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EC_POINT_point2bn(3)




EC_POINT_new(3)              OpenSSL              EC_POINT_new(3)


NAME

     EC_POINT_new, EC_POINT_free, EC_POINT_clear_free,
     EC_POINT_copy, EC_POINT_dup, EC_POINT_method_of,
     EC_POINT_set_to_infinity,
     EC_POINT_set_Jprojective_coordinates,
     EC_POINT_get_Jprojective_coordinates_GFp,
     EC_POINT_set_affine_coordinates_GFp,
     EC_POINT_get_affine_coordinates_GFp,
     EC_POINT_set_compressed_coordinates_GFp,
     EC_POINT_set_affine_coordinates_GF2m,
     EC_POINT_get_affine_coordinates_GF2m,
     EC_POINT_set_compressed_coordinates_GF2m,
     EC_POINT_point2oct, EC_POINT_oct2point, EC_POINT_point2bn,
     EC_POINT_bn2point, EC_POINT_point2hex, EC_POINT_hex2point -
     Functions for creating, destroying and manipulating EC_POINT
     objects.


SYNOPSIS

      #include <openssl/ec.h>
      #include <openssl/bn.h>

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EC_POINT_new(3)              OpenSSL              EC_POINT_new(3)

      EC_POINT *EC_POINT_new(const EC_GROUP *group);
      void EC_POINT_free(EC_POINT *point);
      void EC_POINT_clear_free(EC_POINT *point);
      int EC_POINT_copy(EC_POINT *dst, const EC_POINT *src);
      EC_POINT *EC_POINT_dup(const EC_POINT *src, const EC_GROUP *group);
      const EC_METHOD *EC_POINT_method_of(const EC_POINT *point);
      int EC_POINT_set_to_infinity(const EC_GROUP *group, EC_POINT *point);
      int EC_POINT_set_Jprojective_coordinates_GFp(const EC_GROUP *group, EC_POINT *p,
             const BIGNUM *x, const BIGNUM *y, const BIGNUM *z, BN_CTX *ctx);
      int EC_POINT_get_Jprojective_coordinates_GFp(const EC_GROUP *group,
             const EC_POINT *p, BIGNUM *x, BIGNUM *y, BIGNUM *z, BN_CTX *ctx);
      int EC_POINT_set_affine_coordinates_GFp(const EC_GROUP *group, EC_POINT *p,
             const BIGNUM *x, const BIGNUM *y, BN_CTX *ctx);
      int EC_POINT_get_affine_coordinates_GFp(const EC_GROUP *group,
             const EC_POINT *p, BIGNUM *x, BIGNUM *y, BN_CTX *ctx);
      int EC_POINT_set_compressed_coordinates_GFp(const EC_GROUP *group, EC_POINT *p,
             const BIGNUM *x, int y_bit, BN_CTX *ctx);
      int EC_POINT_set_affine_coordinates_GF2m(const EC_GROUP *group, EC_POINT *p,
             const BIGNUM *x, const BIGNUM *y, BN_CTX *ctx);
      int EC_POINT_get_affine_coordinates_GF2m(const EC_GROUP *group,
             const EC_POINT *p, BIGNUM *x, BIGNUM *y, BN_CTX *ctx);
      int EC_POINT_set_compressed_coordinates_GF2m(const EC_GROUP *group, EC_POINT *p,
             const BIGNUM *x, int y_bit, BN_CTX *ctx);
      size_t EC_POINT_point2oct(const EC_GROUP *group, const EC_POINT *p,
             point_conversion_form_t form,
             unsigned char *buf, size_t len, BN_CTX *ctx);
      int EC_POINT_oct2point(const EC_GROUP *group, EC_POINT *p,
             const unsigned char *buf, size_t len, BN_CTX *ctx);
      BIGNUM *EC_POINT_point2bn(const EC_GROUP *, const EC_POINT *,
             point_conversion_form_t form, BIGNUM *, BN_CTX *);
      EC_POINT *EC_POINT_bn2point(const EC_GROUP *, const BIGNUM *,
             EC_POINT *, BN_CTX *);
      char *EC_POINT_point2hex(const EC_GROUP *, const EC_POINT *,
             point_conversion_form_t form, BN_CTX *);
      EC_POINT *EC_POINT_hex2point(const EC_GROUP *, const char *,
             EC_POINT *, BN_CTX *);


DESCRIPTION

     An EC_POINT represents a point on a curve. A new point is
     constructed by calling the function EC_POINT_new and
     providing the group object that the point relates to.

     EC_POINT_free frees the memory associated with the EC_POINT.

     EC_POINT_clear_free destroys any sensitive data held within
     the EC_POINT and then frees its memory.

     EC_POINT_copy copies the point src into dst. Both src and
     dst must use the same EC_METHOD.

