NSString Crypto category

NSString+Crypto.h

#import <Foundation/Foundation.h>
#import <CommonCrypto/CommonHMAC.h>

@interface NSString (Crypto)

- (NSString *)md5;
+ (NSString *)encodeBase64WithString:(NSString *)strData;
+ (NSString *)encodeBase64WithData:(NSData *)objData;
+ (NSData *)decodeBase64WithString:(NSString *)strBase64;
- (NSString*)sha1;
- (NSString*)base64;

@end

NSString+Crypto.m

#import "NSString+Crypto.h"

@implementation NSString (Crypto)

- (NSString *) md5
{
    const char *cStr = [self UTF8String];
    unsigned char result[16];
    CC_MD5( cStr, strlen(cStr), result ); // This is the md5 call
    return [NSString stringWithFormat:
            @"%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x",
            result[0], result[1], result[2], result[3], 
            result[4], result[5], result[6], result[7],
            result[8], result[9], result[10], result[11],
            result[12], result[13], result[14], result[15]
            ];  
}

-(NSString*)sha1{
    const char *cstr = [self cStringUsingEncoding:NSUTF8StringEncoding];
    NSData *data = [NSData dataWithBytes:cstr length:self.length];
    
    uint8_t digest[CC_SHA1_DIGEST_LENGTH];
    
    CC_SHA1(data.bytes, data.length, digest);
    
    NSMutableString* output = [NSMutableString stringWithCapacity:CC_SHA1_DIGEST_LENGTH * 2];
    
    for(int i = 0; i < CC_SHA1_DIGEST_LENGTH; i++)
        [output appendFormat:@"%02x", digest[i]];
    
    
    return output;

}

-(NSString*)base64{
    return [NSString encodeBase64WithString:self];
}

static const char _base64EncodingTable[64] = "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
};


+ (NSString *)encodeBase64WithString:(NSString *)strData {
    return [NSString encodeBase64WithData:[strData dataUsingEncoding:NSUTF8StringEncoding]];
}

+ (NSString *)encodeBase64WithData:(NSData *)objData {
    const unsigned char * objRawData = [objData bytes];
    char * objPointer;
    char * strResult;
    
    // Get the Raw Data length and ensure we actually have data
    int intLength = [objData 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++ = '=';
        }
    }
    
    // Terminate the string-based result
    *objPointer = '\0';
    
    NSString *resultString = [NSString stringWithCString:strResult encoding:NSASCIIStringEncoding];
    
    free(strResult);
    
    // Return the results as an NSString object
    return resultString;
}

+ (NSData *)decodeBase64WithString:(NSString *)strBase64 {
    const char * objPointer = [strBase64 cStringUsingEncoding:NSASCIIStringEncoding];
    int intLength = strlen(objPointer);
    int intCurrent;
    int i = 0, j = 0, k;
    
    char * objResult;
    objResult = calloc(intLength, sizeof(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);
                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);
            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);
                return nil;
                
            case 2:
                k++;
                // flow through
            case 3:
                objResult[k] = 0;
        }
    }
    
    // Cleanup and setup the return NSData
    NSData * objData = [[[NSData alloc] initWithBytes:objResult length:j] autorelease];
    free(objResult);
    return objData;
}


@end