Elliptic curves over GF(p), new BIGNUM functions, Montgomery re-implementation.

These new files will not be included literally in OpenSSL, but I intend
to integrate most of their contents.  Most file names will change,
and when the integration is done, the superfluous files will be deleted.

Submitted by: Lenka Fibikova <fibikova@exp-math.uni-essen.de>

crypto/bn/bn_modfs.c

+/*
+ *
+ *	bn_modfs.c
+ *
+ *	Some Modular Arithmetic Functions.
+ *
+ *	Copyright (C) Lenka Fibikova 2000
+ *
+ *
+ */
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <assert.h>
+
+#include "bn_modfs.h"
+
+#define MAX_ROUNDS	10
+
+int BN_smod(BIGNUM *rem, BIGNUM *m, BIGNUM *d, BN_CTX *ctx)
+{
+	int r_sign;
+
+	assert(rem != NULL && m != NULL && d != NULL && ctx != NULL);
+
+	if (d->neg) return 0;
+	r_sign = m->neg;
+
+	if (r_sign) m->neg = 0;
+	if (!(BN_div(NULL,rem,m,d,ctx))) return 0;
+	if (r_sign) 
+	{
+		m->neg = r_sign;
+		if (!BN_is_zero(rem))
+		{
+			rem->neg = r_sign;
+			BN_add(rem, rem, d);
+		}
+	}
+	return 1;
+}
+
+int BN_mod_sub(BIGNUM *r, BIGNUM *a, BIGNUM *b, BIGNUM *m, BN_CTX *ctx) 
+{
+	assert(r != NULL && a != NULL && b != NULL && m != NULL && ctx != NULL);
+
+	if (!BN_sub(r, a, b)) return 0;
+	return BN_smod(r, r, m, ctx);
+
+}
+
+int BN_mod_add(BIGNUM *r, BIGNUM *a, BIGNUM *b, BIGNUM *m, BN_CTX *ctx) 
+{
+	assert(r != NULL && a != NULL && b != NULL && m != NULL && ctx != NULL);
+
+	if (!BN_add(r, a, b)) return 0;
+	return BN_smod(r, r, m, ctx);
+
+}
+
+int BN_mod_sqr(BIGNUM *r, BIGNUM *a, BIGNUM *p, BN_CTX *ctx)
+{
+	assert(r != NULL && a != NULL && p != NULL && ctx != NULL);
+
+	if (!BN_sqr(r, a, ctx)) return 0;
+	return BN_div(NULL, r, r, p, ctx);
+}
+
+int BN_swap(BIGNUM *x, BIGNUM *y)
+{
+	BIGNUM *c;
+
+	assert(x != NULL && y != NULL);
+
+	if ((c = BN_dup(x)) == NULL) goto err;
+	if ((BN_copy(x, y)) == NULL) goto err;
+	if ((BN_copy(y, c)) == NULL) goto err;
+	BN_clear_free(c);
+	return 1;
+
+err:
+	if (c != NULL) BN_clear_free(c);
+	return 0;
+}
+
+
+int BN_legendre(BIGNUM *a, BIGNUM *p, BN_CTX *ctx) 
+{
+	BIGNUM *x, *y, *y2;
+	BN_ULONG m;
+	int L;
+
+	assert(a != NULL && p != NULL && ctx != NULL);
+
+	x = ctx->bn[ctx->tos]; 
+	y = ctx->bn[ctx->tos + 1]; 
+	y2 = ctx->bn[ctx->tos + 2]; 
+
+	ctx->tos += 3;
+
+	if (!BN_smod(x, a, p, ctx)) goto err;
+	if (BN_is_zero(x)) 
+	{
+
+		ctx->tos -= 3;
+		return 0;
+	}
+
+	if (BN_copy(y, p) == NULL) goto err;
+	L = 1;
+
+	while (1)
+	{
+		if (!BN_rshift1(y2, y)) goto err;
+		if (BN_cmp(x, y2) > 0)
+		{
+			if (!BN_sub(x, y, x)) goto err;
+			if (BN_mod_word(y, 4) == 3)
+				L = -L;			
+		}
+		while (BN_mod_word(x, 4) == 0)
+			BN_div_word(x, 4);
+		if (BN_mod_word(x, 2) == 0)
+		{
+			BN_div_word(x, 2);
+			m = BN_mod_word(y, 8);
+			if (m == 3 || m == 5) L = -L;			
+		}
