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。创建签名似乎是困难的部分。在此页面上：
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”。 Amazon 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，但它似乎不包含产品广告 API。
【问题讨论】：
标签： objective-c ios amazon-web-services amazon amazon-product-api
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。
也许你应该看看AmazonAuthUtils.h：
+(NSString *)HMACSign:(NSData *)data withKey:(NSString *)key usingAlgorithm:(CCHmacAlgorithm)algorithm;
+(NSData *)sha256HMac:(NSData *)data withKey:(NSString *)key;
可以在文档中找到：http://docs.amazonwebservices.com/AWSiOSSDK/latest/Classes/AmazonAuthUtils.html
【讨论】：
只是为 camelcc 的出色观察添加一点。这确实适用于签署对亚马逊产品广告 API 的请求。我不得不搞砸一点才能让它工作。
安装 SDK 并#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。我发现此页面在解释如何订购请求方面非常有用
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"
任何地方都没有空格，但\n 字符在正确的位置。像这样将其转换为NSData
NSData *dataToSign = [unsignedString dataUsingEncoding:NSUTF8StringEncoding];
然后调用
[AmazonAuthUtils HMACSign:dataToSign withKey:SECRET_KEY usingAlgorithm:kCCHmacAlgSHA256]
这会将您的签名返回为NSString。您需要对其进行 URL 编码（即用 %0x 符号交换非法/不安全字符（即 '=' 转换为 '%3D'））
完成后，将其粘贴在您的请求中，希望您一切顺利！
【讨论】：
查看我的亚马逊产品广告客户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;
}
【讨论】：
感谢此页面上的所有答案。这对我有用（Swift 3.0）：
Pod 文件：
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)=\($1)" }.joined(separator: "&")
let url = "http://webservices.amazon.com/onca/xml?" + query
let reply = send(url: url)
// USE THE RESPONSE
}
【讨论】：
P-double 帖子缺少几个步骤。
在构造无符号字符串之前，您需要获取正确的时间戳值。
NSTimeZone *zone = [NSTimeZone defaultTimeZone]; //get the current application default time zone
NSInteger interval = [zone secondsFromGMTForDate:[NSDate date]];//sec Returns the time difference of the current application with the world standard time (Green Venice time)
NSDate *nowDate = [NSDate dateWithTimeIntervalSinceNow:interval];
NSDateFormatter * formatter = [[NSDateFormatter alloc] init];
[formatter setTimeZone:[NSTimeZone systemTimeZone]];// get current date/time
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setTimeZone:[NSTimeZone systemTimeZone]];
// display in 12HR/24HR (i.e. 11:25PM or 23:25) format according to User Settings
[dateFormatter setDateFormat:@"yyyy'-'MM'-'dd'T'HH':'mm':'ss'Z'"];
NSString *currentTime = [dateFormatter stringFromDate:nowDate];
NSString* encodedTime = (NSString *)CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(NULL, (__bridge CFStringRef) currentTime,NULL, CFSTR("!*'();:@&=+$,/?%#[]"),kCFStringEncodingUTF8));
NSString* unsignedString = [NSString stringWithFormat:@"GET\nwebservices.amazon.com\n/onca/xml\nAWSAccessKeyId=AKIAI443QEMWI6KW55QQ&AssociateTag=sajjmanz-20&Condition=All&IdType=ASIN&ItemId=3492264077&Operation=ItemLookup&ResponseGroup=Images%%2CItemAttributes%%2COffers&Service=AWSECommerceService&Timestamp=%@&Version=2011-08-01", encodedTime];
一旦日期是 url 友好的编码，其余的步骤就像一个魅力。
最后，我还使用上面列出的 CFURLCreateStringByAddingPercentEscapes 对 AmazonAuthUtils HMACSign 消息调用生成的字符串进行编码。
【讨论】：
如果没有亚马逊的明确书面同意，在 iOS 应用程序中使用亚马逊的产品广告 API 是不“合法的”（根据亚马逊自己的指南），我错了吗？
【讨论】：
Swift 2.0
这是一个为 Swift 签名一组参数的函数。请注意，此代码需要安装 Alamofire 和 AWSCore Cocoapods。您还需要将 #import <CommonCrypto/CommonCrypto.h> 添加到您的 Objective-C 桥接头标头，否则将找不到 kCCHmacAlgSHA256。
private func signedParametersForParameters(parameters: [String: String]) -> [String: String] {
let sortedKeys = Array(parameters.keys).sort(<)
var components: [(String, String)] = []
for key in sortedKeys {
components += ParameterEncoding.URLEncodedInURL.queryComponents(key, parameters[key]!)
}
let query = (components.map { "\($0)=\($1)" } as [String]).joinWithSeparator("&")
let stringToSign = "GET\nwebservices.amazon.com\n/onca/xml\n\(query)"
let dataToSign = stringToSign.dataUsingEncoding(NSUTF8StringEncoding)
let signature = AWSSignatureSignerUtility.HMACSign(dataToSign, withKey: kAmazonAccessSecretKey, usingAlgorithm: UInt32(kCCHmacAlgSHA256))!
let signedParams = parameters + ["Signature": signature]
return signedParams
}
它是这样称呼的：
let operationParams: [String: String] = ["Service": "AWSECommerceService", "Operation": "ItemLookup", "ItemId": "045242127733", "IdType": "UPC", "ResponseGroup": "Images,ItemAttributes", "SearchIndex": "All"]
let keyParams = ["AWSAccessKeyId": kAmazonAccessID, "AssociateTag": kAmazonAssociateTag, "Timestamp": timestampFormatter.stringFromDate(NSDate())]
let fullParams = operationParams + keyParams
let signedParams = signedParametersForParameters(fullParams)
Alamofire.request(.GET, "http://webservices.amazon.com/onca/xml", parameters: signedParams).responseString { (response) in
print("Success: \(response.result.isSuccess)")
print("Response String: \(response.result.value)")
}
最后，timestampFormatter 是这样声明的：
private let timestampFormatter: NSDateFormatter
init() {
timestampFormatter = NSDateFormatter()
timestampFormatter.dateFormat = AWSDateISO8601DateFormat3
timestampFormatter.timeZone = NSTimeZone(name: "GMT")
timestampFormatter.locale = NSLocale(localeIdentifier: "en_US_POSIX")
}
您可以使用/修改以满足您的需要，但所有必要的东西都应该在那里。
【讨论】：
SignatureDoesNotMatch除了使用现代 OS X 中已弃用的 CommonCrypto，您还可以使用 SecTransforms：
CFErrorRef error = NULL;
SecTransformRef digestRef = SecDigestTransformCreate(kSecDigestHMACSHA2, 256, &error);
SecTransformSetAttribute(digestRef, kSecTransformInputAttributeName, (__bridge CFDataRef)self, &error);
SecTransformSetAttribute(digestRef, kSecDigestHMACKeyAttribute, (__bridge CFDataRef)key, &error);
CFDataRef resultData = SecTransformExecute(digestRef, &error);
NSData* hashData = (__bridge NSData*)resultData;
CFRelease(digestRef);
【讨论】：