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To: cs551@merlot.usc.edu
Subject: Re: CS551: Final Project 2 : Delete Msg
Date: Wed, 26 Nov 2008 09:53:55 -0800
From: Bill Cheng <william@bourbon.usc.edu>

Someone wrote:

  > Any ideas on how do we convert unsigned char * to ASCII character array ?

You mean from binary data (unsigned char *) to ASCII string
(also unsigned char *)?

To convert one byte of binary data to a string of length 2
in ASCII, you can do the following:

    void BinaryCharToTwoAsciiChars(unsigned char ch, unsigned char buf[2])
    {
        unsigned char hi_nibble = ch >> 4;
        unsigned char lo_nibble = ch & 0x0f;

        switch (hi_nibble & 0x0f)
        {
            case 0x0: buf[0] = '0'; break;
            case 0x1: buf[0] = '1'; break;
            case 0x2: buf[0] = '2'; break;
            ...
            case 0xe: buf[0] = 'e'; break;
            case 0xf: buf[0] = 'f'; break;
        }
        switch (lo_nibble & 0x0f)
        {
            case 0x0: buf[1] = '0'; break;
            case 0x1: buf[1] = '1'; break;
            case 0x2: buf[1] = '2'; break;
            ...
            case 0xe: buf[1] = 'e'; break;
            case 0xf: buf[1] = 'f'; break;
        }
    }
--
Bill Cheng // bill.cheng@usc.edu <URL:http://merlot.usc.edu/william/usc/>





  On Tue, Nov 25, 2008 at 11:11 PM, Bill Cheng <william@bourbon.usc.edu>wrote:
  > Someone wrote:
  >
  >  > While sending the delete msg we have the format
  >  >  FileName=foo
  >  >  SHA1=63de...
  >  >  Nonce=fcca...
  >  >  Password=bac9...
  >  >
  >  > So we have to store all values as characters .. correct ?
  >
  > ASCII characters.
  >
  >  > i.e the length of SHA1, Nonce and Password will be 40 bytes.
  >
  > 40 ASCII characters (which takes 40 bytes each to send).
  >
  >  > and the total data part length will be > 120.
  >
  > Yes.
  > --
  > Bill Cheng // bill.cheng@usc.edu <URL:http://merlot.usc.edu/william/usc/>