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/* LibTomCrypt, modular cryptographic library -- Tom St Denis
*
* LibTomCrypt is a library that provides various cryptographic
* algorithms in a highly modular and flexible manner.
*
* The library is free for all purposes without any express
* guarantee it works.
*/
#include "tomcrypt_private.h"
#ifdef LTC_MECC
int ltc_ecc_export_point(unsigned char *out, unsigned long *outlen, void *x, void *y, unsigned long size, int compressed)
{
int err;
unsigned char buf[ECC_BUF_SIZE];
unsigned long xsize, ysize;
if (size > sizeof(buf)) return CRYPT_BUFFER_OVERFLOW;
if ((xsize = mp_unsigned_bin_size(x)) > size) return CRYPT_BUFFER_OVERFLOW;
if ((ysize = mp_unsigned_bin_size(y)) > size) return CRYPT_BUFFER_OVERFLOW;
if(compressed) {
if (*outlen < (1 + size)) {
*outlen = 1 + size;
return CRYPT_BUFFER_OVERFLOW;
}
/* store first byte */
out[0] = mp_isodd(y) ? 0x03 : 0x02;
/* pad and store x */
zeromem(buf, sizeof(buf));
if ((err = mp_to_unsigned_bin(x, buf + (size - xsize))) != CRYPT_OK) return err;
XMEMCPY(out+1, buf, size);
/* adjust outlen */
*outlen = 1 + size;
}
else {
if (*outlen < (1 + 2*size)) {
*outlen = 1 + 2*size;
return CRYPT_BUFFER_OVERFLOW;
}
/* store byte 0x04 */
out[0] = 0x04;
/* pad and store x */
zeromem(buf, sizeof(buf));
if ((err = mp_to_unsigned_bin(x, buf + (size - xsize))) != CRYPT_OK) return err;
XMEMCPY(out+1, buf, size);
/* pad and store y */
zeromem(buf, sizeof(buf));
if ((err = mp_to_unsigned_bin(y, buf + (size - ysize))) != CRYPT_OK) return err;
XMEMCPY(out+1+size, buf, size);
/* adjust outlen */
*outlen = 1 + 2*size;
}
return CRYPT_OK;
}
#endif
/* ref: $Format:%D$ */
/* git commit: $Format:%H$ */
/* commit time: $Format:%ai$ */
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