// Generate a Shared secret key from
BIGNUM * CAlphaCrypt::GenerateSharedSecretKey(BIGNUM * pMasterKey, EC_POINT * lpPeerPubKey) {
EC_KEY * lpFullCurve = NULL; // Full elliptic curve
EC_POINT * pubKey = NULL; // The peer public key (bad guys one)
ECDH_DATA * ecdh_data = NULL; // Elliptic Curve data structure
BYTE secretKey[0x20] = {0}; // Shared secret key
BIGNUM * pSecretBn = NULL; // Secret shared key BIGNUM
int iRet = 0;
if (!lpPeerPubKey)
// Get the default AlphaCrypt peer public key
pubKey = GetAlphaCryptPublicKey(); // DON'T forget to delete it, damn heck! :-)
else
// Don't delete the following one:
pubKey = lpPeerPubKey;
if (!pubKey) return NULL;
// Create the FULL curve that contains public/private key pair
lpFullCurve = EC_KEY_new_by_curve_name(NID_secp256k1);
//EC_KEY_set_public_key(lpFullCurve, pStartKey); // No my own public key (I need to calculate it)
iRet = SetPrivateKey(lpFullCurve, pMasterKey);
iRet = EC_KEY_check_key(lpFullCurve);
// Compute the shared secret key
ecdh_data = ecdh_check(lpFullCurve);
if (ecdh_data)
ecdh_data->meth = ECDH_OpenSSL();
// Calculate shared secret key: My private Key * Peer public key
iRet = ECDH_compute_key(secretKey, 0x20, pubKey, lpFullCurve, NULL);
// Convert the secret key in a BIGNUMBER
pSecretBn = BN_bin2bn(secretKey, 0x20, NULL);
/*////////////////////////////////////////////////////////////////////////
// Brief explaination: //
Here is what "ECDH_compute_key" does:
Calculate "da * Qb" (that is equal to "da * db * G"). Where:
da = my ownPrivate key (the master key)
Qb = the peer Public key (standard one inserted in AlphaCrypt)
*////////////////////////////////////////////////////////////////////////
// Cleanup
EC_KEY_free(lpFullCurve);
if (pubKey != lpPeerPubKey)
EC_POINT_free(pubKey);
return pSecretBn;
}
void CryptoManager::RestoreKeyForAccount (IAccount *acc)
{
const auto pgp = qobject_cast<ISupportPGP*> (acc->GetQObject ());
if (!pgp)
return;
QSettings settings { QCoreApplication::organizationName (),
QCoreApplication::applicationName () + "_Azoth" };
settings.beginGroup ("PrivateKeys");
const auto& keyId = settings.value (acc->GetAccountID ()).toString ();
settings.endGroup ();
if (keyId.isEmpty ())
return;
for (const auto& key : GetPrivateKeys ())
if (key.keyId () == keyId)
{
pgp->SetPrivateKey (key);
break;
}
}
