annotate base64_encode.c @ 15:6362d3854bb4 libtomcrypt-orig

0.96 release of LibTomCrypt
author Matt Johnston <matt@ucc.asn.au>
date Tue, 15 Jun 2004 14:07:21 +0000
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1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
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2 *
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3 * LibTomCrypt is a library that provides various cryptographic
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4 * algorithms in a highly modular and flexible manner.
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5 *
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6 * The library is free for all purposes without any express
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7 * guarantee it works.
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8 *
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9 * Tom St Denis, [email protected], http://libtomcrypt.org
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10 */
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11 /* compliant base64 code donated by Wayne Scott ([email protected]) */
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12 #include "mycrypt.h"
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13
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14 #ifdef BASE64
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15
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16 static const char *codes =
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17 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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18
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19 int base64_encode(const unsigned char *in, unsigned long len,
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20 unsigned char *out, unsigned long *outlen)
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21 {
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22 unsigned long i, len2, leven;
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23 unsigned char *p;
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24
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25 _ARGCHK(in != NULL);
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26 _ARGCHK(out != NULL);
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27 _ARGCHK(outlen != NULL);
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28
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29 /* valid output size ? */
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30 len2 = 4 * ((len + 2) / 3);
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31 if (*outlen < len2 + 1) {
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32 return CRYPT_BUFFER_OVERFLOW;
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33 }
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34 p = out;
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35 leven = 3*(len / 3);
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36 for (i = 0; i < leven; i += 3) {
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37 *p++ = codes[(in[0] >> 2) & 0x3F];
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38 *p++ = codes[(((in[0] & 3) << 4) + (in[1] >> 4)) & 0x3F];
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39 *p++ = codes[(((in[1] & 0xf) << 2) + (in[2] >> 6)) & 0x3F];
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40 *p++ = codes[in[2] & 0x3F];
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41 in += 3;
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42 }
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43 /* Pad it if necessary... */
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44 if (i < len) {
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45 unsigned a = in[0];
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46 unsigned b = (i+1 < len) ? in[1] : 0;
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47
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48 *p++ = codes[(a >> 2) & 0x3F];
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49 *p++ = codes[(((a & 3) << 4) + (b >> 4)) & 0x3F];
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50 *p++ = (i+1 < len) ? codes[(((b & 0xf) << 2)) & 0x3F] : '=';
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51 *p++ = '=';
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52 }
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53
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54 /* append a NULL byte */
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55 *p = '\0';
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56
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57 /* return ok */
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58 *outlen = p - out;
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59 return CRYPT_OK;
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60 }
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61
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62 #endif
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63