Condensat (informatique, cryptographie)

Condensat - calcul d'un code cryptographique, par une fonction de hachage, produisant une clé unique (hashcode, empreinte) d'un contenu (un fichier...).

cr  01.04.2012      r+  21.08.2020      r-  20.04.2024      Pierre Pinard.         (Alertes et avis de sécurité au jour le jour)

Condensat est le mot français pour désigner le calcul de l'empreinte du contenu d'un fichier, selon divers algotithmes (sans jamais tenir compte de son enveloppe).

En informatique, le terme consacré et utilisé est HashCode.

Voir HashCode

La réputation de l'algorithme de calcul d'un hashcode (calcul d'un condensat - fonction de hachage) est de ne jamais produire deux hashcode identiques si les objets (contenu d'un fichiers) contiennent la moindre différence. La fonction de hachage doit donc produire une clé unique d'identification d'une donnée unique (calcul homogène).

Réputation des fonctions de hachage

On voit souvent, en matière de sécurité informatique, principalement avec les services d'analyses antivirus, qu'il ne faut pas/plus identifier le contenu d'un fichier avec certaines fonctions de hachage (hashcodes, condensats, Empreinte cryptographique), dont les fonctions MD5 et SHA-1, car les créations de collisions, les attaques en force brute ou les utilisations de tables Arc-en-ciel permettent de casser l'unicité du condensat ou de remonter à son contenu crypté. Le tableau suivant, établi par les auteurs de Whirlpool(dernière version de ce tableau le 7 novembre 2017), donne l'état de l'art des principales fonctions de hachages et leurs poursuites de résistance ou leurs échecs aux attaques.

• (†) Par sa propre nature, FSB (Fast Syndrome-Based) est moins résistant à la recherche de collision que les attaques par le paradoxe des anniversaires. Pour cette raison, sa taille de résumé (condensat) doit toujours être supérieure à deux fois la sécurité de bit souhaitée.
  

• (‡) MAA est un code d'authentification de message (MAC - Message Authentication Code) plutôt qu'une fonction de hachage. Il a été inclus ici en raison de son importance dans le cadre de la norme ISO 8731-2.
  

