1EC_POINT_new(3)                     OpenSSL                    EC_POINT_new(3)
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NAME

6       EC_POINT_new, EC_POINT_free, EC_POINT_clear_free, EC_POINT_copy,
7       EC_POINT_dup, EC_POINT_method_of, EC_POINT_set_to_infinity,
8       EC_POINT_set_Jprojective_coordinates,
9       EC_POINT_get_Jprojective_coordinates_GFp,
10       EC_POINT_set_affine_coordinates_GFp,
11       EC_POINT_get_affine_coordinates_GFp,
12       EC_POINT_set_compressed_coordinates_GFp,
13       EC_POINT_set_affine_coordinates_GF2m,
14       EC_POINT_get_affine_coordinates_GF2m,
15       EC_POINT_set_compressed_coordinates_GF2m, EC_POINT_point2oct,
16       EC_POINT_oct2point, EC_POINT_point2bn, EC_POINT_bn2point,
17       EC_POINT_point2hex, EC_POINT_hex2point - Functions for creating,
18       destroying and manipulating EC_POINT objects.
19

SYNOPSIS

21        #include <openssl/ec.h>
22        #include <openssl/bn.h>
23
24        EC_POINT *EC_POINT_new(const EC_GROUP *group);
25        void EC_POINT_free(EC_POINT *point);
26        void EC_POINT_clear_free(EC_POINT *point);
27        int EC_POINT_copy(EC_POINT *dst, const EC_POINT *src);
28        EC_POINT *EC_POINT_dup(const EC_POINT *src, const EC_GROUP *group);
29        const EC_METHOD *EC_POINT_method_of(const EC_POINT *point);
30        int EC_POINT_set_to_infinity(const EC_GROUP *group, EC_POINT *point);
31        int EC_POINT_set_Jprojective_coordinates_GFp(const EC_GROUP *group, EC_POINT *p,
32               const BIGNUM *x, const BIGNUM *y, const BIGNUM *z, BN_CTX *ctx);
33        int EC_POINT_get_Jprojective_coordinates_GFp(const EC_GROUP *group,
34               const EC_POINT *p, BIGNUM *x, BIGNUM *y, BIGNUM *z, BN_CTX *ctx);
35        int EC_POINT_set_affine_coordinates_GFp(const EC_GROUP *group, EC_POINT *p,
36               const BIGNUM *x, const BIGNUM *y, BN_CTX *ctx);
37        int EC_POINT_get_affine_coordinates_GFp(const EC_GROUP *group,
38               const EC_POINT *p, BIGNUM *x, BIGNUM *y, BN_CTX *ctx);
39        int EC_POINT_set_compressed_coordinates_GFp(const EC_GROUP *group, EC_POINT *p,
40               const BIGNUM *x, int y_bit, BN_CTX *ctx);
41        int EC_POINT_set_affine_coordinates_GF2m(const EC_GROUP *group, EC_POINT *p,
42               const BIGNUM *x, const BIGNUM *y, BN_CTX *ctx);
43        int EC_POINT_get_affine_coordinates_GF2m(const EC_GROUP *group,
44               const EC_POINT *p, BIGNUM *x, BIGNUM *y, BN_CTX *ctx);
45        int EC_POINT_set_compressed_coordinates_GF2m(const EC_GROUP *group, EC_POINT *p,
46               const BIGNUM *x, int y_bit, BN_CTX *ctx);
47        size_t EC_POINT_point2oct(const EC_GROUP *group, const EC_POINT *p,
48               point_conversion_form_t form,
49               unsigned char *buf, size_t len, BN_CTX *ctx);
50        int EC_POINT_oct2point(const EC_GROUP *group, EC_POINT *p,
51               const unsigned char *buf, size_t len, BN_CTX *ctx);
52        BIGNUM *EC_POINT_point2bn(const EC_GROUP *, const EC_POINT *,
53               point_conversion_form_t form, BIGNUM *, BN_CTX *);
54        EC_POINT *EC_POINT_bn2point(const EC_GROUP *, const BIGNUM *,
55               EC_POINT *, BN_CTX *);
56        char *EC_POINT_point2hex(const EC_GROUP *, const EC_POINT *,
57               point_conversion_form_t form, BN_CTX *);
58        EC_POINT *EC_POINT_hex2point(const EC_GROUP *, const char *,
59               EC_POINT *, BN_CTX *);
60

