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Secure signatures without a private key

Reproducible builds allow anyone to verify that a binary matches its source code. But what if the build artifact must contain a cryptographic signature? Reproducing the signature requires the private key, which defeats the purpose of reproducibility. In this post, we present a technique based on ECDSA public key recovery that produces signatures which are both secure and fully reproducible,…

Reproducing and mitigating BadAML

BadAML is an attack that exploits host-supplied ACPI tables to gain arbitrary code execution inside confidential VMs, bypassing their memory isolation guarantees. Working on Contrast, we reproduced the attack end-to-end against our stack and mitigated it with an AML sandbox that restricts bytecode execution to shared memory pages. On untrusted ground: Protecting guests with confidential computing…