(Objective-C) Verify and Unwrap S/MIME, and get Information about CMS Signature

Demonstrates calling the Verify method to verify and unwrap S/MIME. The MIME is restored to the original structure that it would have originally had prior to signing. The Verify method works with both detached signatures, as well as opaque/attached signatures.

Calls LastJsonData to get information about the signature(s) that were verified.

Chilkat Objective-C Library Downloads MAC OS X (Cocoa) Libs iOS Libs

#import <CkoMime.h>
#import <CkoJsonObject.h>
#import <CkoDtObj.h>
#import <NSString.h>

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

CkoMime *mime = [[CkoMime alloc] init];

// Load the signed MIME from a file...
BOOL success = [mime LoadMimeFile: @"qa_data/mime/detached_sig.eml"];
if (success == NO) {
    NSLog(@"%@",mime.LastErrorText);
    return;
}

// Verify the S/MIME and restore the MIME
// to the structure/content it had prior to signing.
BOOL verified = [mime Verify];
if (verified == NO) {
    NSLog(@"%@",mime.LastErrorText);
    return;
}

// Examine the details of what was verified.
CkoJsonObject *json = [mime LastJsonData];
json.EmitCompact = NO;
NSLog(@"%@",[json Emit]);

// The code to parse the following JSON (i.e. extract desired information) is shown below..

// {
//   "pkcs7": {
//     "verify": {
//       "certs": [
//         {
//           "issuerCN": "VeriSign Class 1 Public Primary Certification Authority - G3",
//           "serial": "0702A21A85B84B659E180A6EE6F5A365"
//         },
//         {
//           "issuerCN": "VeriSign Class 1 Public Primary Certification Authority - G3",
//           "serial": "008B5B75568454850B00CFAF3848CEB1A4"
//         },
//         {
//           "issuerCN": "Symantec Class 1 Individual Subscriber CA - G5",
//           "serial": "619C55C32FF6BD1A7B7E0330D21C8F3C"
//         }
//       ],
//       "digestAlgorithms": [
//         "sha1"
//       ],
//       "signerInfo": [
//         {
//           "cert": {
//             "serialNumber": "619C55C32FF6BD1A7B7E0330D21C8F3C",
//             "issuerCN": "Symantec Class 1 Individual Subscriber CA - G5",
//             "digestAlgOid": "1.3.14.3.2.26",
//             "digestAlgName": "SHA1"
//           },
//           "contentType": "1.2.840.113549.1.7.1",
//           "signingTime": "160428055000Z",
//           "messageDigest": "2hJJVmO/jtaJV5uCKMFzIkRRvtY=",
//           "signingAlgOid": "1.2.840.113549.1.1.1",
//           "signingAlgName": "RSA-PKCSV-1_5",
//           "authAttr": {
//             "1.2.840.113549.1.9.3": {
//               "name": "contentType",
//               "oid": "1.2.840.113549.1.7.1"
//             },
//             "1.2.840.113549.1.9.5": {
//               "name": "signingTime",
//               "utctime": "160428055000Z"
//             },
//             "1.2.840.113549.1.9.4": {
//               "name": "messageDigest",
//               "digest": "2hJJVmO/jtaJV5uCKMFzIkRRvtY="
//             },
//             "1.2.840.113549.1.9.15": {
//               "der": "MFAwCwYJYIZIAWUDBAECMAoGCCqGSIb3DQMHMA4GCCqGSIb3DQMCAgIAgDANBggqhkiG9w0DAgIBQDAHBgUrDgMCBzANBggqhkiG9w0DAgIBKA=="
//             },
//             "1.3.6.1.4.1.311.16.4": {
//               "der": "MIG7MIG...7fgMw0hyPPA=="
//             }
//           }
//         }
//       ]
//     }
//   }
// }

// Use this online tool to generate parsing code from sample JSON: 
// Generate Parsing Code from JSON

