Re: Base64 question

["Charles Wilt" <charles.wilt@xxxxxxxxx>]

And so, if whoever is going to do the decode is expecting ASCII, then your
RPG program first needs to convert the EBCDIC to ASCII and then do the
base64 encoding.

Charles


On Thu, Nov 6, 2008 at 1:39 PM, Scott Klement
<midrange-l@xxxxxxxxxxxxxxxx>wrote:

> Hi John,
>
> The purpose behind base64 is to allow binary data to be sent through a
> text transfer medium.  For example, if you have a JPEG picture and want
> to send it through e-mail, you have a problem.  Pictures aren't made up
> of letters and numbers, instead the actual bit values of the bytes
> control what the picture looks like.  However, e-mail was designed for
> text.  If you send e-mail from a computer running ASCII to a computer
> running EBCDIC, all of the bytes in the message will be translated from
> ASCII to EBCDIC -- so a picture would become a corrupt mess.
>
> Base64 is a solution to that problem.   Base64 takes the actual bit
> values that make up a string of data, and converts them to to a
> text-safe format.  The text can then be translated to
> ASCII/EBCDIC/Unicode, whatever, it doesn't matter.  When it's decoded,
> the data will be decoded back to the exact same binary values that you
> started with.
>
> That being the case, a text string encoded on an EBCDIC platform will
> CERTAINLY encode to a different string than a text string encoded on an
> ASCII platform!   Of course it will, since the underlying bit values are
> different.
>
> If you take the string 'Hello' and encode it on an EBCDIC platform,
> you've encoded x'C885939396' into base64.  When you decode it on an
> ASCII platform, it'll decode to x'C885939396' -- which is NOT the word
> Hello in ASCII (If it did that, there'd be no point to base64) but
> rather, it's the exact same bit values you started with...
>
> Hope you understand.