DESCRIPTION

62       An EC_POINT represents a point on a curve. A new point is constructed
63       by calling the function EC_POINT_new and providing the group object
64       that the point relates to.
65
66       EC_POINT_free frees the memory associated with the EC_POINT.
67
68       EC_POINT_clear_free destroys any sensitive data held within the
69       EC_POINT and then frees its memory.
70
71       EC_POINT_copy copies the point src into dst. Both src and dst must use
72       the same EC_METHOD.
73
74       EC_POINT_dup creates a new EC_POINT object and copies the content from
75       src to the newly created EC_POINT object.
76
77       EC_POINT_method_of obtains the EC_METHOD associated with point.
78
79       A valid point on a curve is the special point at  infinity. A point is
80       set to be at infinity by calling EC_POINT_set_to_infinity.
81
82       The affine co-ordinates for a point describe a point in terms of its x
83       and y position. The functions EC_POINT_set_affine_coordinates_GFp and
84       EC_POINT_set_affine_coordinates_GF2m set the x and y co-ordinates for
85       the point p defined over the curve given in group.
86
87       As well as the affine co-ordinates, a point can alternatively be
88       described in terms of its Jacobian projective co-ordinates (for Fp
89       curves only). Jacobian projective co-ordinates are expressed as three
90       values x, y and z. Working in this co-ordinate system provides more
91       efficient point multiplication operations.  A mapping exists between
92       Jacobian projective co-ordinates and affine co-ordinates. A Jacobian
93       projective co-ordinate (x, y, z) can be written as an affine co-
94       ordinate as (x/(z^2), y/(z^3)). Conversion to Jacobian projective to
95       affine co-ordinates is simple. The co-ordinate (x, y) is mapped to (x,
96       y, 1). To set or get the projective co-ordinates use
97       EC_POINT_set_Jprojective_coordinates_GFp and
98       EC_POINT_get_Jprojective_coordinates_GFp respectively.
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100       Points can also be described in terms of their compressed co-ordinates.
101       For a point (x, y), for any given value for x such that the point is on
102       the curve there will only ever be two possible values for y. Therefore
103       a point can be set using the EC_POINT_set_compressed_coordinates_GFp
104       and EC_POINT_set_compressed_coordinates_GF2m functions where x is the x
105       co-ordinate and y_bit is a value 0 or 1 to identify which of the two
106       possible values for y should be used.
107
108       In addition EC_POINTs can be converted to and from various external
109       representations. Supported representations are octet strings, BIGNUMs
110       and hexadecimal. Octet strings are stored in a buffer along with an
111       associated buffer length. A point held in a BIGNUM is calculated by
112       converting the point to an octet string and then converting that octet
113       string into a BIGNUM integer.  Points in hexadecimal format are stored
114       in a NULL terminated character string where each character is one of
115       the printable values 0-9 or A-F (or a-f).
116
117       The functions EC_POINT_point2oct, EC_POINT_oct2point,
118       EC_POINT_point2bn, EC_POINT_bn2point, EC_POINT_point2hex and
119       EC_POINT_hex2point convert from and to EC_POINTs for the formats: octet
120       string, BIGNUM and hexadecimal respectively.
121
122       The function EC_POINT_point2oct must be supplied with a buffer long
123       enough to store the octet string. The return value provides the number
124       of octets stored. Calling the function with a NULL buffer will not
125       perform the conversion but will still return the required buffer
126       length.
127
128       The function EC_POINT_point2hex will allocate sufficient memory to
129       store the hexadecimal string. It is the caller's responsibility to free
130       this memory with a subsequent call to OPENSSL_free().
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RETURN VALUES

133       EC_POINT_new and EC_POINT_dup return the newly allocated EC_POINT or
134       NULL on error.
135
136       The following functions return 1 on success or 0 on error:
137       EC_POINT_copy, EC_POINT_set_to_infinity,
138       EC_POINT_set_Jprojective_coordinates_GFp,
139       EC_POINT_get_Jprojective_coordinates_GFp,
140       EC_POINT_set_affine_coordinates_GFp,
141       EC_POINT_get_affine_coordinates_GFp,
142       EC_POINT_set_compressed_coordinates_GFp,
143       EC_POINT_set_affine_coordinates_GF2m,
144       EC_POINT_get_affine_coordinates_GF2m,
145       EC_POINT_set_compressed_coordinates_GF2m and EC_POINT_oct2point.
146
147       EC_POINT_method_of returns the EC_METHOD associated with the supplied
148       EC_POINT.
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150       EC_POINT_point2oct returns the length of the required buffer, or 0 on
151       error.
152
153       EC_POINT_point2bn returns the pointer to the BIGNUM supplied, or NULL
154       on error.
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156       EC_POINT_bn2point returns the pointer to the EC_POINT supplied, or NULL
157       on error.
158
159       EC_POINT_point2hex returns a pointer to the hex string, or NULL on
160       error.
161
162       EC_POINT_hex2point returns the pointer to the EC_POINT supplied, or
163       NULL on error.
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SEE ALSO

166       crypto(3), ec(3), EC_GROUP_new(3), EC_GROUP_copy(3), EC_POINT_add(3),
167       EC_KEY_new(3), EC_GFp_simple_method(3), d2i_ECPKParameters(3)
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1711.0.2o                            2019-09-10                   EC_POINT_new(3)
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