CkoDtObj *signingTime = [[CkoDtObj alloc] init];
CkoDtObj *authAttrSigningTimeUtctime = [[CkoDtObj alloc] init];
NSString *issuerCN = 0;
NSString *serial = 0;
NSString *strVal = 0;
NSString *certSerialNumber = 0;
NSString *certIssuerCN = 0;
NSString *certDigestAlgOid = 0;
NSString *certDigestAlgName = 0;
NSString *contentType = 0;
NSString *messageDigest = 0;
NSString *signingAlgOid = 0;
NSString *signingAlgName = 0;
NSString *authAttrContentTypeName = 0;
NSString *authAttrContentTypeOid = 0;
NSString *authAttrSigningTimeName = 0;
NSString *authAttrMessageDigestName = 0;
NSString *authAttrMessageDigestDigest = 0;
NSString *authAttr1_2_840_113549_1_9_15Der = 0;
NSString *authAttr1_3_6_1_4_1_311_16_4Der = 0;

int i = 0;
int count_i = [[json SizeOfArray: @"pkcs7.verify.certs"] intValue];
while (i < count_i) {
    json.I = [NSNumber numberWithInt: i];
    issuerCN = [json StringOf: @"pkcs7.verify.certs[i].issuerCN"];
    serial = [json StringOf: @"pkcs7.verify.certs[i].serial"];
    i = i + 1;
}

i = 0;
count_i = [[json SizeOfArray: @"pkcs7.verify.digestAlgorithms"] intValue];
while (i < count_i) {
    json.I = [NSNumber numberWithInt: i];
    strVal = [json StringOf: @"pkcs7.verify.digestAlgorithms[i]"];
    i = i + 1;
}

i = 0;
count_i = [[json SizeOfArray: @"pkcs7.verify.signerInfo"] intValue];
while (i < count_i) {
    json.I = [NSNumber numberWithInt: i];
    certSerialNumber = [json StringOf: @"pkcs7.verify.signerInfo[i].cert.serialNumber"];
    certIssuerCN = [json StringOf: @"pkcs7.verify.signerInfo[i].cert.issuerCN"];
    certDigestAlgOid = [json StringOf: @"pkcs7.verify.signerInfo[i].cert.digestAlgOid"];
    certDigestAlgName = [json StringOf: @"pkcs7.verify.signerInfo[i].cert.digestAlgName"];
    contentType = [json StringOf: @"pkcs7.verify.signerInfo[i].contentType"];
    [json DtOf: @"pkcs7.verify.signerInfo[i].signingTime" bLocal: NO dt: signingTime];
    messageDigest = [json StringOf: @"pkcs7.verify.signerInfo[i].messageDigest"];
    signingAlgOid = [json StringOf: @"pkcs7.verify.signerInfo[i].signingAlgOid"];
    signingAlgName = [json StringOf: @"pkcs7.verify.signerInfo[i].signingAlgName"];
    authAttrContentTypeName = [json StringOf: @"pkcs7.verify.signerInfo[i].authAttr.\"1.2.840.113549.1.9.3\".name"];
    authAttrContentTypeOid = [json StringOf: @"pkcs7.verify.signerInfo[i].authAttr.\"1.2.840.113549.1.9.3\".oid"];
    authAttrSigningTimeName = [json StringOf: @"pkcs7.verify.signerInfo[i].authAttr.\"1.2.840.113549.1.9.5\".name"];
    [json DtOf: @"pkcs7.verify.signerInfo[i].authAttr.\"1.2.840.113549.1.9.5\".utctime" bLocal: NO dt: authAttrSigningTimeUtctime];
    authAttrMessageDigestName = [json StringOf: @"pkcs7.verify.signerInfo[i].authAttr.\"1.2.840.113549.1.9.4\".name"];
    authAttrMessageDigestDigest = [json StringOf: @"pkcs7.verify.signerInfo[i].authAttr.\"1.2.840.113549.1.9.4\".digest"];
    authAttr1_2_840_113549_1_9_15Der = [json StringOf: @"pkcs7.verify.signerInfo[i].authAttr.\"1.2.840.113549.1.9.15\".der"];
    authAttr1_3_6_1_4_1_311_16_4Der = [json StringOf: @"pkcs7.verify.signerInfo[i].authAttr.\"1.3.6.1.4.1.311.16.4\".der"];
    i = i + 1;
}