+		if (BN_is_one(x)) 
+		{
+			ctx->tos -= 3;
+			return L;
+		}
+		
+		if (BN_mod_word(x, 4) == 3 && BN_mod_word(y, 4) == 3) L = -L;
+		if (!BN_swap(x, y)) goto err;
+
+		if (!BN_smod(x, x, y, ctx)) goto err;
+
+	}
+
+
+err:
+	ctx->tos -= 3;
+	return -2;
+
+}
+
+int BN_mod_sqrt(BIGNUM *x, BIGNUM *a, BIGNUM *p, BN_CTX *ctx) 
+/* x^2 = a (mod p) */
+{
+	int ret;
+	BIGNUM *n0, *n1, *r, *b, *m;
+	int max;
+
+	assert(x != NULL && a != NULL && p != NULL && ctx != NULL);
+	assert(BN_cmp(a, p) < 0);
+
+	ret = BN_legendre(a, p, ctx);
+	if (ret < 0 || ret > 1) return 0;
+	if (ret == 0)
+	{
+		if (!BN_zero(x)) return 0;
+		return 1;
+	}
+
+	n0 = ctx->bn[ctx->tos]; 
+	n1 = ctx->bn[ctx->tos + 1]; 
+	ctx->tos += 2;
+
+	if ((r = BN_new()) == NULL) goto err;
+	if ((b = BN_new()) == NULL) goto err;
+	if ((m = BN_new()) == NULL) goto err;
+
+
+	if (!BN_zero(n0)) goto err;
+	if (!BN_zero(n1)) goto err;
+	if (!BN_zero(r)) goto err;
+	if (!BN_zero(b)) goto err;
+	if (!BN_zero(m)) goto err;
+
+	max = 0;
+
+	do{
+		if (max++ > MAX_ROUNDS) goto err; /* if p is not prime could never stop*/
+		if (!BN_add_word(m, 1)) goto err;
+		ret = BN_legendre(m, p, ctx);
+		if (ret < -1 || ret > 1) goto err;
+
+	}while(ret != -1);
+
+	if (BN_copy(n1, p) == NULL) goto err;
+	if (!BN_sub_word(n1, 1)) goto err;
+
+	while (!BN_is_odd(n1))
+	{
+		if (!BN_add_word(r, 1)) goto err;
+		if (!BN_rshift1(n1, n1)) goto err;
+	}
+
+	if (!BN_mod_exp_simple(n0, m, n1, p, ctx)) goto err;
+
+	if (!BN_sub_word(n1, 1)) goto err;
+	if (!BN_rshift1(n1, n1)) goto err;
+	if (!BN_mod_exp_simple(x, a, n1, p, ctx)) goto err;
+
+	if (!BN_mod_sqr(b, x, p, ctx)) goto err;
+	if (!BN_mod_mul(b, b, a, p, ctx)) goto err;
+
+	if (!BN_mod_mul(x, x, a, p, ctx)) goto err;
+
+	while (!BN_is_one(b))
+	{
+		
+		if (!BN_one(m)) goto err;
+		if (!BN_mod_sqr(n1, b, p, ctx)) goto err;
+		while(!BN_is_one(n1))
+		{
+			if (!BN_mod_mul(n1, n1, n1, p, ctx)) goto err;
+			if (!BN_add_word(m, 1)) goto err;
+		}
+
+		if (!BN_sub(r, r, m)) goto err;
+		if (!BN_sub_word(r, 1)) goto err;
+		if (r->neg) goto err;
+
+		if (BN_copy(n1, n0) == NULL) goto err;
+		while(!BN_is_zero(r))
+		{
+			if (!BN_mod_mul(n1, n1, n1, p, ctx)) goto err;
+			if (!BN_sub_word(r, 1)) goto err;
+		}
+
+		if (!BN_mod_mul(n0, n1, n1, p, ctx)) goto err;
+		if (BN_copy(r, m) == NULL) goto err;
+		if (!BN_mod_mul(x, x, n1, p, ctx)) goto err;
+		if (!BN_mod_mul(b, b, n0, p, ctx)) goto err;
+	}
+
+
+#ifdef TEST
+	BN_mod_sqr(n0, x, p, ctx);
+	if (BN_cmp(n0, a)) goto err;
+#endif
+
+	if (r != NULL) BN_clear_free(r);
+	if (b != NULL) BN_clear_free(b);
+	if (m != NULL) BN_clear_free(m);
+	ctx->tos -= 2;
+	return 1;
+err:
+	if (r != NULL) BN_clear_free(r);
+	if (b != NULL) BN_clear_free(b);
+	if (m != NULL) BN_clear_free(m);
+	ctx->tos -= 2;
+	return 0;
+}

