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string to byte array (to string to XML) and back again

i know there are 1million questions about "string - byte array" conversion out there but none of them fit my problem.
For the installation of my software i need to save some informations from the user (serveraddress, userID, password and so on). Some of these informations need do be protected (encrypted using DPAPI). For that i have to convert the string (SecureString) to byte[]
public static byte[] StringToByte(string s)
{
return Convert.FromBase64String(s);
}
where i get my first problem. If the strings lenght is a not a multiple of 4 (s.lenght % 4 == 0) i get a "Invalid length for a Base-64 char array" error. I've read that i can (have to) add "=" to the end of the string but some of these strings may be passwords (which may contain "="). I need to store the (encrypted) data in a XML-file why i can't use Unicode encoding (i don't know why but it corrupts the XML file ... because of encoding i would suppose).
As last step i have to go back the way to get the stored data on app startup.
Does someone of you can help me solving this problem ? I don't care the output in the XML as long as it is "readable".
best regards Alex

where i get my first problem. If the strings lenght is a not a multiple of 4 (s.lenght % 4 == 0) i get a "Invalid length for a Base-64 char array" error.
That suggests that it's not base64 to start with. It sounds like you're going in the wrong direction here - base64 is used to convert binary data into text. To convert text into a binary form, you should normally just use Encoding.GetBytes:
return Encoding.UTF8.GetBytes(text);
Now if you needed to encode the result of the encryption (which will be binary data) as text, then you'd use base64. (Because the result of encrypting UTF-8-encoded text is not UTF-8-encoded text.)
So something like:
public static string EncryptText(string input)
{
byte[] unencryptedBytes = Encoding.UTF8.GetBytes(input);
byte[] encryptedBytes = EncryptBytes(unencryptedBytes); // Not shown here
return Convert.ToBase64String(encryptedBytes);
}
public static string DecryptText(string input)
{
byte[] encryptedBytes = Convert.FromBase64String(input);
byte[] unencryptedBytes = DecryptBytes(encryptedBytes); // Not shown here
return Encoding.UTF8.GetString(unencryptedBytes);
}

Error in converting from Encrypted value

I have a encryption method GetDecryptedSSN(). I tested it’s correctness by the following test. It works fine
//////////TEST 2//////////
byte[] encryptedByteWithIBMEncoding2 = DecryptionServiceHelper.GetEncryptedSSN("123456789");
string clearTextSSN2 = DecryptionServiceHelper.GetDecryptedSSN(encryptedByteWithIBMEncoding2);
But when I do a conversion to ASCII String and then back, it is not working correctly. What is the problem in the conversion logic?
//////////TEST 1//////////
//String -- > ASCII Byte --> IBM Byte -- > encryptedByteWithIBMEncoding
byte[] encryptedByteWithIBMEncoding = DecryptionServiceHelper.GetEncryptedSSN("123456789");
//encryptedByteWithIBMEncoding --> Encrypted Byte ASCII
string EncodingFormat = "IBM037";
byte[] encryptedByteWithASCIIEncoding = Encoding.Convert(Encoding.GetEncoding(EncodingFormat), Encoding.ASCII,
encryptedByteWithIBMEncoding);
//Encrypted Byte ASCII - ASCII Encoded string
string encodedEncryptedStringInASCII = System.Text.ASCIIEncoding.ASCII.GetString(encryptedByteWithASCIIEncoding);
//UpdateSSN(encodedEncryptedStringInASCII);
byte[] dataInBytesASCII = System.Text.ASCIIEncoding.ASCII.GetBytes(encodedEncryptedStringInASCII);
byte[] bytesInIBM = Encoding.Convert(Encoding.ASCII, Encoding.GetEncoding(EncodingFormat),
dataInBytesASCII);
string clearTextSSN = DecryptionServiceHelper.GetDecryptedSSN(bytesInIBM);
Helper Class
public static class DecryptionServiceHelper
{
public const string EncodingFormat = "IBM037";
public const string SSNPrefix = "0000000";
public const string Encryption = "E";
public const string Decryption = "D";
public static byte[] GetEncryptedSSN(string clearTextSSN)
{
return GetEncryptedID(SSNPrefix + clearTextSSN);
}
public static string GetDecryptedSSN(byte[] encryptedSSN)
{
return GetDecryptedID(encryptedSSN);
}
private static byte[] GetEncryptedID(string id)
{
ServiceProgram input = new ServiceProgram();
input.RequestText = Encodeto64(id);
input.RequestType = Encryption;
ProgramInterface inputRequest = new ProgramInterface();
inputRequest.Test__Request = input;
using (MY_Service operation = new MY_Service())
{
return ((operation.MY_Operation(inputRequest)).Test__Response.ResponseText);
}
}
private static string GetDecryptedID(byte[] id)
{
ServiceProgram input = new ServiceProgram();
input.RequestText = id;
input.RequestType = Decryption;
ProgramInterface request = new ProgramInterface();
request.Test__Request = input;
using (MY_Service operationD = new MY_Service())
{
ProgramInterface1 response = operationD.MY_Operation(request);
byte[] encodedBytes = Encoding.Convert(Encoding.GetEncoding(EncodingFormat), Encoding.ASCII,
response.Test__Response.ResponseText);
return System.Text.ASCIIEncoding.ASCII.GetString(encodedBytes);
}
}
private static byte[] Encodeto64(string toEncode)
{
byte[] dataInBytes = System.Text.ASCIIEncoding.ASCII.GetBytes(toEncode);
Encoding encoding = Encoding.GetEncoding(EncodingFormat);
return Encoding.Convert(Encoding.ASCII, encoding, dataInBytes);
}
}
REFERENCE:
Getting incorrect decryption value using AesCryptoServiceProvider

