C BASE64編解碼函數(shù)

langue

--

通常是把預(yù)先計算好的 tab 放到全局數(shù)組里，這個叫 pre-computation

--

01072541

int main()
{
        char *p,*q;
        p="xygyqwg";
        char en[20],de[20];
        printf(encode(p,&en));
        printf("\n");
        q=en;
        printf(decode(q,&de));
        printf("\n");
        printf("end");
}
我這樣可以嗎？？編碼好像可以，就是不能解碼？不知道為什么

langue

/* 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.com
*/

#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <assert.h>

int base64_encode(const unsigned char *,  unsigned long,
                        unsigned char *, unsigned long *);

int base64_decode(const unsigned char *,  unsigned long,
                        unsigned char *, unsigned long *);

static const char *codes =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

/* error codes [will be expanded in future releases] */
enum {
   CRYPT_OK=0,             /* Result OK */
   CRYPT_ERROR,            /* Generic Error */
   CRYPT_NOP,              /* Not a failure but no operation was performed */

   CRYPT_INVALID_KEYSIZE,  /* Invalid key size given */
   CRYPT_INVALID_ROUNDS,   /* Invalid number of rounds */
   CRYPT_FAIL_TESTVECTOR,  /* Algorithm failed test vectors */

   CRYPT_BUFFER_OVERFLOW,  /* Not enough space for output */
   CRYPT_INVALID_PACKET,   /* Invalid input packet given */

   CRYPT_INVALID_PRNGSIZE, /* Invalid number of bits for a PRNG */
   CRYPT_ERROR_READPRNG,   /* Could not read enough from PRNG */

   CRYPT_INVALID_CIPHER,   /* Invalid cipher specified */
   CRYPT_INVALID_HASH,     /* Invalid hash specified */
   CRYPT_INVALID_PRNG,     /* Invalid PRNG specified */

   CRYPT_MEM,              /* Out of memory */

   CRYPT_PK_TYPE_MISMATCH, /* Not equivalent types of PK keys */
   CRYPT_PK_NOT_PRIVATE,   /* Requires a private PK key */

   CRYPT_INVALID_ARG,      /* Generic invalid argument */
   CRYPT_FILE_NOTFOUND,    /* File Not Found */

   CRYPT_PK_INVALID_TYPE,  /* Invalid type of PK key */
   CRYPT_PK_INVALID_SYSTEM,/* Invalid PK system specified */
   CRYPT_PK_DUP,           /* Duplicate key already in key ring */
   CRYPT_PK_NOT_FOUND,     /* Key not found in keyring */
   CRYPT_PK_INVALID_SIZE,  /* Invalid size input for PK parameters */

   CRYPT_INVALID_PRIME_SIZE,/* Invalid size of prime requested */
   CRYPT_PK_INVALID_PADDING /* Invalid padding on input */
};

#define LTC_ARGCHK(x) assert(x)

/**
   base64 Encode a buffer (NUL terminated)
   @param in      The input buffer to encode
   @param inlen   The length of the input buffer
   @param out     [out] The destination of the base64 encoded data
   @param outlen  [in/out] The max size and resulting size
   @return CRYPT_OK if successful
*/
int base64_encode(const unsigned char *in,  unsigned long inlen,
                        unsigned char *out, unsigned long *outlen)
{
   unsigned long i, len2, leven;
   unsigned char *p;

   LTC_ARGCHK(in     != NULL);
   LTC_ARGCHK(out    != NULL);
   LTC_ARGCHK(outlen != NULL);

   /* valid output size ? */
   len2 = 4 * ((inlen + 2) / 3);
   if (*outlen < len2 + 1) {
      *outlen = len2 + 1;
      return CRYPT_BUFFER_OVERFLOW;
   }
   p = out;
   leven = 3*(inlen / 3);
   for (i = 0; i < leven; i += 3) {
       *p++ = codes[(in[0] >> 2) & 0x3F];
       *p++ = codes[(((in[0] & 3) << 4) + (in[1] >> 4)) & 0x3F];
       *p++ = codes[(((in[1] & 0xf) << 2) + (in[2] >> 6)) & 0x3F];
       *p++ = codes[in[2] & 0x3F];
       in += 3;
   }
   /* Pad it if necessary...  */
   if (i < inlen) {
       unsigned a = in[0];
       unsigned b = (i+1 < inlen) ? in[1] : 0;

       *p++ = codes[(a >> 2) & 0x3F];
       *p++ = codes[(((a & 3) << 4) + (b >> 4)) & 0x3F];
       *p++ = (i+1 < inlen) ? codes[(((b & 0xf) << 2)) & 0x3F] : '=';
       *p++ = '=';
   }

   /* append a NULL byte */
   *p = '\0';

   /* return ok */
   *outlen = p - out;
   return CRYPT_OK;
}

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;
}

不過上面的代碼也有問題，比如數(shù)據(jù)長度什么的還是用 size_t 類型比較好。

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[ 本帖最后由 langue 于 2007-2-5 10:39 編輯 ]

熊貓燒香

echo "blablabla"| openssl base64 -e(-d)
不行么？

langue

--

openssl enc -a -(e|d) 也可以。

--

熊貓燒香

我記的沒錯的話perl里面也應(yīng)該有相應(yīng)的模塊吧，不用自己動手編的。

lovesaka

原帖由 思一克 于 2007-2-5 10:08 發(fā)表
decode函數(shù)中是每次都填BASE表？

呵呵那肯定是要填的不然手功輸入那么多字符太不現(xiàn)實了,而且這字符大多數(shù)都分開的搞不好掉一兩個那就很麻煩
開始寫的時候也用的是全局變量,結(jié)果中間掉了三個字符RST最后結(jié)果老是不對勁調(diào)試了半個多少時后來數(shù)編碼表才發(fā)現(xiàn)少了幾個字符

回復(fù)01072541 (飛冰)
但是我就一個字符串啊就一個參數(shù)
這函數(shù)需要有2個參數(shù)傳入啊
int main()
{
        char *p,*q;
        p="xygyqwg";
        char en[20],de[20];
        printf(encode(p,&en));
        printf("\n");
        q=en;
        printf(decode(q,&de));
        printf("\n");
        printf("end");
}

呵呵為了更加方便你只需定義一個指針把指針的地址傳給函數(shù)的第二個參數(shù)就行了
它會為你分配解碼后存放字符串的內(nèi)存
你應(yīng)該這樣寫

1. 
   
2. int main()
   
3. {
   
4. char *p="xygyqwg";
   
5. char *en,*de;
   
6. printf("[%s]=[%s]\n",p,encode(p,&en));      
   
7. printf("[%s]=[%s]\n",en,decode(en,&de));
   
8. /*在后面用完后釋放內(nèi)存就行了*/
   
9. }
   
10. 結(jié)果應(yīng)該是這樣的
    
11. minuit@SuSe:~> ./a.out
    
12. [xygyqwg]=[eHlneXF3Zw==]
    
13. [eHlneXF3Zw==]=[xygyqwg]
    
14. minuit@SuSe:~>
    

復(fù)制代碼

我想這樣子會更好用些.
最后多謝版主加精^_^

lovesaka

原帖由 思一克 于 2007-2-5 10:08 發(fā)表
decode函數(shù)中是每次都填BASE表？

你的意思應(yīng)該是這樣子吧
看來開始把你的意思想錯了^_^

ilovegjy

這個程序有問題！編碼不正確

net_robber

http://www.google.com/codesearch ... 2%E4%BB%A3%E7%A0%81

總有一個適合你的