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

Commit 3b1abba6 authored by Kenny Root's avatar Kenny Root
Browse files

OBB: use PBKDF2 for key generation. 

Switch to using PBKDF2 for the key generation for OBBs. Any previously
generated OBBs will stop being read correctly. A small pbkdf2gen program
is available to allow generation of appropriate keys with the salts.

Bug: 3059950
Change-Id: If4305c989fd692fd1150eb270dbf751e09c37295
parent dfc07279

core/java/android/content/res/ObbInfo.java

+9 −0
Original line number Diff line number Diff line
@@ -48,6 +48,13 @@ public class ObbInfo implements Parcelable { 
     */

    public int flags;



    /**

     * The salt for the encryption algorithm.

     * 

     * @hide

     */

    public byte[] salt;



    // Only allow things in this package to instantiate.

    /* package */ ObbInfo() {

    }
@@ -75,6 +82,7 @@ public class ObbInfo implements Parcelable { 
        dest.writeString(packageName);

        dest.writeInt(version);

        dest.writeInt(flags);

        dest.writeByteArray(salt);

    }



    public static final Parcelable.Creator<ObbInfo> CREATOR
@@ -93,5 +101,6 @@ public class ObbInfo implements Parcelable { 
        packageName = source.readString();

        version = source.readInt();

        flags = source.readInt();

        salt = source.createByteArray();

    }

}

core/jni/android_content_res_ObbScanner.cpp

+11 −0
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ static struct { 
    jfieldID packageName;

    jfieldID version;

    jfieldID flags;

    jfieldID salt;

} gObbInfoClassInfo;



static void doThrow(JNIEnv* env, const char* exc, const char* msg = NULL)
@@ -69,6 +70,14 @@ static void android_content_res_ObbScanner_getObbInfo(JNIEnv* env, jobject clazz 
    env->SetObjectField(obbInfo, gObbInfoClassInfo.packageName, packageName);

    env->SetIntField(obbInfo, gObbInfoClassInfo.version, obb->getVersion());

    env->SetIntField(obbInfo, gObbInfoClassInfo.flags, obb->getFlags());



    size_t saltLen;

    const unsigned char* salt = obb->getSalt(&saltLen);

    if (saltLen > 0) {

        jbyteArray saltArray = env->NewByteArray(saltLen);

        env->SetByteArrayRegion(saltArray, 0, saltLen, (jbyte*)salt);

        env->SetObjectField(obbInfo, gObbInfoClassInfo.salt, saltArray);

    }

}



/*
@@ -99,6 +108,8 @@ int register_android_content_res_ObbScanner(JNIEnv* env) 
            "version", "I");

    GET_FIELD_ID(gObbInfoClassInfo.flags, gObbInfoClassInfo.clazz,

            "flags", "I");

    GET_FIELD_ID(gObbInfoClassInfo.salt, gObbInfoClassInfo.clazz,

            "salt", "[B");



    return AndroidRuntime::registerNativeMethods(env, "android/content/res/ObbScanner", gMethods,

            NELEM(gMethods));

core/tests/coretests/res/raw/test1.obb

+8 B (36.6 KiB)

File changed.

No diff preview for this file type.

View original file
View changed file

include/utils/ObbFile.h

+27 −0
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ namespace android { 


// OBB flags (bit 0)

#define OBB_OVERLAY         (1 << 0)

#define OBB_SALTED          (1 << 1)



class ObbFile : public RefBase {

protected:
@@ -70,6 +71,26 @@ public: 
        mFlags = flags;

    }



    const unsigned char* getSalt(size_t* length) const {

        if ((mFlags & OBB_SALTED) == 0) {

            *length = 0;

            return NULL;

        }



        *length = sizeof(mSalt);

        return mSalt;

    }



    bool setSalt(const unsigned char* salt, size_t length) {

        if (length != sizeof(mSalt)) {

            return false;

        }



        memcpy(mSalt, salt, sizeof(mSalt));

        mFlags |= OBB_SALTED;

        return true;

    }



    bool isOverlay() {

        return (mFlags & OBB_OVERLAY) == OBB_OVERLAY;

    }
@@ -103,6 +124,12 @@ private: 
    /* Flags for this OBB type. */

    int32_t mFlags;



    /* Whether the file is salted. */

    bool mSalted;



    /* The encryption salt. */

    unsigned char mSalt[8];



    const char* mFileName;



    size_t mFileSize;