Some declarations that outline what I intend to implement.

crypto/ec/ec.h

@@ -64,6 +64,58 @@ extern "C" {
 #endif
 
 
+typedef enum {
+	POINT_CONVERSION_COMPRESSED = 2,
+	POINT_CONVERSION_UNCOMPRESSED = 4,
+	POINT_CONVERSION_HYBRID = 6
+} point_conversion_form_t;
+
+
+typedef struct ec_method_st EC_METHOD;
+
+typedef struct ec_group_st
+	/*
+	 EC_METHOD *meth;
+	 -- field definition
+	 -- curve coefficients
+	 -- optional generator with associated information (order, cofactor)
+	 -- optional Lim/Lee precomputation table
+	*/
+	EC_GROUP;
+
+typedef struct ec_point_st EC_POINT;
+
+
+/* EC_METHODs for curves over GF(p).
+ * EC_GFp_simple_method provides the basis for the optimized methods.
+ */
+ 
+const EC_METHOD *EC_GFp_simple_method(void);
+const EC_METHOD *EC_GFp_mont_method(void);
+const EC_METHOD *EC_GFp_recp_method(void);
+const EC_METHOD *EC_GFp_nist_method(void);
+
+
+EC_GROUP *EC_GROUP_new(const EC_METHOD *);
+/* We don't have types for field specifications and field elements in general.
+ * Otherwise we would declare
+ *     int EC_GROUP_set(EC_GROUP *, .....);
+ */
+int EC_GROUP_set_GFp(EC_GROUP *, const BIGNUM *p, const BIGNUM *a, const BIGNUM *b);
+void EC_GROUP_free(EC_GROUP *);
+
+EC_POINT *EC_POINT_new(const EC_GROUP *);
+void EC_POINT_free(EC_POINT *);
+ 
+int EC_POINT_add(const EC_GROUP *, EC_POINT *r, EC_POINT *a, EC_POINT *b);
+int EC_POINT_dbl(const EC_GROUP *, EC_POINT *r, EC_POINT *a);
+
+size_t EC_POINT_point2oct(const EC_GROUP *, EC_POINT *, unsigned char *buf,
+        size_t len, point_conversion_form_t form);
+int EC_POINT_oct2point(const EC_GROUP *, EC_POINT *, unsigned char *buf, size_t len);
+
+
+/* TODO: scalar multiplication */
 
 
 

crypto/ec/ec_lcl.h

@@ -54,4 +54,68 @@
  *
  */
 
+
+#include <stdlib.h>
+
 #include <openssl/ec.h>
+
+
+/* Structure details are not part of the exported interface,
+ * so all this may change in future versions. */
+
+struct ec_method_st {
+	/* used by EC_GROUP_new, EC_GROUP_set_GFp, EC_GROUP_free: */
+	int (*group_init)(EC_GROUP *);
+	/* int (*group_set)(EC_GROUP *, .....); */
+	int (*group_set_GFp)(EC_GROUP *, BIGNUM *p, BIGNUM *a, BIGNUM *b);
+	void (*group_finish)(EC_GROUP *);
+
+	/* used by EC_POINT_new, EC_POINT_free: */
+	int (*point_init)(EC_POINT *);
+	void (*point_finish)(EC_POINT *);
+
+	/* used by EC_POINT_add, EC_POINT_dbl: */
+	int (*add)(const EC_GROUP *, EC_POINT *r, EC_POINT *a, EC_POINT *b);
+	int (*dbl)(const EC_GROUP *, EC_POINT *r, EC_POINT *a);
+
+	/* used by EC_POINT_add, EC_POINT_dbl: */
+	size_t (*point2oct)(const EC_GROUP *, EC_POINT *, unsigned char *buf,
+	        size_t len, point_conversion_form_t form);
+	int (*oct2point)(const EC_GROUP *, EC_POINT *, unsigned char *buf, size_t len);
+
+
+	/* internal functions */
+
+	/* 'field_mult' and 'field_sqr' can be used by 'add' and 'dbl' so that
+	 * the same implementations of point operations can be used with different
+	 * implementations of field operations: */
+	int (*field_mult)(const EC_GROUP *, BIGNUM *r, BIGNUM *a, BIGNUM *b);
+	int (*field_sqr)(const EC_GROUP *, BIGNUM *r, BIGNUM *a);
+} /* EC_METHOD */;
+
+
+struct ec_group_st {
+	EC_METHOD *meth;
+
+	BIGNUM field; /* Field specification.
+	               * For curves over GF(p), this is the modulus. */
+	void *field_data; /* method-specific (e.g., Montgomery structure) */
+
+	BIGNUM a, b; /* Curve coefficients.
+	              * (Here the assumption is that BIGNUMs can be used
+	              * or abused for all kinds of fields, not just GF(p).) */
+	int a_is_minus3; /* enable optimized point arithmetics for special case */
+
+	/* TODO: optional generator with associated information (order, cofactor) */
+	/*       optional Lim/Lee precomputation table */
+} /* EC_GROUP */;
+
+
+struct ec_point_st {
+	EC_METHOD *meth;
+
+	BIGNUM x;
+	BIGNUM y;
+	BIGNUM z; /* Jacobian projective coordinates */
+	int z_is_one; /* enable optimized point arithmetics for special case */
+} /* EC_POINT */;