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admin 发表于 2022-5-12 20:24:34

base64算法

#include"base64.h"

const char * base64char = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

char * base64_encode( unsigned char * bindata, char * base64, int binlength )
{
    int i, j;
    unsigned char current;

    for ( i = 0, j = 0 ; i < binlength ; i += 3 )
    {
      current = (bindata >> 2) ;
      current &= (unsigned char)0x3F;
      base64 = base64char[(int)current];

      current = ( (unsigned char)(bindata << 4 ) ) & ( (unsigned char)0x30 ) ;
      if ( i + 1 >= binlength )
      {
            base64 = base64char[(int)current];
            base64 = '=';
            base64 = '=';
            break;
      }
      current |= ( (unsigned char)(bindata >> 4) ) & ( (unsigned char) 0x0F );
      base64 = base64char[(int)current];

      current = ( (unsigned char)(bindata << 2) ) & ( (unsigned char)0x3C ) ;
      if ( i + 2 >= binlength )
      {
            base64 = base64char[(int)current];
            base64 = '=';
            break;
      }
      current |= ( (unsigned char)(bindata >> 6) ) & ( (unsigned char) 0x03 );
      base64 = base64char[(int)current];

      current = ( (unsigned char)bindata ) & ( (unsigned char)0x3F ) ;
      base64 = base64char[(int)current];
    }
    base64 = '\0';
    return base64;
}

int base64_decode(char * base64, unsigned char * bindata )
{
    int i, j;
    unsigned char k;
    unsigned char temp;
    for ( i = 0, j = 0; base64 != '\0' ; i += 4 )
    {
      memset( temp, 0xFF, sizeof(temp) );
      for ( k = 0 ; k < 64 ; k ++ )
      {
            if ( base64char == base64 )
                temp= k;
      }
      for ( k = 0 ; k < 64 ; k ++ )
      {
            if ( base64char == base64 )
                temp= k;
      }
      for ( k = 0 ; k < 64 ; k ++ )
      {
            if ( base64char == base64 )
                temp= k;
      }
      for ( k = 0 ; k < 64 ; k ++ )
      {
            if ( base64char == base64 )
                temp= k;
      }

      bindata = ((unsigned char)(((unsigned char)(temp << 2))&0xFC)) |
                ((unsigned char)((unsigned char)(temp>>4)&0x03));
      if ( base64 == '=' )
            break;

      bindata = ((unsigned char)(((unsigned char)(temp << 4))&0xF0)) |
                ((unsigned char)((unsigned char)(temp>>2)&0x0F));
      if ( base64 == '=' )
            break;

      bindata = ((unsigned char)(((unsigned char)(temp << 6))&0xF0)) |
                ((unsigned char)(temp&0x3F));
    }
    return j;
}

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