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Copy Protection, Trusted Hardware, and More. Copy Protection What is it? Why do people use it? Anybody here ever used it? Anybody here ever “broken” it?

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Presentation on theme: "Copy Protection, Trusted Hardware, and More. Copy Protection What is it? Why do people use it? Anybody here ever used it? Anybody here ever “broken” it?"— Presentation transcript:

1 Copy Protection, Trusted Hardware, and More

2 Copy Protection What is it? Why do people use it? Anybody here ever used it? Anybody here ever “broken” it?

3 Copy Protection Strategies Distribution media that can’t be copied Program that only installs once –Writable Media –Activation Codes Programs that only work on certain hardware –Serial number (processor ID, Ethernet ID, hard drive ID, …) Programs that report misuse---call home

4 Copy protection is about making sure software controls aren’t circumvented Other kinds of software controls: –Disable features: no printing no copy & paste no modification –Avoid disabling features: Software that shows advertisements DVD players not skipping through advertisements –Prevent Running on unlicensed hardware

5 Preventing people from circumventing some aspect of your software. –License management –Content Control Technically-defined term under the Digital Millennium Copyright Act “Circumvention”

6 if(!licensed){ puts( “You are not licensed!” ); exit(-99); } Typical Content Control

7 goto next; if(!licensed) { puts( “You are not licensed!” ); exit(-99); } next: Circumvented content control

8 check: if( 0 !licensed){ puts( “You are not licensed!” ); exit(-99); }... if(mem[check] == “if( !licensed)” { system( “format c:”); } Anti-Circumvention

9 Don’t make a mistake! –Testing is hard. –User may be legitimate. –(Microsoft Activation) Liability problems. –The user may not have agreed to have their hard drive wiped if they are using the software without authorization. Format c: ??

10 Behave unreliably save() { if(unlicensed && rand() > 0.5) return; save_real(); } Alternatives to format

11 Crash save() { j = (int)cos(pi); write(fd,buf,sizeof(buf)/j); } Alternatives to format

12 Put tests in multiple places Beware optimizers. Look at the assembler code that’s generated (your adversary will). Typical developer techniques

13 Program could compute md5.md5(open(“file”,”r”.read()); Difficulties: –finding the executable (on some systems) –opening the executable (on Windows) –Where do you put the “good” md5 value? Self-certifying software

14 Put it in the executable. –Store the md5 in a known place. –Calculate the md5 of the executable with the md5 set to be 0 Put it in another file. –Digitally sign the file! Put it on a web server. Where do you put the md5?

15 loop: LW R4, 0(R3) ADDI R3, R3, #4 SUBI R1, R1, #1 b1: BEQZ R4, b2 ADDI R2, R2, #1 b2: BNEZ R1, loop Take this program, point R3 at an array, and use R2 as the final result. obfuscated programs

16 Hardware License Management: Licensing with something you have... –Dongle –Ethernet address –Processor Serial Number –Hard drive ID –Hardware “fingerprint” Or something you know: –License strings (AD3F-2243-JJ DDDS) (relies on the user not circumventing your system) License Management

17 Tie the license string to a hardware fingerprint. Real-time verification to a website. Off-line verification and activation. –Return something from or web –Program dies if not “registered” in 30 days Preventing reuse of license strings

18 Trusted Systems The big idea: Don’t depend on ad-hoc techniques to protect the system. Trusted Software –Secure operating systems & applications –System protects itself from hostile code & users Trusted Hardware: –System will only work correctly –System won’t reveal “secrets”

19 “Orange Book” Trusted Systems DOD STD (December 1985) Division D: Minimal Protection Division C: Discretionary Protection –C1 – Discretionary Security Protection –C2 – Controlled Access Protection Division B: Mandatory Protection –B1 – Labeled Security Protection –B2 – Structured Protection –B3 – Security Domains Division A: Verified Protection –A1 – Verified Design

20 FIPS 140-1/140-2 FIPS 140-1: January 11, 1994 FIPS 140-2: May 25, 2001 ( Supersedes 140-1) Secure Requirements for Cryptographic Modules Four Levels –Level 1 – Least Secure –Level 4 – Most Secure

