Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 119dcabc authored by Eric Biggers's avatar Eric Biggers
Browse files

Store output of SP800Derive in non-movable byte array 

Bug: 320392352
Test: atest FrameworksServicesTests:com.android.server.locksettings
Flag: EXEMPT bug fix
Change-Id: Ic61adda98d8148345b10266e5772c064fb4a6dfc
parent b8ddf755

services/core/java/com/android/server/locksettings/SP800Derive.java

+22 −3
Original line number Diff line number Diff line
@@ -16,11 +16,14 @@ 


package com.android.server.locksettings;



import com.android.internal.util.ArrayUtils;



import java.nio.ByteBuffer;

import java.security.InvalidKeyException;

import java.security.NoSuchAlgorithmException;



import javax.crypto.Mac;

import javax.crypto.ShortBufferException;

import javax.crypto.spec.SecretKeySpec;



/**
@@ -34,6 +37,8 @@ import javax.crypto.spec.SecretKeySpec; 
 * L suffix: 32 bits

 */

class SP800Derive {

    private static final int OUTPUT_LENGTH = 32; // length of output in bytes



    private final byte[] mKeyBytes;



    SP800Derive(byte[] keyBytes) {
@@ -44,6 +49,9 @@ class SP800Derive { 
        try {

            final Mac m = Mac.getInstance("HmacSHA256");

            m.init(new SecretKeySpec(mKeyBytes, m.getAlgorithm()));

            if (m.getMacLength() != OUTPUT_LENGTH) {

                throw new IllegalStateException("Wrong output length");

            }

            return m;

        } catch (InvalidKeyException | NoSuchAlgorithmException e) {

            throw new RuntimeException(e);
@@ -61,7 +69,7 @@ class SP800Derive { 
        final Mac m = getMac();

        update32(m, 1); // Hardwired counter value

        m.update(fixedInput);

        return m.doFinal();

        return doFinal(m);

    }



    /**
@@ -76,7 +84,18 @@ class SP800Derive { 
        m.update((byte) 0);

        m.update(context);

        update32(m, context.length * 8); // Disambiguate context

        update32(m, 256); // Hardwired output length

        return m.doFinal();

        update32(m, OUTPUT_LENGTH * 8); // Hardwired output length

        return doFinal(m);

    }



    // Same as m.doFinal(), but returns the output in a non-movable byte array.

    private byte[] doFinal(Mac m) {

        final byte[] mac = ArrayUtils.newNonMovableByteArray(OUTPUT_LENGTH);

        try {

            m.doFinal(mac, 0);

            return mac;

        } catch (ShortBufferException e) {

            throw new RuntimeException(e);

        }

    }

}

services/tests/servicestests/src/com/android/server/locksettings/SP800DeriveTests.java

+14 −0
Original line number Diff line number Diff line
@@ -49,4 +49,18 @@ public class SP800DeriveTests { 
                "770dfab6a6a4a4bee0257ff335213f78"

                + "d8287b4fd537d5c1fffa956910e7c779").toUpperCase(), HexDump.toHexString(res));

    }



    @Test

    public void testWithContext() throws Exception {

        byte[] keyBytes = HexDump.hexStringToByteArray(

            "e204d6d466aad507ffaf6d6dab0a5b26"

            + "152c9e21e764370464e360c8fbc765c6");

        SP800Derive sk = new SP800Derive(keyBytes);

        byte[] label = HexDump.hexStringToByteArray("ed8282442dbfe03aaa1799faa5");

        byte[] context = HexDump.hexStringToByteArray("6c0b857412ef52");

        byte[] res = sk.withContext(label, context);

        assertEquals((

                "21658822e750a33d9ed743627697f0ea"

                + "12543b5edef19cc453f01da949e5e37f").toUpperCase(), HexDump.toHexString(res));

    }

}