Références

1.  [AB96] R. Anderson, E. Biham, "Tiger: A Fast New Hash Function", Fast Software Encryption -- FSE'96, LNCS 1039, Springer (1996), pp. 89--97.
2.  [AFS05] D. Augot, M. Finiasz, N. Sendrier, "A Family of Fast Syndrome Based Cryptographic Hash Functions", LNCS 3715, Springer (2005), pp. 64--83.
3.  [AR92] ISO N179, "AR Fingerprint Function", working document, ISO-IEC/JTC1/SC27/WG2, International Organization for Standardization, 1992.
4.  [BC04] E. Biham, R. Chen, "Near-Collisions of SHA-0", Advances in Cryptology -- Crypto'2004, LNCS 3152, Springer (2004), pp. 290--305. Updated version.
5.  [BDPvA06] G. Bertoni, J. Daemen, M. Peeters, G. van Assche, "RadioGatún, a belt-and-mill hash function", Second NIST Cryptographic Hash Workshop, Santa Barbara, USA, August 24--25, 2006.
6.  [BGG92] T. Baritaud, H. Gilbert, M. Girault, "F.F.T. hashing is not collision-free", Advances in Cryptology -- Eurocrypt'92, LNCS 658, Springer (1992), pp. 35--44.
7.  [BPSSS06] K. Bentahar, D. Page, J. H. Silverman, M.-J. O. Saarinen, N. P. Smart, "LASH", Second NIST Cryptographic Hash Workshop, Santa Barbara, USA, August 24--25, 2006.
8.  [BR00] P. S. L. M. Barreto, V. Rijmen, "The Whirlpool Hashing Function", First open NESSIE Workshop, Leuven, Belgium, November 13--14, 2000.
9.  [BRS02] J. Black, P. Rogaway, and T. Shrimpton, "Black-Box Analysis of the Block-Cipher-Based Hash-Function Constructions from PGV", Advances in Cryptology -- CRYPTO'2002, LNCS 2442, Springer (2002), pp. 320--335.
10.  [BS91] E. Biham and A. Shamir, "Differential cryptanalysis of Feal and N-Hash", Advances in Cryptology -- Eurocrypt'91, LNCS 547, Springer (1991), pp. 1-­16.
11.  [BS93] E. Biham and A. Shamir, "Differential Cryptanalysis of the Data Encryption Standard", Springer (1993).
12.  [CJ98] F. Chabaud and A. Joux, "Differential Collisions in SHA-0", Advances in Cryptology -- Crypto'98, LNCS 1462, Springer (1998), pp. 56--71.
13.  [D95] J. Daemen, " Cipher and Hash Function Design, Strategies Based on Linear and Differential Cryptanalysis", Doctoral dissertation, Katholiek Universiteit Leuven, 1995.
14.  [D89] I. B. Damgård, "A Design Principle for Hash Functions," Advances in Cryptology -- Crypto'89, LNCS 435, Springer (1989), pp. 416--427.
15.  [D96] H. Dobbertin, "The Status of MD5 after a Recent Attack", CryptoBytes2:2 (1996), pp. 1--6.
16.  [D97] H. Dobbertin, "RIPEMD with Two-Round Compress Function is Not Collision-Free", Journal of Cryptology10:1 (1997), pp. 51--70.
17.  [D98] H. Dobbertin, "Cryptanalysis of MD4", Journal of Cryptology11:4 (1998), pp. 253--271.
18.  [D02] J. Daemen, personal communication, 2002 (if you are curious, it merely states that Boognish is "certainly weak").
19.  [DBGV91] J. Daemen, A. Bosselaers, R. Govaerts, J. Vandewalle, "Collisions for Schnorr's Hash Function FFT-Hash", Advances in Cryptology -- Asiacrypt'91, LNCS 739, Springer (1993), pp. 447--480.
20.  [DBP96] H. Dobbertin, A. Bosselaers, and B. Preneel, "RIPEMD-160, a strengthened version of RIPEMD", Fast Software Encryption -- FSE'96, LNCS 1039, Springer (1996), pp. 71--82.
21.  [DC98] J. Daemen and C. Clapp, "Fast Hashing and Stream Encryption with PANAMA", Fast Software Encryption -- FSE'98, LNCS 1372, Springer (1998), pp. 60--74.
22.  [DGV91] J. Daemen, R. Govaerts, and J. Vandewalle, "A Framework for the Design of One-Way Hash Functions Including Cryptanalysis of Damgård's One-Way Function Based on Cellular Automata", Advances in Cryptology - Asiacrypt'91, LNCS 739, Springer (1993), pp. 82--96.
23.  [DGV92a] J. Daemen, R. Govaerts, and J. Vandewalle, "Fast Hashing Both in Hard- and Software", ESAT-COSIC Report92-2, Department of Electrical Engineering, Katholieke Universiteit Leuven, April 1992.
24.  [DGV92b] J. Daemen, R. Govaerts, and J. Vandewalle, "A Hardware Design Model for Cryptographic Algorithms", European Symposium on Research in Computer Security - ESORICS, 1992, pp. 419--434.
25.  [DK93] I. B. Damgård, and L. R. Knudsen, "The breaking of the AR Hash Function", Advances in Cryptology -- EUROCRYPT'93, LNCS 765, Springer (1994), pp. 286--292.
26.  [DV07] J. Daemen, G. van Assche, " Producing Collisions for Panama, Instantaneously, Fast Software Encryption -- FSE'2007, LNCS 4593, Springer (2007), pp. 1--18.
