(C# UWP/WinRT) Convert Java KeyStore to PKCS12 / PFX

Loads a Java keystore file and saves it as a PKCS12 / PFX. A Java keystore (JKS) can contain two types of entries: (1) trusted root certificates or (2) private keys + cert chains. Usually a JKS will contain all entries of one type or another (and thus a particular JKS serves one purpose or another; meaning that a JKS containing trusted roots is used as a source for verifying pre-trusted roots, and a JKS containing private keys (and cert chains) is used as a secure, encrypted store for private keys).

A PKCS12 / PFX typically contains one or more private keys, along with each private key's certificate chain. Therefore, it typically makes sense to only write the private key entries to a PKCS12 (and the associated certificate chains). If a JKS contains trusted root certificates, it makes more sense to conver it to a PEM file (such as the CA cert bundle in PEM format from mozilla.org).

Chilkat Universal Windows Platform (UWP) / WinRT Downloads Chilkat for the Universal Windows Platform (UWP)

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

Chilkat.JavaKeyStore jks = new Chilkat.JavaKeyStore();

string jksPassword = "myJksPassword";

// Load the Java keystore from a file.  The JKS file password is used
// to verify the keyed digest that is found at the very end of the keystore.
// It verifies that the keystore has not been modified.
bool success = jks.LoadFile(jksPassword,"/someDir/keyStore.jks");
if (success != true) {
    Debug.WriteLine(jks.LastErrorText);
    return;
}

// To convert, we'll access the private key entries
// from the JKS, add each to the PKCS12, and then save the PKCS12.
Chilkat.Pfx pkcs12 = new Chilkat.Pfx();

int numPrivateKeys = jks.NumPrivateKeys;
int i;

Chilkat.PrivateKey privKey = null;
Chilkat.CertChain certChain = null;

// For each private key entry, get the private key and
// the associated certificate chain.
// Each private key is password protected.  Usually it is the same
// password as used for the keyed digest of the entire JKS.  
// However, this does not have to be.  The password is passed
// here to handle the possibility of each private key requiring
// a different password.
i = 0;
while (i < numPrivateKeys) {
    privKey = jks.GetPrivateKey(jksPassword,i);
    Debug.WriteLine(jks.GetPrivateKeyAlias(i));
    certChain = jks.GetCertChain(i);

    // Add the private key and it's associated certificate chain to the PKCS12.
    success = pkcs12.AddPrivateKey(privKey,certChain);
    if (success != true) {
        Debug.WriteLine(pkcs12.LastErrorText);

        return;
    }

    i = i + 1;
}

// Save the PKCS12 / PFX to a file.
// The password can be the same as the JKS password, or something new.
// (With the PKCS12 format, there is a single password for the entire contents
// of the file.  With the JKS format, there is flexibility in allowing each private key
// to have it's own password.)
string pkcs12Password = "myNewPassword";
success = pkcs12.ToFile(pkcs12Password,"/pkcs12_files/myPfx.p12");
if (success != true) {
    Debug.WriteLine(pkcs12.LastErrorText);
}
else {
    Debug.WriteLine("Successfully saved to PKCS12 format.");
}