1. Removed attestKey function and combined inside generateKey itself.

2. Made some memory optimizations.

Author: subrahmanyaman

Applet/src/com/android/javacard/keymaster/KMEncoder.java

@@ -77,6 +77,20 @@ private void encode(short obj) {
     push(obj);
   }
 
+  // Use this function, when the max len
+  public short encode(short object, byte[] buffer, short startOff, short maxLength) {
+    scratchBuf[STACK_PTR_OFFSET] = 0;
+    bufferRef[0] = buffer;
+    scratchBuf[START_OFFSET] = startOff;
+    if ((short) (startOff + maxLength) > buffer.length) {
+      ISOException.throwIt(ISO7816.SW_CONDITIONS_NOT_SATISFIED);
+    }
+    scratchBuf[LEN_OFFSET] = (short) (startOff + maxLength);
+    push(object);
+    encode();
+    return (short) (scratchBuf[START_OFFSET] - startOff);
+  }
+
   public short encode(short object, byte[] buffer, short startOff) {
     scratchBuf[STACK_PTR_OFFSET] = 0;
     bufferRef[0] = buffer;
@@ -87,60 +101,32 @@ public short encode(short object, byte[] buffer, short startOff) {
     } else {
       scratchBuf[LEN_OFFSET] = (short) buffer.length;
     }
-    //this.length = (short)(startOff + length);
     push(object);
     encode();
     return (short) (scratchBuf[START_OFFSET] - startOff);
   }
 
-  // array{KMError.OK,Array{KMByteBlobs}}
-  public void encodeCertChain(byte[] buffer, short offset, short length, short errInt32Ptr) {
-    bufferRef[0] = buffer;
-    scratchBuf[START_OFFSET] = offset;
-    scratchBuf[LEN_OFFSET] = (short) (offset + 1);
-    //Total length is ArrayHeader + [UIntHeader + length(errInt32Ptr)]
-    scratchBuf[LEN_OFFSET] += (short) (1 + getEncodedIntegerLength(errInt32Ptr));
-
-    writeMajorTypeWithLength(ARRAY_TYPE, (short) 2); // Array of 2 elements
-    encodeUnsignedInteger(errInt32Ptr);
-  }
-
   //array{KMError.OK,Array{KMByteBlobs}}
-  public short encodeCert(byte[] certBuffer, short bufferStart, short certStart, short certLength, short errInt32Ptr) {
+  public short encodeCert(byte[] certBuffer, short bufferStart, short certStart, short certLength) {
+    if (bufferStart > certStart) {
+      ISOException.throwIt(ISO7816.SW_DATA_INVALID);
+    }
     bufferRef[0] = certBuffer;
     scratchBuf[START_OFFSET] = certStart;
     scratchBuf[LEN_OFFSET] = (short) (certStart + 1);
-    //Array header - 2 elements i.e. 1 byte
-    scratchBuf[START_OFFSET]--;
-    // errInt32Ptr - PowerResetStatus + ErrorCode - 4 bytes
-    // Integer header - 1 byte
-    scratchBuf[START_OFFSET] -= getEncodedIntegerLength(errInt32Ptr);
-    //Array header - 2 elements i.e. 1 byte
+    // Byte Header + cert length
+    scratchBuf[START_OFFSET] -= getEncodedBytesLength(certLength);
+    //Array header - 1 elements i.e. 1 byte
     scratchBuf[START_OFFSET]--;
-    // Cert Byte blob - typically 2 bytes length i.e. 3 bytes header
-    scratchBuf[START_OFFSET] -= 2;
-    if (certLength >= SHORT_PAYLOAD) {
-      scratchBuf[START_OFFSET]--;
-    }
     if (scratchBuf[START_OFFSET] < bufferStart) {
       ISOException.throwIt(ISO7816.SW_WRONG_LENGTH);
     }
     bufferStart = scratchBuf[START_OFFSET];
-    writeMajorTypeWithLength(ARRAY_TYPE, (short) 2); // Array of 2 elements
-    encodeUnsignedInteger(errInt32Ptr); //PowerResetStatus + ErrorCode
-    writeMajorTypeWithLength(ARRAY_TYPE, (short) 1); // Array of 1 element
+    writeMajorTypeWithLength(ARRAY_TYPE, (short) 1); // Array of 1 elements
     writeMajorTypeWithLength(BYTES_TYPE, certLength); // Cert Byte Blob of length
     return bufferStart;
   }
 
-  public short encodeError(short errInt32Ptr, byte[] buffer, short startOff, short length) {
-    bufferRef[0] = buffer;
-    scratchBuf[START_OFFSET] = startOff;
-    scratchBuf[LEN_OFFSET] = (short) (startOff + length + 1);
-    encodeUnsignedInteger(errInt32Ptr);
-    return (short) (scratchBuf[START_OFFSET] - startOff);
-  }
-
   private void encode() {
     while (scratchBuf[STACK_PTR_OFFSET] > 0) {
       short exp = pop();
@@ -637,7 +623,7 @@ private short getEncodedArrayLen(short obj) {
     return len;
   }
 
-  private short getEncodedBytesLength(short len) {
+  public short getEncodedBytesLength(short len) {
     short ret = 0;
     if (len < KMEncoder.UINT8_LENGTH && len >= 0) {
       ret = 1;

Applet/src/com/android/javacard/keymaster/KMKeyCharacteristics.java

@@ -37,15 +37,13 @@ private KMKeyCharacteristics() {
   }
 
   public static short exp() {
-    short sb = KMKeyParameters.exp();
-    short tee = KMKeyParameters.exp();
-    short keystore = KMKeyParameters.exp();
+    short keyParamExp = KMKeyParameters.exp();
     short arrPtr = KMArray.instance((short) 3);
 
     KMArray arr = KMArray.cast(arrPtr);
-    arr.add(STRONGBOX_ENFORCED, sb);
-    arr.add(TEE_ENFORCED, tee);
-    arr.add(KEYSTORE_ENFORCED, keystore);
+    arr.add(STRONGBOX_ENFORCED, keyParamExp);
+    arr.add(TEE_ENFORCED, keyParamExp);
+    arr.add(KEYSTORE_ENFORCED, keyParamExp);
     return instance(arrPtr);
   }