This is the problem, I suspect:
string encodedEncryptedStringInASCII =
System.Text.ASCIIEncoding.ASCII.GetString(encryptedByteWithASCIIEncoding);
(It's not entirely clear because of all the messing around with encodings beforehand, which seems pointless to me, but...)
The result of encryption is not "text encoded in ASCII" - so you shouldn't try to treat it that way. (You haven't said what kind of encryption you're using, but it would be very odd for it to produce ASCII text.)
It's just an arbitrary byte array. In order to represent that in text only using the ASCII character set, the most common approach is to use base64. So the above code would become:
string encryptedText = Convert.ToBase64(encryptedByteWithIBMEncoding);
Then later, you'd convert it back to a byte array ready for decryption as:
encryptedByteWithIBMEncoding = Convert.FromBase64String(encryptedText);
I would strongly advise you to avoid messing around with the encodings like this if you can help it though. It's not clear why ASCII needs to get involved at all. If you really want to encode your original text as IBM037 before encryption, you should just use:
Encoding encoding = Encoding.GetEncoding("IBM037");
string unencryptedBinary = encoding.GetBytes(textInput);
Personally I'd usually use UTF-8, as an encoding which can handle any character data rather than just a limited subset, but that's up to you. I think you're making the whole thing much more complicated than it needs to be though.
A typical "encrypt a string, getting a string result" workflow is:
Convert input text to bytes using UTF-8. The result is a byte array.
Encrypt result of step 1. The result is a byte array.
Convert result of step 2 into base64. The result is a string.
To decrypt:
Convert the string from base64. The result is a byte array.
Decrypt the result of step 1. The result is a byte array.
Convert the result of step 2 back to a string using the same encoding as step 1 of the encryption process.

In DecryptionServiceHelper.GetEncryptedSSN you are encoding the text in IBM037 format BEFORE encrypting.
So the following piece of code is not correct as you are converting the encrypted bytes to ASCII assuming that its in the IBM037 format. That's wrong as the encrypted bytes is not in IBM037 format (the text was encoded before encryption)
//encryptedByteWithIBMEncoding --> Encrypted Byte ASCII
string EncodingFormat = "IBM037";
byte[] encryptedByteWithASCIIEncoding = Encoding.Convert(Encoding.GetEncoding(EncodingFormat), Encoding.ASCII,
encryptedByteWithIBMEncoding);
One possible solution is to encode the encrypted text using IBM037 format, that should fix the issue I guess.

