(Xojo Plugin) Verify Opaque Signature and Retrieve Signing Certificates

Demonstrates how to verify a PCKS7 opaque digital signature (signed data), extract the original file/data, and then extract the certificate(s) that were used to sign.

Chilkat Xojo Plugin Download Xojo Plugin for Windows, Linux, Mac OS X, and ARM, ARM64

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

Dim crypt As New Chilkat.Crypt2

// Verify a PKCS7 signed-data (opaque signature) file and extract the original content to a file.
Dim success As Boolean
success = crypt.VerifyP7M("qa_data/p7m/opaqueSig.p7","qa_output/originalData.dat")
If (success <> True) Then
    System.DebugLog(crypt.LastErrorText)
    Return
End If

// Alternatively, we can do it in memory...
Dim binData As New Chilkat.BinData
success = binData.LoadFile("qa_data/p7m/opaqueSig.p7")
// Your app should check for success, but we'll skip the check for brevity..

// If verified, the signature is unwrapped and binData is replaced with the original data that was signed.
success = crypt.OpaqueVerifyBd(binData)
If (success <> True) Then
    System.DebugLog(crypt.LastErrorText)
    Return
End If

// For our testing, we signed some text, so we can get it from the binData..
System.DebugLog("Original Data:")
System.DebugLog(binData.GetString("utf-8"))

// After any method call that verifies a signature, the crypt object will contain the certificate(s)
// that were used for signing (assuming the X.509 certs were available in the signature, which is typically the case).

// Get the number of signing certificates, and get each..
Dim numCerts As Int32
numCerts = crypt.NumSignerCerts
Dim i As Int32
i = 0
While i < numCerts
    Dim cert As Chilkat.Cert
    cert = crypt.GetSignerCert(i)
    System.DebugLog(cert.SubjectDN)

    i = i + 1
Wend

// We could also get the complete certificate chain of each signer cert,
// assuming the certs in the chain of authentication to the trusted root
// are available on the system, or provided to Chilkat by some other means
// (such as via the XmlCertVault class, the TrustedRoots class, etc.)
i = 0
While i < numCerts
    Dim certChain As Chilkat.CertChain
    certChain = crypt.GetSignerCertChain(i)
    // You can examine the various properties and methods for certChain in the online
    // reference documentation...

    i = i + 1
Wend