(Excel) Verify a CAdES-BES Signature and Examine Signature Contents

Demonstrates how to validate a .p7m (.p7s) signature and examine the contents of the signature.

Download Excel Class Modules Chilkat Excel Class Modules

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

Dim crypt As Chilkat.Crypt2
Set crypt = Chilkat.NewCrypt2


outputFile = "qa_output/original.xml"

inFile = "qa_data/p7m/fattura_signature.xml.p7m"

' Verify the signature and extract the contained file, which in this case is XML.

success = crypt.VerifyP7M(inFile,outputFile)
If (success = False) Then
    Debug.Print crypt.LastErrorText
    Exit Sub
End If

Debug.Print "Signature validated."

' Now let's examine the information about the signature.

Set json = crypt.LastJsonData()
If (crypt.LastMethodSuccess = False) Then
    ' This should never be the case...
    Debug.Print "No information available."
    Exit Sub
End If

json.EmitCompact = False
Debug.Print json.Emit()

' Here's an example of the information about the signature:
' {
'   "pkcs7": {
'     "verify": {
'       "certs": [
'         {
'           "issuerCN": "Xyz EU Qualified Certificates CA G1",
'           "serial": "99A28A51AC389999"
'         }
'       ],
'       "useConstructedOctets": true,
'       "digestAlgorithms": [
'         "sha256"
'       ],
'       "signerInfo": [
'         {
'           "cert": {
'             "subjectKeyIdentifier": "5VM4x8AWnXf07yzbXuLtbb0U3yY=",
'             "digestAlgOid": "2.16.840.1.101.3.4.2.1",
'             "digestAlgName": "SHA256"
'           },
'           "signingAlgOid": "1.2.840.113549.1.1.11",
'           "signingAlgName": "RSA-SHA256-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": "190901152340Z"
'             },
'             "1.2.840.113549.1.9.4": {
'               "name": "messageDigest",
'               "digest": "y+gd/zAQK33A//HInhaZba7w1fUJleV9AHbP1Ntx6U0="
'             },
'             "1.2.840.113549.1.9.16.2.47": {
'               "name": "signingCertificateV2",
'               "der": "MIH4MI..w4vv0="
'             }
'           }
'         }
'       ]
'     }
'   }
' }

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

Dim authAttrSigningTimeUtctime As Chilkat.DtObj
Set authAttrSigningTimeUtctime = Chilkat.NewDtObj


i = 0

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
    certSubjectKeyIdentifier = json.StringOf("pkcs7.verify.signerInfo[i].cert.subjectKeyIdentifier")
    certDigestAlgOid = json.StringOf("pkcs7.verify.signerInfo[i].cert.digestAlgOid")
    certDigestAlgName = json.StringOf("pkcs7.verify.signerInfo[i].cert.digestAlgName")
    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")
    Dim success As Boolean
    success = json.DtOf("pkcs7.verify.signerInfo[i].authAttr.""1.2.840.113549.1.9.5"".utctime",False,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")
    authAttrSigningCertificateV2Name = json.StringOf("pkcs7.verify.signerInfo[i].authAttr.""1.2.840.113549.1.9.16.2.47"".name")
    authAttrSigningCertificateV2Der = json.StringOf("pkcs7.verify.signerInfo[i].authAttr.""1.2.840.113549.1.9.16.2.47"".der")
    i = i + 1
Loop