B4X Requires Chilkat v11.0.0+

Verify a .p7m and get Algorithm Information

See more Digital Signatures Examples

Demonstrates how to verify a .p7m and then examine the algorithms used by the signature. B4X

Dim success As Boolean = False

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

Dim crypt As ChilkatCrypt2
crypt.Initialize("crypt")

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

'  Verify and extract the signed data.
success = crypt.VerifyP7M(inFile, outFile)
If success = False Then
    Log(crypt.LastErrorText)
    Return
End If


'  Examine details about the signature(s)
Dim json As ChilkatJsonObject
json.Initialize
crypt.GetLastJsonData(json)
json.EmitCompact = False
Log(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 Int
Dim count_i As Int
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 Int
Dim count_j As Int
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

Log("Success!")