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How to convert AES byte[] into string and vice versa?

My method AESEncrypt(string text) is returning a byte array.
If I encrypt a message, and use the returned byte array as an input for AESDecrypt(byte[] text), everything is working fine. The problem is, that I need to convert it to a string and vice versa, so I tried the following:
byte[] encrypted = enc.AESEncrypt("Testmessage");
string encryptedStr = Convert.ToBase64String(encrypted);
byte[] test = Convert.FromBase64String(encryptedStr);
Console.WriteLine((encrypted == test));
I also tried this with Encoding.ASCII.GetString(), Encoding.UTF8.GetString(),
but encrypted == test returns false everytime...
What method do I need to use to convert the AES byte[] to a string and vice versa?
This is the AESEncrypt method:
public byte[] AESEncrypt(string s)
{
byte[] encrypted;
using (AesManaged aes = new AesManaged()) {
ICryptoTransform encryptor = aes.CreateEncryptor(AESKey, AESIV);
using (MemoryStream ms = new MemoryStream()) {
using (CryptoStream cs = new CryptoStream(ms, encryptor, CryptoStreamMode.Write)) {
using (StreamWriter sw = new StreamWriter(cs)) {
sw.Write(s);
}
encrypted = ms.ToArray();
}
}
}
return encrypted;
}

An encrypted payload held in a byte array is not directly convertible to a string, or at least not without using an ANSI encoding and both sides (encoding and decoding) agreeing on the string's code page. And if you use any Unicode encoding (UTF-8, UTF-16, ...) you're bound to have bytes that contain invalid code points, so who can't be decoded to a character.
That's where base64 comes into play. This is a safe way to represent byte arrays as ASCII strings, a subset implemented by almost every (if not every) encoding. So using that base64 code is fine.
You'll simply want encrypted.SequenceEquals(test), as explained in Comparing two byte arrays in .NET.

The base64 is directly used for this.
here is an example:
Encode
public static string Base64Encode(string plainText)
{
var plainTextBytes = System.Text.Encoding.UTF8.GetBytes(plainText);
return System.Convert.ToBase64String(plainTextBytes);
}
Decode
public static string Base64Decode(string base64EncodedData)
{
var base64EncodedBytes = System.Convert.FromBase64String(base64EncodedData);
return System.Text.Encoding.UTF8.GetString(base64EncodedBytes);
}

Consider byte[] encrypted and byte[] test, when you test for equality with == by default the references are compared not their content. This explains, why you test encrypted == test fails.
You are also asking about how to convert byte[] into a string, which is not related to your encrypted == test test at all. In general you the various System.Text.Encoding.*.GetString(byteArray); preform the conversion but you need to know what encoding was used for the byteArray. This information has to be passed along separately, you might have a specification which says all byte arrays are encoded in UTF-8 or you might pass the encoding along together with the data but there exists no general answer.

Convert C# to Ruby - MD5 and Base 64 a String

I have this code that I need to convert to ruby, this snippet is to create a security key used for a particular API. The string that I am encrypting is a JSON object.
Should I use Digest::MD5.hexdigest() or Digest::MD5.digest()?
C# Code
string strResponse = "[{\"Key\":\"BookNumber\", \"Value\"=>\"BJAK123\"},{\"Key\"=>\"AuthorCode\", \"Value\"=>\"BNA123\"}]";
using (MD5 md5 = MD5.Create())
{
byte[] bPayload = Encoding.UTF8.GetBytes(strPayload);
byte[] bPayloadHash = md5.ComputeHash(bPayload);
strPayloadBase64 = Convert.ToBase64String(bPayloadHash);
}
Ruby Code
payload = [{"Key"=>"BookNumber", "Value"=>"BJAK123"},{"Key"=>"AuthorCode", "Value"=>"BNA123"}]
utf8_params = payload.to_json.force_encoding("iso-8859-1").force_encoding("utf-8")
payload_base64 = Base64.encode64(Digest::MD5.hexdigest(utf8_params))

Use
payload_base64 = Digest::MD5.base64digest(utf8_params)
as Digest::MD5.hexdigest produces a hex string of digest, whereas C# code is performing base64 encoding of the digest.

