Ahn pacsec2017 key-recovery_attacks_against_commercial_white-box_cryptography_implementations_h2spice_draft
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The document discusses key recovery attacks against commercial white-box cryptography implementations. It provides an overview of white-box cryptography, existing attacks against academic white-box implementations, and the speaker's work analyzing commercial white-box implementations. The speaker's motivation is that while all academic white-box crypto has been broken, no attacks have been demonstrated on commercial versions. The talk covers side-channel attacks like correlation power analysis and differential fault analysis that have been used to break academic white-box crypto.
![Software execution trace with DBI
[.code execution]
start_addr : 000000000400c1b7
end_addr : 000000000400c1d0
instruction info
000000000400c1b7: mov eax, dword ptr [ebp + 8]
000000000400c1ba: add dword ptr [ebx + 0x550], 1
000000000400c1c1: mov edx, dword ptr [eax + 0x228]
000000000400c1c7: mov edi, dword ptr [eax + 0x224]
000000000400c1cd: mov dword ptr [ebp - 0x44], edx
000000000400c1d0: jmp 0x400b3c1
[.mem write]
code_addr : 000000000400c1ba
mem_addr : 0000000004023550
size : 4
data : 30040000
[.mem write]
code_addr : 000000000400c1c1
mem_addr : 0000000004025da8
size : 4
data : 347b0608
[.mem write]
code_addr : 000000000400c1c7
mem_addr : 0000000004025da4
size : 4
data : 38390204
[.mem read]
code_addr : 000000000400c1b7
mem_addr : 00000000beef7470
size : 4
data : 805b0204
[.mem read]
code_addr : 000000000400c1b7
mem_addr : 00000000beef7470
size : 4
data : 805b0204
[.mem read]
code_addr : 000000000400c1ba
mem_addr : 0000000004023550
size : 4
data : 2f040000](https://image.slidesharecdn.com/ahnpacsec2017-keyrecoveryattacksagainstcommercialwhite-boxcryptographyimplementationsh2spicedraft-171031100842/85/Ahn-pacsec2017-key-recovery_attacks_against_commercial_white-box_cryptography_implementations_h2spice_draft-36-320.jpg)
Ahn pacsec2017 key-recovery_attacks_against_commercial_white-box_cryptography_implementations_h2spice_draft
- 1. The Key Recovery Attacks against Commercial White-box cryptography Implementations Sanghwan Ahn | LINE Corporation PACSEC 2017 —Tokyo — Nov 1, 2017
- 2. About me • Ahn Sanghwan(@h2spice) • Senior security engineer, LINE Corporation • Application security • Security assessment • Security design and development • Other works related to app security
- 3. About this talk • Security threats in the application • Introduction to white-box cryptography(WBC) • Existing attacks against published white-box implementation • Our works against commercial white-box Implementation • Simple security guides on applying WBC to service
- 4. Motivation All academic white-box implementation have been broken, But No attack has been observed to date on commercial WBC.
- 5. Application security Digital rights management - Data encryption - Watermarks - Signature End-to-End Encryption Digital signature Payment tokenization - Easy payment service - Masking sensitive data Transport layer protection - SSL/TLS Authentication(id/password, biometric) + 2-Factor-Authentication(SMS, Call, OTP), FIDO
- 6. • Design of algorithms and protocols to protect a communication channel • End points are assumed to be trusted and safe Alice Bob Mallory Traditional cryptography
- 7. Attacking end-point directly Digital rights management - Data encryption - Watermarks - Signature Tamper resistant - Anti-debug - Integrity - Obfuscation End-to-End Encryption Digital signature Payment tokenization - Easy payment service - Masking sensitive data Transport layer protection - SSL/TLS Authentication(id/password, biometric) + 2-Factor-Authentication(SMS, Call, OTP), FIDO Mallory
- 8. Mallory own devices Mallory Bob The person who purchased the device or content is attacking it
- 9. • Binary is completely visible to an attacker • Attacker has full access to the cryptography algorithm • Attacker has full control over its execution environment • Unlimited amount of queries • Static Analysis • Code Analysis(reverse engineering) • Dynamic Analysis • Debugging • DBI(dynamic binary instrumentation) White-box threat model
- 10. • Trusted execution environment(TEE) • ARM Trustzone, Intel SGX, AMD Memory Encryption • It’s almost safe, but not many supported devices (mostly latest devices) • White-box cryptography(WBC) • All academic WBC solutions have been broken. • No attack has been observed to date on commercial WBC Solutions for white-box threat model Virtual Black box
- 12. Key partial evaluation Key S INPUT x (0-255) Sbox ( x ⊕ key ) Tbox
- 13. Table based AES implementation T-Box XOR Table ShiftRows AddRoundKey SubByte MixColumns Data flow for round one of table based AES 128 implementation, 2-9 rounds are the same.
