On 18/11/14 16:25, Indtiny S wrote:
> Dear All,
>
> I have written below code to generate a ECC based private and public key .
>
> But I am missing logic , my keys are not generated .
>
> My goal is to generate , Client :- private = Ca , public= Ca,G and
> Server:- private=Sa, pub = Sa.G
>
> and prove Ca.(Sa.G) = Sa.(CaG)
>
>
>
> #include <openssl/obj_mac.h>
> #include <openssl/ec.h>
>
> void handleErrors(void){
>
> printf("\n error ");
> }
> EC_GROUP *create_curve(void)
> {
> BN_CTX *ctx;
> EC_GROUP *curve;
> BIGNUM *a, *b, *p, *order, *x, *y;
> EC_POINT *generator;
>
> /* Binary data for the curve parameters */
> unsigned char a_bin[28] =
> {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
> 0xFF,0xFF,0xFF,0xFF,0xFF,0xFE,0xFF,0xFF,0xFF,0xFF,
> 0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFE};
> unsigned char b_bin[28] =
> {0xB4,0x05,0x0A,0x85,0x0C,0x04,0xB3,0xAB,0xF5,0x41,
> 0x32,0x56,0x50,0x44,0xB0,0xB7,0xD7,0xBF,0xD8,0xBA,
> 0x27,0x0B,0x39,0x43,0x23,0x55,0xFF,0xB4};
> unsigned char p_bin[28] =
> {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
> 0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x00,0x00,0x00,0x00,
> 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01};
> unsigned char order_bin[28] =
> {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
> 0xFF,0xFF,0xFF,0xFF,0x16,0xA2,0xE0,0xB8,0xF0,0x3E,
> 0x13,0xDD,0x29,0x45,0x5C,0x5C,0x2A,0x3D };
> unsigned char x_bin[28] =
> {0xB7,0x0E,0x0C,0xBD,0x6B,0xB4,0xBF,0x7F,0x32,0x13,
> 0x90,0xB9,0x4A,0x03,0xC1,0xD3,0x56,0xC2,0x11,0x22,
> 0x34,0x32,0x80,0xD6,0x11,0x5C,0x1D,0x21};
> unsigned char y_bin[28] =
> {0xbd,0x37,0x63,0x88,0xb5,0xf7,0x23,0xfb,0x4c,0x22,
> 0xdf,0xe6,0xcd,0x43,0x75,0xa0,0x5a,0x07,0x47,0x64,
> 0x44,0xd5,0x81,0x99,0x85,0x00,0x7e,0x34};
>
> /* Set up the BN_CTX */
> if(NULL == (ctx = BN_CTX_new())) handleErrors();
>
> /* Set the values for the various parameters */
> if(NULL == (a = BN_bin2bn(a_bin, 28, NULL))) handleErrors();
> if(NULL == (b = BN_bin2bn(b_bin, 28, NULL))) handleErrors();
> if(NULL == (p = BN_bin2bn(p_bin, 28, NULL))) handleErrors();
> if(NULL == (order = BN_bin2bn(order_bin, 28, NULL))) handleErrors();
> if(NULL == (x = BN_bin2bn(x_bin, 28, NULL))) handleErrors();
> if(NULL == (y = BN_bin2bn(y_bin, 28, NULL))) handleErrors();
>
> /* Create the curve */
> if(NULL == (curve = EC_GROUP_new_curve_GFp(p, a, b, ctx))) handleErrors();
>
> /* Create the generator */
> if(NULL == (generator = EC_POINT_new(curve))) handleErrors();
> if(1 != EC_POINT_set_affine_coordinates_GFp(curve, generator, x, y, ctx))
> handleErrors();
>
> /* Set the generator and the order */
> if(1 != EC_GROUP_set_generator(curve, generator, order, NULL))
> handleErrors();
>
> EC_POINT_free(generator);
> BN_free(y);
> BN_free(x);
> BN_free(order);
> BN_free(p);
> BN_free(b);
> BN_free(a);
> BN_CTX_free(ctx);
>
> return curve;
> }
>
>
> void myPrint( BIGNUM * x, char * t ) {
> char * s = BN_bn2dec( x ) ;
> printf("%s%s", s, t ) ;
> // OPENSSL_free(s) ;
> free(s) ;
> }
>
> int main()
> {
> EC_GROUP * cur = create_curve();
You've gone to a lot of effort to create a custom curve, and then...
> if(NULL == cur)
> {
> handleErrors();
> }
>
> EC_KEY *key;
>
> if(NULL == (key = EC_KEY_new_by_curve_name(NID_secp224r1)))
...you ignore all of that and use a standard curve. Why do you want to
create a custom curve anyway (there's rarely a need for that).
> handleErrors();
>
> if(1 != EC_KEY_generate_key(key)) handleErrors();
This creates the private and public key...
>
> BIGNUM *prv;
> EC_POINT *pub;
>
> /* Set up private key in prv */
> /* Set up public key in pub */
>
> if(1 != EC_KEY_set_private_key(key, prv)) handleErrors();
... and then you overwrite the private key with garbage (prv is not
initialised). You probably want EC_KEY_get0_private_key
>
> myPrint(prv,"\n");
> if(1 != EC_KEY_set_public_key(key, pub)) handleErrors();
and the same here (but EC_KEY_get0_public_key).
Matt
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