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/*
* Copyright(C) 2020 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;
/**
* KMBignumTag represents BIGNUM Tag Type from android keymaster hal specifications. The tag value
* of this tag is the KMByteBlob pointer i.e. offset of KMByteBlob in memory heap. struct{byte
* TAG_TYPE; short length; struct{short BIGNUM_TAG; short tagKey; short blobPtr}}
*/
public class KMBignumTag extends KMTag {
private static KMBignumTag prototype;
private KMBignumTag() {}
private static KMBignumTag proto(short ptr) {
if (prototype == null) {
prototype = new KMBignumTag();
}
KMType.instanceTable[KM_BIGNUM_TAG_OFFSET] = ptr;
return prototype;
}
// pointer to an empty instance used as expression
public static short exp() {
short blobPtr = KMByteBlob.exp();
short ptr = instance(TAG_TYPE, (short) 6);
Util.setShort(heap, (short) (ptr + TLV_HEADER_SIZE), BIGNUM_TAG);
Util.setShort(heap, (short) (ptr + TLV_HEADER_SIZE + 2), INVALID_TAG);
Util.setShort(heap, (short) (ptr + TLV_HEADER_SIZE + 4), blobPtr);
return ptr;
}
public static short instance(short key, short byteBlob) {
if (!validateKey(key, byteBlob)) {
ISOException.throwIt(ISO7816.SW_DATA_INVALID);
}
if (heap[byteBlob] != BYTE_BLOB_TYPE) {
ISOException.throwIt(ISO7816.SW_DATA_INVALID);
}
short ptr = instance(TAG_TYPE, (short) 6);
Util.setShort(heap, (short) (ptr + TLV_HEADER_SIZE), BIGNUM_TAG);
Util.setShort(heap, (short) (ptr + TLV_HEADER_SIZE + 2), key);
Util.setShort(heap, (short) (ptr + TLV_HEADER_SIZE + 4), byteBlob);
return ptr;
}
public static KMBignumTag cast(short ptr) {
if (heap[ptr] != TAG_TYPE) {
ISOException.throwIt(ISO7816.SW_CONDITIONS_NOT_SATISFIED);
}
if (Util.getShort(heap, (short) (ptr + TLV_HEADER_SIZE)) != BIGNUM_TAG) {
ISOException.throwIt(ISO7816.SW_CONDITIONS_NOT_SATISFIED);
}
return proto(ptr);
}
private static boolean validateKey(short key, short byteBlob) {
short valueLen = KMByteBlob.cast(byteBlob).length();
switch (key) {
case CERTIFICATE_SERIAL_NUM:
if (valueLen > MAX_CERTIFICATE_SERIAL_SIZE) {
return false;
}
break;
default:
return false;
}
return true;
}
public short getKey() {
return Util.getShort(
heap, (short) (KMType.instanceTable[KM_BIGNUM_TAG_OFFSET] + TLV_HEADER_SIZE + 2));
}
public short getTagType() {
return KMType.BIGNUM_TAG;
}
public short getValue() {
return Util.getShort(
heap, (short) (KMType.instanceTable[KM_BIGNUM_TAG_OFFSET] + TLV_HEADER_SIZE + 4));
}
public short length() {
short blobPtr =
Util.getShort(
heap, (short) (KMType.instanceTable[KM_BIGNUM_TAG_OFFSET] + TLV_HEADER_SIZE + 4));
return KMByteBlob.cast(blobPtr).length();
}
}
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