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Traditionally, the world of cryptography has been the domain of mathematicians and computer scientists. However, recent advancements, particularly in zero-knowledge technologies, are changing the landscape. Cryptographic system designs are evolving from intricate mathematical structures into more user-friendly programming tasks. This evolution, known as programmable cryptography, is closing the gap between theoretical protocol designs and their practical applications, with significant implications for security and privacy both online and on-chain.
Cryptography, at its core, is about sending secure messages between parties. This process entails ensuring that the sender and receiver can understand the messages, while preventing any third-party interceptors from doing so. It also involves safeguarding the message from tampering before reaching its destination. For example, digital signatures provide authentication and integrity for communication over insecure channels.
Modern cryptographic systems now cater to protecting various types of online data and messages during storage, transmission, and computation, encompassing areas such as banking, e-commerce, auctions, and blockchain. These systems include zero-knowledge proofs (ZKPs), multi-party computation (MPC), fully homomorphic encryption (FHE), and more, each addressing specific needs and scenarios based on mathematical principles.
MPC safeguards input data privacy in collaborative computing scenarios involving multiple parties. One application of MPC is institutional custody, as utilized by companies like Fireblocks, to delegate responsibility for overseeing a wallet. ZKPs enable efficient verifiable computation and data privacy in single-party contexts, currently deployed in blockchain privacy and scalability efforts.
The introduction of advanced cryptographic systems opens up exciting possibilities for the digital realm, but also presents significant challenges. For a long time, access to specialized cryptographic protocols tailored for specific applications like private intersections, auctions, voting, and physical identity verification has been limited. Implementing these systems in practical settings is complex and requires meticulous planning to address security assumptions, primitive choices, and performance optimization, hindering widespread adoption.
Programmable cryptography plays a crucial role in bridging the gap between theory and application by incorporating circuit-based functional descriptions that enhance the usability of cryptosystems. By enabling cryptosystems to emulate Turing machines through circuit descriptions, programmable cryptography aims to tackle the adoption challenges faced by cryptosystems. However, the practical application of these systems can become unrealistic as they grow in complexity with computational problem size, necessitating continuous refinement and optimization by cryptographers.
Researchers at 0xPARC and Privacy and Scaling Explorations are at the forefront of developing programmable zkSNARKs, a zero-knowledge proof construction widely used in blockchain infrastructure like ZCash and zkEVM. They have demonstrated programmable ZKPs for identity claims, allowing for confidential verification of service eligibility without revealing personal information, and for calculating credit scores from user interactions with web2 services in a privacy-centric manner, transforming financial trustworthiness evaluation.
Programmable cryptography offers flexibility and adaptability in practical cryptographic applications, expanding accessibility beyond academia to developers worldwide for experimentation and innovation. While currently focused on zkSNARKs, ongoing research and innovation in cryptography could lead to programmable breakthroughs in MPC or homomorphic encryption, opening up new possibilities for encryption technology.
As our lives become increasingly digital, the need to secure and authenticate our data and communications grows more critical. Programmable cryptography has the potential to revolutionize modern encryption, making it more accessible and ripe for further development, breaking down barriers for a new era of secure communication.