En Fri, 28 Mar 2008 13:22:06 -0300, Clodoaldo <[EMAIL PROTECTED]> escribió: > On Mar 28, 12:09 pm, "Gabriel Genellina" <[EMAIL PROTECTED]> wrote: >> En Fri, 28 Mar 2008 10:54:49 -0300, Clodoaldo >> <[EMAIL PROTECTED]> escribió: >> >> > What i need to know is where can an equal char appear in a >> > urlsafe_b64encoded string?: >> >> > a)only at end; >> > b)both at the end and at the begginig; >> > c)anywhere in the string; >> >> > A sure answer will make my regexp safer. >> >> Only at the end. The encoded string has 4*n chars when the input string >> has 3*n chars; when the input length is 3*n+1 or 3*n+2, the output has >> 4*(n+1) chars right padded with 2 or 1 "=" chars. >> If your input has 3n chars, the output won't have any "=" > > Thanks. But I'm not sure i get it. What is n?
(Any nonnegative integer...) I mean: For base64 encoding, the length of the output depends solely of the length of the input. If the input string length is a multiple of 3, the output length is a multiple of 4, with no "=". If the input length is one more than a multiple of 3, the output has two "==" at the end. If the input length is two more than a multiple of 3, the output has only one "=" at the end. In all cases, the output length is a multiple of 4. [base64 uses 64=2**6 characters so it encodes 6 bits per character; to encode 3 bytes=3*8=24 bits one requires 24/6=4 characters] > A md5 digest will always be 16 bytes length. So if i understand it > correctly (not sure) the output will always be 22 chars plus two > trailing equal chars. Right? Exactly. -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