crypto/bn/bn_modfs.h

+/*
+ *
+ *	bn_modfs.h
+ *
+ *	Some Modular Arithmetic Functions.
+ *
+ *	Copyright (C) Lenka Fibikova 2000
+ *
+ *
+ */
+
+#ifndef HEADER_BN_MODFS_H
+#define HEADER_BN_MODFS_H
+
+
+#include "bn.h"
+
+#ifdef BN_is_zero
+#undef BN_is_zero
+#define BN_is_zero(a)	(((a)->top == 0) || (((a)->top == 1) && ((a)->d[0] == (BN_ULONG)0)))
+#endif /*BN_is_zero(a)*/
+
+
+int BN_smod(BIGNUM *rem, BIGNUM *m, BIGNUM *d, BN_CTX *ctx);
+int BN_mod_sub(BIGNUM *r, BIGNUM *a, BIGNUM *b, BIGNUM *m, BN_CTX *ctx);
+int BN_mod_add(BIGNUM *r, BIGNUM *a, BIGNUM *b, BIGNUM *m, BN_CTX *ctx); 
+int BN_mod_sqr(BIGNUM *r, BIGNUM *a, BIGNUM *p, BN_CTX *ctx);
+int BN_swap(BIGNUM *x, BIGNUM *y);
+int BN_legendre(BIGNUM *a, BIGNUM *p, BN_CTX *ctx);
+int BN_mod_sqrt(BIGNUM *x, BIGNUM *a, BIGNUM *p, BN_CTX *ctx);
+
+#endif
\ No newline at end of file

