regname = snewn(3 * (strlen(hostname) + strlen(keytype)) + 15, char);
hostkey_regname(regname, hostname, port, keytype);
if (RegOpenKey(HKEY_CURRENT_USER, PUTTY_REG_POS "\\SshHostKeys",
regname = snewn(3 * (strlen(hostname) + strlen(keytype)) + 15, char);
hostkey_regname(regname, hostname, port, keytype);
if (RegOpenKey(HKEY_CURRENT_USER, PUTTY_REG_POS "\\SshHostKeys",