sshecdsag.c

/*
 * EC key generation.
 */

#include "ssh.h"

/* Forward reference from sshecc.c */
struct ec_point *ecp_mul(const struct ec_point *a, const Bignum b);

int ec_generate(struct ec_key *key, int bits, progfn_t pfn, void *pfnparam)
{
  struct ec_point *publicKey;

  if (!ec_nist_alg_and_curve_by_bits(
          bits, &key->publicKey.curve, &key->signalg))
    return 0;

  key->privateKey = bignum_random_in_range(One, key->publicKey.curve->w.n);
  if (!key->privateKey)
    return 0;

  publicKey = ec_public(key->privateKey, key->publicKey.curve);
  if (!publicKey) {
    freebn(key->privateKey);
    key->privateKey = NULL;
    return 0;
  }

  key->publicKey.x = publicKey->x;
  key->publicKey.y = publicKey->y;
  key->publicKey.z = NULL;
  sfree(publicKey);

  return 1;
}

int ec_edgenerate(struct ec_key *key, int bits, progfn_t pfn, void *pfnparam)
{
  struct ec_point *publicKey;

  if (!ec_ed_alg_and_curve_by_bits(bits, &key->publicKey.curve, &key->signalg))
    return 0;

  {
    /* EdDSA secret keys are just 32 bytes of hash preimage; the
     * 64-byte SHA-512 hash of that key will be used when signing,
     * but the form of the key stored on disk is the preimage
     * only. */
    Bignum privMax = bn_power_2(bits);
    if (!privMax)
      return 0;
    key->privateKey = bignum_random_in_range(Zero, privMax);
    freebn(privMax);
    if (!key->privateKey)
      return 0;
  }

  publicKey = ec_public(key->privateKey, key->publicKey.curve);
  if (!publicKey) {
    freebn(key->privateKey);
    key->privateKey = NULL;
    return 0;
  }

  key->publicKey.x = publicKey->x;
  key->publicKey.y = publicKey->y;
  key->publicKey.z = NULL;
  sfree(publicKey);

  return 1;
}