crypto/bn/bn_mont2.c

+/*
+ *
+ *	bn_mont2.c
+ *
+ *	Montgomery Modular Arithmetic Functions.
+ *
+ *	Copyright (C) Lenka Fibikova 2000
+ *
+ *
+ */
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <assert.h>
+
+#include "bn.h"
+#include "bn_modfs.h"
+#include "bn_mont2.h"
+
+#define BN_mask_word(x, m) ((x->d[0]) & (m))
+
+BN_MONTGOMERY *BN_mont_new()
+{
+	BN_MONTGOMERY *ret;
+
+	ret=(BN_MONTGOMERY *)malloc(sizeof(BN_MONTGOMERY));
+
+	if (ret == NULL) return NULL;
+
+	if ((ret->p = BN_new()) == NULL)
+	{
+		free(ret);
+		return NULL;
+	}
+
+	return ret;
+}
+
+
+void BN_mont_clear_free(BN_MONTGOMERY *mont)
+{
+	if (mont == NULL) return;
+
+	if (mont->p != NULL) BN_clear_free(mont->p);
+
+	mont->p_num_bytes = 0;
+	mont->R_num_bits = 0;
+	mont->p_inv_b_neg = 0;
+}
+
+int BN_to_mont(BIGNUM *x, BN_MONTGOMERY *mont, BN_CTX *ctx)
+{
+	assert(x != NULL);
+
+	assert(mont != NULL);
+	assert(mont->p != NULL);
+
+	assert(ctx != NULL);
+
+	if (!BN_lshift(x, x, mont->R_num_bits)) return 0;
+	if (!BN_mod(x, x, mont->p, ctx)) return 0;
+
+	return 1;
+}
+
+
+static BN_ULONG BN_mont_inv(BIGNUM *a, int e, BN_CTX *ctx)
+/* y = a^{-1} (mod 2^e) for an odd number a */
+{
+	BN_ULONG y, exp, mask;
+	BIGNUM *x, *xy, *x_sh;
+	int i;
+
+	assert(a != NULL && ctx != NULL);
+	assert(e <= BN_BITS2);
+	assert(BN_is_odd(a));
+	assert(!BN_is_zero(a) && !a->neg);
+
+
+	y = 1;
+	exp = 2;
+	mask = 3;
+	if((x = BN_dup(a)) == NULL) return 0;
+	if(!BN_mask_bits(x, e)) return 0;
+
+	xy = ctx->bn[ctx->tos]; 
+	x_sh = ctx->bn[ctx->tos + 1]; 
+	ctx->tos += 2;
+
+	if (BN_copy(xy, x) == NULL) goto err;
+	if (!BN_lshift1(x_sh, x)) goto err;
+
+
+	for (i = 2; i <= e; i++)
+	{
+		if (exp < BN_mask_word(xy, mask))
+		{
+			y = y + exp;
+			if (!BN_add(xy, xy, x_sh)) goto err;
+		}
+
+		exp <<= 1;
+		if (!BN_lshift1(x_sh, x_sh)) goto err;
+		mask <<= 1;
+		mask++;
+	}
+
+
+#ifdef TEST
+	if (xy->d[0] != 1) goto err;
+#endif
+
+	if (x != NULL) BN_clear_free(x);
+	ctx->tos -= 2;
+	return y;
+
+
+err:
+	if (x != NULL) BN_clear_free(x);
+	ctx->tos -= 2;
+	return 0;
+
+}
+
+int BN_mont_set(BIGNUM *p, BN_MONTGOMERY *mont, BN_CTX *ctx)
+{
+	assert(p != NULL && ctx != NULL);
+	assert(mont != NULL);
+	assert(mont->p != NULL);
+	assert(!BN_is_zero(p) && !p->neg);
+
+
+	mont->p_num_bytes = p->top;
+	mont->R_num_bits = (mont->p_num_bytes) * BN_BITS2;
+
+	if (BN_copy(mont->p, p) == NULL);
+	
+	mont->p_inv_b_neg =  BN_mont_inv(p, BN_BITS2, ctx);
+	mont->p_inv_b_neg = 0 - mont->p_inv_b_neg;
+
+	return 1;
+}
+
+static int BN_cpy_mul_word(BIGNUM *ret, BIGNUM *a, BN_ULONG w)
+/* ret = a * w */
+{
+	if (BN_copy(ret, a) == NULL) return 0;
+
+	if (!BN_mul_word(ret, w)) return 0;
+
+	return 1;
+}
+
+
+int BN_mont_red(BIGNUM *y, BN_MONTGOMERY *mont, BN_CTX *ctx)
+/* yR^{-1} (mod p) */
+{
+	int i;
+	BIGNUM *up, *p;
+	BN_ULONG u;
+
+	assert(y != NULL && mont != NULL && ctx != NULL);
+	assert(mont->p != NULL);
+	assert(BN_cmp(y, mont->p) < 0);
+	assert(!y->neg);
+
+
+	if (BN_is_zero(y)) return 1;
+
+	p = mont->p;
+	up = ctx->bn[ctx->tos]; 
+	ctx->tos += 1;
+
+
+	for (i = 0; i < mont->p_num_bytes; i++)
+	{
+		u = (y->d[0]) * mont->p_inv_b_neg;			/* u = y_0 * p' */
+
+		if (!BN_cpy_mul_word(up, p, u)) goto err;	/* up = u * p */
+
+		if (!BN_add(y, y, up)) goto err;			
+#ifdef TEST
+		if (y->d[0]) goto err;
+#endif
+		if (!BN_rshift(y, y, BN_BITS2)) goto err;	/* y = (y + up)/b */
+	}
+
+
+	if (BN_cmp(y, mont->p) >= 0) 
