iphone 开发 : verify the certificate information from a https url

Question

当用户连接到“https url”时，例如:“https://encrypted.google.com”，使用网络浏览器(Safari、Chrome 等)，则用户可以获得关于与此类“https url”相关的证书；也就是说，在连接到url“https://encrypted.google.com”的情况下，可以验证以下证书信息:

1. Equifax 安全证书颁发机构
2. *.google.com 发布者:Google Internet Authority。证书的到期日期。证书是否有效
3. 有关证书的更多详细信息，如签名算法、公钥信息、指纹等。

因此，问题是:“为了获得上述信息(或者至少知道证书是否有效)，正确的 Objective C 函数调用是什么？”

提前致谢

Answer 1

可以使用 NSURLConnection 委托(delegate)方法获取证书信息:

- (BOOL)connection:(NSURLConnection *)connection canAuthenticateAgainstProtectionSpace:(NSURLProtectionSpace *)protectionSpace

- (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge

即:

- (BOOL)connection:(NSURLConnection *)connection canAuthenticateAgainstProtectionSpace:(NSURLProtectionSpace *)protectionSpace {
BOOL  result = [protectionSpace.authenticationMethod isEqualToString:NSURLAuthenticationMethodServerTrust];
NSLog(@"<%p %@: %s line:%d> Result:%s", self, [[NSString stringWithUTF8String:__FILE__] lastPathComponent], __PRETTY_FUNCTION__, __LINE__, (result == YES) ? "YES" : "NO");
return result;
}

- (void)connection:(NSURLConnection *)connection      didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge {
NSArray *trustedHosts = [NSArray arrayWithObject:@"encrypted.google.com"];
BOOL isAuthMethodServerTrust = [challenge.protectionSpace.authenticationMethod isEqualToString:NSURLAuthenticationMethodServerTrust];
NSLog(@"<%p %@: %s line:%d> Result:%s", self, [[NSString stringWithUTF8String:__FILE__] lastPathComponent], __PRETTY_FUNCTION__, __LINE__, (isAuthMethodServerTrust == YES) ? "YES" : "NO");
if (isAuthMethodServerTrust)
{
    if ([trustedHosts containsObject:challenge.protectionSpace.host])
    {
        NSLog(@"<%p %@: %s line:%d> trustedHosts containsObject:challenge.protectionSpace.host", self, [[NSString stringWithUTF8String:__FILE__] lastPathComponent], __PRETTY_FUNCTION__, __LINE__);
        NSURLCredential* urlCredential = [NSURLCredential credentialForTrust:challenge.protectionSpace.serverTrust];
        NSLog(@"<%p %@: %s line:%d> Url credential", self, [[NSString stringWithUTF8String:__FILE__] lastPathComponent], __PRETTY_FUNCTION__, __LINE__);         
        [challenge.sender useCredential:urlCredential forAuthenticationChallenge:challenge];

        //Code to verify certificate info
        SecTrustRef trustRef = [[challenge protectionSpace] serverTrust];
        CFIndex count = SecTrustGetCertificateCount(trustRef); 

        for (CFIndex i = 0; i < count; i++)
        {
            SecCertificateRef certRef = SecTrustGetCertificateAtIndex(trustRef, i);
            CFStringRef certSummary = SecCertificateCopySubjectSummary(certRef);
            CFDataRef certData = SecCertificateCopyData(certRef);
            NSLog(@"<%p %@: %s line:%d> Certificate summary:%@", self, [[NSString stringWithUTF8String:__FILE__] lastPathComponent], __PRETTY_FUNCTION__, __LINE__, (NSString*) certSummary);
            NSLog(@"<%p %@: %s line:%d> Certificate data:%@", self, [[NSString stringWithUTF8String:__FILE__] lastPathComponent], __PRETTY_FUNCTION__, __LINE__, (NSString*) certData);
            CFRelease(certData);
        }
    }
}
}

此代码为您提供以下与“https://encrypted.google.com”相关的信息: 在“certSummary”NSString 中，证书的颁发者。 在证书的“certData”数据中。问题是目前我不知道如何从此类数据中提取信息(过期日期、公钥...)，因此欢迎任何帮助。