ec_check.c 4.0 KB

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  1. /* crypto/ec/ec_check.c */
  2. /* ====================================================================
  3. * Copyright (c) 1998-2002 The OpenSSL Project. All rights reserved.
  4. *
  5. * Redistribution and use in source and binary forms, with or without
  6. * modification, are permitted provided that the following conditions
  7. * are met:
  8. *
  9. * 1. Redistributions of source code must retain the above copyright
  10. * notice, this list of conditions and the following disclaimer.
  11. *
  12. * 2. Redistributions in binary form must reproduce the above copyright
  13. * notice, this list of conditions and the following disclaimer in
  14. * the documentation and/or other materials provided with the
  15. * distribution.
  16. *
  17. * 3. All advertising materials mentioning features or use of this
  18. * software must display the following acknowledgment:
  19. * "This product includes software developed by the OpenSSL Project
  20. * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
  21. *
  22. * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  23. * endorse or promote products derived from this software without
  24. * prior written permission. For written permission, please contact
  25. * openssl-core@openssl.org.
  26. *
  27. * 5. Products derived from this software may not be called "OpenSSL"
  28. * nor may "OpenSSL" appear in their names without prior written
  29. * permission of the OpenSSL Project.
  30. *
  31. * 6. Redistributions of any form whatsoever must retain the following
  32. * acknowledgment:
  33. * "This product includes software developed by the OpenSSL Project
  34. * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
  35. *
  36. * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  37. * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  38. * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  39. * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
  40. * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  41. * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  42. * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  43. * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  44. * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  45. * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  46. * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  47. * OF THE POSSIBILITY OF SUCH DAMAGE.
  48. * ====================================================================
  49. *
  50. * This product includes cryptographic software written by Eric Young
  51. * (eay@cryptsoft.com). This product includes software written by Tim
  52. * Hudson (tjh@cryptsoft.com).
  53. *
  54. */
  55. #include "ec_lcl.h"
  56. #include <openssl/err.h>
  57. int EC_GROUP_check(const EC_GROUP *group, BN_CTX *ctx)
  58. {
  59. int ret = 0;
  60. BIGNUM *order;
  61. BN_CTX *new_ctx = NULL;
  62. EC_POINT *point = NULL;
  63. if (ctx == NULL)
  64. {
  65. ctx = new_ctx = BN_CTX_new();
  66. if (ctx == NULL)
  67. {
  68. ECerr(EC_F_EC_GROUP_CHECK, ERR_R_MALLOC_FAILURE);
  69. goto err;
  70. }
  71. }
  72. BN_CTX_start(ctx);
  73. if ((order = BN_CTX_get(ctx)) == NULL) goto err;
  74. /* check the discriminant */
  75. if (!EC_GROUP_check_discriminant(group, ctx))
  76. {
  77. ECerr(EC_F_EC_GROUP_CHECK, EC_R_DISCRIMINANT_IS_ZERO);
  78. goto err;
  79. }
  80. /* check the generator */
  81. if (group->generator == NULL)
  82. {
  83. ECerr(EC_F_EC_GROUP_CHECK, EC_R_UNDEFINED_GENERATOR);
  84. goto err;
  85. }
  86. if (!EC_POINT_is_on_curve(group, group->generator, ctx))
  87. {
  88. ECerr(EC_F_EC_GROUP_CHECK, EC_R_POINT_IS_NOT_ON_CURVE);
  89. goto err;
  90. }
  91. /* check the order of the generator */
  92. if ((point = EC_POINT_new(group)) == NULL) goto err;
  93. if (!EC_GROUP_get_order(group, order, ctx)) goto err;
  94. if (BN_is_zero(order))
  95. {
  96. ECerr(EC_F_EC_GROUP_CHECK, EC_R_UNDEFINED_ORDER);
  97. goto err;
  98. }
  99. if (!EC_POINT_mul(group, point, order, NULL, NULL, ctx)) goto err;
  100. if (!EC_POINT_is_at_infinity(group, point))
  101. {
  102. ECerr(EC_F_EC_GROUP_CHECK, EC_R_INVALID_GROUP_ORDER);
  103. goto err;
  104. }
  105. ret = 1;
  106. err:
  107. BN_CTX_end(ctx);
  108. if (new_ctx != NULL)
  109. BN_CTX_free(new_ctx);
  110. if (point)
  111. EC_POINT_free(point);
  112. return ret;
  113. }