(Go) 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).

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

    jks := chilkat.NewJavaKeyStore()

    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.
    success := jks.LoadFile(jksPassword,"/someDir/keyStore.jks")
    if success != true {
        fmt.Println(jks.LastErrorText())
        jks.DisposeJavaKeyStore()
        return
    }

    // To convert, we'll access the private key entries
    // from the JKS, add each to the PKCS12, and then save the PKCS12.
    pkcs12 := chilkat.NewPfx()

    numPrivateKeys := jks.NumPrivateKeys()
    var i int

    // privKey is a PrivateKey
    // certChain is a CertChain

    // 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
    for i < numPrivateKeys {
        privKey := jks.GetPrivateKey(jksPassword,i)
        fmt.Println(*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 {
            fmt.Println(pkcs12.LastErrorText())
            certChain.DisposeCertChain()
            privKey.DisposePrivateKey()
            jks.DisposeJavaKeyStore()
            pkcs12.DisposePfx()
            return
        }

        certChain.DisposeCertChain()
        privKey.DisposePrivateKey()
        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.)
    pkcs12Password := "myNewPassword"
    success = pkcs12.ToFile(pkcs12Password,"/pkcs12_files/myPfx.p12")
    if success != true {
        fmt.Println(pkcs12.LastErrorText())
    }
    else {
        fmt.Println("Successfully saved to PKCS12 format.")
    }


    jks.DisposeJavaKeyStore()
    pkcs12.DisposePfx()