- 14. Example code Reference : https://github.com/0vercl0k/stuffz/tree/master/wbaes_attack/wbaes128
- 15. Encoding A1 A0 T1 A2 A1 -1 T2 An An-1 -1 Tn IN A0 -1 An -1 OUT … Obfuscated Table, Tn’ A * A-1 = I(identity matrix)
- 16. WB-AES implementation - internal encoding XOR Table XOR Table Internal Decoding it cancels encoding in the previous round T’Box Internal Encoding it will be canceled in the next round T’Box transformed With Mixing Bijection it will be canceled in the next transformation Data flow for second round of table based AES 128 implementation.
- 17. WB-AES implementation - external encoding First round Input Sender White-box Decode the input Final round Encode the output Output Receiver Decode the output Encode the input
- 18. Network of look-up tables
- 19. ShiftRows SubBytes MixColumns AddRoundKey Conventional AES and white-box AES Implementation
- 20. Possible attacks : table-decomposition Ciphertext Plaintext WBC f(…) Table decomposition function
- 21. Possible attacks : power analysis Ciphertext Plaintext WBC Recode intermediate computation result And then compare it and simulated data ShiftRows SubBytes MixColumns AddRoundKey Ciphertext PlaintextKey Simulator
- 22. Typical example of a (hardware) power trace of an unprotected AES-128 implementation (one can observe the ten rounds) Power analysis on the hardware Reference : Joppe W. Bos et al. - Differential Computation Analysis: Hiding your White-Box Designs is Not Enough
- 23. Typical example of a (hardware) power trace of an unprotected AES-128 implementation (one can observe the ten rounds) Power analysis on the hardware Reference : Joppe W. Bos et al. - Differential Computation Analysis: Hiding your White-Box Designs is Not Enough
- 24. Typical example of a portion of a serialized software trace of stack writes in an WBAES-128, with only two possible values: 0 or 1 Power analysis on the software Reference : Joppe W. Bos et al. - Differential Computation Analysis: Hiding your White-Box Designs is Not Enough
- 25. The correlation between the sensitive data and the power consumption for the 256 key guesses for a single byte Correlation power analysis(CPA) Reference : W. Hnath, J. Pettengill, “Differential Power Analysis Side-Channel Attacks in Cryptography,” Major Qualifying Project, Worcester Polytechnic Institute, April 2010
- 26. The correlation between the sensitive data and the power consumption for the 256 key guesses for 16 byte Correlation power analysis(CPA) Reference : W. Hnath, J. Pettengill, “Differential Power Analysis Side-Channel Attacks in Cryptography,” Major Qualifying Project, Worcester Polytechnic Institute, April 2010
- 27. Possible attacks : fault analysis Faulty Ciphertext (incorrect result) Plaintext WBC Ciphertext(correct result) Plaintext WBC 1. Modify intermediate data 2. Record changes to the output 3, Compare incorrect result and correct result
- 28. Differential fault analysis(DFA) 87 F2 4D 97 6E 4C 90 EC 46 E7 4A C3 A6 8C D8 95 After ShiftRow9 99 F2 4D 97 6E 4C 90 EC 46 E7 4A C3 A6 8C D8 95 Fault injected ‘1E’ 7B 40 43 4C 29 D4 70 9F 8A E4 3A 42 CF A5 A6 BC After Mixcolumn AC 19 28 57 77 FA D1 5C 66 DC 29 00 F3 21 41 6E K9 D7 59 8B 1B 5E 2E A1 C3 EC 38 13 42 3C 84 E7 D2 After AddRoundKey9 0E CB 3D AF 58 31 32 2E CE 07 7D 2C EB 5F 94 B5 After SubBytes10 0E CB 3D AF 31 32 2E 58 7D 2C CE 07 B5 EB 5F 94 After ShiftRows10 D0 C9 E1 B6 14 EE 3F 63 F9 25 0C 0C A8 89 C8 A6 K10 DE 02 DC 19 25 DC 11 3B 84 09 C2 0B 1D 62 97 32 Output with faults 39 02 DC 19 25 DC 11 6A 84 09 85 0B 1D FB 97 32 Output without fault ⊕ ⊕ = Input = ’3243F6A8885A308D313198A2E0370734’ Cipher Key =’2B7E151628AED2A6ABF7158809CF4F3C’ Output= ’3925841D02DC09FBDC118597196A0B32’ Reference : P. Dusart, G. Letourneux and O. Vivolo, “Differential Fault Analysis on A.E.S.,” Cryptology ePrint Archive of IACR, No. 010, 2003
- 29. Differential fault analysis(DFA) 87 F2 4D 97 6E 4C 90 EC 46 E7 4A C3 A6 8C D8 95 After ShiftRow9 99 F2 4D 97 6E 4C 90 EC 46 E7 4A C3 A6 8C D8 95 Fault injected ‘1E’ 7B 40 43 4C 29 D4 70 9F 8A E4 3A 42 CF A5 A6 BC After Mixcolumn AC 19 28 57 77 FA D1 5C 66 DC 29 00 F3 21 41 6E K9 D7 59 8B 1B 5E 2E A1 C3 EC 38 13 42 3C 84 E7 D2 After AddRoundKey9 0E CB 3D AF 58 31 32 2E CE 07 7D 2C EB 5F 94 B5 After SubBytes10 0E CB 3D AF 31 32 2E 58 7D 2C CE 07 B5 EB 5F 94 After ShiftRows10 D0 C9 E1 B6 14 EE 3F 63 F9 25 0C 0C A8 89 C8 A6 K10 DE 02 DC 19 25 DC 11 3B 84 09 C2 0B 1D 62 97 32 Output with faults 39 02 DC 19 25 DC 11 6A 84 09 85 0B 1D FB 97 32 Output without fault E7 00 00 00 00 00 00 51 00 00 47 00 00 99 00 00 Error ⊕ ⊕ ⊕= = Input = ’3243F6A8885A308D313198A2E0370734’ Cipher Key =’2B7E151628AED2A6ABF7158809CF4F3C’ Output= ’3925841D02DC09FBDC118597196A0B32’ Reference : P. Dusart, G. Letourneux and O. Vivolo, “Differential Fault Analysis on A.E.S.,” Cryptology ePrint Archive of IACR, No. 010, 2003
- 30. 87 F2 4D 97 6E 4C 90 EC 46 E7 4A C3 A6 8C D8 95 After ShiftRow9 99 F2 4D 97 6E 4C 90 EC 46 E7 4A C3 A6 8C D8 95 Fault injected ‘1E’ 7B 40 43 4C 29 D4 70 9F 8A E4 3A 42 CF A5 A6 BC After Mixcolumn AC 19 28 57 77 FA D1 5C 66 DC 29 00 F3 21 41 6E K9 D7 59 8B 1B 5E 2E A1 C3 EC 38 13 42 3C 84 E7 D2 After AddRoundKey9 0E CB 3D AF 58 31 32 2E CE 07 7D 2C EB 5F 94 B5 After SubBytes10 0E CB 3D AF 31 32 2E 58 7D 2C CE 07 B5 EB 5F 94 After ShiftRows10 D0 C9 E1 B6 14 EE 3F 63 F9 25 0C 0C A8 89 C8 A6 K10 DE 02 DC 19 25 DC 11 3B 84 09 C2 0B 1D 62 97 32 Output with faults 39 02 DC 19 25 DC 11 6A 84 09 85 0B 1D FB 97 32 Output without fault ⊕ ⊕ ⊕= = Differential fault analysis(DFA) E7 00 00 00 00 00 00 51 00 00 47 00 00 99 00 00 Error Input = ’3243F6A8885A308D313198A2E0370734’ Cipher Key =’2B7E151628AED2A6ABF7158809CF4F3C’ Output= ’3925841D02DC09FBDC118597196A0B32’ Reference : P. Dusart, G. Letourneux and O. Vivolo, “Differential Fault Analysis on A.E.S.,” Cryptology ePrint Archive of IACR, No. 010, 2003
- 31. Secret Key 4A 32 4D 72 39 33 33 6C 61 54 4E 6B 32 4D 4A 30 WB Engine Protected Key 49 D8 AD DC 2B AE 89 D1 EE 67 D0 5F CB F3 5C 07 35 2D B4 93 F1 63 D8 51 DC 58 BB DA E0 9A 60 0B 11 6E 12 15 B9 53 0E 66 F6 34 98 43 AC 80 7D F7 DA 02 DF 95 66 21 AE B4 5F 9E 7F 13 75 35 C3 95 5B D6 7A 81 4E 75 7D 55 56 CE 47 69 32 5A 5E D8 12 15 DA E0 2D 2B AE D8 … Commercial white-box implementation
- 32. Secret Key 4A 32 4D 72 39 33 33 6C 61 54 4E 6B 32 4D 4A 30 WB Engine Protected Key 49 D8 AD DC 2B AE 89 D1 EE 67 D0 5F CB F3 5C 07 35 2D B4 93 F1 63 D8 51 DC 58 BB DA E0 9A 60 0B 11 6E 12 15 B9 53 0E 66 F6 34 98 43 AC 80 7D F7 DA 02 DF 95 66 21 AE B4 5F 9E 7F 13 75 35 C3 95 5B D6 7A 81 4E 75 7D 55 56 CE 47 69 32 5A 5E D8 12 15 DA E0 2D 2B AE D8 … It's very difficult to recover protected key to plain key Commercial white-box implementation
- 33. • Side channel attacks • Correlation Power analysis (CPA) • Differential Fault Analysis (DFA) • Control flow visualization White-box cryptanalysis — existing research References - Joppe W. Bos et al. - Differential Computation Analysis: Hiding your White-Box Designs is Not Enough - Paul Bottinelli and Joppe W. Bos - Computational Aspects of Correlation Power Analysis - Eloi Sanfelix, Cristofaro Mune, Job de Haas - Unboxing The White-Box: Practical Attacks Against Obfuscated Ciphers
- 34. Typical example of a (hardware) power trace of an unprotected AES-128 implementation (one can observe the ten rounds) Cryptographic primitive Reference : Kevin Meritt, “Differential Power Analysis attacks on AES”
- 35. White-box cryptanalysis — existing research • Side channel attacks • Correlation Power analysis (CPA) • Differential Fault Analysis (DFA) • Control flow visualization References - Joppe W. Bos et al. - Differential Computation Analysis: Hiding your White-Box Designs is Not Enough - Paul Bottinelli and Joppe W. Bos - Computational Aspects of Correlation Power Analysis - Eloi Sanfelix, Cristofaro Mune, Job de Haas - Unboxing The White-Box: Practical Attacks Against Obfuscated Ciphers
