Question

我有一个c＃代码，它在infopath中获取附件的加密编码字符串并对其进行解密。这是下面的代码：

    private int fileSize;
    private int attachmentNameLength;
    private string attachmentName;
    private byte[] decodedAttachment;


    /// <summary>
    /// Accepts the Base64 encoded string
    /// that is the attachment.
    /// </summary>
    public InfoPathAttachmentDecoder(string theBase64EncodedString)
    {
        **byte[] theData =     Convert.FromBase64String(theBase64EncodedString);** //This line throws a   System.FormatException: Invalid length for a Base-64 char array or string.
        using (MemoryStream ms = new MemoryStream(theData))
        {
            BinaryReader theReader = new BinaryReader(ms);
            DecodeAttachment(theReader);
        }
    }

    private void DecodeAttachment(BinaryReader theReader)
    {
        //Position the reader to obtain the file size.
        byte[] headerData = new byte[FIXED_HEADER];
        headerData = theReader.ReadBytes(headerData.Length);

        fileSize = (int)theReader.ReadUInt32();
        attachmentNameLength = (int)theReader.ReadUInt32() * 2;

        byte[] fileNameBytes = theReader.ReadBytes(attachmentNameLength);
        //InfoPath uses UTF8 encoding.
        Encoding enc = Encoding.Unicode;
        attachmentName = enc.GetString(fileNameBytes, 0,  attachmentNameLength - 2);
        decodedAttachment = theReader.ReadBytes(fileSize);
    }

    public void SaveAttachment(string saveLocation)
    {
        string fullFileName = saveLocation;
        if (!fullFileName.EndsWith(Path.DirectorySeparatorChar.ToString()))
        {
            fullFileName += Path.DirectorySeparatorChar;
        }

        fullFileName += attachmentName;

        if (File.Exists(fullFileName))
            File.Delete(fullFileName);

        FileStream fs = new FileStream(fullFileName, FileMode.CreateNew);
        BinaryWriter bw = new BinaryWriter(fs);
        bw.Write(decodedAttachment);

        bw.Close();
        fs.Close();
    }

    public string Filename
    {
        get { return attachmentName; }
    }

    public byte[] DecodedAttachment
    {
        get { return decodedAttachment; }
    }

}

line byte [] theData = Convert.FromBase64String（theBase64EncodedString）;抛出基本64数组或字符串的系统格式异常无效长度。

Answer 1

你所拥有的不是Base64编码，似乎被tqo部分所损害。

提供的＆＃34; Base64数据：

x0lGQRQAAAABAAAAAAAAAH8IAAALAAAAdABlAHMAdAAwADEALgB0AHgAdAAA AHVzaW5nIFN5c3RlbTsN CnVzaW5nIFN5c3RlbS5D b2xsZWN0aW9ucy5HZW5l cmljOw0KdXNpbmcgU3lz dGVtLkxpbnE7DQp1c2lu ZyBTeXN0ZW0uV2ViOw0K dXNpbmcgU3lzdGVtLldl Yi5NdmM7DQoNCm5hbWVz cGFjZSBNb3ZpZXNBcHAu Q29udHJvbGxlcnM

由于重复的字符，这不是加密数据。

如果查看数据的十六进制值，您将看到：

78306c4751525141414141424141414141414141414838494141414c414141416441426c41484d4164414177414445414c6742304148674164414141e2808ce2808b4148567a6157356e49464e356333526c6254734ee2808ce2808b436e567a6157356e49464e356333526c62533544e2808ce2808b623278735a574e3061573975637935485a57356ce2808ce2808b636d6c6a4f77304b64584e70626d636755336c7ae2808ce2808b644756744c6b7870626e45374451703163326c75e2808ce2808b5a79425465584e305a573075563256694f77304be2808ce2808b64584e70626d636755336c7a644756744c6c646ce2808ce2808b5969354e646d4d3744516f4e436d35686257567ae2808ce2808b6347466a5a53424e62335a705a584e4263484175e2808ce2808b5132397564484a766247786c636e4d

请注意，Base64字符集中有一些字符，如0xe2,0x80,0x8c，0xe2,0x80,0x8b。

另外，似乎有两个部分，有一个60字节的初始部分似乎确实是Base64。 Base64解码为十六进制的部分是：

EFCDF4E9CE3BE75E76E75E35E35E35E35E36E35E35E35E35E35E35E35E35E35E3CDFCE3DE35E35E35E1CE35E35E35E35EB8E35E36E9CE35E3CE1DE35EB8E35E35EFBE35E38E39E35E1CEBBE36DF4E35E3CEBBE35EB8E35E35E35

附件解密System.FormatException：Base-64 char数组或字符串的长度无效

1 个答案: