CODEWITHSUNDEEP
javaencryption
Conner Dassen
Conner Dassen

Reputation: 740

KeyStore.getKey() is returning null

I generated a keystore using keytool with this command:

keytool -genkey -alias serverprivate -keystore serverprivate.jks -storetype JKS -keyalg RSA -sigalg SHA256withRSA -keysize 2048 -storepass doyouknowdewey

The key pass and store pass are the same. Then I extract the public key and insert it into it's own keystore:

keytool -export -alias serverprivate -keystore serverprivate.jks -file temp.key -storepass doyouknowdewey
keytool -import -noprompt -alias serverpublic -keystore serverpublic.jks -file temp.key -storepass public

Now I create an InputStream in java with a keystore and create a KeyStore object:

InputStream is = getClass().getResourceAsStream("keys/serverprivate.jks");
KeyStore serverPrivate = KeyStore.getInstance("JKS");
serverPrivate.load(is, "doyouknowdewey".toCharArray());

And I extract the key to make a cipher instance so can encrypt and decrypt the text:

Key key = serverPrivate.getKey("serverprivate", "douyouknowdewey".toCharArray());

This all works fine, and I can encrypt data with the private key. But if I try decrpyting/encrypting with the public key, the Key object is null:

InputStream is = getClass().getResourceAsStream("keys/serverpublic.jks");
KeyStore serverPublic = KeyStore.getInstance("JKS");
serverPublic.load(is, "public".toCharArray());
Key key = serverPrivate.getKey("serverpublic", "public".toCharArray());
if(key == null) {
    System.err.println("Key is null");
} 
//returns null

So how do I make this work?

EDIT:

Apparently serverpublic isn't a key, but a certificate. I found out by running serverPublic.isKeyEntry("serverpublic");, which returned false, while serverPublic.isCertificateEntry("serverpublic"); returned true. So I changed the code to this:

InputStream is = getClass().getResourceAsStream("keys/serverpublic.jks");
KeyStore serverPublic = KeyStore.getInstance("JKS");
serverPublic.load(is, "public".toCharArray());
Certificate cert = serverPrivate.getCertificate("serverpublic");
if(cert == null) {
    System.err.println("Key is null");
}

This doesn't return null any longer. But when I run this, cipher.init still throws a nullpointer exception:

Cipher cipher;
cipher.init(Cipher.ENCRYPT_MODE, cert);

Upvotes: 0

Views: 4974

Answers (1)

Conner Dassen
Conner Dassen

Reputation: 740

serverpublic wasn't a key, but a certificate. I had to load it using 

Certificate cert = serverPrivate.getCertificate("serverpublic");

and then call

Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, cert);

Upvotes: 1

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