- 36. Software execution trace with DBI [.code execution] start_addr : 000000000400c1b7 end_addr : 000000000400c1d0 instruction info 000000000400c1b7: mov eax, dword ptr [ebp + 8] 000000000400c1ba: add dword ptr [ebx + 0x550], 1 000000000400c1c1: mov edx, dword ptr [eax + 0x228] 000000000400c1c7: mov edi, dword ptr [eax + 0x224] 000000000400c1cd: mov dword ptr [ebp - 0x44], edx 000000000400c1d0: jmp 0x400b3c1 [.mem write] code_addr : 000000000400c1ba mem_addr : 0000000004023550 size : 4 data : 30040000 [.mem write] code_addr : 000000000400c1c1 mem_addr : 0000000004025da8 size : 4 data : 347b0608 [.mem write] code_addr : 000000000400c1c7 mem_addr : 0000000004025da4 size : 4 data : 38390204 [.mem read] code_addr : 000000000400c1b7 mem_addr : 00000000beef7470 size : 4 data : 805b0204 [.mem read] code_addr : 000000000400c1b7 mem_addr : 00000000beef7470 size : 4 data : 805b0204 [.mem read] code_addr : 000000000400c1ba mem_addr : 0000000004023550 size : 4 data : 2f040000
- 37. Visualized map of open-source WBAES-128 Write Read Execution Memory Address Time
- 38. 10 rounds of AES-128 (white-box implementation, opensource) 10 rounds of WBAES-128
- 39. rank 1 rank 2 rank 3 rank 4 rank 5 rank 6 rank 7 rank 8 rank 9 rank 10 key 1 0x2b (2.00538) 0x07 (1.80379) 0xc1 (1.73824) 0xee (1.70429) 0x08 (1.697) 0x0c (1.69357) 0x72 (1.67844) 0x2c (1.67127) 0x81 (1.66722) 0x0a (1.65412) key 2 0x7e (2.51091) 0x93 (1.74067) 0x06 (1.68867) 0x02 (1.68841) 0xa8 (1.67424) 0x54 (1.67341) 0x62 (1.67227) 0xb6 (1.66756) 0xe9 (1.66338) 0x86 (1.65473) key 3 0x15 (2.48606) 0xc8 (1.72634) 0xe4 (1.72553) 0x20 (1.70805) 0x92 (1.69391) 0x74 (1.68563) 0x1e (1.68499) 0x89 (1.67014) 0x43 (1.66724) 0xd6 (1.66098) key 4 0x16 (2.28568) 0xb5 (1.69677) 0x8f (1.68429) 0xbb (1.67537) 0x45 (1.66008) 0xe9 (1.64984) 0xcf (1.64378) 0xc2 (1.63327) 0x38 (1.61959) 0x6c (1.61645) key 5 0x28 (2.31281) 0x7d (1.69297) 0x5a (1.69283) 0xc9 (1.69053) 0x8e (1.68747) 0xfb (1.6714) 0xf3 (1.66702) 0x5b (1.6599) 0xaa (1.65702) 0x67 (1.65374) key 6 0xae (2.5603) 0x69 (1.73705) 0x8a (1.73109) 0xf5 (1.67828) 0xc4 (1.67624) 0xfe (1.67155) 0xa0 (1.66758) 0xe5 (1.66617) 0x98 (1.6579) 0xb8 (1.65789) key 7 0xd2 (2.47133) 0xb4 (1.81599) 0x5f (1.75024) 0xe0 (1.74447) 0xa1 (1.73202) 0x5a (1.71384) 0x8b (1.70006) 0x0b (1.69626) 0xcd (1.68755) 0x68 (1.66165) key 8 0xa6 (1.80113) 0x4b (1.70776) 0x9d (1.69386) 0x2d (1.67404) 0x01 (1.6456) 0x0d (1.64192) 0xbf (1.63917) 0xea (1.63454) 0xe7 (1.62918) 0x3e (1.62822) key 9 0xab (2.4717) 0x1d (1.7161) 0xc9 (1.71101) 0xe5 (1.70354) 0x7c (1.69538) 0x77 (1.68859) 0x2f (1.65904) 0xc4 (1.65721) 0xa1 (1.65257) 0x60 (1.64843) key 10 0xf7 (3.61634) 0xb8 (3.41278) 0xa4 (3.39504) 0x76 (3.38843) 0xc4 (3.38602) 0x17 (3.38253) 0xea (3.37196) 0xbe (3.35624) 0x8b (3.3548) 0x97 (3.33779) key 11 0x15 (2.02783) 0x16 (1.71121) 0xb6 (1.69905) 0x69 (1.69321) 0xbe (1.69316) 0x7b (1.69135) 0x41 (1.6857) 0x2f (1.67168) 0x91 (1.65783) 0x22 (1.65519) key 12 0x88 (2.8446) 0x3c (1.75204) 0xe4 (1.70494) 0x52 (1.66283) 0x79 (1.66221) 0x08 (1.64197) 0xb9 (1.62887) 0x40 (1.62375) 0x42 (1.61559) 0xb5 (1.60839) key 13 0x09 (1.88167) 0x96 (1.71604) 0xf2 (1.68481) 0xb4 (1.68284) 0x0d (1.67969) 0x6d (1.67959) 0x3f (1.67024) 0xaf (1.66383) 0x78 (1.66288) 0xe6 (1.66193) key 14 0xcf (2.3232) 0x19 (1.76684) 0x9a (1.74075) 0x3d (1.72711) 0x03 (1.69709) 0xe2 (1.68798) 0x07 (1.68521) 0xd2 (1.67812) 0x6f (1.67621) 0xca (1.67311) key 15 0x4f (2.11058) 0xd7 (1.80632) 0xce (1.71211) 0xad (1.71185) 0x45 (1.70138) 0x0e (1.69954) 0x62 (1.68237) 0x76 (1.67043) 0xc0 (1.66782) 0x48 (1.66293) key 16 0x3c (2.22229) 0x97 (1.70098) 0xa7 (1.69181) 0x5d (1.68828) 0x02 (1.67629) 0xea (1.65554) 0x07 (1.65372) 0x7e (1.65026) 0xe6 (1.6479) 0x29 (1.64527) WBAES-128 key recovery with CPA
- 40. • Two commercial AES implementations • Simple-cipher mode for performance • Complex-cipher mode for security Commercial white-box ciphers
- 41. Commercial white-box ciphers • Two commercial AES implementations • Simple-cipher mode for performance • Complex-cipher mode for security
- 42. Write Read Execution Visualized map of simple-cipher
- 43. Visualized map of simple-cipher the round pattern not found
- 44. • Taint analysis instead of binary-visualization • Correlation power analysis (CPA) • Code analysis(reverse engineering) • Differential fault analysis (DFA) White-box cryptanalysis — our works
- 46. Taint analysis - plaintext trace Cryptographic primitive
- 47. Taint analysis for simple-cipher 0x4200986: (in /lib/i386-linux-gnu/libc-2.21.so) 0x42B34AE: (in /lib/i386-linux-gnu/libc-2.21.so) 0x42B34B3: (in /lib/i386-linux-gnu/libc-2.21.so) 0x42B34B8: (in /lib/i386-linux-gnu/libc-2.21.so) 0x42B34BD: (in /lib/i386-linux-gnu/libc-2.21.so) … 0x8181ABA: (in Commercial-SimpleWB-AES) 0x8181AC4: (in Commercial-SimpleWB-AES) 0x8181ACC: (in Commercial-SimpleWB-AES) 0x8181AD0: (in Commercial-SimpleWB-AES) 0x8181AE0: (in Commercial-SimpleWB-AES) 0x8181AE4: (in Commercial-SimpleWB-AES) 0x8181AEE: (in Commercial-SimpleWB-AES) 0x8181AF2: (in Commercial-SimpleWB-AES) 0x8181B04: (in Commercial-SimpleWB-AES) 0x8181B08: (in Commercial-SimpleWB-AES) 0x8181B10: (in Commercial-SimpleWB-AES) 0x8181B14: (in Commercial-SimpleWB-AES) 0x8181B24: (in Commercial-SimpleWB-AES) 0x8181B28: (in Commercial-SimpleWB-AES) 0x8181B32: (in Commercial-SimpleWB-AES) … Cryptographic primitive
- 48. Cryptographic primitive of simple-cipher
