clarify documentation

[openssl.git] / crypto / ec / ec_cvt.c

diff --git a/crypto/ec/ec_cvt.c b/crypto/ec/ec_cvt.c
index 01453a283c711e88c92c2e14edaed455d577383b..d45640bab902fb6ce28f5302ed2d9c1cb8259649 100644 (file)
--- a/crypto/ec/ec_cvt.c
+++ b/crypto/ec/ec_cvt.c
@@ -1,4 +1,7 @@
 /* crypto/ec/ec_cvt.c */
+/*
+ * Originally written by Bodo Moeller for the OpenSSL project.
+ */
 /* ====================================================================
  * Copyright (c) 1998-2002 The OpenSSL Project.  All rights reserved.
  *
@@ -61,24 +64,12 @@
  * The Contribution is licensed pursuant to the OpenSSL open source
  * license provided above.
  *
- * In addition, Sun covenants to all licensees who provide a reciprocal
- * covenant with respect to their own patents if any, not to sue under
- * current and future patent claims necessarily infringed by the making,
- * using, practicing, selling, offering for sale and/or otherwise
- * disposing of the Contribution as delivered hereunder 
- * (or portions thereof), provided that such covenant shall not apply:
- *  1) for code that a licensee deletes from the Contribution;
- *  2) separates from the Contribution; or
- *  3) for infringements caused by:
- *       i) the modification of the Contribution or
- *      ii) the combination of the Contribution with other software or
- *          devices where such combination causes the infringement.
- *
  * The elliptic curve binary polynomial software is originally written by
  * Sheueling Chang Shantz and Douglas Stebila of Sun Microsystems Laboratories.
  *
  */
 
+#include <openssl/err.h>
 #include "ec_lcl.h"
 
 
@@ -86,11 +77,8 @@ EC_GROUP *EC_GROUP_new_curve_GFp(const BIGNUM *p, const BIGNUM *a, const BIGNUM
        {
        const EC_METHOD *meth;
        EC_GROUP *ret;
-       
-       /* Finally, this will use EC_GFp_nist_method if 'p' is a special
-        * prime with optimized modular arithmetics (for NIST curves)
-        */
-       meth = EC_GFp_mont_method();
+
+       meth = EC_GFp_nist_method();
        
        ret = EC_GROUP_new(meth);
        if (ret == NULL)
@@ -98,13 +86,43 @@ EC_GROUP *EC_GROUP_new_curve_GFp(const BIGNUM *p, const BIGNUM *a, const BIGNUM
 
        if (!EC_GROUP_set_curve_GFp(ret, p, a, b, ctx))
                {
+               unsigned long err;
+                 
+               err = ERR_peek_last_error();
+
+               if (!(ERR_GET_LIB(err) == ERR_LIB_EC &&
+                       ((ERR_GET_REASON(err) == EC_R_NOT_A_NIST_PRIME) ||
+                        (ERR_GET_REASON(err) == EC_R_NOT_A_SUPPORTED_NIST_PRIME))))
+                       {
+                       /* real error */
+                       
+                       EC_GROUP_clear_free(ret);
+                       return NULL;
+                       }
+                       
+               
+               /* not an actual error, we just cannot use EC_GFp_nist_method */
+
+               ERR_clear_error();
+
                EC_GROUP_clear_free(ret);
-               return NULL;
+               meth = EC_GFp_mont_method();
+
+               ret = EC_GROUP_new(meth);
+               if (ret == NULL)
+                       return NULL;
+
+               if (!EC_GROUP_set_curve_GFp(ret, p, a, b, ctx))
+                       {
+                       EC_GROUP_clear_free(ret);
+                       return NULL;
+                       }
                }
 
        return ret;
        }
 
+
 EC_GROUP *EC_GROUP_new_curve_GF2m(const BIGNUM *p, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx)
        {
        const EC_METHOD *meth;