1 files changed, 80 insertions, 0 deletions
diff --git a/ready_se/google/keymint/KM200/Applet/src/com/android/javacard/keymaster/KMSemanticTag.java b/ready_se/google/keymint/KM200/Applet/src/com/android/javacard/keymaster/KMSemanticTag.java
new file mode 100644
index 0000000..07b2675
--- /dev/null
+++ b/ready_se/google/keymint/KM200/Applet/src/com/android/javacard/keymaster/KMSemanticTag.java
@@ -0,0 +1,80 @@
+package com.android.javacard.keymaster;
+
+import javacard.framework.ISO7816;
+import javacard.framework.ISOException;
+import javacard.framework.Util;
+
+/**
+ * KMSemanticTag corresponds to CBOR type of tagged item. The structure is defined as struct{byte
+ * SEMANTIC_TAG_TYPE; short length; tag, short ptr }. Tag is INTEGER_TYPE and the possible values
+ * are defined here https://www.rfc-editor.org/rfc/rfc7049#section-2.4
+ */
+public class KMSemanticTag extends KMType {
+
+  public static final short COSE_MAC_SEMANTIC_TAG = (short) 0x0011;
+  public static final short ROT_SEMANTIC_TAG = (short) 0x9C41;
+  private static KMSemanticTag prototype;
+
+  private KMSemanticTag() {}
+
+  private static KMSemanticTag proto(short ptr) {
+    if (prototype == null) {
+      prototype = new KMSemanticTag();
+    }
+    instanceTable[KM_SEMANTIC_TAG_OFFSET] = ptr;
+    return prototype;
+  }
+
+  // pointer to an empty instance used as expression
+  public static short exp(short valuePtr) {
+    short ptr = KMType.instance(SEMANTIC_TAG_TYPE, (short) 6);
+    Util.setShort(heap, (short) (ptr + TLV_HEADER_SIZE + 2), KMInteger.exp());
+    Util.setShort(heap, (short) (ptr + TLV_HEADER_SIZE + 4), valuePtr);
+    return ptr;
+  }
+
+  public static KMSemanticTag cast(short ptr) {
+    if (heap[ptr] != SEMANTIC_TAG_TYPE) {
+      ISOException.throwIt(ISO7816.SW_CONDITIONS_NOT_SATISFIED);
+    }
+    return proto(ptr);
+  }
+
+  public static short instance(short tag, short value) {
+    if (!isSemanticTagSupported(tag)) {
+      ISOException.throwIt(ISO7816.SW_DATA_INVALID);
+    }
+    // The maximum tag size can be UINT32. Currently, we support
+    // only two tags which are short.
+    short ptr = KMType.instance(SEMANTIC_TAG_TYPE, (short) 6);
+    Util.setShort(heap, (short) (ptr + TLV_HEADER_SIZE + 2), tag);
+    Util.setShort(heap, (short) (ptr + TLV_HEADER_SIZE + 4), value);
+    return ptr;
+  }
+
+  private static boolean isSemanticTagSupported(short tag) {
+    tag = KMInteger.cast(tag).getShort();
+    switch (tag) {
+      case COSE_MAC_SEMANTIC_TAG:
+      case ROT_SEMANTIC_TAG:
+        break;
+      default:
+        return false;
+    }
+    return true;
+  }
+
+  public short length() {
+    return Util.getShort(heap, (short) (instanceTable[KM_SEMANTIC_TAG_OFFSET] + 1));
+  }
+
+  public short getKeyPtr() {
+    return Util.getShort(
+        heap, (short) (instanceTable[KM_SEMANTIC_TAG_OFFSET] + TLV_HEADER_SIZE + 2));
+  }
+
+  public short getValuePtr() {
+    return Util.getShort(
+        heap, (short) (instanceTable[KM_SEMANTIC_TAG_OFFSET] + TLV_HEADER_SIZE + 4));
+  }
+}