A Digital Rights Enabled Graphics Processing System

A Digital Rights Enabled Graphics Processing System

Weidong Shi

Hsien-Hsin “Sean” Lee

Richard M. Yoo

Alexandra Boldyreva

Motorola Labs

Georgia Tech

Georgia Tech

Georgia Tech

Why Digital Rights Management (DRM) and Content Protection? Why Digital Rights Management (DRM) and Content Protection?

• id software Kevin Cloud

• "this (piracy) is what’s killing

PC games"

• “… but you may literally have more games being played illegitimately than being played

legitimately.”

• “… it is a very serious problem. 

There isn’t any magical solution, or else we’d solve

it.”

Graphics As AssetsGraphics As Assets

• Protect graphics apps by protecting the graphics assets instead of the sw.

• Avatars, in-game graphics assets sale raise steadily

• $10M per month in-game assets sale in Korea alone

• $880M trading in US (2004)

It is a non-trivial taskIt is a non-trivial task

• If security is easy to add, it is easy to remove.

• Never underestimate the hackers (XBOX incidence)

• Graphics DRM

• Protect against SW attacks

• Protect against simple

“Radioshack” HW attacks

Software-based DRMSoftware-based DRM

• Disadvantages

• Insecure

• Not tamper proof

• Advantages

• Easy to change

• Flexible

3D apps3D apps

meshmesh texturetexture shadershader

OpenGL/Direct3DOpenGL/Direct3D SW

DRMDRM

Frame Buffer

DRM Design SpaceDRM Design Space

• Many design choices for unlocking DRMed contents.

• Hackers can always go to the level below to defeat a DRM system.

• Typical SW DRM unlocks at App level.

Real time3D apps

Real time3D apps

Graphics API(OpenGL/Direct3D)

Graphics API(OpenGL/Direct3D)

Device Driver

Device Driver

DRMed Contents

Unlock at App level

Unlock at API level

Unlock at Driver level

Unlock at Device level

Our Idea – DRM Enabled GPUOur Idea – DRM Enabled GPU

DRM Enabled GPU

Protected Graphics Assets

(mesh, textures, shaders)

• Protect graphics assets with encryption and rights licenses.

• Decrypt graphics assets by a DRM enabled GPU

DRMDRM

DRM Enabled GPUDRM Enabled GPU

• Advantages

• Strong security protection, contents decrypted

right before their consumption

• Against SW tampers/attacks

• API hijack, graphics file reverse engineering, etc.

• High performance

• HW decryption vs. SW decryption

• Disadvantages

• Less flexible

GPU with DRM BlockGPU with DRM Block

PCI-ExpressPCI-Express

Host/MemoryInterface

Host/MemoryInterface

Graphics/VideoMemory

Graphics/VideoMemory

GPU PipelineGPU Pipeline

VertexCacheVertexCache

TextureCache

TextureCache

CryptographicUnit

CryptographicUnit

LicenseProcessing Unit

LicenseProcessing Unit

Context Information

Context Information

DRMBlock

Rights License and Content KeysRights License and Content Keys

Public(GPU)

Private-pair(GPU)

license

licenseContent keys

• Graphics contents or assets are licensed

• Graphics contents or assets are encrypted with content keys. Encrypted content keys included in graphics content licenses.

• Content licenses are certified and distributed

• Only targeted GPU can extract/use the content keys from the licenses.

Binding ContextBinding Context

• Constraints of binding among vertex data, textures, and shaders

• Created based on graphics assets licenses

• Security context (protected when stored in exposed storage)

• Contains all information for decrypting graphics assets by a GPU

Binding Context

Vertex Attr Decryption Key, Digest Key

Texture Decryption Key, Digest Key

Shader Digest Key

Graphics API ExtensionGraphics API Extension

• Encrypted Data Array/Texture Types

• Encrypted{234}f, Encrypted_R8G8B8A8, …

• Encrypt collection of vertex attributes or texture tile as a chunk.

