Examples with HybridEncrypt com.google.crypto.tink.HybridEncrypt used on opensource projects

Example 16 with HybridEncrypt

use of com.google.crypto.tink.HybridEncrypt in project tink by google.

the class WebPushHybridDecryptTest method testModifyCiphertext.

@Test
public void testModifyCiphertext() throws Exception {
    KeyPair uaKeyPair = EllipticCurves.generateKeyPair(WebPushConstants.NIST_P256_CURVE_TYPE);
    ECPrivateKey uaPrivateKey = (ECPrivateKey) uaKeyPair.getPrivate();
    ECPublicKey uaPublicKey = (ECPublicKey) uaKeyPair.getPublic();
    byte[] authSecret = Random.randBytes(16);
    HybridEncrypt hybridEncrypt = new WebPushHybridEncrypt.Builder().withAuthSecret(authSecret).withRecipientPublicKey(uaPublicKey).build();
    HybridDecrypt hybridDecrypt = new WebPushHybridDecrypt.Builder().withAuthSecret(authSecret).withRecipientPublicKey(uaPublicKey).withRecipientPrivateKey(uaPrivateKey).build();
    byte[] plaintext = Random.randBytes(20);
    byte[] ciphertext = hybridEncrypt.encrypt(plaintext, null);
    // Flipping bits.
    for (int b = 0; b < ciphertext.length; b++) {
        for (int bit = 0; bit < 8; bit++) {
            byte[] modified = Arrays.copyOf(ciphertext, ciphertext.length);
            modified[b] ^= (byte) (1 << bit);
            try {
                byte[] unused = hybridDecrypt.decrypt(modified, null);
                fail("Decrypting modified ciphertext should fail");
            } catch (GeneralSecurityException ex) {
            // This is expected.
            }
        }
    }
    // Truncate the message.
    for (int length = 0; length < ciphertext.length; length++) {
        byte[] modified = Arrays.copyOf(ciphertext, length);
        try {
            byte[] unused = hybridDecrypt.decrypt(modified, null);
            fail("Decrypting modified ciphertext should fail");
        } catch (GeneralSecurityException ex) {
        // This is expected.
        }
    }
}