R – Compact Framework – Invalid URI: Hostname could not be parsed

This is one question for which the only correct answer is that "it depends". In this case, it depends on the CryptoAPI provider(s) that were built into the OS image on the target device.

Or you could simply split your string and call Uri.EscapeDataString(string) for each block, in order to avoid reimplementing the function.

Sample Code:

        String value = "large string to encode";
        int limit = 2000;

        StringBuilder sb = new StringBuilder();
        int loops = value.Length / limit;

        for (int i = 0; i <= loops; i++)
        {
            if (i < loops)
            {
                sb.Append(Uri.EscapeDataString(value.Substring(limit * i, limit)));
            }
            else
            {
                sb.Append(Uri.EscapeDataString(value.Substring(limit * i)));
            }
        }