iOS中的亚马逊产品广告API签名

Question

我正在尝试在我的iOS应用程序中访问亚马逊的产品广告API.创建签名似乎是一个艰难的部分.在本页面:

http://docs.amazonwebservices.com/AWSECommerceService/latest/DG/rest-signature.html

它说"使用SHA256哈希算法计算符合RFC 2104的HMAC".亚马逊还提供了一个java类来为您执行此操作:

http://docs.amazonwebservices.com/AWSECommerceService/latest/DG/AuthJavaSampleSig2.html

有人知道我如何在Objective-C中做到这一点吗？我查看了AWS iOS SDK,但它似乎没有包含Product Advertising API.

Answer 1

实际上,AWS iOS SDK DID有一个静态方法来处理所有身份验证情况.也许你应该看一眼AmazonAuthUtils.h:

+(NSString *)HMACSign:(NSData *)data withKey:(NSString *)key usingAlgorithm:(CCHmacAlgorithm)algorithm;
+(NSData *)sha256HMac:(NSData *)data withKey:(NSString *)key;

你可以在文档中找到它:http://docs.amazonwebservices.com/AWSiOSSDK/latest/Classes/AmazonAuthUtils.html

Answer 2

只是为camelcc的优秀观察添加一点.这确实适用于签署对Amazon Product Advertising API的请求.我不得不搞砸了一下才能让它发挥作用.

安装SDK并安装 #import <AWSiOSSDK/AmazonAuthUtils.h>

首先,您必须按照亚马逊文档将请求字符串组织成正确的顺序.我发现这个页面在解释如何订购请求时非常有用

http://skilldrick.co.uk/2010/02/amazon-product-information-via-amazon-web-services/

注意字符串中需要换行符,我的无符号字符串看起来像这样

@"GET\necs.amazonaws.com\n/onca/xml\nAWSAccessKeyId=<ACCESS_KEY_ID>&AssociateTag=<ASSOCIATE_ID>&Keywords=harry%20potter&Operation=ItemSearch&SearchIndex=Books&Service=AWSECommerceService&Timestamp=2012-07-03T10%3A52%3A21.000Z&Version=2011-08-01"

在任何地方都没有空格,但\n在正确的位置有字符.把它转换成NSData这样

NSData *dataToSign = [unsignedString dataUsingEncoding:NSUTF8StringEncoding];

然后打电话

[AmazonAuthUtils HMACSign:dataToSign withKey:SECRET_KEY usingAlgorithm:kCCHmacAlgSHA256]

这将您的签名作为NSString.您需要对此进行URL编码(即交换%0x符号的非法/不安全字符(即'='转换为'%3D'))

一旦完成,请将其粘贴在您的请求中,希望您好好去!

Answer 3

查看我的亚马逊产品广告客户端https://github.com/m1entus/RWMAmazonProductAdvertisingManager

一些带有请求序列化的代码:

NSString * const RWMAmazonProductAdvertisingStandardRegion = @"webservices.amazon.com";
NSString * const RWMAmazonProductAdvertisingAWSAccessKey = @"AWSAccessKeyId";
NSString * const RWMAmazonProductAdvertisingTimestampKey = @"Timestamp";
NSString * const RWMAmazonProductAdvertisingSignatureKey = @"Signature";
NSString * const RWMAmazonProductAdvertisingVersionKey = @"Version";
NSString * const RWMAmazonProductAdvertisingCurrentVersion = @"2011-08-01";

NSData * RWMHMACSHA256EncodedDataFromStringWithKey(NSString *string, NSString *key) {
    NSData *data = [string dataUsingEncoding:NSASCIIStringEncoding];
    CCHmacContext context;
    const char *keyCString = [key cStringUsingEncoding:NSASCIIStringEncoding];

    CCHmacInit(&context, kCCHmacAlgSHA256, keyCString, strlen(keyCString));
    CCHmacUpdate(&context, [data bytes], [data length]);

    unsigned char digestRaw[CC_SHA256_DIGEST_LENGTH];
    NSUInteger digestLength = CC_SHA256_DIGEST_LENGTH;

    CCHmacFinal(&context, digestRaw);

    return [NSData dataWithBytes:digestRaw length:digestLength];
}

NSString * RWMISO8601FormatStringFromDate(NSDate *date) {
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setTimeZone:[NSTimeZone timeZoneWithName:@"GMT"]];
    [dateFormatter setDateFormat:@"YYYY-MM-dd'T'HH:mm:ss'Z'"];
    [dateFormatter setLocale:[[NSLocale alloc] initWithLocaleIdentifier:@"en_US_POSIX"]];

    return [dateFormatter stringFromDate:date];
}

NSString * RWMBase64EncodedStringFromData(NSData *data) {

#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 70000
    return [data base64EncodedStringWithOptions:0];
#else
    return [data base64Encoding];
#endif

}

//http://docs.aws.amazon.com/AWSECommerceService/latest/DG/rest-signature.html

- (NSURLRequest *)requestBySerializingRequest:(NSURLRequest *)request
                               withParameters:(id)parameters
                                        error:(NSError * __autoreleasing *)error
{
    NSParameterAssert(request);

    NSMutableURLRequest *mutableRequest = [request mutableCopy];

    if (self.accessKey && self.secret) {
        NSMutableDictionary *mutableParameters = [parameters mutableCopy];
        NSString *timestamp = RWMISO8601FormatStringFromDate([NSDate date]);

        if (!mutableParameters[RWMAmazonProductAdvertisingAWSAccessKey]) {
            [mutableParameters setObject:self.accessKey forKey:RWMAmazonProductAdvertisingAWSAccessKey];
        }
        mutableParameters[RWMAmazonProductAdvertisingVersionKey] = RWMAmazonProductAdvertisingCurrentVersion;
        mutableParameters[RWMAmazonProductAdvertisingTimestampKey] = timestamp;

