6

我正在尝试实现 Apple 发布的新VerificationController.m类，以解决应用内购买欺诈问题。

作为 Apple 发布的所有内容，这是一份更加模糊、不完整和糟糕的解释文档，其中包含许多无法被所有人规避/理解的空白和未知数。

我正在尝试实现它，但在代码末尾我们看到这四种方法：

- (NSString *)encodeBase64:(const uint8_t *)input length:(NSInteger)length
{
#warning Replace this method.
    return nil;
}

- (NSString *)decodeBase64:(NSString *)input length:(NSInteger *)length
{
#warning Replace this method.
    return nil;
}

#warning Implement this function.
char* base64_encode(const void* buf, size_t size)
{ return NULL; }

#warning Implement this function.
void * base64_decode(const char* s, size_t * data_len)
{ return NULL; }

您可以看到 Apple 在代码末尾懒于实现 C 函数。由于我的 C/C++ 能力很差，我看到我需要在 C/C++ 中实现这两个函数，并且它们必须返回 char 和 void (???)。其他人已经在 SO 上发布了执行此操作的例程，但他们要么在 Objective-C 中，要么不返回 chars 和 void (??)。

注意：这是我遇到的另一个问题：如果 Apple 以这种形式使用方法，它如何返回 void？

uint8_t *purchase_info_bytes = base64_decode([purchase_info_string cStringUsingEncoding:NSASCIIStringEncoding],                                                 &purchase_info_length);

它不应该返回 uint8_t 吗？

注意 2：我遇到的另一个问题是苹果说 base64_encode 是必需的，但它没有用于他们提供的代码。我认为他们在吸毒，或者我的 C/C++ 知识真的很臭。

所以，回到我的第一个问题。有人可以发布/指向一个可以完成符合声明的方法 base64_encode 和 base64_decode 要求的工作的方法吗？请不要发布与 Apple 提出的这些要求不兼容的 Objective-c 方法。

谢谢。

4

3 回答 3

8

该解决方案应该非常简单，其中包括填充缺失信息的所有方法。在沙盒中经过测试和功能。

//  single base64 character conversion
static int POS(char c)
{
    if (c>='A' && c<='Z') return c - 'A';
    if (c>='a' && c<='z') return c - 'a' + 26;
    if (c>='0' && c<='9') return c - '0' + 52;
    if (c == '+') return 62;
    if (c == '/') return 63;
    if (c == '=') return -1;

    [NSException raise:@"invalid BASE64 encoding" format:@"Invalid BASE64 encoding"];
    return 0;
}

- (NSString *)encodeBase64:(const uint8_t *)input length:(NSInteger)length
{
    return [NSString stringWithUTF8String:base64_encode(input, (size_t)length)];
}

- (NSString *)decodeBase64:(NSString *)input length:(NSInteger *)length
{
    size_t retLen;
    uint8_t *retStr = base64_decode([input UTF8String], &retLen);
    if (length)
        *length = (NSInteger)retLen;
    NSString *st = [[[NSString alloc] initWithBytes:retStr
                                             length:retLen
                                           encoding:NSUTF8StringEncoding] autorelease];
    free(retStr);    // If base64_decode returns dynamically allocated memory
    return st;
}

char* base64_encode(const void* buf, size_t size)
{
    static const char base64[] =  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

    char* str = (char*) malloc((size+3)*4/3 + 1);

    char* p = str;
    unsigned char* q = (unsigned char*) buf;
    size_t i = 0;

    while(i < size) {
        int c = q[i++];
        c *= 256;
        if (i < size) c += q[i];
        i++;

        c *= 256;
        if (i < size) c += q[i];
        i++;

        *p++ = base64[(c & 0x00fc0000) >> 18];
        *p++ = base64[(c & 0x0003f000) >> 12];

        if (i > size + 1)
            *p++ = '=';
        else
            *p++ = base64[(c & 0x00000fc0) >> 6];

        if (i > size)
            *p++ = '=';
        else
            *p++ = base64[c & 0x0000003f];
    }

    *p = 0;

    return str;
}

void* base64_decode(const char* s, size_t* data_len_ptr)
{
    size_t len = strlen(s);

    if (len % 4)
        [NSException raise:@"Invalid input in base64_decode" format:@"%d is an invalid length for an input string for BASE64 decoding", len];

    unsigned char* data = (unsigned char*) malloc(len/4*3);

    int n[4];
    unsigned char* q = (unsigned char*) data;

    for(const char*p=s; *p; )
    {
        n[0] = POS(*p++);
        n[1] = POS(*p++);
        n[2] = POS(*p++);
        n[3] = POS(*p++);

        if (n[0]==-1 || n[1]==-1)
            [NSException raise:@"Invalid input in base64_decode" format:@"Invalid BASE64 encoding"];

        if (n[2]==-1 && n[3]!=-1)
            [NSException raise:@"Invalid input in base64_decode" format:@"Invalid BASE64 encoding"];

        q[0] = (n[0] << 2) + (n[1] >> 4);
        if (n[2] != -1) q[1] = ((n[1] & 15) << 4) + (n[2] >> 2);
        if (n[3] != -1) q[2] = ((n[2] & 3) << 6) + n[3];
        q += 3;
    }

