base64.c

#import "base64.h"

static const char _base64EncodingTable[65] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
static const short _base64DecodingTable[256] = {
	-2, -2, -2, -2, -2, -2, -2, -2, -2, -1, -1, -2, -1, -1, -2, -2,
	-2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2,
	-1, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, 62, -2, -2, -2, 63,
	52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -2, -2, -2, -2, -2, -2,
	-2,  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, -2, -2, -2, -2, -2,
	-2, 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, -2, -2, -2, -2, -2,
	-2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2,
	-2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2,
	-2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2,
	-2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2,
	-2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2,
	-2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2,
	-2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2,
	-2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2
};

@implementation NSString (base64)

- (NSString *)encodeBase64;
{
	return [[self dataUsingEncoding:NSUTF8StringEncoding] encodeBase64];
}

- (NSData *)decodeBase64ToData;
{
	const char * objPointer = [self cStringUsingEncoding:NSASCIIStringEncoding];
	if (objPointer == NULL)  return nil;
	size_t intLength = strlen(objPointer);
	int intCurrent;
	int i = 0, j = 0, k;
    
	unsigned char * objResult = (unsigned char *)calloc(intLength, sizeof(unsigned char));
    
	// Run through the whole string, converting as we go
	while ( ((intCurrent = *objPointer++) != '\0') && (intLength-- > 0) ) {
		if (intCurrent == '=') {
			if (*objPointer != '=' && ((i % 4) == 1)) {// || (intLength > 0)) {
				// the padding character is invalid at this point -- so this entire string is invalid
				free(objResult);
                objResult=NULL;
				return nil;
			}
			continue;
		}
        
		intCurrent = _base64DecodingTable[intCurrent];
		if (intCurrent == -1) {
			// we're at a whitespace -- simply skip over
			continue;
		} else if (intCurrent == -2) {
			// we're at an invalid character
			free(objResult);
            objResult=NULL;
			return nil;
		}
        
		switch (i % 4) {
			case 0:
				objResult[j] = intCurrent << 2;
				break;
                
			case 1:
				objResult[j++] |= intCurrent >> 4;
				objResult[j] = (intCurrent & 0x0f) << 4;
				break;
                
			case 2:
				objResult[j++] |= intCurrent >>2;
				objResult[j] = (intCurrent & 0x03) << 6;
				break;
                
			case 3:
				objResult[j++] |= intCurrent;
				break;
		}
		i++;
	}
    
	// mop things up if we ended on a boundary
	k = j;
	if (intCurrent == '=') {
		switch (i % 4) {
			case 1:
				// Invalid state
				free(objResult);
                objResult=NULL;
				return nil;
                
			case 2:
				k++;
				// flow through
			case 3:
				objResult[k] = 0;
		}
	}
    
#if  __has_feature(objc_arc)
	return [[NSData alloc] initWithBytesNoCopy:objResult length:j freeWhenDone:YES];
#else
	return [[[NSData alloc] initWithBytesNoCopy:objResult length:j freeWhenDone:YES] autorelease];
#endif
    
}

- (NSString *)decodeBase64ToString;
{
    NSData *d=[self decodeBase64ToData];
    return [NSString stringWithUTF8String:[d bytes]];
}

@end


@implementation NSData (base64)

- (NSString *)encodeBase64;
{
	const unsigned char * objRawData = [self bytes];
	char * objPointer;
	char * strResult;
    
	// Get the Raw Data length and ensure we actually have data
	size_t intLength = [self length];
	if (intLength == 0) return nil;
    
	// Setup the String-based Result placeholder and pointer within that placeholder
	strResult = (char *)calloc(((intLength + 2) / 3) * 4, sizeof(char));
	objPointer = strResult;
	
	// Iterate through everything
	while (intLength > 2) { // keep going until we have less than 24 bits
		*objPointer++ = _base64EncodingTable[objRawData[0] >> 2];
		*objPointer++ = _base64EncodingTable[((objRawData[0] & 0x03) << 4) + (objRawData[1] >> 4)];
		*objPointer++ = _base64EncodingTable[((objRawData[1] & 0x0f) << 2) + (objRawData[2] >> 6)];
		*objPointer++ = _base64EncodingTable[objRawData[2] & 0x3f];
		
		// we just handled 3 octets (24 bits) of data
		objRawData += 3;
		intLength -= 3; 
	}
    
	// now deal with the tail end of things
	if (intLength != 0) {
		*objPointer++ = _base64EncodingTable[objRawData[0] >> 2];
		if (intLength > 1) {
			*objPointer++ = _base64EncodingTable[((objRawData[0] & 0x03) << 4) + (objRawData[1] >> 4)];
			*objPointer++ = _base64EncodingTable[(objRawData[1] & 0x0f) << 2];
			*objPointer++ = '=';
		} else {
			*objPointer++ = _base64EncodingTable[(objRawData[0] & 0x03) << 4];
			*objPointer++ = '=';
			*objPointer++ = '=';
		}
	}
	
	NSString *strToReturn = [[NSString alloc] initWithBytesNoCopy:strResult length:objPointer - strResult encoding:NSASCIIStringEncoding freeWhenDone:YES];
    
#if  __has_feature(objc_arc)
	return strToReturn;
#else
	return [strToReturn autorelease];
#endif

}

@end


const char *b64_encode(const unsigned char *bytes, int length)
{
    const unsigned char *objRawData = bytes;
	char * objPointer;
	char * strResult;
    
	// Get the Raw Data length and ensure we actually have data
	size_t intLength = length;
	if (intLength == 0) return "";
    
	// Setup the String-based Result placeholder and pointer within that placeholder
	strResult = (char *)calloc(((intLength + 2) / 3) * 4 + 1 , sizeof(char));
	objPointer = strResult;
    memset(strResult, 0, (((intLength + 2) / 3) * 4 + 1) * sizeof(char) );
	
	// Iterate through everything
	while (intLength > 2) { // keep going until we have less than 24 bits
		*objPointer++ = _base64EncodingTable[objRawData[0] >> 2];
		*objPointer++ = _base64EncodingTable[((objRawData[0] & 0x03) << 4) + (objRawData[1] >> 4)];
		*objPointer++ = _base64EncodingTable[((objRawData[1] & 0x0f) << 2) + (objRawData[2] >> 6)];
		*objPointer++ = _base64EncodingTable[objRawData[2] & 0x3f];
		
		// we just handled 3 octets (24 bits) of data
		objRawData += 3;
		intLength -= 3;
	}
    
	// now deal with the tail end of things
	if (intLength != 0) {
		*objPointer++ = _base64EncodingTable[objRawData[0] >> 2];
		if (intLength > 1) {
			*objPointer++ = _base64EncodingTable[((objRawData[0] & 0x03) << 4) + (objRawData[1] >> 4)];
			*objPointer++ = _base64EncodingTable[(objRawData[1] & 0x0f) << 2];
			*objPointer++ = '=';
		} else {
			*objPointer++ = _base64EncodingTable[(objRawData[0] & 0x03) << 4];
			*objPointer++ = '=';
			*objPointer++ = '=';
		}
	}
    //strResult[objPointer - strResult]=0;
	return strResult;
}

base64.h

@interface NSString (base64)
- (NSString *)encodeBase64;
- (NSData *)decodeBase64ToData;
- (NSString *)decodeBase64ToString;
@end

@interface NSData (base64)
- (NSString *)encodeBase64;
@end


#ifdef __cplusplus
extern "C" {
#endif
    
    const char *b64_encode(const unsigned char *bytes, int length);
    
#ifdef __cplusplus
}
#endif