Traditional fully homomorphic encryption (FHE) schemes only allow computation on data encrypted under a single key. López-Alt, Tromer, and Vaikuntanathan (STOC 2012) proposed the notion of multi-key FHE, which allows homomorphic computation on ciphertexts encrypted under different keys, and also gave a construction based on a (somewhat nonstandard) assumption related to NTRU. More recently, Cle...

Gentry, Sahai and Waters recently presented the first (leveled) identity-based fully homomorphic (IBFHE) encryption scheme (CRYPTO 2013). Their scheme however only works in the single-identity setting; that is, homomorphic evaluation can only be performed on ciphertexts created with the same identity. In this work, we extend their results to the multi-identity setting and obtain a multi-identit...

With this work we provide further evidence that latticebased cryptography is a promising and efficient alternative to secure embedded applications. So far it is known for solid security reductions but implementations of specific instances have often been reported to be too complex beyond any practicability. In this work, we present an efficient and scalable micro-code engine for Ring-LWE encryp...

We propose a new zero-knowledge protocol applicable to additively homomorphic functions that map integer vectors to an Abelian group. The protocol demonstrates knowledge of a short preimage and achieves amortised efficiency comparable to the approach of Cramer and Damg̊ard from Crypto 2010, but gives a much tighter bound on what we can extract from a dishonest prover. Towards achieving this resu...

Several ideal-lattice-based cryptosystems have been broken by recent attacks that exploit special structures of the rings used in those cryptosystems. The same structures are also used in the leading proposals for post-quantum lattice-based cryptography, including the classic NTRU cryptosystem and typical Ring-LWE-based cryptosystems. This paper (1) proposes NTRU Prime, which tweaks NTRU to use...

We present a generic, yet simple and efficient transformation to obtain a forward secure authenticated key exchange protocol from a two-move passively secure unauthenticated key agreement scheme (such as standard Diffie–Hellman or Frodo or NewHope). Our construction requires only an IND-CCA public key encryption scheme (such as RSA-OAEP or a method based on ring-LWE), and a message authenticati...

Password-based Authenticated Key Exchange (PAKE) protocol assumes that the parties share a low-entropy, easy-to-remember password to achieve the authentication with a high-entropy session key. PAKE protocols can be employed to hand-held devices for access control of sensitive personal data remotely. For communication with more than one user, the user needs to remember all passwords between othe...

Security parameters and attack countermeasures for Lattice-based cryptosystems have not yet matured to the level that we now expect from RSA and Elliptic Curve implementations. Many modern Ring-LWE and other lattice-based public key algorithms require high precision random sampling from the Discrete Gaussian distribution. The sampling procedure often represents the biggest implementation bottle...

Traditional fully homomorphic encryption (FHE) schemes support computation on data encrypted under a single key. In STOC 2012, López-Alt et al. introduced the notion of multi-key FHE (MKFHE), which allows homomorphic computation on ciphertexts encrypted under different keys. In this work, we focus on MKFHE constructions from standard assumptions and propose a new construction of ring-LWE-based ...

Introduced as a new protocol implemented in “Chrome Canary” for the Google Inc. Chrome browser, “New Hope” is engineered as a postquantum key exchange for the TLS 1.2 protocol. The structure of the exchange is a combination of elliptic curve enhancements along with revised lattice-based cryptography. New Hope incorporates the key-encapsulation mechanism of Peikert which itself is a modified Rin...