base64 encoding

Hello,
has anyone the idea, how to do base64 encoding of the short string? I need it to encode the e-mail username and password...

I would take your input array of bytes and using a simple loop, create an array of bits.

Then using a second loop, read those bits 6 at a time and use a combination of math and a lookup table to generate the output.

The wikipedia article on Base64 has a lot of useful info, including C code for encoding and decoding:

http://en.wikipedia.org/wiki/Base64

Was bored, so I figured i would give this a shot.

Untested, so try at your own risk :)

Code:

STRING_LENGTH CON 24 ; Must be divisable by 3 in_string VAR BYTE[STRING_LENGTH] in_byte VAR BYTE in_bit VAR BYTE b64_string VAR BYTE[STRING_LENGTH*4/3] b64_byte VAR BYTE b64_bit VAR BYTE temp VAR BYTE in_byte=0 ; Start at byte 0 in_bit=7 ; Most significant bit first FOR b64_byte=0 TO (STRING_LENGTH*4/3)-1 ; For each base64 byte: b64_string[b64_byte]=0 ; Clear the byte FOR b64_bit=5 TO 0 STEP -1 ; For each bit 5 thru 0: temp=in_string[in_byte] ; Get the current input byte temp=temp >> in_bit ; Shift to get the current bit as bit 0 temp=temp & 1 ; Clear the other bits temp=temp << b64_bit ; Shift to the correct output bit position b64_string[b64_byte]=temp|b64_string[b64_byte] ; Add the bit to the base64 byte in_bit=in_bit-1 ; Next less significant bit IF in_bit=255 THEN ; If we past bit 0: in_bit=7 ; Set to bit 7 of the next byte in_byte=in_byte+1 ENDIF NEXT b64_bit SELECT CASE b64_string[b64_byte] ; Convert to base64 coded ASCII CASE IS<=25 ; 0-25 b64_string[b64_byte]=b64_string[b64_byte]+65; "A"-"Z" CASE IS<=51 ; 26-51 b64_string[b64_byte]=b64_string[b64_byte]+71; "a"-"z" CASE IS<=61 ; 52-61 b64_string[b64_byte]=b64_string[b64_byte]-4 ; "0"-"9" CASE 62 ; 62 b64_string[b64_byte]=43 ; "+" CASE 63 ; 63 b64_string[b64_byte]=47 ; "/" END SELECT NEXT b64_byte

Boban, which PIC you plan to use?

Who's interested to participate to a "convenient and ease of use routine" contest ? Just for fun though...

No one? ;)

i had a 1/2 hour to kill so i did this one. No matter if your string is dividable by three or not, the software will adjust it. I've compare my results with the following online converter tool

http://makcoder.sourceforge.net/demo/base64.php

Everything seems ok. Personnal and deliberate decision from myself to remove the comments... oh i'm a monster :D

You just need to figure out ;)

This assume your PIC have a 256 bytes EEPROM. I used a dusty F877

Code:

 @ __CONFIG _HS_OSC & _LVP_OFF & _WDT_OFF DEFINE OSC 20 DEFINE HSER_RCSTA 90h ' Enable serial port & continuous receive DEFINE HSER_TXSTA 24h ' Enable transmit, BRGH = 1 DEFINE HSER_SPBRG 129 ' 9600 Baud @ 20MHz, 0.16% DEFINE HSER_CLROERR 1 ' Clear overflow automatically Len VAR BYTE ByteA VAR BYTE buffer VAR BYTE[3] Encoded VAR BYTE[4] EncodedCounter VAR BYTE CounterA VAR BYTE CounterB VAR BYTE String1 DATA "Man is distinguished, not only by his reason, but by this singular passion ";from other animals, which is a lust of the mind, that by a perseverance of delight in the continued and indefatigable generation of knowledge, exceeds the short vehemence of any carnal pleasure." String2 DATA 0 BASE64Table DATA @191, "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=" Len = String2 - String1 IF (Len//3) THEN ByteA=3-(Len//3) FOR CounterA=0 TO (ByteA-1) WRITE (Len+CounterA),0 NEXT Len=Len+ByteA ENDIF HSEROUT ["Len=",DEC Len,13,10,_ "Original string",13,10] FOR CounterA=0 TO (Len-1) READ CounterA,ByteA IF ByteA THEN HSEROUT [ByteA] ENDIF NEXT HSEROUT [13,10, "Encoded String",13,10] EncodedCounter=0 FOR CounterA=0 TO (Len-3) STEP 3 READ CounterA, buffer[0] READ (CounterA+1), buffer[1] READ (CounterA+2), buffer[2] Encoded[0]=buffer[0]>>2 Encoded[1]=((buffer[0]&3) <<4) | (buffer[1]>>4) IF buffer[1] THEN Encoded[2]=((buffer[1]&$0F)<<2) | (buffer[2]>>6) ELSE Encoded[2]=64 ENDIF IF buffer[2] THEN Encoded[3]=buffer[2] & %00111111 ELSE Encoded[3]=64 ENDIF EncodedCounter=EncodedCounter+4 FOR CounterB=0 TO 3 READ (Base64Table+Encoded[CounterB]),ByteA HSEROUT [ByteA] NEXT NEXT STOP END 

There's load of room for improvement. At least it works!

There's still the "convenient" part to do... if really needed and asked.

Touché

:)

Quote:

Originally Posted by mister_e

Personnal and deliberate decision from myself to remove the comments.

Do you mean:

Quote:

Personal and deliberate decision from myself to be lazy and not write any comments in the first place.

:P

mmm time saving... maybe true ;)

Sorry for the late response

Cus, I am very soory for the too late delay, I have a lot personal stuff to do and didn't had time for the playing.I see, that you have spent a lot of time to do it, it is nice inspiration for me to use your code. Thans a lot - it is both of you!!!