int start = dstIndex;
        byte[] descr;
        int which = subCommand == NET_SERVER_ENUM2 ? 0 : 1;

        try {
            descr = DESCR[which].getBytes( "ASCII" );
        } catch( UnsupportedEncodingException uee ) {
            return 0;
        }

        writeInt2( subCommand & 0xFF, dst, dstIndex );
        dstIndex += 2;

                break;
            case 1:
                /*
                 * Get ASCII hex value and convert to platform dependent
                 * encoding like EBCDIC perhaps
                 */
                b[ 0 ] = (byte) ( Integer.parseInt(str.substring(i, i + 2), 16) & 0xFF );
                out[ j++ ] = ( new String(b, 0, 1, "ASCII") ).charAt(0);
                i++;
                state = 0;
            }
        }

        byte[] derived = new byte[16];
        gen.generateBytes(derived, 0, 16);
        return derived;
    }


    /**
     * @param string
     * @return null terminated ASCII bytes
     */
    private static byte[] toCBytes ( String string ) {
        byte[] data = new byte[string.length() + 1];
        System.arraycopy(string.getBytes(StandardCharsets.US_ASCII), 0, data, 0, string.length());

## 检查用户名

以下是更完整的示例。

使用依赖项检查用户名与密码是否正确。

为此要使用 Python 标准模块 <a href="https://docs.python.org/3/library/secrets.html" class="external-link" target="_blank">`secrets`</a> 检查用户名与密码。

`secrets.compare_digest()` 需要仅包含 ASCII 字符（英语字符）的 `bytes` 或 `str`，这意味着它不适用于像`á`一样的字符，如 `Sebastián`。

为了解决这个问题，我们首先将 `username` 和 `password` 转换为使用 UTF-8 编码的 `bytes` 。

// or any other common encoding).
func detectUTF8(s string) (valid, require bool) {
	for i := 0; i < len(s); {
		r, size := utf8.DecodeRuneInString(s[i:])
		i += size
		// Officially, ZIP uses CP-437, but many readers use the system's
		// local character encoding. Most encoding are compatible with a large
		// subset of CP-437, which itself is ASCII-like.
		//

 *  Fix: Don't crash when URLs have IPv4-mapped IPv6 addresses.
 *  Fix: Don't crash when building `HandshakeCertificates` on Android API 28.
 *  Fix: Permit multipart file names to contain non-ASCII characters.
 *  New: API to get MockWebServer's dispatcher.
 *  New: API to access headers as `java.time.Instant`.
 *  New: Fail fast if a `SSLSocketFactory` is used as a `SocketFactory`.

            dst[ dstIndex++ ] = (byte) 0x00;
        }
        dstIndex += writeString(this.path, dst, dstIndex);
        try {
            System.arraycopy(this.service.getBytes("ASCII"), 0, dst, dstIndex, this.service.length());
        }
        catch ( UnsupportedEncodingException uee ) {
            return 0;
        }
        dstIndex += this.service.length();

            // no password in tree connect
            dst[dstIndex++] = (byte)0x00;
        }
        dstIndex += writeString( path, dst, dstIndex );
        try {
            System.arraycopy( service.getBytes( "ASCII" ), 0, dst, dstIndex, service.length() );
        } catch( UnsupportedEncodingException uee ) {
            return 0;
        }
        dstIndex += service.length();
        dst[dstIndex++] = (byte)'\0';

	}
	return formattedName
}

var (
	// https://github.com/golang/lint/blob/master/lint.go#L770
	commonInitialisms         = []string{"API", "ASCII", "CPU", "CSS", "DNS", "EOF", "GUID", "HTML", "HTTP", "HTTPS", "ID", "IP", "JSON", "LHS", "QPS", "RAM", "RHS", "RPC", "SLA", "SMTP", "SSH", "TLS", "TTL", "UID", "UI", "UUID", "URI", "URL", "UTF8", "VM", "XML", "XSRF", "XSS"}

`secrets.compare_digest()` benötigt `bytes` oder einen `str`, welcher nur ASCII-Zeichen (solche der englischen Sprache) enthalten darf, das bedeutet, dass es nicht mit Zeichen wie `á`, wie in `Sebastián`, funktionieren würde.