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The following definitions are ordered from lowest to highest achieved security, in other words, from most powerful to the weakest attack. The definitions form a hierarchy, meaning that an attacker able to mount a specific attack can execute all the attacks further down the list. Likewise, a scheme
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544:
182:. An adversary capable of universal forgery is able to sign messages they chose themselves (as in selective forgery), messages chosen at random, or even specific messages provided by an opponent.
421:, is valid, the adversary has succeeded in constructing an existential forgery. Thus, creating an existential forgery is easier than a selective forgery, because the attacker may select a message
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This notion is a stronger (more secure) variant of the existential forgery detailed above. Weak existential forgery is the creation (by an adversary) of at least one message/signature pair,
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produced by the legitimate signer. In contrast to existential forgeries, an adversary is also considered successful if they manage to create a new signature for an already signed message
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for which a forgery can easily be created, whereas in the case of a selective forgery, the challenger can ask for the signature of a “difficult” message.
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Bleumer G. (2011) Selective
Forgery. In: van Tilborg H.C.A., Jajodia S. (eds) Encyclopedia of Cryptography and Security. Springer, Boston, MA.
289:
The ability to successfully conduct a selective forgery attack implies the ability to successfully conduct an existential forgery attack.
130:: when adversary can recover the private information and keys used by the signer, they can create any possible signature on any message.
109:
definitions can be associated. A signature scheme is secure by a specific definition if no forgery of the associated type is possible.
266:
may be chosen to have interesting mathematical properties with respect to the signature algorithm; however, in selective forgery,
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Existential forgery (existential unforgeability, EUF) is the creation (by an adversary) of at least one message/signature pair,
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Strong existential forgery is essentially the weakest adversarial goal, therefore the strongest schemes are those that are
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102:, but has not been created in the past by the legitimate signer. There are different types of forgery.
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need not have any particular meaning; the message content is irrelevant — as long as the pair,
992:
708:{\displaystyle \sigma \left(m'\right)=\sigma (m_{1}\cdot m_{2})=\sigma (m_{1})\cdot \sigma (m_{2})}
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Weak existential forgery (strong existential unforgeability, strong unforgeability; sEUF, or SUF)
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A Classical
Introduction to Cryptography: Applications for Communications Security
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539:{\displaystyle \sigma (m_{1})\cdot \sigma (m_{2})=\sigma (m_{1}\cdot m_{2})}
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Universal forgery is the creation (by an adversary) of a valid signature,
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has never been signed by the legitimate signer. The adversary can choose
185:
133:
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118:
that reaches a certain security goal also reaches all prior ones.
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Selective forgery is the creation of a message/signature pair
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Lecture Notes on
Cryptography. Summer course on cryptography
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More general than the following attacks, there is also a
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is the ability to create a pair consisting of a message,
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This property can be exploited by creating a message
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186:Selective forgery (selective unforgeability, SUF)
134:Universal forgery (universal unforgeability, UUF)
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956:. La Sapienza University of Rome. pp. 8–9
286:must be fixed before the start of the attack.
1012:
935:https://doi.org/10.1007/978-1-4419-5906-5_225
453:has the following multiplicative property:
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1005:
888:Goldwasser, Shafi; Bellare, Mihir (2008).
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769:{\displaystyle \left(m',\sigma '\right)}
987:This cryptography-related article is a
867:(1st ed.). Springer. p. 254.
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718:A common defense to this attack is to
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246:by the attacker prior to the attack.
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916:Shafi Goldwasser and Mihir Bellare.
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593:{\displaystyle m'=m_{1}\cdot m_{2}}
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838:strongly existentially unforgeable
722:the messages before signing them.
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445:Example of an existential forgery
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949:Fabrizio d'Amore (April 2012).
918:"Lecture Notes on Cryptography"
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894:. p. 170. Archived from
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991:. You can help Knowledge by
62:, and a signature (or MAC),
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801:{\displaystyle (m,\sigma )}
414:{\displaystyle (m,\sigma )}
322:{\displaystyle (m,\sigma )}
215:{\displaystyle (m,\sigma )}
10:
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951:"Digital signatures - DSA"
40:digital signature forgery
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105:To each of these types,
222:by an adversary, where
151:{\displaystyle \sigma }
75:{\displaystyle \sigma }
863:(September 16, 2005).
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18:Existential forgery
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382:{\displaystyle m}
362:{\displaystyle m}
342:{\displaystyle m}
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175:{\displaystyle m}
95:{\displaystyle m}
55:{\displaystyle m}
32:digital signature
16:(Redirected from
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29:cryptographic
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993:expanding it
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900:. Retrieved
896:the original
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128:total break
122:Total break
1032:Categories
902:2011-01-30
844:References
793:σ
755:σ
687:σ
684:⋅
665:σ
646:⋅
630:σ
608:σ
578:⋅
521:⋅
505:σ
483:σ
480:⋅
461:σ
406:σ
314:σ
242:has been
207:σ
146:σ
70:σ
960:July 27,
820:′
758:′
747:′
619:′
561:′
369:freely;
329:, where
107:security
38:system,
871:
244:chosen
158:, for
954:(PDF)
921:(PDF)
113:Types
27:In a
989:stub
962:2018
869:ISBN
720:hash
449:The
160:any
36:MAC
34:or
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941:^
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