+	{
+		if (!BN_sub(y, y, mont->p)) goto err;
+	}
+
+	ctx->tos -= 1;
+	return 1;
+
+err:
+	ctx->tos -= 1;
+	return 0;
+
+}
+
+
+int BN_mont_mod_mul(BIGNUM *r, BIGNUM *x, BIGNUM *y, BN_MONTGOMERY *mont, BN_CTX *ctx)
+/* r = x * y mod p */
+/* r != x && r! = y !!! */
+{
+	BIGNUM *xiy, *up;
+	BN_ULONG u;
+	int i;
+	
+
+	assert(r != x && r != y);
+	assert(r != NULL && x != NULL  && y != NULL && mont != NULL && ctx != NULL);
+	assert(mont->p != NULL);
+	assert(BN_cmp(x, mont->p) < 0);
+	assert(BN_cmp(y, mont->p) < 0);
+	assert(!x->neg);
+	assert(!y->neg);
+
+	if (BN_is_zero(x) || BN_is_zero(y))
+	{
+		if (!BN_zero(r)) return 0;
+		return 1;
+	}
+
+
+
+	xiy = ctx->bn[ctx->tos]; 
+	up = ctx->bn[ctx->tos + 1]; 
+	ctx->tos += 2;
+
+	if (!BN_zero(r)) goto err;
+
+	for (i = 0; i < x->top; i++)
+	{
+		u = (r->d[0] + x->d[i] * y->d[0]) * mont->p_inv_b_neg;
+
+		if (!BN_cpy_mul_word(xiy, y, x->d[i])) goto err;
+		if (!BN_cpy_mul_word(up, mont->p, u)) goto err;
+
+		if (!BN_add(r, r, xiy)) goto err;
+		if (!BN_add(r, r, up)) goto err;
+
+#ifdef TEST
+		if (r->d[0]) goto err;
+#endif
+		if (!BN_rshift(r, r, BN_BITS2)) goto err; 
+	}
+
+	for (i = x->top; i < mont->p_num_bytes; i++)
+	{
+		u = (r->d[0]) * mont->p_inv_b_neg;
+
+		if (!BN_cpy_mul_word(up, mont->p, u)) goto err;
+
+		if (!BN_add(r, r, up)) goto err;
+
+#ifdef TEST
+		if (r->d[0]) goto err;
+#endif
+		if (!BN_rshift(r, r, BN_BITS2)) goto err; 
+	}
+
+
+	if (BN_cmp(r, mont->p) >= 0) 
+	{
+		if (!BN_sub(r, r, mont->p)) goto err;
+	}
+
+
+	ctx->tos -= 2;
+	return 1;
+
+err:
+	ctx->tos -= 2;
+	return 0;
+}
+
+int BN_mont_mod_add(BIGNUM *r, BIGNUM *x, BIGNUM *y, BN_MONTGOMERY *mont)
+{
+	assert(r != NULL && x != NULL  && y != NULL && mont != NULL);
+	assert(mont->p != NULL);
+	assert(BN_cmp(x, mont->p) < 0);
+	assert(BN_cmp(y, mont->p) < 0);
+	assert(!x->neg);
+	assert(!y->neg);
+
+	if (!BN_add(r, x, y)) return 0;
+	if (BN_cmp(r, mont->p) >= 0) 
+	{
+		if (!BN_sub(r, r, mont->p)) return 0;
+	}
+
+	return 1;
+}
+
+
+int BN_mont_mod_sub(BIGNUM *r, BIGNUM *x, BIGNUM *y, BN_MONTGOMERY *mont)
+{
+	assert(r != NULL && x != NULL  && y != NULL && mont != NULL);
+	assert(mont->p != NULL);
+	assert(BN_cmp(x, mont->p) < 0);
+	assert(BN_cmp(y, mont->p) < 0);
+	assert(!x->neg);
+	assert(!y->neg);
+
+	if (!BN_sub(r, x, y)) return 0;
+	if (r->neg) 
+	{
+		if (!BN_add(r, r, mont->p)) return 0;
+	}
+
+	return 1;
+}
+
+int BN_mont_mod_lshift1(BIGNUM *r, BIGNUM *x, BN_MONTGOMERY *mont)
+{
+	assert(r != NULL && x != NULL && mont != NULL);
+	assert(mont->p != NULL);
+	assert(BN_cmp(x, mont->p) < 0);
+	assert(!x->neg);
+
+	if (!BN_lshift1(r, x)) return 0;
+
+	if (BN_cmp(r, mont->p) >= 0) 
+	{
+		if (!BN_sub(r, r, mont->p)) return 0;
+	}
+
+	return 1;
+}
+
+int BN_mont_mod_lshift(BIGNUM *r, BIGNUM *x, int n, BN_MONTGOMERY *mont)
+{
+	int sh_nb;
+
+	assert(r != NULL && x != NULL && mont != NULL);
+	assert(mont->p != NULL);
+	assert(BN_cmp(x, mont->p) < 0);
+	assert(!x->neg);
+	assert(n > 0);
+
+	if (r != x)
+	{
+		if (BN_copy(r, x) == NULL) return 0;
+	}
+
+	while (n)
+	{
+		sh_nb = BN_num_bits(mont->p) - BN_num_bits(r);
+		if (sh_nb > n) sh_nb = n;
+
+		if (sh_nb)
+		{
+			if(!BN_lshift(r, r, sh_nb)) return 0;
+		}
+		else 
+		{
+			sh_nb = 1;
+			if (!BN_lshift1(r, r)) return 0;
+		}
+
+		if (BN_cmp(r, mont->p) >= 0) 
+		{
+			if (!BN_sub(r, r, mont->p)) return 0;
+		}
+
+		n -= sh_nb;
+	}
+
+	return 1;
+}

crypto/bn/bn_mont2.h

+/*
+ *
+ *	bn_mont2.h
+ *
+ *	Montgomery Modular Arithmetic Functions.
+ *
+ *	Copyright (C) Lenka Fibikova 2000
+ *
+ *
+ */
+
+#ifndef HEADER_MONT2_H
+#define HEADER_MONT2_H
+
+#define MONTGOMERY
+
+#include "bn.h"
+
+typedef struct bn_mont_st{
+	int R_num_bits;
+	int p_num_bytes;
+	BIGNUM *p;
+	BN_ULONG p_inv_b_neg;	/* p' = p^{-1} mod b; b = 2^BN_BITS */
+} BN_MONTGOMERY;
+
+#define BN_from_mont(x, mont, ctx) (BN_mont_red((x), (mont), (ctx)))
+
+
+BN_MONTGOMERY *BN_mont_new();
+int BN_to_mont(BIGNUM *x, BN_MONTGOMERY *mont, BN_CTX *ctx); 
+void BN_mont_clear_free(BN_MONTGOMERY *mont);
+int BN_mont_set(BIGNUM *p, BN_MONTGOMERY *mont, BN_CTX *ctx);
+int BN_mont_red(BIGNUM *y, BN_MONTGOMERY *mont, BN_CTX *ctx);
+BN_ULONG BN_mont_inv(BIGNUM *x, int e, BN_CTX *ctx);
+int BN_mont_mod_mul(BIGNUM *r, BIGNUM *x, BIGNUM *y, BN_MONTGOMERY *mont, BN_CTX *ctx);
+int BN_mont_mod_add(BIGNUM *r, BIGNUM *x, BIGNUM *y, BN_MONTGOMERY *mont);
+int BN_mont_mod_sub(BIGNUM *r, BIGNUM *x, BIGNUM *y, BN_MONTGOMERY *mont);
+int BN_mont_mod_lshift1(BIGNUM *r, BIGNUM *x, BN_MONTGOMERY *mont);
+int BN_mont_mod_lshift(BIGNUM *r, BIGNUM *x, int n, BN_MONTGOMERY *mont);
+
+#endif
\ No newline at end of file

