NSString en / decode base64

Question

我试图使这些php函数的等价物在目标c中加密/解密但到目前为止没有运气。

我在obj-c中找不到任何base64_en / decode方法，有没有？

function encrypt($string, $key) {

    $result = '';

    for($i = 0; $i < strlen($string); $i++) {

        $char = substr($string, $i, 1);
        $keychar = substr($key, ($i % strlen($key))-1, 1);
        $char = chr(ord($char) + ord($keychar));
        $result .= $char;
    }

    return base64_encode($result);
}


function decrypt($string, $key) {

    $result = '';
    $string = base64_decode($string);

    for($i = 0; $i < strlen($string); $i++) {

        $char = substr($string, $i, 1);
        $keychar = substr($key, ($i % strlen($key))-1, 1);
        $char = chr(ord($char) - ord($keychar));
        $result.=$char;
    }

    return $result;
}

已经Ty！

Answer 1

查看我用于此任务的此类别，它是用于将字符串转换为md5，base64等的NSString类别...

https://gist.github.com/3907443

从NSString到NSData：

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

从NSData编码：

+ (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';

    // Return the results as an NSString object
    return [NSString stringWithCString:strResult encoding:NSASCIIStringEncoding];
}

解码：

+ (NSData *)decodeBase64WithString:(NSString *)strBase64 {
    const char * objPointer = [strBase64 cStringUsingEncoding:NSASCIIStringEncoding];
    int intLength = strlen(objPointer);
    int intCurrent;
    int i = 0, j = 0, k;

    unsigned 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;
}