Lianja

Verify Opaque Signature and Retrieve Signing Certificates

See more Digital Signatures Examples

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. Lianja

llSuccess = .F.

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

loCrypt = createobject("CkCrypt2")

// Verify a PKCS7 signed-data (opaque signature) file and extract the original content to a file.
llSuccess = loCrypt.VerifyP7M("qa_data/p7m/opaqueSig.p7","qa_output/originalData.dat")
if (llSuccess = .F.) then
    ? loCrypt.LastErrorText
    release loCrypt
    return
endif

// Alternatively, we can do it in memory...
loBinData = createobject("CkBinData")
llSuccess = loBinData.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.
llSuccess = loCrypt.OpaqueVerifyBd(loBinData)
if (llSuccess = .F.) then
    ? loCrypt.LastErrorText
    release loCrypt
    release loBinData
    return
endif

// For our testing, we signed some text, so we can get it from the binData..
? "Original Data:"
? loBinData.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 each signing certificate, and build the certificate chain for each.
loCert = createobject("CkCert")
loCertChain = createobject("CkCertChain")
lnNumCerts = loCrypt.NumSignerCerts
i = 0
do while i < lnNumCerts
    loCrypt.LastSignerCert(i,loCert)
    ? loCert.SubjectDN

    llSuccess = loCert.BuildCertChain(loCertChain)
    if (llSuccess = .F.) then
        ? loCert.LastErrorText
        release loCrypt
        release loBinData
        release loCert
        release loCertChain
        return
    endif

    i = i + 1
enddo


release loCrypt
release loBinData
release loCert
release loCertChain