27.  [G94] Government Committee of Russia for Standards, "Information technology. Cryptographic Data Security. Hashing function.", GOST R 34.10-94, Gosudarstvennyi Standard of Russian Federation, 1994. See also " Using the GOST R 34.10-94, GOST R 34.10-2001 and GOST R 34.11-94 algorithms with the Internet X.509 Public Key Infrastructure Certificate and CRL Profile, Serguei Leontiev, 2005.02.08.
28.  [GBR06] D. L. Gazzoni Filho, P. S. L. M. Barreto, V. Rijmen, "The Maelstrom-0 Hash Function", VI Brazilian Symposium on Information and Computer Systems Security -- SBSeg'2006.
29.  [GMDV06] P. Gauravaram, W. Millan, E. Dawson, K. Viswanathan, "Constructing Secure Hash Functions by Enhancing Merkle-Damgård Construction", Cryptology ePrint Archive, Report 2006/061.
30.  [HPR04] P. Hawkes, M. Paddon, G. G. Rose, "On Corrective Patterns for the SHA-2 Family", Cryptology ePrint Archive, Report 2004/207.
31.  [HS06] J. J. Hoch, A. Shamir, "Breaking the ICE - Finding Multicollisions in Iterated Concatenated and Expanded (ICE) Hash Functions", Fast Software Encryption -- FSE'2006, LNCS 4047, Springer (2006), pp 179--194. Preliminary version.
32.  [ISO88] ISO Standard 8731-2, 1988. More information can be found here.
33.  [J04] A. Joux, "Multicollisions in Iterated Hash Functions. Applications to Cascaded Constructions", Advances in Cryptology - Crypto'2004, LNCS 3152, Springer (2004), pp. 306--316.
34.  [JP05] C. S. Jutla and A. C. Patthak, "A Simple and Provably Good code for SHA Message Expansion", First NIST Cryptographic Hash Workshop, Gaithersburg, USA, October 31 -- November 01, 2005. Full version: C. S. Jutla and A. C. Patthak, "Provably Good Codes for Hash Function Design", Selected Areas in Cryptography - SAC'2006, LNCS , Springer (2007), to appear.
35.  [K92] B. Kaliski, "The MD2 Message-Digest Algorithm", RFC 1319 (1992).
36.  [KS05] J. Kelsey, B. Schneier, " Second Preimages on n-Bit Hash Functions for Much Less than 2ⁿ Work," Advances in Cryptology - Eurocrypt'2005, LNCS 3494, Springer (2005), pp. 474--490.
37.  [K05a] V. Klima, "Finding MD5 Collisions -- a Toy For a Notebook", Cryptology ePrint Archive, Report 2005/075.
38.  [K05b] V. Klima, "Finding MD5 Collisions on a Notebook PC Using Multi-message Modifications", Cryptology ePrint Archive, Report 2005/102.
39.  [K06] V. Klima, "Tunnels in Hash Functions: MD5 Collisions Within a Minute", Cryptology ePrint Archive, Report 2006/105.
40.  [K05] L. R. Knudsen, "SMASH - A Cryptographic Hash Function", Fast Software Encryption - FSE'2005, LNCS 3557, Springer (2005), pp. 228--242.
41.  [KBPL05] J. Kim, A. Biryukov, B. Preneel, S. Lee, "On the Security of Encryption Modes of MD4, MD5 and HAVAL", Cryptology ePrint Archive, report 2005/327.
42.  [KK06] T. Kohno, J. Kelsey, " Herding Hash Functions and the Nostradamus Attack", First NIST Cryptographic Hash Workshop, Gaithersburg, USA, October 31 -- November 01, 2005. Full version: Advances in Cryptology -- Eurocrypt'2006, LNCS 4004, Springer (2006), pp. 183--200.
43.  [KL06] J. Kelsey, S. Lucks, " Collisions and Near-Collisions for Reduced-Round Tiger", Full version: Fast Software Encryption -- FSE'2006, LNCS 4047, Springer (2006), pp. 111--125.
44.  [KP00] P. Kasselman, W. Penzhorn, "Cryptanalysis of Reduced Version of HAVAL", Electronics letters, Vol. 36, No. 1, January 2000, pp. 30--31.
45.  [L04] S. Lucks, "Design Principles for Iterated Hash Functions", Cryptology ePrint Archive, report 2004/253.
46.  [M89] R. C. Merkle, "One Way Hash Functions and DES", Advances in Cryptology - Crypto'89, LNCS 435, Springer (1989), pp. 428--446.
47.  [M90] R. C. Merkle, "A Fast Software One-Way Hash Function", Journal of Cryptology3:1 (1990), pp 43--58.
48.  [M04] F. Muller, " The MD2 Hash Function Is Not One-Way," Advances in Cryptology - Asiacrypt'2004, LNCS 3329, Springer (2004), pp. 214--229.
49.  [MOI90] S. Miyaguchi, K. Ohta, and M. Iwata, "128-bit hash function (N-hash)", NTT Review, vol. 2 (no. 6), Nov. 1990, pp. 128--132.
50.  [MPRYW06] F. Mendel, B. Preneel, V. Rijmen, H. Yoshida, D. Watanabe, "Update on Tiger", Progress in Cryptology -- INDOCRYPT'2006, LNCS 4329, Springer (2006), pp. 63--79.
