(Visual Basic 6.0) Verify a .p7m and get Algorithm Information

Demonstrates how to verify a .p7m and then examine the algorithms used by the signature.

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 crypt As New ChilkatCrypt2

Dim inFile As String
inFile = "qa_data/p7m/brainpoolP256r1.p7m"
Dim outFile As String
outFile = "qa_output/something.dat"

' Verify and extract the signed data.
Dim success As Long
success = crypt.VerifyP7M(inFile,outFile)
If (success = 0) Then
    Debug.Print crypt.LastErrorText
    Exit Sub
End If

' Examine details about the signature(s)
Dim json As ChilkatJsonObject
Set json = crypt.LastJsonData()
json.EmitCompact = 0
Debug.Print json.Emit()

' Sample output

' {
'   "pkcs7": {
'     "verify": {
'       "digestAlgorithms": [
'         "sha256"
'       ],
'       "signerInfo": [
'         {
'           "cert": {
'             "serialNumber": "FFFFE552B302FFFFFF1E34C3ACEB2FFFF",
'             "issuerCN": "The common name of the cert...",
'             "issuerDN": "",
'             "digestAlgOid": "2.16.840.1.101.3.4.2.1",
'             "digestAlgName": "SHA256"
'           },
'           "contentType": "1.2.840.113549.1.7.1",
'           "signingTime": "190409140500Z",
'           "messageDigest": "lQe9If7vZKFf/NlSYu5Esmlw3phVK/RFsbbb1uH73t8=",
'           "signingAlgOid": "1.2.840.10045.4.3.2",
'           "signerDigest": "lQe9If7vZKFf/NlSYu5Esmlw3phVK/RFsbbb1uH73t8=",
'           "authAttr": [
'             {
'               "oid": "1.2.840.113549.1.9.3",
'               "oidName": "contentType"
'             },
'             {
'               "oid": "1.2.840.113549.1.9.5",
'               "oidName": "signingTime"
'             },
'             {
'               "oid": "1.2.840.113549.1.9.52",
'               "oidName": "1.2.840.113549.1.9.52",
'               "der": "MBs ... AwI="
'             },
'             {
'               "oid": "1.2.840.113549.1.9.4",
'               "oidName": "messageDigest"
'             },
'             {
'               "oid": "1.2.840.113549.1.9.16.2.47",
'               "oidName": "signingCertificateV2",
'               "der": "MCYw .. 7PlQ=="
'             },
'             {
'               "oid": "1.2.840.113549.1.9.20",
'               "oidName": "1.2.840.113549.1.9.20"
'             }
'           ]
'         }
'       ]
'     }
'   }
' }

' Code for parsing the above JSON...
Dim i As Long
Dim count_i As Long
Dim strVal As String
Dim certSerialNumber As String
Dim certIssuerCN As String
Dim certIssuerDN As String
Dim certDigestAlgOid As String
Dim certDigestAlgName As String
Dim contentType As String
Dim signingTime As String
Dim messageDigest As String
Dim signingAlgOid As String
Dim signerDigest As String
Dim j As Long
Dim count_j As Long
Dim oid As String
Dim oidName As String
Dim der As String

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")
    certIssuerDN = json.StringOf("pkcs7.verify.signerInfo[i].cert.issuerDN")
    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")
    signingTime = json.StringOf("pkcs7.verify.signerInfo[i].signingTime")
    messageDigest = json.StringOf("pkcs7.verify.signerInfo[i].messageDigest")
    signingAlgOid = json.StringOf("pkcs7.verify.signerInfo[i].signingAlgOid")
    signerDigest = json.StringOf("pkcs7.verify.signerInfo[i].signerDigest")
    j = 0
    count_j = json.SizeOfArray("pkcs7.verify.signerInfo[i].authAttr")
    Do While j < count_j
        json.J = j
        oid = json.StringOf("pkcs7.verify.signerInfo[i].authAttr[j].oid")
        oidName = json.StringOf("pkcs7.verify.signerInfo[i].authAttr[j].oidName")
        der = json.StringOf("pkcs7.verify.signerInfo[i].authAttr[j].der")
        j = j + 1
    Loop
    i = i + 1
Loop

Debug.Print "Success!"