ready_se/google/keymint/KM300/Applet/src/com/android/javacard/keymaster/KMCosePairNegIntegerTag.java

/*
 * Copyright(C) 2021 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.javacard.keymaster;

import javacard.framework.ISO7816;
import javacard.framework.ISOException;
import javacard.framework.Util;

/**
 * KMCosePairNegIntegerTag represents a key-value type, where key can be KMInteger or KMNInteger and
 * value is KMNInteger type. struct{byte TAG_TYPE; short length; struct{short NINT_VALUE_TYPE; short
 * key; short value}}.
 */
public class KMCosePairNegIntegerTag extends KMCosePairTagType {

  private static KMCosePairNegIntegerTag prototype;

  private KMCosePairNegIntegerTag() {}

  private static KMCosePairNegIntegerTag proto(short ptr) {
    if (prototype == null) {
      prototype = new KMCosePairNegIntegerTag();
    }
    instanceTable[KM_COSE_KEY_NINT_VAL_OFFSET] = ptr;
    return prototype;
  }

  // pointer to an empty instance used as expression
  public static short exp() {
    short ptr = instance(COSE_PAIR_TAG_TYPE, (short) 6);
    Util.setShort(heap, (short) (ptr + TLV_HEADER_SIZE), KMType.COSE_PAIR_NEG_INT_TAG_TYPE);
    Util.setShort(heap, (short) (ptr + TLV_HEADER_SIZE + 2), KMType.INVALID_VALUE);
    Util.setShort(heap, (short) (ptr + TLV_HEADER_SIZE + 4), KMNInteger.exp());
    return ptr;
  }

  public static KMCosePairNegIntegerTag cast(short ptr) {
    byte[] heap = repository.getHeap();
    if (heap[ptr] != COSE_PAIR_TAG_TYPE) {
      ISOException.throwIt(ISO7816.SW_CONDITIONS_NOT_SATISFIED);
    }
    // Validate the value ptr.
    short valuePtr = Util.getShort(heap, (short) (ptr + TLV_HEADER_SIZE + 4));
    if (NEG_INTEGER_TYPE != getType(valuePtr)) {
      ISOException.throwIt(ISO7816.SW_CONDITIONS_NOT_SATISFIED);
    }
    return proto(ptr);
  }

  public static short instance(short keyPtr, short valuePtr) {
    short offset = KMCosePairTagType.getKeyStartOffset(keyPtr);
    if (!KMCosePairTagType.isKeyPairValid(
        heap, offset, KMCose.COSE_KEY_MAX_SIZE, KMNInteger.cast(valuePtr).getShort())) {
      ISOException.throwIt(ISO7816.SW_CONDITIONS_NOT_SATISFIED);
    }
    short ptr = KMType.instance(COSE_PAIR_TAG_TYPE, (short) 6);
    Util.setShort(heap, (short) (ptr + TLV_HEADER_SIZE), KMType.COSE_PAIR_NEG_INT_TAG_TYPE);
    Util.setShort(heap, (short) (ptr + TLV_HEADER_SIZE + 2), keyPtr);
    Util.setShort(heap, (short) (ptr + TLV_HEADER_SIZE + 4), valuePtr);
    return ptr;
  }

  @Override
  public short getKeyPtr() {
    return Util.getShort(
        heap, (short) (instanceTable[KM_COSE_KEY_NINT_VAL_OFFSET] + TLV_HEADER_SIZE + 2));
  }

  @Override
  public short getValuePtr() {
    return Util.getShort(
        heap, (short) (instanceTable[KM_COSE_KEY_NINT_VAL_OFFSET] + TLV_HEADER_SIZE + 4));
  }
}