Rework build: add special cases for AIX
[openssl.git] / crypto / ec / ec2_oct.c
index 4788a1ea9d30679383c2adbcd3de11b990142ea9..59258392a20a882b95f3de6cee0a14e7d41a2ee3 100644 (file)
@@ -1,70 +1,11 @@
-/* crypto/ec/ec2_oct.c */
-/* ====================================================================
- * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
- *
- * The Elliptic Curve Public-Key Crypto Library (ECC Code) included
- * herein is developed by SUN MICROSYSTEMS, INC., and is contributed
- * to the OpenSSL project.
- *
- * The ECC Code is licensed pursuant to the OpenSSL open source
- * license provided below.
- *
- * The software is originally written by Sheueling Chang Shantz and
- * Douglas Stebila of Sun Microsystems Laboratories.
- *
- */
-/* ====================================================================
- * Copyright (c) 1998-2005 The OpenSSL Project.  All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer. 
- *
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in
- *    the documentation and/or other materials provided with the
- *    distribution.
- *
- * 3. All advertising materials mentioning features or use of this
- *    software must display the following acknowledgment:
- *    "This product includes software developed by the OpenSSL Project
- *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
- *
- * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
- *    endorse or promote products derived from this software without
- *    prior written permission. For written permission, please contact
- *    openssl-core@openssl.org.
- *
- * 5. Products derived from this software may not be called "OpenSSL"
- *    nor may "OpenSSL" appear in their names without prior written
- *    permission of the OpenSSL Project.
- *
- * 6. Redistributions of any form whatsoever must retain the following
- *    acknowledgment:
- *    "This product includes software developed by the OpenSSL Project
- *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
- *
- * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
- * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
- * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
- * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
- * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
- * OF THE POSSIBILITY OF SUCH DAMAGE.
- * ====================================================================
- *
- * This product includes cryptographic software written by Eric Young
- * (eay@cryptsoft.com).  This product includes software written by Tim
- * Hudson (tjh@cryptsoft.com).
+/*
+ * Copyright 2011-2018 The OpenSSL Project Authors. All Rights Reserved.
+ * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved
  *
+ * Licensed under the Apache License 2.0 (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
  */
 
 #include <openssl/err.h>
 
 /*-
  * Calculates and sets the affine coordinates of an EC_POINT from the given
- * compressed coordinates.  Uses algorithm 2.3.4 of SEC 1. 
+ * compressed coordinates.  Uses algorithm 2.3.4 of SEC 1.
  * Note that the simple implementation only uses affine coordinates.
  *
  * The method is from the following publication:
- * 
+ *
  *     Harper, Menezes, Vanstone:
  *     "Public-Key Cryptosystems with Very Small Key Lengths",
  *     EUROCRYPT '92, Springer-Verlag LNCS 658,
  * the same method, but claim no priority date earlier than July 29, 1994
  * (and additionally fail to cite the EUROCRYPT '92 publication as prior art).