51.  [MZ06] I. Mironov, L. Zhang, "Applications of SAT Solvers to Cryptanalysis of Hash Functions", Theory and Applications of Satisfiability Testing -- SAT 2006, LNCS 4121, Springer (2006), pp. 102--115.
52.  [NN91] NIST/NSA, "FIPS 180" (superseded by FIPS 180-1 and FIPS 180-2). See also NIST's Secure Hashing site.
53.  [NN02] NIST/NSA, "FIPS 180-2: Secure Hash Standard (SHS)", August 2002 (change notice: February 2004). See also NIST's Secure Hashing site.
54.  [PGV93] B. Preneel, R. Govaerts, J. Vandewalle, "Hash Functions Based on Block Ciphers: A Synthetic Approach", Advances in Cryptology - Crypto'93, LNCS 773, Springer (1990), pp. 368--378.
55.  [PRO97] B. Preneel, V. Rijmen, and P. van Oorschot, "Security analysis of the Message Authenticator Algorithm (MAA)", European Transactions on Telecommunications, Vol. 8, No. 5 (Sept./Oct. 1997), pp. 455--470.
56.  [PRR05] N. Pramstaller, C. Rechberger, V. Rijmen, "Smashing SMASH", Cryptology ePrint Archive, report 2005/081.
57.  [R90] R. L. Rivest, "The MD4 Message Digest Algorithm", Advances in Cryptology - Crypto'90, LNCS 537, Springer (1990), pp. 303--311.
58.  [R92] R. L. Rivest, "The MD5 Message Digest Algorithm", RFC 1321 (1992).
59.  [R04] V. Rijmen, "Update on SHA-1", Topics in Cryptography -- CT-RSA'2005, LNCS 3376, Springer (2005), pp. 58--71.
60.  [RC95] N. Rogier, P. Chauvaud, "The compression function of MD2 is not collision free", Selected Areas in Cryptography -- SAC'95, Ottawa, Canada, May 18--19, 1995 (workshop record).
61.  [RIPE92] Research and Development in Advanced Communication Technologies in Europe, "RIPE Integrity Primitives: Final Report of RACE Integriy Primitives Evaluation (R1040)", RACE, June 1992.
62.  [RRPV01] V. Rijmen, B. Van Rompay, B. Preneel, J. Vandewalle, "Producing Collisions for PANAMA", Fast Software Encryption - FSE'2001, LNCS 2355, Springer (2002), pp. 37--51.
63.  [RBPV03] B. Van Rompay, A. Biryukov, B. Preneel, J. Vandewalle, " Cryptanalysis of 3-pass HAVAL", Advances in Cryptology - Asiacrypt'2003, LNCS 2894, Springer (2003), pp. 228--245.
64.  [S91] C. Schnorr, "FFT-Hash, An Efficient Cryptographic Hash Function", Crypto'91 rump session, unpublished manuscript, 1991.
65.  [S92] C. Schnorr, "FFT-Hash II, efficient cryptographic hashing", Advances in Cryptology - Eurocrypt'92, LNCS 658, Springer (1992), pp. 45--54.
66.  [S06] M. Stevens, "Fast Collision Attack on MD5", Cryptology ePrint Archive, report 2006/104.
67.  [SV93] C. Schnorr, S. Vaudenay, "Parallel FFT-Hashing", Fast Software Encryption - FSE'93, LNCS 809, Springer (1994), pp. 149--156.
68.  [TTA05] Telecommunications Technology Association, "TTAS.KO-12.0011/R2: Hash Function Standard - Part 2: Hash Function Algorithm Standard (HAS-160)", December 2005.
69.  [V92] S. Vaudenay, "FFT-Hash-II is not yet Collision-free", Advances in Cryptology - Crypto'92, LNCS 740, Springer (1993), pp. 587--593.
70.  [WFLY04] X. Wang, D. Feng, X. Lai, H. Yu, "Collisions for Hash Functions MD4, MD5, HAVAL-128 and RIPEMD", Cryptology ePrint Archive, Report 2004/199.
71.  [WLFCY05] X. Wang, X. Lai, D. Feng, H. Chen, X. Yu, " Cryptanalysis of the Hash Functions MD4 and RIPEMD", Advances in Cryptology -- Eurocrypt'2005, LNCS 3494, Springer (2005), pp. 1--18.
72.  [WY05] X. Wang, H. Yu, " How to Break MD5 and Other Hash Functions", Advances in Cryptology -- Eurocrypt'2005, LNCS 3494, Springer (2005), pp. 19--35.
73.  [WYY05] X. Wang, Y. L. Yin, H. Yu, "Collision Search Attacks on SHA1", research summary, 2005.
74.  [ZPS92] Y. Zheng, J. Pieprzyk, and J. Seberry, "HAVAL - a one-way hashing algorithm with variable length of output", Advances in Cryptology - Auscrypt'92, LNCS 718, Springer (1993), pp. 83--104.

1. Condensat

Recherches dans Assiste.com		Recherches sur le Web
Condensat avec Qwant Condensat avec DuckDuckGo Condensat avec StartPage Condensat avec Google Condensat avec Bing Condensat avec Yandex Condensat avec Yahoo! Condensat avec Baidu		Condensat avec Qwant Condensat avec DuckDuckGo Condensat avec StartPage Condensat avec Google Condensat avec Bing Condensat avec Yandex Condensat avec Yahoo! Condensat avec Baidu