Algorithm and Padding from PKCS 12 File

You mean:

public class MyPKCS12 {

public static void main(String args[]) throws Exception {

FileInputStream fis = new FileInputStream("./mypass.p12");

KeyStore ks = KeyStore.getInstance("PKCS12");

ks.load(fis, "xyzzy".toCharArray());

for (Enumeration<String> e = ks.aliases() ; e.hasMoreElements() ;) {

String s = e.nextElement();

System.out.println("Alias: " + s);

Key k = ks.getKey(s, "xyzzy".toCharArray());

System.out.println("Private Key = " + k);

System.out.println("k.getAlgorithm() = " + k.getAlgorithm());

System.out.println("k.getFormat() = " + k.getFormat());

k = ks.getCertificate(s).getPublicKey();

System.out.println("Public Key = " + k);

System.out.println("k.getAlgorithm() = " + k.getAlgorithm());

System.out.println("k.getFormat() = " + k.getFormat());

}

}

}

Hopefully, the following reference isn't too in-depth, but here is in the standard.

http://www.rsasecurity.com/rsalabs/node.asp?id=2138

It assumes you understand basic ASN.1.

You can also have a look at the PKCS12 provider source in the JDK 5.0 JSSE code, which is available through SCSL in the JDK security bundle. Sun's implementation doesn't support every possible mode/attribute, but does all of the common ones.

wetmorea at 2007-7-16 12:59:37 >

> On one hand I can see where the padding wouldn't

> necessarily be stored with the key since you can use

> any padding scheme you like with the key. But on the

> other hand, that info must be available somewhere,

> otherwise how would you know what padding scheme to

> use to decrypt data encrypted with the public key? I

> have to have pass the correct info to the

> Cipher.getInstance() method.

I'm a little confused here.

Are you trying to write your own PKCS12 keystore implementation? Or use the private keys obtained from a PKCS keystore to do some Cipher initialization to recover some plaintext from ciphertext? If the latter, which I think is the case, you need to find out what the encryption side originally used for padding the data to be encrypted. This is not a function how the key itself was stored. I may be misunderstanding the question, so apologies if it takes another round of Q&A.

c = Cipher.getInstance("RSA/ECB/PKCS1Padding");

c.init(ENCRYPT_MODE, publicKey);

byte [] b = c.doFinal(plainText);

Peer sends you b

c = Cipher.getInstance("RSA/ECB/PKCS1Padding");

c.init(ENCRYPT_MODE, privateKey);

byte [] recoveredText = c.doFinal(b);

AFAIK, Sun's RSA implementation in SunJCE has NoPadding (aka RawDSA-rarely used), PKCS1Padding (most common), & OAEP. Also note, you can't use RSA for bulk encipherment. There's no standard for bulk encipherment, besides it would be too slow compared to a symmetric cipher. RSA is typically used when settling on a bulk symmetric session key (AES/DES/RC4/etc.)

Hope this helps.

wetmorea at 2007-7-16 12:59:37 >