122 lines
2.4 KiB
C
122 lines
2.4 KiB
C
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/*
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*
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* ec.c
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*
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* Elliptic Curve Arithmetic Functions
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*
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* Copyright (C) Lenka Fibikova 2000
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*
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*
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <assert.h>
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#include "ec.h"
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#include "bn_modfs.h"
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EC *EC_new()
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{
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EC *ret;
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ret=(EC *)malloc(sizeof(EC));
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if (ret == NULL) return NULL;
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ret->A = BN_new();
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ret->B = BN_new();
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ret->p = BN_new();
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ret->h = BN_new();
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ret->is_in_mont = 0;
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if (ret->A == NULL || ret->B == NULL || ret->p == NULL || ret->h == NULL)
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{
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if (ret->A != NULL) BN_free(ret->A);
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if (ret->B != NULL) BN_free(ret->B);
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if (ret->p != NULL) BN_free(ret->p);
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if (ret->h != NULL) BN_free(ret->h);
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free(ret);
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return(NULL);
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}
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return(ret);
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}
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void EC_clear_free(EC *E)
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{
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if (E == NULL) return;
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if (E->A != NULL) BN_clear_free(E->A);
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if (E->B != NULL) BN_clear_free(E->B);
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if (E->p != NULL) BN_clear_free(E->p);
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if (E->h != NULL) BN_clear_free(E->h);
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E->is_in_mont = 0;
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free(E);
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}
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#ifdef MONTGOMERY
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int EC_to_montgomery(EC *E, BN_MONTGOMERY *mont, BN_CTX *ctx)
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{
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assert(E != NULL);
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assert(E->A != NULL && E->B != NULL && E->p != NULL && E->h != NULL);
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assert(mont != NULL);
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assert(mont->p != NULL);
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assert(ctx != NULL);
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if (E->is_in_mont) return 1;
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if (!BN_lshift(E->A, E->A, mont->R_num_bits)) return 0;
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if (!BN_mod(E->A, E->A, mont->p, ctx)) return 0;
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if (!BN_lshift(E->B, E->B, mont->R_num_bits)) return 0;
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if (!BN_mod(E->B, E->B, mont->p, ctx)) return 0;
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if (!BN_lshift(E->h, E->h, mont->R_num_bits)) return 0;
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if (!BN_mod(E->h, E->h, mont->p, ctx)) return 0;
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E->is_in_mont = 1;
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return 1;
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}
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int EC_from_montgomery(EC *E, BN_MONTGOMERY *mont, BN_CTX *ctx)
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{
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assert(E != NULL);
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assert(E->A != NULL && E->B != NULL && E->p != NULL && E->h != NULL);
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assert(mont != NULL);
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assert(mont->p != NULL);
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assert(ctx != NULL);
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if (!E->is_in_mont) return 1;
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if (!BN_mont_red(E->A, mont, ctx)) return 0;
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if (!BN_mont_red(E->B, mont, ctx)) return 0;
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if (!BN_mont_red(E->h, mont, ctx)) return 0;
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E->is_in_mont = 0;
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return 1;
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}
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#endif /* MONTGOMERY */
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int EC_set_half(EC *E)
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/* h <- 1/2 mod p = (p + 1)/2 */
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{
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assert(E != NULL);
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assert(E->p != NULL);
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assert(E->h != NULL);
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assert(!E->is_in_mont);
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if (BN_copy(E->h, E->p) == NULL) return 0;
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if (!BN_add_word(E->h, 1)) return 0;
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if (!BN_rshift1(E->h, E->h)) return 0;
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return 1;
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}
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