    // make sure that data_len_ptr is not null
    if (!data_len_ptr)
        [NSException raise:@"Invalid input in base64_decode" format:@"Invalid destination for output string length"];

    *data_len_ptr = q-data - (n[2]==-1) - (n[3]==-1);

    return data;
}
于 2012-07-25T04:32:38.957 回答
3

NSString这是to的 base 64 编码函数NSString：

+(NSString *) encodeString:(NSString *)inString
{
    NSData *data = [inString dataUsingEncoding:NSUTF8StringEncoding];
    //Point to start of the data and set buffer sizes
    int inLength = [data length];
    int outLength = ((((inLength * 4)/3)/4)*4) + (((inLength * 4)/3)%4 ? 4 : 0);
    const char *inputBuffer = [data bytes];
    char *outputBuffer = malloc(outLength);
    outputBuffer[outLength] = 0;

    //64 digit code
    static char Encode[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

    //start the count
    int cycle = 0;
    int inpos = 0;
    int outpos = 0;
    char temp;

    outputBuffer[outLength-1] = '=';
    outputBuffer[outLength-2] = '=';

    while (inpos < inLength){
        switch (cycle) {
            case 0:
                outputBuffer[outpos++] = Encode[(inputBuffer[inpos]&0xFC)>>2];
                cycle = 1;
                break;
            case 1:
                temp = (inputBuffer[inpos++]&0x03)<<4;
                outputBuffer[outpos] = Encode[temp];
                cycle = 2;
                break;
            case 2:
                outputBuffer[outpos++] = Encode[temp|(inputBuffer[inpos]&0xF0)>> 4];
                temp = (inputBuffer[inpos++]&0x0F)<<2;
                outputBuffer[outpos] = Encode[temp];
                cycle = 3;                  
                break;
            case 3:
                outputBuffer[outpos++] = Encode[temp|(inputBuffer[inpos]&0xC0)>>6];
                cycle = 4;
                break;
            case 4:
                outputBuffer[outpos++] = Encode[inputBuffer[inpos++]&0x3f];
                cycle = 0;
                break;                          
            default:
                cycle = 0;
                break;
        }
    }

    NSString *pictemp = [NSString stringWithUTF8String:outputBuffer];
    free(outputBuffer); 

    return pictemp;
}

NSString这是to的 base 64 解码函数NSString：

+(NSString *) decodeString:(NSString *)inString
{
    const char* string = [inString cStringUsingEncoding:NSASCIIStringEncoding];

    NSInteger inputLength = inString.length;

    static char decodingTable[128];

    static char encodingTable[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

    for (NSInteger i = 0; i < 128; i++) {
        decodingTable[encodingTable[i]] = i;
    }

    if ((string == NULL) || (inputLength % 4 != 0)) {
        return nil;
    }

    while (inputLength > 0 && string[inputLength - 1] == '=') {
        inputLength--;
    }

    NSInteger outputLength = inputLength * 3 / 4;
    NSMutableData* data = [NSMutableData dataWithLength:outputLength];
    uint8_t* output = data.mutableBytes;

    NSInteger inputPoint = 0;
    NSInteger outputPoint = 0;
    while (inputPoint < inputLength) {
        char i0 = string[inputPoint++];
        char i1 = string[inputPoint++];
        char i2 = inputPoint < inputLength ? string[inputPoint++] : 'A'; /* 'A' will decode to \0 */
        char i3 = inputPoint < inputLength ? string[inputPoint++] : 'A';

        output[outputPoint++] = (decodingTable[i0] << 2) | (decodingTable[i1] >> 4);
        if (outputPoint < outputLength) {
            output[outputPoint++] = ((decodingTable[i1] & 0xf) << 4) | (decodingTable[i2] >> 2);
        }
        if (outputPoint < outputLength) {
            output[outputPoint++] = ((decodingTable[i2] & 0x3) << 6) | decodingTable[i3];
        }
    }

    NSLog(@"%@",data);

    NSString *finalString = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];

    return finalString;
}

这些是我前一段时间在互联网上搜索它们时在互联网上各个地方找到的示例拼凑而成的。它们可能对您来说更容易实施。我刚刚创建了一个Base64类并将这些方法放入其中。

于 2012-07-24T16:12:57.503 回答
2

以下是贾斯汀答案的 C 包装器：

char* base64_encode(const void* buf, size_t size)
{ 
    NSData* data = [NSData dataWithBytesNoCopy:(void*)buf length:size];
    NSString* string = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
    return [[_Class_ encode:string] UTF8String];
}

void* base64_Decode (const char* s, size_t* data_len)
{
    NSString* result = [_Class_ decode:[NSString stringWithCString:s encoding:NSASCIIStringEncoding]];
    *data_len = result.length;
    return [result UTF8String];
}

其中Class是包含 Justin 函数的类。

于 2012-07-24T17:25:07.950 回答