我正在尝试生成 oauth_signature 以使用Fatsecret API，但出现无效签名错误 - 无法弄清楚原因。我尝试按照此处提到的所有步骤（参见步骤 2）尽可能准确地生成签名值。他们说：
使用 [RFC2104] 定义的 HMAC-SHA1 签名算法对请求进行签名，其中 text 是 Signature Base String，key 是 Consumer Secret 和 Access Secret 的连接值，由 '&' 字符分隔（显示 '&'即使 Access Secret 为空，因为某些方法不需要访问令牌）。
计算出的摘要八位字节字符串，首先按照 [RFC2045] 进行 base64 编码，然后使用 [RFC3986] 百分比编码 (%xx) 机制进行转义，即 oauth_signature。
对于 base64 编码，我使用了 QSStrings.h
我编码的步骤如下：
- (void)viewDidLoad
{
NSTimeInterval intervalFloat = [[NSDate date] timeIntervalSince1970];
int interval = (int) intervalFloat;
NSLog(@"time interval: %d",interval);
//for oauth_nonce random string
NSString *randomString = [self genRandString]; //see definition below
NSLog(@"%@",randomString);
NSString *requestString = [NSString stringWithFormat:@"POST&http%3A%2F%2Fplatform.fatsecret.com%2Frest%2Fserver.api&format%3Djson%26method%3Dprofile.create%26oauth_consumer_key%3Db753c99ccxxxxxx%26oauth_nonce%3D%@%26oauth_signature_method%3DHMAC-SHA1%26oauth_timestamp%3D%d%26oauth_version%3D1.0",randomString,interval];
NSString *secret = @"3959096c04xxxxxxxx&";
NSString *encodedStr = [self hmacsha1:requestString secret:secret]; //see definition below
NSLog(@"encodedStr: %@",encodedStr);
NSString *encodedString = [self urlEncodeValue:encodedStr]; //see definition below
NSLog(@"encodedString: %@",encodedString);
NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:@"http://platform.fatsecret.com/rest/server.api?format=json&method=profile.create&oauth_consumer_key=b753c99ccxxxxxx&oauth_nonce=%@&oauth_signature=%@&oauth_signature_method=HMAC-SHA1&oauth_timestamp=%d&oauth_version=1.0",randomString, encodedString,interval]];
_request = [ASIFormDataRequest requestWithURL:url];
[_request setPostValue:@"json" forKey:@"format"];
[_request setPostValue:@"profile.create" forKey:@"method"];
[_request setPostValue:@"b753c99ccxxxxxx" forKey:@"oauth_consumer_key"];
[_request setPostValue:randomString forKey:@"oauth_nonce"];
[_request setPostValue:encodedString forKey:@"oauth_signature"];
[_request setPostValue:@"HMAC-SHA1" forKey:@"oauth_signature_method"];
[_request setPostValue:[NSNumber numberWithInt:interval] forKey:@"oauth_timestamp"];
[_request setPostValue:@"1.0" forKey:@"oauth_version"];
[_request setDelegate:self];
_request.timeOutSeconds = 60.0;
[_request startAsynchronous];
}
我在上面代码中使用的方法的定义如下：
- (NSString *)hmacsha1:(NSString *)data secret:(NSString *)key {
const char *cKey = [key cStringUsingEncoding:NSASCIIStringEncoding];
const char *cData = [data cStringUsingEncoding:NSASCIIStringEncoding];
unsigned char cHMAC[CC_SHA1_DIGEST_LENGTH];
CCHmac(kCCHmacAlgSHA1, cKey, strlen(cKey), cData, strlen(cData), cHMAC);
NSData *HMAC = [[NSData alloc] initWithBytes:cHMAC length:sizeof(cHMAC)];
NSString *hash = [QSStrings encodeBase64WithData:HMAC];
NSLog(@"Hash: %@", hash);
return hash;
}
NSString *letters = @"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
-(NSString *) genRandString {
//fixing length of 4 chars
NSMutableString *randomString = [NSMutableString stringWithCapacity: 4];
for (int i=0; i<4; i++) {
[randomString appendFormat: @"%C", [letters characterAtIndex: arc4random() % [letters length]]];
}
return randomString;
}
- (NSString *)urlEncodeValue:(NSString *)str
{
NSMutableString * output = [NSMutableString string];
const unsigned char * source = (const unsigned char *)[str UTF8String];
int sourceLen = strlen((const char *)source);
for (int i = 0; i < sourceLen; ++i) {
const unsigned char thisChar = source[i];
if (thisChar == ' '){
[output appendString:@"+"];
} else if (thisChar == '.' || thisChar == '-' || thisChar == '_' || thisChar == '~' ||
(thisChar >= 'a' && thisChar <= 'z') ||
(thisChar >= 'A' && thisChar <= 'Z') ||
(thisChar >= '0' && thisChar <= '9')) {
[output appendFormat:@"%c", thisChar];
} else {
[output appendFormat:@"%%%02X", thisChar];
}
}
return output;
}
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