(VB.NET) Verify a .p7m and get Algorithm Information

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

Chilkat .NET Downloads Chilkat .NET Framework Chilkat for .NET Core

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

Dim crypt As New Chilkat.Crypt2

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

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


' Examine details about the signature(s)
Dim json As Chilkat.JsonObject = crypt.LastJsonData()
json.EmitCompact = False
Debug.WriteLine(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 Integer
Dim count_i As Integer
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 Integer
Dim count_j As Integer
Dim oid As String
Dim oidName As String
Dim der As String

i = 0
count_i = json.SizeOfArray("pkcs7.verify.digestAlgorithms")
While i < count_i
    json.I = i
    strVal = json.StringOf("pkcs7.verify.digestAlgorithms[i]")
    i = i + 1
End While
i = 0
count_i = json.SizeOfArray("pkcs7.verify.signerInfo")
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")
    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
    End While
    i = i + 1
End While



Debug.WriteLine("Success!")