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/* LibTomCrypt, modular cryptographic library -- Tom St Denis
*
* LibTomCrypt is a library that provides various cryptographic
* algorithms in a highly modular and flexible manner.
*
* The library is free for all purposes without any express
* guarantee it works.
*
* Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.org
*/
#include "tomcrypt.h"
/**
@file base64_decode.c
Compliant base64 code donated by Wayne Scott (wscott@bitmover.com)
*/
#ifdef BASE64
static const unsigned char map[256] = {
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 62, 255, 255, 255, 63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 255, 255,
255, 254, 255, 255, 255, 0, 1, 2, 3, 4, 5, 6,
7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,
19, 20, 21, 22, 23, 24, 25, 255, 255, 255, 255, 255,
255, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36,
37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48,
49, 50, 51, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255 };
/**
base64 decode a block of memory
@param in The base64 data to decode
@param inlen The length of the base64 data
@param out [out] The destination of the binary decoded data
@param outlen [in/out] The max size and resulting size of the decoded data
@return CRYPT_OK if successful
*/
int base64_decode(const unsigned char *in, unsigned long inlen,
unsigned char *out, unsigned long *outlen)
{
unsigned long t, x, y, z;
unsigned char c;
int g;
LTC_ARGCHK(in != NULL);
LTC_ARGCHK(out != NULL);
LTC_ARGCHK(outlen != NULL);
g = 3;
for (x = y = z = t = 0; x < inlen; x++) {
c = map[in[x]&0xFF];
if (c == 255) continue;
/* the final = symbols are read and used to trim the remaining bytes */
if (c == 254) {
c = 0;
/* prevent g < 0 which would potentially allow an overflow later */
if (--g < 0) {
return CRYPT_INVALID_PACKET;
}
} else if (g != 3) {
/* we only allow = to be at the end */
return CRYPT_INVALID_PACKET;
}
t = (t<<6)|c;
if (++y == 4) {
if (z + g > *outlen) {
return CRYPT_BUFFER_OVERFLOW;
}
out[z++] = (unsigned char)((t>>16)&255);
if (g > 1) out[z++] = (unsigned char)((t>>8)&255);
if (g > 2) out[z++] = (unsigned char)(t&255);
y = t = 0;
}
}
if (y != 0) {
return CRYPT_INVALID_PACKET;
}
*outlen = z;
return CRYPT_OK;
}
#endif
/* $Source: /cvs/libtom/libtomcrypt/src/misc/base64/base64_decode.c,v $ */
/* $Revision: 1.3 $ */
/* $Date: 2005/05/05 14:35:59 $ */
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