AES key converting to string and byte[] C#

I have an application that generates a AES Key (using Security.Cryptography). I take that AES Key, convert it to string and put it in a cookie like this:
string keyToSend = Encoding.UTF8.GetString(CurrentKey);
HttpCookie sessionKeyCookie = new HttpCookie("SessionKey", JsonConvert.SerializeObject(keyToSend));
keyToSend looks like this: "���K��Ui ����&��Ӂ*��()".
Then, I want to take back that key and use it to decrypt something, and I do this:
string keyString = JsonConvert.DeserializeObject<string>(context.Cookies["SessionKey"].Value);
byte[] ascii = Encoding.ASCII.GetBytes(cevaString);
byte[] utf8 = Encoding.UTF8.GetBytes(cevaString);
byte[] utf32 = Encoding.UTF32.GetBytes(cevaString);
Also, my keyToString looks like this: "���K��Ui ����&��Ӂ*��()".
And my browser cookie looks like this: "�\u0010��K��Ui �\u0010�\u000f�\u001f\u0005�\u0012\u0018&��Ӂ*��()\u001e"
The initial key should have 256bits, so 32 entries in that array, but all my variables (ascii, utf8, utf32) have different lengths. Why is that, how can I retrieve the cookie and convert it to a byte[32] array?

It sounds like CurrentKey is arbitrary binary data - not a UTF-8 encoded string. If you've got arbitrary data which you need to encode as a string (e.g. an image, or encrypted or compressed data) you're usually best off using Base64 or hex encoding. Base64 is pretty easy:
string keyToSend = Convert.ToBase64String(CurrentKey);
...
byte[] recoveredKey = Convert.FromBase64String(keyString);

Convert UTF-8 to Chinese Simplified (GB2312)

Is there a way to convert UTF-8 string to Chinese Simplified (GB2312) in C#. Any help is greatly appreciated.
Regards
Jyothish George

The first thing to be aware of is that there's no such thing as a "UTF-8 string" in .NET. All strings in .NET are effectively UTF-16. However, .NET provides the Encoding class to allow you to decode binary data into strings, and re-encode it later.
Encoding.Convert can convert a byte array representing text encoded with one encoding into a byte array with the same text encoded with a different encoding. Is that what you want?
Alternatively, if you already have a string, you can use:
byte[] bytes = Encoding.GetEncoding("gb2312").GetBytes(text);
If you can provide more information, that would be helpful.

Try this;
public string GB2312ToUtf8(string gb2312String)
{
Encoding fromEncoding = Encoding.GetEncoding("gb2312");
Encoding toEncoding = Encoding.UTF8;
return EncodingConvert(gb2312String, fromEncoding, toEncoding);
}
public string Utf8ToGB2312(string utf8String)
{
Encoding fromEncoding = Encoding.UTF8;
Encoding toEncoding = Encoding.GetEncoding("gb2312");
return EncodingConvert(utf8String, fromEncoding, toEncoding);
}
public string EncodingConvert(string fromString, Encoding fromEncoding, Encoding toEncoding)
{
byte[] fromBytes = fromEncoding.GetBytes(fromString);
byte[] toBytes = Encoding.Convert(fromEncoding, toEncoding, fromBytes);
string toString = toEncoding.GetString(toBytes);
return toString;
}
source here

C# and utf8_decode

Is there a C# utf8_decode equivalent?

Use the Encoding class.
For example:
byte[] bytes = something;
string str = Encoding.UTF8.GetString(bytes);

Yes. You can use the System.Text.Encoding class to convert the encoding.
string source = "Déjà vu";
Encoding unicode = Encoding.Unicode;
// iso-8859-1 <- codepage 28591
Encoding latin1 = Encoding.GetEncoding(28591);
Byte[] result = Encoding.Convert(unicode, latin1, unicode.GetBytes(s));
// result contains the byte sequence for the latin1 encoded string
edit: or simply
string source = "Déjà vu";
Byte[] latin1 = Encoding.GetEncoding(28591).GetBytes(source);
string (System.String) is always unicode encoded, i.e. if you convert the byte sequence back to string (Encoding.GetString()) your data will again be stored as utf-16 codepoints again.

If your input is a string here is a method that would probably work (assuming your from wester europe :)
public string Utf8Decode(string inputDate)
{
return Encoding.GetEncoding("iso-8859-1").GetString(Encoding.UTF8.GetBytes(inputDate));
}
Of course, if the current encoding of the inputData is not latin1, change the "iso-8859-1" to the correct encoding.

I tried to make this implementation on Xamarin C#.
The code below worked for me:
public static string Utf8Encode(string inputDate)
{
byte[] bytes = Encoding.UTF8.GetBytes(inputDate);
return Encoding.GetEncoding("iso-8859-1").GetString(bytes,0, bytes.Length);
}
public static string Utf8Decode(string inputDate)
{
byte[] bytes = Encoding.GetEncoding("iso-8859-1").GetBytes(inputDate);
return Encoding.UTF8.GetString(bytes, 0, bytes.Length);
}