        NSMutableArray *canonicalStringArray = [[NSMutableArray alloc] init];
        for (NSString *key in [[mutableParameters allKeys] sortedArrayUsingSelector:@selector(compare:)]) {
            id value = [mutableParameters objectForKey:key];
            [canonicalStringArray addObject:[NSString stringWithFormat:@"%@=%@", key, value]];
        }
        NSString *canonicalString = [canonicalStringArray componentsJoinedByString:@"&"];
        canonicalString = CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault,
                                                                                    (__bridge CFStringRef)canonicalString,
                                                                                    NULL,
                                                                                    CFSTR(":,"),
                                                                                    kCFStringEncodingUTF8));

        NSString *method = [request HTTPMethod];

        NSString *signature = [NSString stringWithFormat:@"%@\n%@\n%@\n%@",method,self.region,self.formatPath,canonicalString];

        NSData *encodedSignatureData = RWMHMACSHA256EncodedDataFromStringWithKey(signature,self.secret);
        NSString *encodedSignatureString = RWMBase64EncodedStringFromData(encodedSignatureData);

        encodedSignatureString = CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault,
                                                                                           (__bridge CFStringRef)encodedSignatureString,
                                                                                           NULL,
                                                                                           CFSTR("+="),
                                                                                           kCFStringEncodingUTF8));

        canonicalString = [canonicalString stringByAppendingFormat:@"&%@=%@",RWMAmazonProductAdvertisingSignatureKey,encodedSignatureString];

        mutableRequest.URL = [NSURL URLWithString:[[mutableRequest.URL absoluteString] stringByAppendingFormat:mutableRequest.URL.query ? @"&%@" : @"?%@", canonicalString]];

    } else {
        if (error) {
            NSDictionary *userInfo = @{NSLocalizedDescriptionKey: NSLocalizedStringFromTable(@"Access Key and Secret Required", @"RWMAmazonProductAdvertisingManager", nil)};
            *error = [[NSError alloc] initWithDomain:RWMAmazonProductAdvertisingManagerErrorDomain code:NSURLErrorUserAuthenticationRequired userInfo:userInfo];
        }
    }

    return mutableRequest;

}

Answer 4

感谢此页面上的所有答案.这对我有用(Swift 3.0):

Podfile:

pod 'AWSAPIGateway', '~> 2.4.7'

SWIFT代码

static let kAmazonAccessID = "BLAH BLAH BLAH"
static let kAmazonAccessSecretKey = "BLAH BLAH BLAH"

static let kAmazonAssociateTag = "BLAH BLAH BLAH"
private let timestampFormatter: DateFormatter

init() {
    timestampFormatter = DateFormatter()
    timestampFormatter.timeZone = TimeZone(identifier: "GMT")
    timestampFormatter.dateFormat = "YYYY-MM-dd'T'HH:mm:ss'Z'"
    timestampFormatter.locale = Locale(identifier: "en_US_POSIX")
}

private func signedParametersForParameters(parameters: [String: String]) -> [String: String] {
    let sortedKeys = Array(parameters.keys).sorted(by: <)

    let query = sortedKeys.map { String(format: "%@=%@", $0, parameters[$0] ?? "") }.joined(separator: "&")

    let stringToSign = "GET\nwebservices.amazon.com\n/onca/xml\n\(query)"

    let dataToSign = stringToSign.data(using: String.Encoding.utf8)
    let signature = AWSSignatureSignerUtility.hmacSign(dataToSign, withKey: AmazonAPI.kAmazonAccessSecretKey, usingAlgorithm: UInt32(kCCHmacAlgSHA256))!

    var signedParams = parameters;
    signedParams["Signature"] = urlEncode(signature)

    return signedParams
}

public func urlEncode(_ input: String) -> String {
    let allowedCharacterSet = (CharacterSet(charactersIn: "!*'();:@&=+$,/?%#[] ").inverted)

    if let escapedString = input.addingPercentEncoding(withAllowedCharacters: allowedCharacterSet) {
        return escapedString
    }

    return ""
}

func send(url: String) -> String {
    guard let url = URL(string: url) else {
        print("Error! Invalid URL!") //Do something else
        return ""
    }

    let request = URLRequest(url: url)
    let semaphore = DispatchSemaphore(value: 0)

    var data: Data? = nil

    URLSession.shared.dataTask(with: request) { (responseData, _, _) -> Void in
        data = responseData
        semaphore.signal()
    }.resume()

    semaphore.wait(timeout: .distantFuture)

    let reply = data.flatMap { String(data: $0, encoding: .utf8) } ?? ""
    return reply
}

这是向亚马逊询问产品价格的功能:

public func getProductPrice(_ asin: AmazonStandardIdNumber) -> Double {

    let operationParams: [String: String] = [
        "Service": "AWSECommerceService",
        "Operation": "ItemLookup",
        "ResponseGroup": "Offers",
        "IdType": "ASIN",
        "ItemId": asin,
        "AWSAccessKeyId": urlEncode(AmazonAPI.kAmazonAccessID),
        "AssociateTag": urlEncode(AmazonAPI.kAmazonAssociateTag),
        "Timestamp": urlEncode(timestampFormatter.string(from: Date())),]

    let signedParams = signedParametersForParameters(parameters: operationParams)

    let query = signedParams.map { "\($0)=\($1)" }.joined(separator: "&")
    let url = "http://webservices.amazon.com/onca/xml?" + query

    let reply = send(url: url)

    // USE THE RESPONSE
}