  */
-int ec_GF2m_simple_set_compressed_coordinates(const EC_GROUP *group, EC_POINT *point,
-       const BIGNUM *x_, int y_bit, BN_CTX *ctx)
-       {
-       BN_CTX *new_ctx = NULL;
-       BIGNUM *tmp, *x, *y, *z;
-       int ret = 0, z0;
-
-       /* clear error queue */
-       ERR_clear_error();
-
-       if (ctx == NULL)
-               {
-               ctx = new_ctx = BN_CTX_new();
-               if (ctx == NULL)
-                       return 0;
-               }
-
-       y_bit = (y_bit != 0) ? 1 : 0;
-
-       BN_CTX_start(ctx);
-       tmp = BN_CTX_get(ctx);
-       x = BN_CTX_get(ctx);
-       y = BN_CTX_get(ctx);
-       z = BN_CTX_get(ctx);
-       if (z == NULL) goto err;
-
-       if (!BN_GF2m_mod_arr(x, x_, group->poly)) goto err;
-       if (BN_is_zero(x))
-               {
-               if (!BN_GF2m_mod_sqrt_arr(y, group->b, group->poly, ctx)) goto err;
-               }
-       else
-               {
-               if (!group->meth->field_sqr(group, tmp, x, ctx)) goto err;
-               if (!group->meth->field_div(group, tmp, group->b, tmp, ctx)) goto err;
-               if (!BN_GF2m_add(tmp, group->a, tmp)) goto err;
-               if (!BN_GF2m_add(tmp, x, tmp)) goto err;
-               if (!BN_GF2m_mod_solve_quad_arr(z, tmp, group->poly, ctx))
-                       {
-                       unsigned long err = ERR_peek_last_error();
-                       
-                       if (ERR_GET_LIB(err) == ERR_LIB_BN && ERR_GET_REASON(err) == BN_R_NO_SOLUTION)
-                               {
-                               ERR_clear_error();
-                               ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES, EC_R_INVALID_COMPRESSED_POINT);
-                               }
-                       else
-                               ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES, ERR_R_BN_LIB);
-                       goto err;
-                       }
-               z0 = (BN_is_odd(z)) ? 1 : 0;
-               if (!group->meth->field_mul(group, y, x, z, ctx)) goto err;
-               if (z0 != y_bit)
-                       {
-                       if (!BN_GF2m_add(y, y, x)) goto err;
-                       }
-               }
-
-       if (!EC_POINT_set_affine_coordinates_GF2m(group, point, x, y, ctx)) goto err;
-
-       ret = 1;
+int ec_GF2m_simple_set_compressed_coordinates(const EC_GROUP *group,
+                                              EC_POINT *point,
+                                              const BIGNUM *x_, int y_bit,
+                                              BN_CTX *ctx)
+{
+    BN_CTX *new_ctx = NULL;
+    BIGNUM *tmp, *x, *y, *z;
+    int ret = 0, z0;
+
+    /* clear error queue */
+    ERR_clear_error();
+
+    if (ctx == NULL) {
+        ctx = new_ctx = BN_CTX_new();
+        if (ctx == NULL)
+            return 0;
+    }
+
+    y_bit = (y_bit != 0) ? 1 : 0;
+
+    BN_CTX_start(ctx);
+    tmp = BN_CTX_get(ctx);
+    x = BN_CTX_get(ctx);
+    y = BN_CTX_get(ctx);
+    z = BN_CTX_get(ctx);
+    if (z == NULL)
+        goto err;
+
+    if (!BN_GF2m_mod_arr(x, x_, group->poly))
+        goto err;
+    if (BN_is_zero(x)) {
+        if (!BN_GF2m_mod_sqrt_arr(y, group->b, group->poly, ctx))
+            goto err;
+    } else {
+        if (!group->meth->field_sqr(group, tmp, x, ctx))
+            goto err;
+        if (!group->meth->field_div(group, tmp, group->b, tmp, ctx))
+            goto err;
+        if (!BN_GF2m_add(tmp, group->a, tmp))
+            goto err;
+        if (!BN_GF2m_add(tmp, x, tmp))
+            goto err;
+        if (!BN_GF2m_mod_solve_quad_arr(z, tmp, group->poly, ctx)) {
+            unsigned long err = ERR_peek_last_error();
+
+            if (ERR_GET_LIB(err) == ERR_LIB_BN
+                && ERR_GET_REASON(err) == BN_R_NO_SOLUTION) {
+                ERR_clear_error();
+                ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES,
+                      EC_R_INVALID_COMPRESSED_POINT);
+            } else
+                ECerr(EC_F_EC_GF2M_SIMPLE_SET_COMPRESSED_COORDINATES,
+                      ERR_R_BN_LIB);
+            goto err;
+        }
+        z0 = (BN_is_odd(z)) ? 1 : 0;
+        if (!group->meth->field_mul(group, y, x, z, ctx))
+            goto err;
+        if (z0 != y_bit) {
+            if (!BN_GF2m_add(y, y, x))
+                goto err;
+        }
+    }
+
+    if (!EC_POINT_set_affine_coordinates(group, point, x, y, ctx))
+        goto err;
+
+    ret = 1;
 
  err:
-       BN_CTX_end(ctx);
-       if (new_ctx != NULL)
-               BN_CTX_free(new_ctx);
-       return ret;
-       }
-
-
-/* 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.
+    BN_CTX_end(ctx);
+    BN_CTX_free(new_ctx);
+    return ret;
+}
+
+/*
+ * 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.
  */
-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;
-
-       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;
-               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]++;
-                       }
-
-               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)
-                       {
-                       skip = field_len - BN_num_bytes(y);
-                       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(y, buf + i);
-                       i += skip;
-                       }
-
-               if (i != ret)
-                       {
-                       ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
-                       goto err;
-                       }
-               }
-       
-       if (used_ctx)
-               BN_CTX_end(ctx);
-       if (new_ctx != NULL)
-               BN_CTX_free(new_ctx);
-       return ret;
+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;
+
+    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(group, point, x, y, ctx))
+            goto err;
+
+        buf[0] = form;
+        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]++;
+        }
+
+        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) {
+            skip = field_len - BN_num_bytes(y);
+            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(y, buf + i);
+            i += skip;
+        }
+
+        if (i != ret) {
+            ECerr(EC_F_EC_GF2M_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
+            goto err;
+        }
+    }
+
+    if (used_ctx)
+        BN_CTX_end(ctx);
+    BN_CTX_free(new_ctx);
+    return ret;
 
  err:
-       if (used_ctx)
-               BN_CTX_end(ctx);
-       if (new_ctx != NULL)
-               BN_CTX_free(new_ctx);
-       return 0;
-       }
-
-
-/* Converts an octet string representation to an EC_POINT. 
- * Note that the simple implementation only uses affine coordinates.
+    if (used_ctx)
+        BN_CTX_end(ctx);
+    BN_CTX_free(new_ctx);
+    return 0;
+}
+
+/*
+ * Converts an octet string representation to an EC_POINT. Note that the
+ * simple implementation only uses affine coordinates.
  */
 int ec_GF2m_simple_oct2point(const EC_GROUP *group, EC_POINT *point,
-       const unsigned char *buf, size_t len, BN_CTX *ctx)
-       {
-       point_conversion_form_t form;
-       int y_bit;
-       BN_CTX *new_ctx = NULL;
-       BIGNUM *x, *y, *yxi;
-       size_t field_len, enc_len;
-       int ret = 0;
-
-       if (len == 0)
-               {
-               ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_BUFFER_TOO_SMALL);
-               return 0;
-               }
-       form = buf[0];
-       y_bit = form & 1;
-       form = form & ~1U;
-       if ((form != 0) && (form != POINT_CONVERSION_COMPRESSED)
-               && (form != POINT_CONVERSION_UNCOMPRESSED)
-               && (form != POINT_CONVERSION_HYBRID))
-               {
-               ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
-               return 0;
-               }
-       if ((form == 0 || form == POINT_CONVERSION_UNCOMPRESSED) && y_bit)
-               {
-               ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
-               return 0;
-               }
-
-       if (form == 0)
-               {
-               if (len != 1)
-                       {
-                       ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
-                       return 0;
-                       }
-
-               return EC_POINT_set_to_infinity(group, point);
-               }
-       
-       field_len = (EC_GROUP_get_degree(group) + 7) / 8;
-       enc_len = (form == POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2*field_len;
-
-       if (len != enc_len)
-               {
-               ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
-               return 0;
-               }
-
-       if (ctx == NULL)
-               {
-               ctx = new_ctx = BN_CTX_new();
-               if (ctx == NULL)
-                       return 0;
-               }
-
-       BN_CTX_start(ctx);
-       x = BN_CTX_get(ctx);
-       y = BN_CTX_get(ctx);
-       yxi = BN_CTX_get(ctx);
-       if (yxi == NULL) goto err;
-
-       if (!BN_bin2bn(buf + 1, field_len, x)) goto err;
-       if (BN_ucmp(x, group->field) >= 0)
-               {
