Sign a File to Create a .p7m File (using a PFX)

C# example to sign a file creating a .p7m file as output. The .p7m contains the signed contents of the original file. It can be verified and restored by calling VerifyP7M.

Download: Chilkat .NET Assemblies

Chilkat.Crypt2 crypt = new Chilkat.Crypt2();

//  Any string argument automatically begins the 30-day trial.
bool success;
success = crypt.UnlockComponent("30-day trial");
if (success != true) {
    textBox1.Text += crypt.LastErrorText + "\r\n";
    return;
}

//  Use a digital certificate and private key from a PFX file (.pfx or .p12).
string signingCertSubject;
signingCertSubject = "Acme Inc";
string pfxFilename;
pfxFilename = "/Users/chilkat/testData/pfx/acme.pfx";
string pfxPassword;
pfxPassword = "test123";

Chilkat.CertStore certStore = new Chilkat.CertStore();
success = certStore.LoadPfxFile(pfxFilename,pfxPassword);
if (success != true) {
    textBox1.Text += certStore.LastErrorText + "\r\n";
    return;
}

Chilkat.Cert cert = null;
cert = certStore.FindCertBySubjectCN(signingCertSubject);
if (cert == null ) {
    textBox1.Text += "Failed to find certificate by subject common name." + "\r\n";
    return;
}

//  Tell the crypt component to use this cert.
crypt.SetSigningCert(cert);

//  We can sign any type of file, creating a .p7m as output:
string inFile;
inFile = "/Users/chilkat/testData/pdf/sample.pdf";
string outFile;
outFile = "/Users/chilkat/testData/p7m/sample.pdf.p7m";
success = crypt.CreateP7M(inFile,outFile);
if (success == false) {
    textBox1.Text += crypt.LastErrorText + "\r\n";

    return;
}

//  Verify and restore the original file:
crypt.SetVerifyCert(cert);

inFile = outFile;
outFile = "/Users/chilkat/testData/pdf/restored.pdf";

success = crypt.VerifyP7M(inFile,outFile);
if (success == false) {
    textBox1.Text += crypt.LastErrorText + "\r\n";

    return;
}

MessageBox.Show("Success!");