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/* This file can be used to test whether the code handles non-canonical curve
* points (i.e. points with the 256th bit set) in the same way as the reference
* implementation. */
#include <stdint.h>
#include <stdio.h>
#include <string.h>
extern void curve25519_donna(unsigned char *output, const unsigned char *a,
const unsigned char *b);
int
main()
{
static const uint8_t point1[32] = {
0x25,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
};
static const uint8_t point2[32] = {
0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
};
static const uint8_t scalar[32] = { 1 };
uint8_t out1[32], out2[32];
curve25519_donna(out1, scalar, point1);
curve25519_donna(out2, scalar, point2);
if (0 == memcmp(out1, out2, sizeof(out1))) {
fprintf(stderr, "Top bit not ignored.\n");
return 1;
}
fprintf(stderr, "Top bit correctly ignored.\n");
return 0;
}
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