Invalid length for a Base-64 char array while decryption

I get the following exception in some cases through (decryption) , and i can't recognize exactly the reason :
Invalid length for a Base-64 char array
My Code :
public static string encodeSTROnUrl(string thisEncode)
{
if (null == thisEncode)
return string.Empty;
return HttpUtility.UrlEncode(Encrypt(thisEncode));
}
// string thisDecode = "3Dn%2bsJJPXprU4%3d"; //this is the value which cause the exception.
public static string decodeSTROnUrl(string thisDecode)
{
return Decrypt(HttpUtility.UrlDecode(thisDecode));
}
QueryStringEncryption.Cryptography.decodeSTROnUrl(Request.QueryString["val"].ToString());
The exact line which throw the exception is :
Byte[] byteArray = Convert.FromBase64String(text);
I thought i fix this problem by encoding and decoding before and after the encryption and the decryption operation.but some values still throw this exception .
Note: i note some strange behavior :
the id as a query string sent to my mail is : n%2bsJJPXprU4%3d and it works without exceptions ..
and the user who has the problem the sent url contains 3Dn%2bsJJPXprU4%3d
is this a browser problem ??!!

Decoding the querystring values is done already when it's parsed into the Request. try without
'HttpUtility.UrlDecode'
public static string decodeSTROnUrl(string thisDecode)
{
return Decrypt(thisDecode);
}

The 64-bit encoding has problems with spaces in the string.
Try to add the following after encrypting
sEncryptedString = sEncryptedString.Replace(' ', '+');

Invalid length for a Base-64 char array

I'm getting a "Invalid length for a Base-64 char array." inside of the IF(){...} are variations i have tried to get it to work. it fails in the first line without calling decrypt(...) proving it's not that functions problem. i get the same error inside with the first decrypt(...) call. the last one using the encoding.ascii... will get me inside the function, but then it fails inside the function. I'm getting the proper encrypted info from the database to string SSnum. it's value is: 4+mFeTp3tPF
try
{
string SSnum = dr.GetString(dr.GetOrdinal("Social Security"));
if (isEncrypted)
{
byte[] temp = Convert.FromBase64String(SSnum);
//SSnum = decrypt(Convert.FromBase64String(SSnum), Key, IV);
//SSnum = decrypt(Encoding.ASCII.GetBytes(SSnum), Key, IV);
}
txt_Social_Security.Text = SSnum;
}
catch { txt_Social_Security.Text = ""; }
I've been told to use the Convert.FromBase64String() and not the ASCII method...so why is it failing, how can i fix it?

Base64 data length should be multiple of 4 and with padding char '='
You can change your data as valid base64 data.
string dummyData = imgData.Trim().Replace(" ", "+");
if (dummyData.Length % 4 > 0)
dummyData = dummyData.PadRight(dummyData.Length + 4 - dummyData.Length % 4, '=');
byte[] byteArray = Convert.FromBase64String(dummyData);
https://stackoverflow.com/a/9301545/2024022
This will help you , try once.
Thanks
suribabu.

it's value is: 4+mFeTp3tPF
You are receiving this error because that value, 4+mFeTp3tPF, is in fact not valid Base64.
Is it possible you are simply missing the required padding character, as so 4+mFeTp3tPF=?

Are you certain that you have a Base64 string? Base64 is a means of encoding binary data into a string while only using standard 7-bit ASCII characters. It's not a string encoding like ASCII and has some control bytes present. You have a Base64 string if you're using Convert.ToBase64String to obtain the value (which, if you're trying to store binary data as a string, is your best bet)
Judging by your error (and your example data), I'm assuming that you do not have a Base64 string. If you need to store binary data in the database, you can either create a column using a binary type or encode the string into Base64 by using Convert.ToBase64String.
byte[] inputData = ...;
string base64String = Convert.ToBase64String(inputData);
byte[] outputData = Convert.FromBase64String(base64String);
Here, outputData should contain the same data as inputData.
If what you have is just an ASCII-encoded string, then your original practice of using System.Text.Encoding.ASCII.GetBytes() is correct, but you should change this to use a Base64 string if you can.