crypto/ec/ec.c

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

crypto/ec/ec.h

+/*
+ *
+ *	ec.h
+ *
+ *	Elliptic Curve Arithmetic Functions
+ *
+ *	Copyright (C) Lenka Fibikova 2000
+ *
+ *
+ */
+
+
+#ifndef HEADER_EC_H
+#define HEADER_EC_H
+
+
+#include "bn.h"
+#include "bn_mont2.h"
+
+typedef struct bn_ec_struct		/* E: y^2 = x^3 + Ax + B  (mod p) */
+{
+	BIGNUM	*A, *B, *p, *h;		/* h = 1/2 mod p = (p + 1)/2 */
+	int is_in_mont;
+} EC;
+
+typedef struct bn_ec_point_struct /* P = [X, Y, Z] */
+{
+	BIGNUM	*X, *Y, *Z;
+	int is_in_mont;
+} EC_POINT;
+
+typedef struct bn_ecp_precompute_struct /* Pi[i] = [2i + 1]P	i = 0..2^{r-1} - 1 */
+{
+	int r;
+	EC_POINT **Pi;
+} ECP_PRECOMPUTE;
+
+
+#define ECP_is_infty(P) (BN_is_zero(P->Z))
+#define ECP_is_norm(P) (BN_is_one(P->Z))
+
+#define ECP_mont_minus(P, mont) (ECP_minus((P), (mont)->p))
+
+
+EC *EC_new();
+void EC_clear_free(EC *E);
+int EC_set_half(EC *E);
+#ifdef MONTGOMERY
+int EC_to_montgomery(EC *E, BN_MONTGOMERY *mont, BN_CTX *ctx);
+int EC_from_montgomery(EC *E, BN_MONTGOMERY *mont, BN_CTX *ctx);
+#endif /* MONTGOMERY */
+
+
+EC_POINT *ECP_new();
+void ECP_clear_free(EC_POINT *P);
+void ECP_clear_free_precompute(ECP_PRECOMPUTE *prec);
+
+EC_POINT *ECP_generate(BIGNUM *x, BIGNUM *z, EC *E, BN_CTX *ctx);
+EC_POINT *ECP_dup(EC_POINT *P);
+int ECP_copy(EC_POINT *R, EC_POINT *P);
+int ECP_normalize(EC_POINT *P, EC *E, BN_CTX *ctx);
+EC_POINT *ECP_minus(EC_POINT *P, BIGNUM *p);
+int ECP_is_on_ec(EC_POINT *P, EC *E, BN_CTX *ctx);
+int ECP_ecp2bin(EC_POINT *P, unsigned char *to, int form); /* form(ANSI 9.62): 1-compressed; 2-uncompressed; 3-hybrid */
+int ECP_bin2ecp(unsigned char *from, int len, EC_POINT *P, EC *E, BN_CTX *ctx);
+
+#ifdef SIMPLE
+int ECP_cmp(EC_POINT *P, EC_POINT *Q, BIGNUM *p, BN_CTX *ctx);
+int ECP_double(EC_POINT *R, EC_POINT *P, EC *E, BN_CTX *ctx);
+int ECP_add(EC_POINT *R, EC_POINT *P, EC_POINT *Q, EC *E, BN_CTX *ctx);
+ECP_PRECOMPUTE *ECP_precompute(int r, EC_POINT *P, EC *E, BN_CTX *ctx);
+int ECP_multiply(EC_POINT *R, BIGNUM *k, ECP_PRECOMPUTE *prec, EC *E, BN_CTX *ctx);
+#endif /* SIMPLE */
+
+#ifdef MONTGOMERY
+int ECP_to_montgomery(EC_POINT *P, BN_MONTGOMERY *mont, BN_CTX *ctx);
+int ECP_from_montgomery(EC_POINT *P, BN_MONTGOMERY *mont, BN_CTX *ctx);
+int ECP_mont_cmp(EC_POINT *P, EC_POINT *Q, BN_MONTGOMERY *mont, BN_CTX *ctx);
+int ECP_mont_double(EC_POINT *R, EC_POINT *P, EC *E, BN_MONTGOMERY *mont, BN_CTX *ctx);
+int ECP_mont_add(EC_POINT *R, EC_POINT *P, EC_POINT *Q, EC *E, BN_MONTGOMERY *mont, BN_CTX *ctx);
+ECP_PRECOMPUTE *ECP_mont_precompute(int r, EC_POINT *P, EC *E, BN_MONTGOMERY *mont, BN_CTX *ctx);
+int ECP_mont_multiply(EC_POINT *R, BIGNUM *k, ECP_PRECOMPUTE *prec, EC *E, BN_MONTGOMERY *mont, BN_CTX *ctx);
+int ECP_mont_multiply2(EC_POINT *R, BIGNUM *k, EC_POINT *P, EC *E, BN_MONTGOMERY *mont, BN_CTX *ctx);
+#endif /* MONTGOMERY */
+
+#endif
\ No newline at end of file