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xs/sc_ssl/openssl/source/crypto/ec/ec2_smpl.c  view on Meta::CPAN

		
 err:
	return ret;
	}


/* Include patented algorithms. */
#include "ec2_smpt.c"


/* Converts an EC_POINT to an octet string.  
 * If buf is NULL, the encoded length will be returned.
 * If the length len of buf is smaller than required an error will be returned.
 *
 * The point compression section of this function is patented by Certicom Corp. 
 * under US Patent 6,141,420.  Point compression is disabled by default and can 
 * be enabled by defining the preprocessor macro OPENSSL_EC_BIN_PT_COMP at 
 * Configure-time.
 */
size_t ec_GF2m_simple_point2oct(const EC_GROUP *group, const EC_POINT *point, point_conversion_form_t form,
	unsigned char *buf, size_t len, BN_CTX *ctx)
	{
	size_t ret;
	BN_CTX *new_ctx = NULL;
	int used_ctx = 0;
	BIGNUM *x, *y, *yxi;
	size_t field_len, i, skip;

#ifndef OPENSSL_EC_BIN_PT_COMP
	if ((form == POINT_CONVERSION_COMPRESSED) || (form == POINT_CONVERSION_HYBRID)) 
		{
		ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_DISABLED);
		goto err;
		}
#endif

	if ((form != POINT_CONVERSION_COMPRESSED)
		&& (form != POINT_CONVERSION_UNCOMPRESSED)
		&& (form != POINT_CONVERSION_HYBRID))
		{
		ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, EC_R_INVALID_FORM);
		goto err;
		}

	if (EC_POINT_is_at_infinity(group, point))
		{
		/* encodes to a single 0 octet */
		if (buf != NULL)
			{
			if (len < 1)
				{
				ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL);
				return 0;
				}
			buf[0] = 0;
			}
		return 1;
		}


	/* ret := required output buffer length */
	field_len = (EC_GROUP_get_degree(group) + 7) / 8;
	ret = (form == POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2*field_len;

	/* if 'buf' is NULL, just return required length */
	if (buf != NULL)
		{
		if (len < ret)
			{
			ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL);
			goto err;
			}

		if (ctx == NULL)
			{
			ctx = new_ctx = BN_CTX_new();
			if (ctx == NULL)
				return 0;
			}

		BN_CTX_start(ctx);
		used_ctx = 1;
		x = BN_CTX_get(ctx);
		y = BN_CTX_get(ctx);
		yxi = BN_CTX_get(ctx);
		if (yxi == NULL) goto err;

		if (!EC_POINT_get_affine_coordinates_GF2m(group, point, x, y, ctx)) goto err;

		buf[0] = form;
#ifdef OPENSSL_EC_BIN_PT_COMP
		if ((form != POINT_CONVERSION_UNCOMPRESSED) && !BN_is_zero(x))
			{
			if (!group->meth->field_div(group, yxi, y, x, ctx)) goto err;
			if (BN_is_odd(yxi)) buf[0]++;
			}
#endif

		i = 1;
		
		skip = field_len - BN_num_bytes(x);
		if (skip > field_len)
			{
			ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
			goto err;
			}
		while (skip > 0)
			{
			buf[i++] = 0;
			skip--;
			}
		skip = BN_bn2bin(x, buf + i);
		i += skip;
		if (i != 1 + field_len)
			{
			ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
			goto err;
			}

		if (form == POINT_CONVERSION_UNCOMPRESSED || form == POINT_CONVERSION_HYBRID)
			{