Valid parameters when generate ECKeyPair

[UNKNwYSHSA]

Code like this:

Code: Select all

         KeyPair keyPair = new KeyPair(KeyPair.ALG_EC_FP, KeyBuilder.LENGTH_EC_FP_160);
         ECPublicKey publicKey = (ECPublicKey) keyPair.getPublic();
         ECPrivateKey privateKey = (ECPrivateKey) keyPair.getPrivate();
         byte[] a1 = {};
         byte[] b1 = {};
         byte[] a2 = {};
         byte[] b2 = {};
         publicKey.setA(a1, (short) 0, (short) a1.length);
         publicKey.setB(b1, (short) 0, (short) b1.length);
         // ...;
         privateKey.setA(a2, (short) 0, (short) a2.length);
         privateKey.setB(b2, (short) 0, (short) b2.length);
         // ...;
         keyPair.genKeyPair();
         break;

when key pair generated, Which parameters play a role? publicKey's or privateKey's???
I'll have a test on the jcop card, wait the result.

[UNKNwYSHSA]

I found that.

class javacard.security.KeyPair
method public final void genKeyPair()
For the EC case, if the Field, A, B, G and R parameters of the public key object are pre-initialized, then they will be retained. Otherwise default pre-specified values MAY be used (e.g. WAP predefined curves), since computation of random generic EC keys is infeasible on the smart card platform.

The parameters of public key is used.

[UNKNwYSHSA]

The usual practice is use the public key parameters to generate keypair. (algorithm is EC, RSA or DSA)