(Visual Basic 6.0) 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 ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

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

Dim mime As New ChilkatMime

' Load the signed MIME from a file...
Dim success As Long
success = mime.LoadMimeFile("qa_data/mime/detached_sig.eml")
If (success = 0) Then
    Debug.Print mime.LastErrorText
    Exit Sub
End If

' Verify the S/MIME and restore the MIME
' to the structure/content it had prior to signing.
Dim verified As Long
verified = mime.Verify()
If (verified = 0) Then
    Debug.Print mime.LastErrorText
    Exit Sub
End If

' Examine the details of what was verified.
Dim json As ChilkatJsonObject
Set json = mime.LastJsonData()
json.EmitCompact = 0
Debug.Print 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

Dim signingTime As New DtObj
Dim authAttrSigningTimeUtctime As New DtObj
Dim issuerCN As String
Dim serial As String
Dim strVal As String
Dim certSerialNumber As String
Dim certIssuerCN As String
Dim certDigestAlgOid As String
Dim certDigestAlgName As String
Dim contentType As String
Dim messageDigest As String
Dim signingAlgOid As String
Dim signingAlgName As String
Dim authAttrContentTypeName As String
Dim authAttrContentTypeOid As String
Dim authAttrSigningTimeName As String
Dim authAttrMessageDigestName As String
Dim authAttrMessageDigestDigest As String
Dim authAttr1_2_840_113549_1_9_15Der As String
Dim authAttr1_3_6_1_4_1_311_16_4Der As String

Dim i As Long
i = 0
Dim count_i As Long
count_i = json.SizeOfArray("pkcs7.verify.certs")
Do While i < count_i
    json.I = i
    issuerCN = json.StringOf("pkcs7.verify.certs[i].issuerCN")
    serial = json.StringOf("pkcs7.verify.certs[i].serial")
    i = i + 1
Loop
i = 0
count_i = json.SizeOfArray("pkcs7.verify.digestAlgorithms")
Do While i < count_i
    json.I = i
    strVal = json.StringOf("pkcs7.verify.digestAlgorithms[i]")
    i = i + 1
Loop
i = 0
count_i = json.SizeOfArray("pkcs7.verify.signerInfo")
Do While i < count_i
    json.I = 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")
    success = json.DtOf("pkcs7.verify.signerInfo[i].signingTime",0,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")
    success = json.DtOf("pkcs7.verify.signerInfo[i].authAttr.""1.2.840.113549.1.9.5"".utctime",0,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
Loop