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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.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;
}
不过上面的代码也有问题,比如数据长度什么的还是用 size_t 类型比较好。
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[ 本帖最后由 langue 于 2007-2-5 10:39 编辑 ] |
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