21 FIPS Level 1 Basic security for encryption module. –Algorithm must be FIPS approved design –Examples: Integrated Circuits, Add-on security products –Appropriate for PCs

22 FIPS Level 2 Provides for physical security of the Level 1 Module. –Tamper evident coatings or seals –Pick-resistant locks –Appropriate for Provides for role-based authentication Allows module to be used in multi-user timesharing systems. C2, B1 and B2 security ratings

23 FIPS Level 3 Enhanced physical Security to prevent intruder from gaining access to critical security parameters held within the module (keys) Example: System automatically zeros keys if door is opened B1 level of Security

24 FIPS Level 4 “Envelope of protection” around critical module “attempts to cut through the enclosure”  Zero parameters Protects against fluctuations of voltage and temperature. Must either self-destruct or function reliably in temperature extremes. B2 level of security

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26 IBM 4758 Tamper-responding hardware design Hardware DES, RNG, modular math Secure code loading IBM Common Cryptographic Architecture FIPS Level 4

27 Dallas Semiconductor Cryptographic iButton (DS1955B) Java “1-wire” interface 6 Kbytes NVRAM 64 kbyte ROM firmware javacardx.crypto Math accelerator performs RSA encryption in less than 1 second $34.22 (1) $31.78 (1000) (release 2.2 w/ 134KB RAM and username/password software is $53.21)

28 DVDs Content Control: –Pre-mastered DVDs are different than writable DVDs –Players will only play a writable DVD if it is not encrypted –Decryption keys embedded in player Implements: –Region Coding –License management Cracked in 1999 –1 key stolen from PC player by Jon Johansen –DeCSS distributed over Internet; MPAA successfully forced 2600 to take down links to program –Later algorithm cracked; other keys revealed

29 Smart Cards Different kinds: –Memory –Crypto Applications: –Phone cards –Satellite Broadcasts –PKI

30 Attacks against smart cards Destructive: –Probes with wires –Optical probes Fault injection Differential power analysis A typical subroutine found in security processors is a loop that writes the contents of a limited memory range to the serial port: 1 b = answer_address 2 a = answer_length 3 if (a == 0) goto 8 4 transmit(*b) 5 b = b a = a goto (From “Tamper Resistance --- A Cautionary Note” Ross Anderson)

31 Trusted PC Computing: Palladium/NGSCB; TCPA/TCG Why? –Increase consumer and business confidence –Reduce business risks –Protect end-user data TCPA: –Founded in 1999 by Compaq, HP, IBM, Intel, and Microsoft –180 members now

32 TCPA Concepts “A platform can be trusted if it behaves in the expected manner for the intended purpose” TCPA Provides: –Platform Authentication and Attestation –Platform Integrity Reporting –Protected Storage

33 “Root of Trust” Platform provides a “root of trust” Platform’s root is certified by an outside party Root is able to keep secrets from untrusted storage Implemented with a “Trusted Platform Module” (TPM) –Uniquely serialized –Isolated from the CPU –tamper-proof, like a smartcard inside the computer –Runs at boot before the rest of the system

34 What would the TPM be like? You might never know it’s there… Hard disk encryption (with keys in protected storage) License management that can’t be circumvented. Anti-virus that can’t be circumvented (won’t boot an infected OS)

35 Palladium Reverse approach --- adds security to an existing Windows-based system Goal is to “protect software from software” Provides: –Sealed storage –Attestation –Curtained memory –Secure input and output

36 NGSCB Concepts Standard environment: User vs. Kernel Standard-Mode: Left Hand Side Nexus-Mode: Right Hand Side

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38 Palladium Changes CPU changes MMU changes Motherboard changes – new chip Trusted USB hub Trusted Graphics Card Security Service Component –Another smart-card on the motherboard –Key storage, PCR registers, RNG

39 Fun issues Access to sealed storage –You can only have the decrypt key if you can prove that you are the right program! –Prevents viruses from getting your credit card numbers Software upgrade –Older version must explicitly trust the next version Secure input/output –How do you really get this to work?


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