- 49. CPA on the simple-cipher rank 1 rank 2 rank 3 rank 4 rank 5 rank 6 rank 7 rank 8 rank 9 rank 10 key 1 0x4a (3.55009) 0x6b(3.38731) 0xbe(3.29755) 0x1e(3.29697) 0x2e(3.27285) 0x35(3.27269) 0x65(3.26551) 0x92(3.26066) 0x1d(3.25067) 0x58(3.24932) key 2 0x32 (4.34452) 0xd0(3.35588) 0xe8(3.31946) 0xcc(3.30517) 0x78(3.29646) 0xdf(3.28295) 0x17(3.27702) 0x64(3.27235) 0x79(3.26674) 0x8a(3.26442) key 3 0x4d (3.82747) 0xcc(3.31759) 0x23(3.29281) 0x91(3.28571) 0xb9(3.28026) 0xb3(3.27443) 0x4e(3.2596) 0xa2(3.25797) 0x8f(3.25309) 0x04(3.24456) key 4 0x72 (3.64867) 0x38(3.35217) 0xdf(3.3211) 0x2f(3.31467) 0xae(3.30714) 0xa1(3.30303) 0xf8(3.28997) 0xd3(3.28245) 0x1b(3.26429) 0x8b(3.26017) key 5 0x39 (4.1895) 0xc4(3.43936) 0xbb(3.32822) 0x8b(3.32537) 0x7c(3.31265) 0x8e(3.30741) 0x13(3.30152) 0x69(3.299) 0x9e(3.28805) 0x89(3.28379) key 6 0x33 (3.62186) 0x2d(3.38423) 0xa8(3.31917) 0xb8(3.30849) 0x72(3.28712) 0x48(3.28305) 0x96(3.27886) 0x4d(3.27446) 0x23(3.27344) 0x9a(3.27234) key 7 0x33 (4.26236) 0xda(3.30169) 0xc8(3.28577) 0x23(3.28246) 0x5f(3.26833) 0x17(3.26592) 0xd3(3.26428) 0xe6(3.26389) 0x64(3.25394) 0x85(3.24545) key 8 0x6c (3.61456) 0x21(3.35728) 0xba(3.3402) 0xb3(3.32199) 0x65(3.29623) 0xaf(3.27848) 0x1f(3.27791) 0x61(3.27659) 0x44(3.27522) 0xc6(3.26389) key 9 0x61 (4.19043) 0x8d(3.33732) 0x68(3.32288) 0x5f(3.30976) 0x1e(3.28015) 0xeb(3.27355) 0x96(3.26578) 0x13(3.26007) 0x0c(3.25348) 0xc0(3.25069) key 10 0x54 (3.66626) 0x42(3.45208) 0xd6(3.38613) 0x5d(3.37338) 0x3f(3.3665) 0xbc(3.34422) 0x3a(3.33917) 0xed(3.33183) 0x2d(3.32099) 0x14(3.3029) key 11 0x4e (3.71877) 0x74(3.32473) 0x39(3.32183) 0xee(3.30932) 0x52(3.30156) 0x68(3.27952) 0x7b(3.27918) 0x1a(3.27585) 0x30(3.25335) 0x16(3.25267) key 12 0x6b (3.65183) 0xab(3.45354) 0x28(3.34018) 0xbc(3.33583) 0xc1(3.33411) 0x02(3.31736) 0x07(3.28696) 0x13(3.27714) 0x75(3.27475) 0xc0(3.26212) key 13 0x32 (3.65053) 0x15(3.38309) 0x72(3.29484) 0xe9(3.28438) 0x88(3.28182) 0x52(3.25202) 0x95(3.24498) 0x6c(3.24336) 0x2d(3.24149) 0xc7(3.22936) key 14 0x4d (3.4734) 0x7d(3.31076) 0xcd(3.30883) 0x8e(3.30059) 0x5f(3.28006) 0x0b(3.27518) 0x10(3.26867) 0xee(3.26289) 0x7b(3.2615) 0x1a(3.24988) key 15 0x4a (3.65855) 0x0a(3.30734) 0x89(3.29788) 0xaf(3.29663) 0xf0(3.2857) 0xf1(3.28402) 0xcd(3.26806) 0x48(3.26561) 0xc8(3.26545) 0x87(3.25869) key 16 0x30 (4.20028) 0xc0(3.36153) 0xce(3.3276) 0x2c(3.32361) 0xe9(3.30428) 0x7b(3.29937) 0x8f(3.29511) 0x4e(3.29502) 0x1c(3.28909) 0xd6(3.27938)
- 50. Commercial white-box ciphers • Two commercial AES implementations • Simple-cipher mode for performance • Complex-cipher mode for security
- 51. Visualized map of complex-cipher
- 52. Plaintext trace on the complex-cipher Ciphertext Plaintext
- 53. White-box cryptanalysis — our works • Taint analysis instead of binary-visualization • Correlation power analysis (CPA) • Code analysis(reverse engineering) • Differential fault analysis (DFA)
- 54. Visualized map of complex-cipher Cryptographic primitive ?
- 55. White-box cryptanalysis — our works • Taint analysis instead of binary-visualization • Correlation power analysis (CPA) • Code analysis(reverse engineering) • Differential fault analysis (DFA)
- 56. Code analysis for complex-cipher
- 57. Day 1 Day 2 Day 3 Day 4 Day 5 … DRAFT
- 58. Complex-cipher control flow Function B Function A Plaintext Ciphertext Repeats many times
- 59. White-box table in complex-cipher
- 60. White-box cryptanalysis — our works • Taint analysis instead of binary-visualization • Correlation power analysis (CPA) • Code analysis(reverse engineering) • Differential fault analysis (DFA)
- 61. White-box table in complex-cipher
- 62. 1 byte flip; 0xBD→ 0x34 White-box table in complex-cipher
- 63. Faulty ciphertext h2spice@ubuntu:~/Documents/WBC/Commercial/DFA/complexWB-AES$ ./complexWB-AES testtesttesttest 6CB721A5633DFD7F94A6474524789026 ← normal cipher-text h2spice@ubuntu:~/Documents/WBC/Commercial/DFA/complexWB-AES$ ./complexWB-AES-mod testtesttesttest FF1E4C03844DD800CE9CF34C6B7EEAE8 ← faulty cipher-text
- 64. DFA on complex-cipher Plaintext(in hex) 0x74657374746573747465737474657374 Correct ciphertext 0x6CB721A5633DFD7F94A6474524789026 Good faulty ciphertexts 0x8EB721A5633DFDB794A61E4524359026 0x6CD921A5113DFD7F94A6479824786026 0x6CB740A563C5FD7F8BA64745247890A8 0x6CB72161633DA97F94A447453D789026 … other 625 good faulty ciphertext Final round key 0x5CB2FAF4F3FB94543BFA87DFE92660FC
- 65. Final round key 0x5CB2FAF4F3FB94543BFA87DFE92660FC Round 9 key 0xEC26DC41AF496EA0C801138BD2DCE723 Round 8 key 0x36991EE3436FB2E167487D2B1ADDF4A8 Round 7 key 0x9C3EF21C75F6AC022427CFCA7D958983 Round 6 key 0xEB64C9D7E9C85E1E51D163C859B24649 Round 5 key 0x305BC5E702AC97C9B8193DD608632581 Round 4 key 0xFAF69E0032F7522EBAB5AA1FB07A1857 Round 3 key 0x78C1CC67C801CC2E8842F8310ACFB248 Round 2 key 0x21177A74B0C000494043341F828D4A79 Round 1 key 0xA8E4495191D77A3DF0833456C2CE7E66 Secret key 0x4A324D723933336C61544E6B324D4A30 DFA on complex-cipher
- 66. The way to use WBC safer in apps • No single key for everything • No hardcoded key(protected key) • No static IV • Use asymmetric crypto algorithm based on WBC (RSA, Elliptic curves … ) • Use tamper resistant embedded integrity checksums • Use device binding
- 67. Device binding • Device Identifier • User Identifier • External Identifier
- 68. Future works • White-box version of crypto libraries • Retrieve a master key embedded white-box engine • Find other vulnerability against WBC