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Cryptography Software Security

Soatok’s Guide to Side-Channel Attacks

If you’re ever tasked with implementing a cryptography feature–whether a high-level protocol or a low-level primitive–you will have to take special care to ensure you’re not leaking secret information through side-channels. The descriptions of algorithms you learn in a classroom or textbook are not sufficient for real-world use. (Yes, that means your toy RSA implementation […]

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Cryptography

Elliptic Curve Diffie-Hellman for Humans and Furries

Suppose you need to encrypt data between two peer-to-peer devices over an untrusted medium (i.e. the Internet), and you have an authenticated low-bandwidth channel that can be used to send and authenticate a few bytes (less than 100), but that channel isn’t itself encrypted (otherwise it’d be a chicken-and-egg problem). Aside: If it helps your […]

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Cryptography

Authenticated Key Exchanges

Authenticated Key Exchanges are an interesting and important building block in any protocol that aims to allow people to communicate privately over an untrusted medium (i.e. the Internet). What’s an AKE? At their core, Authenticated Key Exchanges (AKEs for short) combine two different classes of protocol. An authentication mechanism, such as a MAC or a […]