Question

我知道有很多关于将NSData转换为NSString，NSData转换为Base64编码字符串，生成HMAC等的帖子，但似乎没有回答如何在iOS和Rails中生成匹配的Base64编码的HMAC-SHA1字符串。

使用下面的代码，签名不匹配。

iOS代码：

NSString *secret = @"xxx";
NSString *data = @"http://someurl?someparams";
const char *cKey = [secret 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 *signature = [HMAC base64EncodedStringWithOptions:NSDataBase64Encoding64CharacterLineLength];

Rails代码：

secret = "xxx";
data = "http://someurl?someparams";
hmac = OpenSSL::HMAC.hexdigest(OpenSSL::Digest::Digest.new('sha1'), secret.encode("ASCII"), data.encode("ASCII"))
signature = Base64.encode64(hmac)
puts "HMAC #{hmac}"
puts "Signature #{signature}"

iOS输出：

HMAC <05651433 c9a3d449 5816ded7 80bef87f dc903e4a> 
Signature BWUUM8mj1ElYFt7XgL74f9yQPko=

Rails输出：

HMAC 05651433c9a3d4495816ded780bef87fdc903e4a
Signature MDU2NTE0MzNjOWEzZDQ0OTU4MTZkZWQ3ODBiZWY4N2ZkYzkwM2U0YQ==

使用以下代码我可以让它们匹配。但它感觉很hacky（在iOS方面使用描述和字符串替换，在Rails中使用chomp）：

iOS代码：

NSString *secret = @"xxx";
NSString *data = @"http://someurl?someparams";
const char *cKey = [secret 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 *HMACStr = [[HMAC description] stringByReplacingOccurrencesOfString:@"<" withString:@""];
HMACStr = [HMACStr stringByReplacingOccurrencesOfString:@">" withString:@""];
HMACStr = [HMACStr stringByReplacingOccurrencesOfString:@" " withString:@""];
HMAC = [HMACStr dataUsingEncoding:NSASCIIStringEncoding];
NSString *signature = [HMAC base64EncodedStringWithOptions:NSDataBase64Encoding64CharacterLineLength];
NSLog(@"HMAC %@", [HMAC description]);
NSLog(@"Signature %@", signature);

Rails代码：

secret = "xxx"
data = "http://someurl?someparams"
hmac = OpenSSL::HMAC.hexdigest(OpenSSL::Digest::Digest.new('sha1'), secret.encode("ASCII"), data.encode("ASCII"))
signature = Base64.encode64(hmac).chomp
puts "HMAC #{hmac}"
puts "Signature #{signature}"

iOS输出：

HMAC <30353635 31343333 63396133 64343439 35383136 64656437 38306265 66383766 64633930 33653461> 
Signature MDU2NTE0MzNjOWEzZDQ0OTU4MTZkZWQ3ODBiZWY4N2ZkYzkwM2U0YQ==

Rails输出：

HMAC 05651433c9a3d4495816ded780bef87fdc903e4a
Signature MDU2NTE0MzNjOWEzZDQ0OTU4MTZkZWQ3ODBiZWY4N2ZkYzkwM2U0YQ==

如何在不使用黑客的情况下生成匹配的签名？

Answer 1

我不熟悉Rails，但在我看来

hmac = OpenSSL::HMAC.hexdigest(OpenSSL::Digest::Digest.new('sha1'), secret.encode("ASCII"), data.encode("ASCII"))

将摘要计算为十六进制字符串，而

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)];

将摘要计算为NSData对象，它只是一个包装器任意字节序列。

您可能应该更改Rails代码以将摘要计算为序列字节也是，而不是十六进制字符串（可能使用digest而不是hexdigest？）

在iOS / Objective-c Ruby / Rails中匹配Base64编码的HMAC-SHA1字符串

1 个答案: