Objective-C

Validate Certificate using OCSP Protocol

See more Certificates Examples

Demonstrates how to validate a certificate (check the revoked status) using the OCSP protocol. Objective-C

#import <CkoCert.h>
#import <NSString.h>
#import <CkoPrng.h>
#import <CkoJsonObject.h>
#import <CkoBinData.h>
#import <CkoHttp.h>
#import <CkoHttpResponse.h>

BOOL success = NO;

//  This requires the Chilkat API to have been previously unlocked.
//  See Global Unlock Sample for sample code.

//  This example will check the revoked status of a certificate loaded from a file.
CkoCert *cert = [[CkoCert alloc] init];
success = [cert LoadFromFile: @"qa_data/certs/google.crt"];
if (success == NO) {
    NSLog(@"%@",cert.LastErrorText);
    return;
}

//  Get the cert's OCSP URL.
NSString *ocspUrl = cert.OcspUrl;

//  Build the JSON that will be the OCSP request.

//  Possible hash algorithms are sha1, sha256, sha384, sha512.  
NSString *hashAlg = @"sha256";
CkoPrng *prng = [[CkoPrng alloc] init];
CkoJsonObject *json = [[CkoJsonObject alloc] init];
json.EmitCompact = NO;
//  Read more about OCSP nonce lengths
[json UpdateString: @"extensions.ocspNonce" value: [prng GenRandom: [NSNumber numberWithInt: 16] encoding: @"base64"]];
json.I = [NSNumber numberWithInt:0];
[json UpdateString: @"request[i].cert.hashAlg" value: hashAlg];
[json UpdateString: @"request[i].cert.issuerNameHash" value: [cert HashOf: @"IssuerDN" hashAlg: hashAlg encoding: @"base64"]];
[json UpdateString: @"request[i].cert.issuerKeyHash" value: [cert HashOf: @"IssuerPublicKey" hashAlg: hashAlg encoding: @"base64"]];
[json UpdateString: @"request[i].cert.serialNumber" value: cert.SerialNumber];

NSLog(@"%@",[json Emit]);

//  Our OCSP request looks something like this:
//  {
//    "extensions": {
//      "ocspNonce": "qZDfbpO+nUxRzz6c/SPjE5QCAsPfpkQlRDxTnGl0gnxt7iXO"
//    },
//    "request": [
//      {
//        "cert": {
//          "hashAlg": "sha1",
//          "issuerNameHash": "9u2wY2IygZo19o11oJ0CShGqbK0=",
//          "issuerKeyHash": "d8K4UJpndnaxLcKG0IOgfqZ+uks=",
//          "serialNumber": "6175535D87BF94B6"
//        }
//      }
//    ]
//  }

CkoBinData *ocspRequest = [[CkoBinData alloc] init];
CkoHttp *http = [[CkoHttp alloc] init];

//  Convert our JSON to a binary (ASN.1) OCSP request
success = [http CreateOcspRequest: json ocspRequest: ocspRequest];
if (success == NO) {
    NSLog(@"%@",http.LastErrorText);
    return;
}

//  Send the OCSP request to the OCSP server
CkoHttpResponse *resp = [[CkoHttpResponse alloc] init];
success = [http HttpBd: @"POST" url: ocspUrl bd: ocspRequest contentType: @"application/ocsp-request" response: resp];
if (success == NO) {
    NSLog(@"%@",http.LastErrorText);
    return;
}

//  Get the binary (ASN.1) OCSP reply
CkoBinData *ocspReply = [[CkoBinData alloc] init];
[resp GetBodyBd: ocspReply];

//  Convert the binary reply to JSON.
//  Also returns the overall OCSP response status.
CkoJsonObject *jsonReply = [[CkoJsonObject alloc] init];
int ocspStatus = [[http ParseOcspReply: ocspReply replyData: jsonReply] intValue];

//  The ocspStatus can have one of these values:
//  -1:  The ARG1 does not contain a valid OCSP reply.
//  0:  Successful - Response has valid confirmations..
//  1: Malformed request - Illegal confirmation request.
//  2: Internal error - Internal error in issuer.
//  3: Try later -  Try again later.
//  4: Not used - This value is never returned.
//  5: Sig required - Must sign the request.
//  6: Unauthorized - Request unauthorized.

if (ocspStatus < 0) {
    NSLog(@"%@",@"Invalid OCSP reply.");
    return;
}

NSLog(@"%@%d",@"Overall OCSP Response Status: ",ocspStatus);

//  Let's examine the OCSP response (in JSON).
jsonReply.EmitCompact = NO;
NSLog(@"%@",[jsonReply Emit]);

//  The JSON reply looks like this:
//  (Use the online tool at https://tools.chilkat.io/jsonParse.cshtml
//  to generate JSON parsing code.)

//  {
//    "responseStatus": 0,
//    "responseTypeOid": "1.3.6.1.5.5.7.48.1.1",
//    "responseTypeName": "ocspBasic",
//    "response": {
//      "responderIdChoice": "KeyHash",
//      "responderKeyHash": "d8K4UJpndnaxLcKG0IOgfqZ+uks=",
//      "dateTime": "20180803193937Z",
//      "cert": [
//        {
//          "hashOid": "1.3.14.3.2.26",
//          "hashAlg": "SHA-1",
//          "issuerNameHash": "9u2wY2IygZo19o11oJ0CShGqbK0=",
//          "issuerKeyHash": "d8K4UJpndnaxLcKG0IOgfqZ+uks=",
//          "serialNumber": "6175535D87BF94B6",
//          "status": 0,
//          "thisUpdate": "20180803193937Z",
//          "nextUpdate": "20180810193937Z"
//        }
//      ]
//    }
//  }
//  

//  The certificate status:
int certStatus = -1;
if ([jsonReply HasMember: @"response.cert[0].status"] == YES) {
    certStatus = [[jsonReply IntOf: @"response.cert[0].status"] intValue];
}

//  Possible certStatus values are:
//  -1: No status returned.
//  0: Good
//  1: Revoked
//  2: Unknown.
NSLog(@"%@%d",@"Certificate Status: ",certStatus);