     EC_POINT_dup creates a new EC_POINT object and copies the
     content from src to the newly created EC_POINT object.

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EC_POINT_new(3)              OpenSSL              EC_POINT_new(3)

     EC_POINT_method_of obtains the EC_METHOD associated with
     point.

     A valid point on a curve is the special point at  infinity.
     A point is set to be at infinity by calling
     EC_POINT_set_to_infinity.

     The affine co-ordinates for a point describe a point in
     terms of its x and y position. The functions
     EC_POINT_set_affine_coordinates_GFp and
     EC_POINT_set_affine_coordinates_GF2m set the x and y co-
     ordinates for the point p defined over the curve given in
     group.

     As well as the affine co-ordinates, a point can
     alternatively be described in terms of its Jacobian
     projective co-ordinates (for Fp curves only). Jacobian
     projective co-ordinates are expressed as three values x, y
     and z. Working in this co-ordinate system provides more
     efficient point multiplication operations.  A mapping exists
     between Jacobian projective co-ordinates and affine
     co-ordinates. A Jacobian projective co-ordinate (x, y, z)
     can be written as an affine co-ordinate as (x/(z^2),
     y/(z^3)). Conversion to Jacobian projective to affine co-
     ordinates is simple. The co-ordinate (x, y) is mapped to (x,
     y, 1). To set or get the projective co-ordinates use
     EC_POINT_set_Jprojective_coordinates_GFp and
     EC_POINT_get_Jprojective_coordinates_GFp respectively.

     Points can also be described in terms of their compressed
     co-ordinates. For a point (x, y), for any given value for x
     such that the point is on the curve there will only ever be
     two possible values for y. Therefore a point can be set
     using the EC_POINT_set_compressed_coordinates_GFp and
     EC_POINT_set_compressed_coordinates_GF2m functions where x
     is the x co-ordinate and y_bit is a value 0 or 1 to identify
     which of the two possible values for y should be used.

     In addition EC_POINTs can be converted to and from various
     external representations. Supported representations are
     octet strings, BIGNUMs and hexadecimal. Octet strings are
     stored in a buffer along with an associated buffer length. A
     point held in a BIGNUM is calculated by converting the point
     to an octet string and then converting that octet string
     into a BIGNUM integer.  Points in hexadecimal format are
     stored in a NULL terminated character string where each
     character is one of the printable values 0-9 or A-F (or
     a-f).

     The functions EC_POINT_point2oct, EC_POINT_oct2point,
     EC_POINT_point2bn, EC_POINT_bn2point, EC_POINT_point2hex and
     EC_POINT_hex2point convert from and to EC_POINTs for the

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EC_POINT_new(3)              OpenSSL              EC_POINT_new(3)

     formats: octet string, BIGNUM and hexadecimal respectively.

     The function EC_POINT_point2oct must be supplied with a
     buffer long enough to store the octet string. The return
     value provides the number of octets stored. Calling the
     function with a NULL buffer will not perform the conversion
     but will still return the required buffer length.

     The function EC_POINT_point2hex will allocate sufficient
     memory to store the hexadecimal string. It is the caller's
     responsibility to free this memory with a subsequent call to
     OPENSSL_free().


RETURN VALUES

     EC_POINT_new and EC_POINT_dup return the newly allocated
     EC_POINT or NULL on error.

     The following functions return 1 on success or 0 on error:
     EC_POINT_copy, EC_POINT_set_to_infinity,
     EC_POINT_set_Jprojective_coordinates_GFp,
     EC_POINT_get_Jprojective_coordinates_GFp,
     EC_POINT_set_affine_coordinates_GFp,
     EC_POINT_get_affine_coordinates_GFp,
     EC_POINT_set_compressed_coordinates_GFp,
     EC_POINT_set_affine_coordinates_GF2m,
     EC_POINT_get_affine_coordinates_GF2m,
     EC_POINT_set_compressed_coordinates_GF2m and
     EC_POINT_oct2point.

     EC_POINT_method_of returns the EC_METHOD associated with the
     supplied EC_POINT.

     EC_POINT_point2oct returns the length of the required
     buffer, or 0 on error.

     EC_POINT_point2bn returns the pointer to the BIGNUM
     supplied, or NULL on error.

     EC_POINT_bn2point returns the pointer to the EC_POINT
     supplied, or NULL on error.

     EC_POINT_point2hex returns a pointer to the hex string, or
     NULL on error.

     EC_POINT_hex2point returns the pointer to the EC_POINT
     supplied, or NULL on error.


SEE ALSO

     crypto(3), ec(3), EC_GROUP_new(3), EC_GROUP_copy(3),
     EC_POINT_add(3), EC_KEY_new(3), EC_GFp_simple_method(3),
     d2i_ECPKParameters(3)

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