(.NET Core C#) Decrypt a .p7m File (using a PFX)

.NET Core C# sample code showing how to decrypt a .p7m using a .p12 / .pfx certificate w/ private key.

Chilkat .NET Downloads Chilkat .NET Assemblies Chilkat for .NET Core Chilkat for Mono

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

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

// Use a digital certificate and private key from a PFX file (.pfx or .p12).
string pfxPath = "myCertAndKey.pfx";
string pfxPassword = "test123";

bool success = crypt.AddPfxSourceFile(pfxPath,pfxPassword);
if (success != true) {
    Debug.WriteLine(crypt.LastErrorText);
    return;
}

// Set the  outPath to whatever is appropriate.
// If you are decrypting a PDF, your output might be "out.pdf"...
string inPath = "smime.p7m";
string outPath = "original.txt";

// Indicate that we're doing public key decryption (i.e. PKCS7)
crypt.CryptAlgorithm = "pki";

success = crypt.CkDecryptFile(inPath,outPath);
if (success == false) {
    Debug.WriteLine(crypt.LastErrorText);
    return;
}

Debug.WriteLine("Success.");