base64编码

const BaseTable:string='ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
　
function FindInTable(CSource:char):integer;
begin
result:=Pos(string(CSource),BaseTable)-1;
end;
////
function DecodeBase64(Source:string):string; //base64 编码
var
SrcLen,Times,i:integer;
x1,x2,x3,x4,xt:byte;
begin
result:='';
SrcLen:=Length(Source);
Times:=SrcLen div 4;
for i:=0 to Times-1 do
begin
x1:=FindInTable(Source[1+i*4]);
x2:=FindInTable(Source[2+i*4]);
x3:=FindInTable(Source[3+i*4]);
x4:=FindInTable(Source[4+i*4]);
x1:=x1 shl 2;
xt:=x2 shr 4;
x1:=x1 or xt;
x2:=x2 shl 4;
result:=result+chr(x1);
if x3= 64 then break;
xt:=x3 shr 2;
x2:=x2 or xt;
x3:=x3 shl 6;
result:=result+chr(x2);
if x4=64 then break;
x3:=x3 or x4;
result:=result+chr(x3);
end;
end;
/////
function EncodeBase64(Source:string):string; //base64 解码
var
Times,LenSrc,i:integer;
x1,x2,x3,x4:char;
xt:byte;
begin
result:='';
LenSrc:=length(Source);
if LenSrc mod 3 =0 then Times:=LenSrc div 3
else Times:=LenSrc div 3 + 1;
for i:=0 to times-1 do
begin
if LenSrc >= (3+i*3) then
begin
x1:=BaseTable[(ord(Source[1+i*3]) shr 2)+1];
xt:=(ord(Source[1+i*3]) shl 4) and 48;
xt:=xt or (ord(Source[2+i*3]) shr 4);
x2:=BaseTable[xt+1];
xt:=(Ord(Source[2+i*3]) shl 2) and 60;
xt:=xt or (ord(Source[3+i*3]) shr 6);
x3:=BaseTable[xt+1];
xt:=(ord(Source[3+i*3]) and 63);
x4:=BaseTable[xt+1];
end
else if LenSrc>=(2+i*3) then
begin
x1:=BaseTable[(ord(Source[1+i*3]) shr 2)+1];
xt:=(ord(Source[1+i*3]) shl 4) and 48;
xt:=xt or (ord(Source[2+i*3]) shr 4);
x2:=BaseTable[xt+1];
xt:=(ord(Source[2+i*3]) shl 2) and 60;
x3:=BaseTable[xt+1];
x4:='=';
end else
begin
x1:=BaseTable[(ord(Source[1+i*3]) shr 2)+1];
xt:=(ord(Source[1+i*3]) shl 4) and 48;
x2:=BaseTable[xt+1];
x3:='=';
x4:='=';
end;
result:=result+x1+x2+x3+x4;
end;
end;
*********************************
unsigned char *base64_encode(const char *str,int length,int *ret_lengt
h)
{
static char base64_table[] =
{ 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L',
'M',
'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y',
'Z',
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l',
'm',
'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y',
'z',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/',
'0'
};
static char base64_pad = '=';
//const char *current = str;
unsigned const char *current = (unsigned const char*)str;
int i = 0;
unsigned char *result = (unsigned char *)malloc(((length + 3 - lengt
h % 3) * 4 / 3 + 1) * sizeof(char));
while (length > 2) { /* keep going until we have less than 24 bits *
/
/
result[i++] = base64_table[current[0] >> 2];
result[i++] = base64_table[((current[0] & 0x03) << 4) + (current[1
] >> 4)];
result[i++] = base64_table[((current[1] & 0x0f) << 2) + (current[2
] >> 6)];
result[i++] = base64_table[current[2] & 0x3f];
current += 3;
length -= 3; /* we just handle 3 octets of data */
}
/* now deal with the tail end of things */
if (length != 0) {
result[i++] = base64_table[current[0] >> 2];
if (length > 1) {
result[i++] = base64_table[((current[0] & 0x03 ) << 4) + (curren
t[1] >> 4)];
result[i++] = base64_table[(current[1] & 0x0f) << 2];
result[i++] = base64_pad;
}
else {
result[i++] = base64_table[(current[0] & 0x03) << 4];
result[i++] = base64_pad;
result[i++] = base64_pad;
}
}
if(ret_length) {
*ret_length = i;
}
result = '0'; // printf("%s",result);
return result;
}