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During the summer of 2023, Entropy Cryptography Inc engaged NCC Group’s Cryptography Services team to perform a cryptography and implementation review of several Rust-based libraries implementing constant-time big integer arithmetic, prime generation, and secp256k1 (k256) elliptic curve functionality. Two consultants performed the review within 40 person-days of effort, which included retesting and report generation. The […]

This executable blog post is the fourth in a series related to machine learning and is a fascinating trifecta involving hardened cryptography software, embedded IoT-type hardware, and deep machine learning techniques. While the AES algorithm is designed such that a brute-force secret key guessing attack would likely finish ‘sometime near eternity’, the power side-channel attack […]

This blog post presents a whirlwind overview of Verifiable Random Functions (VRFs) as used by several leading-edge blockchains, and shows how a very interesting and recently found implementation oversight causes the VRF’s assurance of uniqueness to fall apart. As VRFs are commonly used for selecting blockchain consensus voting committees, this can result in a rigged […]

This executable blog post is the third in a series related to machine learning and explores code generation from a 16 billion parameter large language model (LLM). After a brief look under the hood at the LLM structure and parameter allocation, we generate a variety of Python functions and make observations related to code quality […]

This blog post is the second in a series related to machine learning, and demonstrates exactly how a data poisoning attack might work to insert a backdoor into a facial authentication system. The simplified system has similarities to that which the TSA is running a proof of concept trial at the Detroit and Atlanta airports. As background, […]

Professor Ron Rivest observed the close relationship between cryptography and machine learning at the ASIACRYPT conference back in 1991. Cross-fertilization of common notions, such as integrity, privacy, confidentiality and authenticity, have only grown in the following three decades as these fields have become more central to our everyday lives. This blog post is the first in […]

This is the second blog post in a new code-centric series about selected optimizations found in pairing-based cryptography. Pairing operations are foundational to the BLS Signatures central to Ethereum 2.0, the zero-knowledge arguments underpinning Filecoin, and a wide variety of other emerging applications. While my prior blog series, “Pairing over BLS12-381,” implemented the entire pairing […]

This is the first blog post in a new code-centric series about selected optimizations found in pairing-based cryptography. Pairing operations are foundational to the BLS Signatures [1] central to Ethereum 2.0, zero-knowledge arguments central to Zcash and Filecoin [2], and a wide variety of other emerging applications. A prior blog series implemented the entire pairing […]

This is the last of three code-centric blog posts on pairing based cryptography. Support for these operations in an Ethereum precompiled contract has been proposed [1], and support for a related pairing configuration in precompiled contracts is already in operation [2, 3]. The first post [4] covered modular arithmetic, finite fields, the embedding degree, and […]

This is the second of three code-centric blog posts on pairing based cryptography. The first post [1] covered modular arithmetic, finite fields, the embedding degree, and presented an implementation of a 12-degree prime extension field tower. The series will ultimately conclude with a detailed review of the popular BLS12-381 pairing operations found in a variety […]