Re: ??Difference Between utf8encoder.GetBytes and Encoding.ASCII.GetBytes
From: Joe Kaplan \(MVP - ADSI\) (joseph.e.kaplan_at_removethis.accenture.com)
Date: 02/24/05
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Date: Thu, 24 Feb 2005 16:52:11 -0600
The easiest thing to do is to write some code to test it and see, but I'll
try to explain too.
UTF8 and Unicode (which is really UTF16 as an encoding) are just two
different ways to create a binary encoding of a unicode string. UTF8 uses a
variable number of bytes for each character (depending on the character) and
UTF16 will use 2 bytes for each character. Since you test string, "test",
is all ASCII characters, the UTF8 version will be 4 bytes and the same as
the ASCII version. The Unicode version will be 8 bytes. To see differences
between ASCII and UTF8, you need to use non-ASCII characters in your test.
The various static/shared properties on the Encoding classes are just
shortcuts to keep you from having to build a new instance of the encoding
class. Generally, it will always be a little faster to just use them:
Encoding.UTF8
Encoding.Unicode
HTH,
Joe K.
"Phil C." <charlestek@rcn.com> wrote in message
news:O1$VxNrGFHA.3628@TK2MSFTNGP15.phx.gbl...
> Thank you Joe, you saved me a lot of grief.
> However, then, what is the difference between
> UTF8Encoding.GetBytes("text")
> and Encoding.Unicode.GetBytes("text)
> or the converse
> UTF8Encoding.GetString(Byte())
> Encoding.Unicode.GetString(Byte())
> ??
>
> -----------------------------------------------------------------------------------------------------------------------------------------------------
> "Joe Kaplan (MVP - ADSI)" <joseph.e.kaplan@removethis.accenture.com> wrote
> in message news:uyWgMXqGFHA.2616@tk2msftngp13.phx.gbl...
>> Generally speaking, the different encoding classes will give you an array
>> of bytes from a string corresponding to how that encoding actually
>> represents a string. Unicode (UTF16) represents each character as 2
>> bytes. UTF8 will use a variable number of bytes for each character, but
>> uses only one for ASCII characters, so it generally uses much less space
>> to store the same Unicode data.
>>
>> ASCII converts characters into a single byte using only 7 bits of each
>> byte. Since it only supports ASCII characters, it can result in data loss
>> if the string in question contains non-ASCII characters. It rarely has a
>> use in .NET crypto since strings are unicode in .NET.
>>
>> If your encryption key is stored as text, it is probably stored in
>> Base64. In that case, you probably want to use Convert.FromBase64String
>> to convert the string key into a byte array.
>>
>> Joe K.
>>
>> "Phil C." <charlestek@rcn.com> wrote in message
>> news:u6LpKgpGFHA.2616@tk2msftngp13.phx.gbl...
>>> Hi. (Using VB.Net) I have a symmetric encryption key stored as text,
>>> encrytped by DPAPI in my web config that I use a handler
>>> class to decrypt by the DPAPI and pass to the class that does the
>>> encryption/decryption.
>>> The decrypted DPAPI key is a string and needs to be converted to a byte
>>> array for use by the encryption/decryption class. I'm confused as to
>>> the difference using utf8encoder.GetBytes() or Encoding.ASCII.GetBytes()
>>> to do this.
>>>
>>> Thanks,
>>>
>>> Phil
>>> Boston, MA
>>>
>>
>>
>
>
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