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Base64 Decoding

Many Internet protocols were not designed to transport binary information, thus there often needs to be a transform between binary data streams into a text format. One of the most common is Base64 which takes the bit stream, and converts each 6-bit binary value into a text value. For example 

The results are then:

Try it with a message of "Hello" , and you should get:

SGVsbG8=

protected void Button3_Click(object sender, EventArgs e)
{
string message;
message = this.message.Text;

this.tbEncode.Text = base64Encode(message);
this.tbDecode64.Text = base64Decode(this.tbEncode.Text);

}
public string base64Decode(string data)
{
// Source: http://www.vbforums.com/showthread.php?s=&threadid=287324
try
{
System.Text.UTF8Encoding encoder = new System.Text.UTF8Encoding();
System.Text.Decoder utf8Decode = encoder.GetDecoder();

byte[] todecode_byte = Convert.FromBase64String(data);
int charCount = utf8Decode.GetCharCount(todecode_byte, 0, todecode_byte.Length);
char[] decoded_char = new char[charCount];
utf8Decode.GetChars(todecode_byte, 0, todecode_byte.Length, decoded_char, 0);
string result = new String(decoded_char);
return result;
}
catch (Exception e)
{
throw new Exception("Error in base64Decode" + e.Message);
}
}
public string base64Encode(string data)
{
// Source: http://www.vbforums.com/showthread.php?s=&threadid=287324
try
{
byte[] encData_byte = new byte[data.Length];
encData_byte = System.Text.Encoding.UTF8.GetBytes(data);
string encodedData = Convert.ToBase64String(encData_byte);
return encodedData;
}
catch (Exception e)
{
throw new Exception("Error in base64Encode" + e.Message);
}
}

Theory

   The coding table for Base64 is given below.

Bit	Encoding	Bit	Encoding	Bit	Encoding	Bit	Encoding
0	A	16	Q	32	g	48	w
1	B	17	R	33	h	49	x
2	C	18	S	34	i	50	y
3	D	19	T	35	j	51	z
4	E	20	U	36	k	52	0
5	F	21	V	37	l	53	1
6	G	22	W	38	m	54	2
7	H	23	X	39	n	55	3
8	I	24	Y	40	o	56	4
9	J	25	Z	41	p	57	5
10	K	26	a	42	q	58	6
11	L	27	b	43	r	59	7
12	M	28	c	44	s	60	8
13	N	29	d	45	t	61	9
14	O	30	e	46	u	62	+
15	P	31	f	47	v	63	/