• Compute a digest or hashed MAC for each encrypted chunk

• Protected Graphics ObjectsglVertexAttribPointerPrivateARB(

0, Encrypted4f, GL_FALSE, 0, &vertex);

glVertexAttribPointerPrivateARB(8, Encrypted2f, GL_FALSE, 0,

&text_coord);

Graphics API ExtensionGraphics API Extension

• API Extension

• GenBindingContext(int size, int* ptr_to_handles)

• ConfigBindingContext( int handle, enum type, int graphics_object_handle, unsigned char* license)

type = Encrypted_VERTEX_ATTR0..15

type = PRIVATE_TEXTURE0..7 type = VERTEX_SHADER|FRAGMENT_SHADER|…

graphics_object_handle = handle to vertex,texture,or shader

license = license byte array

• EnableBindingContext(int handle)

• DisableBindingContext(int handle)

• DeleteBindingContext(int handle)

Graphics Data Protection Check Graphics Data Protection Check

Vertex/TexCache

&Vertex/TexFetch Unit

Vertex/TexCache

&Vertex/TexFetch Unit

Encrypted Vertex Attr/Tex Tiles

Encrypted Vertex Attr/Tex Tiles

Encrypted Vertex Attr/Tex Tiles

Encrypted Vertex Attr/Tex Tiles…

Encrypted Vertex Attr/Tex Tiles

Encrypted Vertex Attr/Tex Tiles

Digest/HMAC

Digest/HMAC

Digest/HMAC

Digest/HMAC

Digest/HMAC

Digest/HMAC

DecryptionUnit

DecryptionUnit

Vertex Attr

Decryption Key,

Digest Key

Texture Decryption Key,

Digest Key

Shader Digest Key

Binding Context

HMACUnit

HMACUnit

?

GPU Front-End

Counter Mode Example (Encrypted Texels)Counter Mode Example (Encrypted Texels)

Vertex/TexCache

&Vertex/TexFetch Unit

Vertex/TexCache

&Vertex/TexFetch Unit

EncryptedTexels

EncryptedTexels

Decryption KeyBinding Context GPU Front-End

Memory UnitMemory Unit

Graphics Memory

Graphics Memory

Graphics Memory

Graphics Memory

…Decryption

PadDecryption

PadAES EngineAES Engine

Texel TileCoord

Texel TileCoord OffsetOffset PaddingPadding

Counter value

Fetch AddressCal/Translation Fetch AddressCal/Translation

XOR

Division of Labor CPU-GPU Level-of-Detail Division of Labor CPU-GPU Level-of-Detail

CPU

GPU

Collision detection

Coarse backface culling

Transformation

Lighting

Animation

Unprotected Graphics Data

Protected Graphics Data

• CPU processes unprotected coarse level graphics data

• GPU processes protected fine-grained graphics data

Optional Depth Buffer ProtectionOptional Depth Buffer Protection

Frame BufferOperation UnitFrame Buffer

Operation Unit

Depth BufferDepth Buffer

DepthDecryption Unit

DepthDecryption Unit

Depth

Buffer

Symmetric Key

Context

DepthEncryption Unit

DepthEncryption Unit

Z-tile Z-tile

• Depth buffer key is applied to an application.

EvaluationEvaluation

Setting

Apps Quake 3D — 4 demo maps

GPU Simulator Qsilver (UVa)

AES unit # 8 (400K gates each)

Decryption Throughput/Latency

40Gb/ps x 8,

2.5ns per stage x 11 = 27.5ns

HMAC Unit # 8 (19K gates each)

HMAC Latency 74ns

Graphics Memory GDDR3 latency

Frame Rate ImpactFrame Rate Impact

• Frame rate slowdown using protected assets against regular assets

• Reasonable impact on frame rate

Normalized Frame Rate (%)

50

60

70

80

90

100

q3dm1 q3dm7 q3dm17 q3tourney average

Decryption Latency Sensitivity Decryption Latency Sensitivity

Normalized Frame Rate (%)

50

55

60

65

7075

80

85

90

95

100

q3dm1 q3dm7 q3dm17 q3tourney average

27.5ns Decryption Lat 40ns Decryption Lat

Sensitivity of Cache Miss RateSensitivity of Cache Miss RateNormalized Frame Rate (%)

50

55

6065

70

75

80

8590

95

100

q3dm1 q3dm7 q3dm17 q3tourney average

Low Miss (5%) Med Miss (10%) High Miss (20%)

ConclusionsConclusions

• Time to introduce DRM protection on real time graphics assets.

• The trend of GPU advancement enables new ways of protecting graphics assets.

• Graphics assets protection advocates joint research from DRM, Graphics, and GPU community.

• GPU-based graphics assets protection is more effective.

• We studied feasibility of GPU based graphics DRM.

• Further research is required.

Thank You!Thank You!

http://arch.ece.gatech.edu