9 votes
Accepted

State of research on SHA-1 Collision Attacks

SHA-1 was SHattered by Stevens et al. They demonstrated that collisions in SHA-1 are practical. They give the first instance of a collision for SHA-1. It is an identical-prefix collision attack that ...
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  • 206
9 votes
Accepted

Factoring assuming smoothness of some numbers

See my paper with Eric Bach, "Factoring with cyclotomic polynomials", where we show that if the cyclotomic polynomial $\Phi_k(p)$ is $B$-smooth for any $p$ dividing $N$, then we can factor $N$ in time ...
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6 votes
Accepted

Is a "complete" cipher possible?

Yes, you can use Levin universal search to construct a "universal one-way function" (e.g., these lecture notes). From this one-way function you can then construct symmetric-key encryption primitives (...
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  • 2,789
6 votes
Accepted

Cryptographic systems that don't leak linear combinations of encrypted bits

Yes, if the encryption algorithm achieves IND-CPA security (semantic security), this implies that an adversary cannot predict any linear combination of encrypted bits better than random guessing. ...
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  • 10.4k

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