#import "BHBase64EncoderDecoder.h"

@implementation BHBase64EncoderDecoder

+ (NSString *)base64Encode:(NSData *)inData {

static char base64EncodingTable[64] = {

'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', '+', '/'

};

int length = (int)[inData length];

unsigned long ixtext, lentext;

long ctremaining;

unsigned char input[3], output[4];

short i, charsonline = 0, ctcopy;

const unsigned char *raw;

NSMutableString *result;

lentext = [inData length];

if (lentext < 1)

return @"";

result = [NSMutableString stringWithCapacity: lentext];

raw = [inData bytes];

ixtext = 0;

while (true) {

ctremaining = lentext - ixtext;

if (ctremaining <= 0)

break;

for (i = 0; i < 3; i++) {

unsigned long ix = ixtext + i;

if (ix < lentext)

input[i] = raw[ix];

else

input[i] = 0;

}

output[0] = (input[0] & 0xFC) >> 2;

output[1] = ((input[0] & 0x03) << 4) | ((input[1] & 0xF0) >> 4);

output[2] = ((input[1] & 0x0F) << 2) | ((input[2] & 0xC0) >> 6);

output[3] = input[2] & 0x3F;

ctcopy = 4;

switch (ctremaining) {

case 1:

ctcopy = 2;

break;

case 2:

ctcopy = 3;

break;

}

for (i = 0; i < ctcopy; i++)

[result appendString: [NSString stringWithFormat: @"%c", base64EncodingTable[output[i]]]];

for (i = ctcopy; i < 4; i++)

[result appendString: @"="];

ixtext += 3;

charsonline += 4;

if ((length > 0) && (charsonline >= length))

charsonline = 0;

}

return result;

}

+ (NSData*) base64Decode:(NSString *)inString {

unsigned long ixtext, lentext;

unsigned char ch, inbuf[4], outbuf[4];

short i, ixinbuf;

Boolean flignore, flendtext = false;

const unsigned char *tempcstring;

NSMutableData *theData;

if (inString == nil) {

return [NSData data];//输入为空，返回空数据

}

ixtext = 0;

tempcstring = (const unsigned char *)[inString UTF8String];

lentext = [inString length];

theData = [NSMutableData dataWithCapacity: lentext];

ixinbuf = 0;

while (true) {

if (ixtext >= lentext){

break;

}

ch = tempcstring [ixtext++];

flignore = false;

if ((ch >= 'A') && (ch <= 'Z')) {

ch = ch - 'A';

} else if ((ch >= 'a') && (ch <= 'z')) {

ch = ch - 'a' + 26;

} else if ((ch >= '0') && (ch <= '9')) {

ch = ch - '0' + 52;

} else if (ch == '+') {

ch = 62;

} else if (ch == '=') {

flendtext = true;

} else if (ch == '/') {

ch = 63;

} else {

flignore = true;

}

if (!flignore) {

short ctcharsinbuf = 3;

Boolean flbreak = false;

if (flendtext) {

if (ixinbuf == 0) {

break;

}

if ((ixinbuf == 1) || (ixinbuf == 2)) {

ctcharsinbuf = 1;

} else {

ctcharsinbuf = 2;

}

ixinbuf = 3;

flbreak = true;

}

inbuf [ixinbuf++] = ch;

if (ixinbuf == 4) {

ixinbuf = 0;

outbuf[0] = (inbuf[0] << 2) | ((inbuf[1] & 0x30) >> 4);

outbuf[1] = ((inbuf[1] & 0x0F) << 4) | ((inbuf[2] & 0x3C) >> 2);

outbuf[2] = ((inbuf[2] & 0x03) << 6) | (inbuf[3] & 0x3F);

for (i = 0; i < ctcharsinbuf; i++) {

[theData appendBytes: &outbuf[i] length: 1];

}

}

if (flbreak) {

break;

}

}

}

return theData;

}

+ (NSString*) customEncode:(NSData *)inData

{

NSInteger len = [inData length];

NSMutableData *xdata = [[NSMutableData alloc] init];

for (NSInteger i=0; i<len; i++) {

uint8_t xt;

[inData getBytes:(void*)(&xt) range:NSMakeRange(i, 1)];

xt = ~xt+0x33;

[xdata appendBytes:(void*)(&xt) length:1];

}//原数据取反加0x33

return [self base64Encode:xdata];

}

+ (NSData*) customDecode:(NSData *)inData

{

NSString *string = [[NSString alloc] initWithData:inData encoding:NSUTF8StringEncoding];//转成字符串

NSData *theData = [NSData dataWithData:[self base64Decode:string]];

NSInteger len = [theData length];

NSMutableData *xdata = [[NSMutableData alloc] init];

for (NSInteger i=0; i<len; i++) {

uint8_t xt;

[theData getBytes:(void*)(&xt) range:NSMakeRange(i, 1)];

xt = ~(xt-0x33);

[xdata appendBytes:(void*)(&xt) length:1];

}//结果数据减0x33再取反

return xdata;

}