How can I convert a Guid to a Byte array in Javascript?

I have a service bus, and the only way to transform data is via JavaScript. I need to convert a Guid to a byte array so I can then convert it to Ascii85 and shrink it into a 20 character string for the receiving customer endpoint.

Any thoughts would be appreciated.

Try this (needs LOTS of tests):

var guid = "{12345678-90ab-cdef-fedc-ba0987654321}";
window.alert(guid + " = " + toAscii85(guid))

function toAscii85(guid)
{
    var ascii85  = ""
    var chars    = guid.replace(/\{?(?:(\w+)-?)\}?/g, "$1");
    var patterns = ["$4$3$2$1", "$2$1$4$3", "$1$2$3$4", "$1$2$3$4"];
    for(var i=0; i < 32; i+=8)
    {
        var block = chars.substr(i, 8)
            .replace(/(..)(..)(..)(..)/, patterns[i / 8]) //poorman shift
        var decValue = parseInt(block, 16);

        var segment = ""
        if(decValue == 0)
        {
            segment = "z"
        }
        else
        {
            for(var n = 4; n >= 0; n--)
            {
                segment = String.fromCharCode((decValue % 85) + 33) + segment;
                decValue /= 85;
            }
        }
        ascii85 += segment
    }
    return "<~" + ascii85 + "~>";
}