RSA Public key getting changed after converting to RSAPublicKeySpec

问题

I have a RSA public key material as byte array (the key format is PKCS1). I create a PublicKey object out of it using RSAPublicKeySpec as shown below.

public Key retrievePubKey(byte[] derStuff){ // der stuff is my key material
    KeySpec ks = null;
    Key wrapKey = null;
    try {
        DerInputStream dis = new DerInputStream(derStuff);
        DerValue val = dis.getDerValue();
        BigInteger first = val.getData().getBigInteger();
        BigInteger second = val.getData().getBigInteger();
        ks = new RSAPublicKeySpec(first, second);
        KeyFactory kf = KeyFactory.getInstance("RSA", "IBMJCE");
        wrapKey = kf.generatePublic(ks);
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    return wrapKey;
}

Then I cast the Key to PublicKey

PublicKey pubKey = (PublicKey) mainObj.retrievePubKey(keyMaterial);

Now when I print the key material inside the pubKey, I get a different key material.

original key material 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

Converted key material

When I do byteArrayToHexString(pubKey.getEncoded());

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

Then I try to verify the signature using the new PublicKey pubKey - but it fails

The validityIndicator is false

Signature signerVerify = Signature.getInstance("SHA256withRSA", "IBMJCE"); // tried with "RSA" - Failing
        signerVerify.initVerify(pubKey);
        signerVerify.update(dataToBeSigned);
        boolean validityIndicator = signerVerify.verify(signature);

The dataToBeSigned and keyMaterial are taken from OASIS test cases I've tried several other methods (see here) explained on stackoverflow but none is working.

来源：https://stackoverflow.com/questions/36053558/rsa-public-key-getting-changed-after-converting-to-rsapublickeyspec

标签

java

encoding

cryptography

rsa

public-key