Are you sure that string 4+mFeTp3tPF is well-formed Base64 string?
I've tried some online services - no one could convert it.

replace
byte[] temp = Convert.FromBase64String(SSnum);
to this
var temp = UTF8Encoding.UTF8.GetBytes(SSnum);

Encoding Conversion problem

I've got a little problem changing the ecoding of a string. Actually I read from a DB strings that are encoded using the codepage 850 and I have to prepare them in order to be suitable for an interoperable WCF service.
From the DB I read characters \x10 and \x11 (triangular shapes) and i want to convert them to the Unicode format in order to prevent serialization/deserialization problem during WCF call. (Chars
and are not valid according of the XML specs even if WCF serialize them).
Now, I use following code in order to covert string encoding, but nothing happens. Result string is in fact identical to the original one.
I'm probably missing something...
Please help me!!!
Emanuele
static class UnicodeEncodingExtension
{
public static string Convert(this Encoding sourceEncoding, Encoding targetEncoding, string value)
{
string reEncodedString = null;
byte[] sourceBytes = sourceEncoding.GetBytes(value);
byte[] targetBytes = Encoding.Convert(sourceEncoding, targetEncoding, sourceBytes);
reEncodedString = sourceEncoding.GetString(targetBytes);
return reEncodedString;
}
}
class Program
{
private static Encoding Cp850Encoding = Encoding.GetEncoding(850);
private static Encoding UnicodeEncoding = Encoding.UTF8;
static void Main(string[] args)
{
string value;
string resultValue;
value = "\x10";
resultValue = Cp850Encoding.Convert(UnicodeEncoding, value);
value = "\x11";
resultValue = Cp850Encoding.Convert(UnicodeEncoding, value);
value = "\u25b6";
resultValue = UnicodeEncoding.Convert(Cp850Encoding, value);
value = "\u25c0";
resultValue = UnicodeEncoding.Convert(Cp850Encoding, value);
}
}

It seems you think there is a problem based on an incorrect understanding. But jmservera is correct - all strings in .NET are encoded internally as unicode.
You didn't say exactly what you want to accomplish. Are you experiencing a problem at the other end of the wire?
Just FYI, you can set the text encoding on a WCF binding with the textMessageEncoding element in the config file.

I suspect this line may be your culprit
reEncodedString = sourceEncoding.GetString(targetBytes);
which seems to take your target encoded string of bytes and asks your sourceEncoding to make a string out of them. I've not had a chance to verify it but I suspect the following might be better
reEncodedString = targetEncoding.GetString(targetBytes);

All the strings stored in string are in fact Unicode.Unicode. Read: Strings in .Net and C# and The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!)
Edit: I suppose that you want the Convert function to automatically change \x11 to \u25c0, but the problem here is that \x11 is valid in almost any encoding, the differences usually start in character \x80, so the Convert function will maintain it even if you do that:
string reEncodedString = null;
byte[] unicodeBytes = UnicodeEncoding.Unicode.GetBytes(value);
byte[] sourceBytes = Encoding.Convert(Encoding.Unicode,
sourceEncoding, unicodeBytes);
You can see in unicode.org the mappings from CP850 to Unicode. So, for this conversion to happen you will have to change these characters manually.

byte[] sourceBytes =Encoding.Default.GetBytes(value)
Encoding.UTF8.GetString(sourceBytes)
this sequence usefull for download unicode file from service(for example xml file that contain persian character)

You should try this:
byte[] sourceBytes = sourceEncoding.GetBytes(value);
var convertedString = Encoding.UTF8.GetString(sourceBytes);