-               ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
-               goto err;
-               }
-
-       if (form == POINT_CONVERSION_COMPRESSED)
-               {
-               if (!EC_POINT_set_compressed_coordinates_GF2m(group, point, x, y_bit, ctx)) goto err;
-               }
-       else
-               {
-               if (!BN_bin2bn(buf + 1 + field_len, field_len, y)) goto err;
-               if (BN_ucmp(y, group->field) >= 0)
-                       {
-                       ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
-                       goto err;
-                       }
-               if (form == POINT_CONVERSION_HYBRID)
-                       {
-                       if (!group->meth->field_div(group, yxi, y, x, ctx)) goto err;
-                       if (y_bit != BN_is_odd(yxi))
-                               {
-                               ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
-                               goto err;
-                               }
-                       }
-
-               if (!EC_POINT_set_affine_coordinates_GF2m(group, point, x, y, ctx)) goto err;
-               }
-       
-       if (!EC_POINT_is_on_curve(group, point, ctx)) /* test required by X9.62 */
-               {
-               ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_POINT_IS_NOT_ON_CURVE);
-               goto err;
-               }
-
-       ret = 1;
-       
+                             const unsigned char *buf, size_t len,
+                             BN_CTX *ctx)
+{
+    point_conversion_form_t form;
+    int y_bit;
+    BN_CTX *new_ctx = NULL;
+    BIGNUM *x, *y, *yxi;
+    size_t field_len, enc_len;
+    int ret = 0;
+
+    if (len == 0) {
+        ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_BUFFER_TOO_SMALL);
+        return 0;
+    }
+    form = buf[0];
+    y_bit = form & 1;
+    form = form & ~1U;
+    if ((form != 0) && (form != POINT_CONVERSION_COMPRESSED)
+        && (form != POINT_CONVERSION_UNCOMPRESSED)
+        && (form != POINT_CONVERSION_HYBRID)) {
+        ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
+        return 0;
+    }
+    if ((form == 0 || form == POINT_CONVERSION_UNCOMPRESSED) && y_bit) {
+        ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
+        return 0;
+    }
+
+    if (form == 0) {
+        if (len != 1) {
+            ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
+            return 0;
+        }
+
+        return EC_POINT_set_to_infinity(group, point);
+    }
+
+    field_len = (EC_GROUP_get_degree(group) + 7) / 8;
+    enc_len =
+        (form ==
+         POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len;
+
+    if (len != enc_len) {
+        ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
+        return 0;
+    }
+
+    if (ctx == NULL) {
+        ctx = new_ctx = BN_CTX_new();
+        if (ctx == NULL)
+            return 0;
+    }
+
+    BN_CTX_start(ctx);
+    x = BN_CTX_get(ctx);
+    y = BN_CTX_get(ctx);
+    yxi = BN_CTX_get(ctx);
+    if (yxi == NULL)
+        goto err;
+
+    if (!BN_bin2bn(buf + 1, field_len, x))
+        goto err;
+    if (BN_ucmp(x, group->field) >= 0) {
+        ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
+        goto err;
+    }
+
+    if (form == POINT_CONVERSION_COMPRESSED) {
+        if (!EC_POINT_set_compressed_coordinates(group, point, x, y_bit, ctx))
+            goto err;
+    } else {
+        if (!BN_bin2bn(buf + 1 + field_len, field_len, y))
+            goto err;
+        if (BN_ucmp(y, group->field) >= 0) {
+            ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
+            goto err;
+        }
+        if (form == POINT_CONVERSION_HYBRID) {
+            if (!group->meth->field_div(group, yxi, y, x, ctx))
+                goto err;
+            if (y_bit != BN_is_odd(yxi)) {
+                ECerr(EC_F_EC_GF2M_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
+                goto err;
+            }
+        }
+
+        /*
+         * EC_POINT_set_affine_coordinates is responsible for checking that
+         * the point is on the curve.
+         */
+        if (!EC_POINT_set_affine_coordinates(group, point, x, y, ctx))
+            goto err;
+    }
+
+    ret = 1;
+
  err:
-       BN_CTX_end(ctx);
-       if (new_ctx != NULL)
-               BN_CTX_free(new_ctx);
-       return ret;
-       }
+    BN_CTX_end(ctx);
+    BN_CTX_free(new_ctx);
+    return ret;
+}
 #endif