i]; /* alpha^i */ + } + + gf2m gf_log(gf2m i) + { + return m_gf_log_table[i]; /* return i when x=alpha^i */ + } + + inline gf2m gf_ord() const + { + return m_gf_multiplicative_order; + } + + inline gf2m get_extension_degree() const + { + return m_gf_extension_degree; + } + + inline gf2m get_cardinality() const + { + return m_gf_cardinality; + } + + gf2m gf_pow(gf2m x, int i) ; + + private: + gf2m m_gf_extension_degree, m_gf_cardinality, m_gf_multiplicative_order; + std::vector<gf2m> m_gf_log_table; + std::vector<gf2m> m_gf_exp_table; + + inline gf2m _gf_modq_1(s32bit d); + void init_log(); + void init_exp(); + }; + +gf2m Gf2m_Field::_gf_modq_1(s32bit d) + { + return (((d) & gf_ord()) + ((d) >> m_gf_extension_degree)); + } + +gf2m Gf2m_Field::gf_mul_fast(gf2m x, gf2m y) + { + return ((y) ? m_gf_exp_table[_gf_modq_1(m_gf_log_table[x] + m_gf_log_table[y])] : 0); + } + +gf2m Gf2m_Field::gf_mul_lll(gf2m a, gf2m b) + { + return (a + b); + } + +gf2m Gf2m_Field::gf_mul_rrr(gf2m a, gf2m b) + { + return (_gf_modq_1(gf_mul_lll(a, b))); + } + +gf2m Gf2m_Field::gf_mul_nrr(gf2m a, gf2m b) + { + return (gf_exp(gf_mul_rrr(a, b))); + } + +gf2m Gf2m_Field::gf_mul_rrn(gf2m a, gf2m y) + { + return _gf_modq_1(gf_mul_lll(a, gf_log(y))); + } + +gf2m Gf2m_Field::gf_mul_rnr(gf2m y, gf2m a) + { + return gf_mul_rrn(a, y); + } + +gf2m Gf2m_Field::gf_mul_lnn(gf2m x, gf2m y) + { + return (m_gf_log_table[x] + m_gf_log_table[y]); + } +gf2m Gf2m_Field::gf_mul_rnn(gf2m x, gf2m y) + { + return _gf_modq_1(gf_mul_lnn(x, y)); + } + +gf2m Gf2m_Field::gf_mul_nrn(gf2m a, gf2m y) + { + return m_gf_exp_table[_gf_modq_1((a) + m_gf_log_table[y])]; + } + +/** +* zero operand allowed +*/ +gf2m Gf2m_Field::gf_mul_zrz(gf2m a, gf2m y) + { + return ( (y == 0) ? 0 : gf_mul_nrn(a, y) ); + } + +gf2m Gf2m_Field::gf_mul_zzr(gf2m a, gf2m y) + { + return gf_mul_zrz(y, a); + } +/** +* non-zero operand +*/ +gf2m Gf2m_Field::gf_mul_nnr(gf2m y, gf2m a) + { + return gf_mul_nrn( a, y); + } + +gf2m Gf2m_Field::gf_sqrt(gf2m x) + { + return ((x) ? m_gf_exp_table[_gf_modq_1(m_gf_log_table[x] << (m_gf_extension_degree-1))] : 0); + } + +gf2m Gf2m_Field::gf_div_rnn(gf2m x, gf2m y) + { + return _gf_modq_1(m_gf_log_table[x] - m_gf_log_table[y]); + } +gf2m Gf2m_Field::gf_div_rnr(gf2m x, gf2m b) + { + return _gf_modq_1(m_gf_log_table[x] - b); + } +gf2m Gf2m_Field::gf_div_nrr(gf2m a, gf2m b) + { + return m_gf_exp_table[_gf_modq_1(a - b)]; + } + +gf2m Gf2m_Field::gf_div_zzr(gf2m x, gf2m b) + { + return ((x) ? m_gf_exp_table[_gf_modq_1(m_gf_log_table[x] - b)] : 0); + } + +gf2m Gf2m_Field::gf_inv(gf2m x) + { + return m_gf_exp_table[gf_ord() - m_gf_log_table[x]]; + } +gf2m Gf2m_Field::gf_inv_rn(gf2m x) + { + return (gf_ord() - m_gf_log_table[x]); + } + +gf2m Gf2m_Field::gf_square_ln(gf2m x) + { + return m_gf_log_table[x] << 1; + } + +gf2m Gf2m_Field::gf_square_rr(gf2m a) + { + return a << 1; + } + +gf2m Gf2m_Field::gf_l_from_n(gf2m x) + { + return m_gf_log_table[x]; + } + +u32bit encode_gf2m(gf2m to_enc, byte* mem); + +gf2m decode_gf2m(const byte* mem); + +} + +} + +#endif |