Convert SSL .pem to .p12 with or without OpenSSL

Question

I get external .pem files that need to be converted to .p12 files - I add a username and password in the process. (I need to do this to utilize a thir

Answer 1

This solutions is an adaptation of @sascha-arthur's to accomodate for:

• Handles edge-case where PrivateKey format is not as expected.
• Gracefully handle scenario where public key is not available
• Fixed a few minor redundancies and formatting

The code:

String alias="myalias";
char[] password = "mypassword".toCharArray();

// Private Key
PEMParser pem = new PEMParser(new FileReader(keyFile));
Object parsedObject = pem.readObject();

PrivateKeyInfo privateKeyInfo = parsedObject instanceof PEMKeyPair ? ((PEMKeyPair)parsedObject).getPrivateKeyInfo() : (PrivateKeyInfo)parsedObject;
PKCS8EncodedKeySpec privateKeySpec = new PKCS8EncodedKeySpec(privateKeyInfo.getEncoded());
KeyFactory factory = KeyFactory.getInstance("RSA");
PrivateKey key = factory.generatePrivate(privateKeySpec);

List certs = new ArrayList<>();
X509CertificateHolder certHolder = (X509CertificateHolder)pem.readObject();
if(certHolder != null) {
    certs.add(new JcaX509CertificateConverter().setProvider("BC").getCertificate(certHolder));
}

// Certificate
pem = new PEMParser(new FileReader(certFile));
while((certHolder = (X509CertificateHolder)pem.readObject()) != null) {
    certs.add(new JcaX509CertificateConverter().setProvider("BC").getCertificate(certHolder));
}

// Keystore
KeyStore ks = KeyStore.getInstance("PKCS12");
ks.load(null);

for (int i = 0; i < certs.size(); i++) {
    ks.setCertificateEntry(alias + "_" + i, certs.get(i));
}

KeyStore keyStore = KeyStore.getInstance("PKCS12");
keyStore.load(null);
keyStore.setKeyEntry(alias, key, password, certs.toArray(new X509Certificate[certs.size()]));

For this to work with a LetsEncrypt certificate, you'll need to use the following files:

• privkey.pem
• fullchain.pem