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The existence of encryption and commitment schemes secure under selective opening attack (SOA) has remained open despite considerable interest and attention. We provide the rst public key encryption schemes secure against sender corruptions in this setting. The underlying tool is lossy encryption. We then show that no non-interactive or perfectly binding(More)
To date, many attempts have been made to fingerprint users on the web. These fingerprints allow browsing sessions to be linked together and possibly even tied to a user's identity. They can be used constructively by sites to supplement traditional means of user authentication such as passwords; and they can be used destructively to counter attempts to stay(More)
We report on the aftermath of the discovery of a severe vulnerability in the Debian Linux version of OpenSSL. Systems affected by the bug generated predictable random numbers, most importantly public/private keypairs. To study user response to this vulnerability, we collected a novel dataset of daily remote scans of over 50,000 SSL/TLS-enabled Web servers,(More)
We present the first Identity-Based Encryption (IBE) schemes that are proven secure against selective opening attack (SOA). This means that if an adversary, given a vector of ciphertexts, adaptively corrupts some fraction of the senders, exposing not only their messages but also their coins, the privacy of the unopened messages is guaranteed. Achieving(More)
We provide the first public key encryption schemes proven secure against selective opening attack (SOA). This means that if an adversary obtains a number of ciphertexts and then corrupts some fraction of the senders, obtaining not only the corresponding messages but also the coins under which they were encrypted then the security of the other messages is(More)
Public-key encryption schemes rely for their IND-CPA security on per-message fresh randomness. In practice, randomness may be of poor quality for a variety of reasons, leading to failure of the schemes. Expecting the systems to improve is unrealistic. What we show in this paper is that we can, instead, improve the cryptography to offset the lack of possible(More)
Multiparty signature protocols need protection against rogue-key attacks, made possible whenever an adversary can choose its public key(s) arbitrarily. For many schemes, provable security has only been established under the knowledge of secret key (KOSK) assumption where the adversary is required to reveal the secret keys it utilizes. In practice,(More)
Lossy Trapdoor Functions (LTDFs), introduced by Peikert and Waters (STOC 2008) have been useful for building many cryptographic primitives. In particular, by using an LTDF that loses a (1 − 1/ω(log n)) fraction of all its input bits, it is possible to achieve CCA security using the LTDF as a black-box. Unfortunately, not all candidate LTDFs achieve such a(More)
We show that no commitment scheme that is hiding and binding according to the standard definition is semantically-secure under selective opening attack (SOA), resolving a long-standing and fundamental open question about the power of SOAs. We also obtain the first examples of IND-CPA encryption schemes that are not secure under SOA, both for sender(More)
Random number generators (RNGs) are consistently a weak link in the secure use of cryptography. Routine cryptographic operations such as encryption and signing can fail spectacularly given predictable or repeated random-ness, even when using good long-lived key material. This has proved problematic in prior settings when RNG implementation bugs, poor(More)