Key mismatch attacks on RLWE encryption schemes
LE3 .A278 2020
Bachelor of Science
Mathematics & Statistics
Ring learning with errors encryption (RLWE) schemes are a class of public key cryptosystems that securely encrypt messages based on the intractability of hard lattice problems. Several RLWE encryption schemes have been proposed as candidates for standardization in the National Institute of Standards and Technology (NIST) post-quantum cryptography project. A key-mismatch oracle is an oracle that allows an attacker to test whether a ciphertext decodes to a given message. This oracle is commonly available when the key pair of an IND-CPA version of these cryptosystems is reused. In this thesis, we examine an attack that uses a key-mismatch oracle to recover the secret key of an RLWE cryptosystem. We survey descriptions of this attack on NIST candidates, and introduce a description of the attack for the NIST candidate LAC.
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