Crate wasmium_securemem
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wasmium-securemem
This crate is used to securely store in memory the Ed25519 Keypair of a Wasmium wallet.
The keys are encrypted when they are not being used and decrypted when they need to be used
to sign some bytes of any length.
This is inspired by sequoia-openpgp’s Encrypted data structure.
An excerpt from their documentation:
This type encrypts sensitive data, such as secret keys, in memory while they are unused, and decrypts them on demand. This protects against cross-protection-boundary readout via microarchitectural flaws like Spectre or Meltdown, via attacks on physical layout like Rowbleed, and even via coldboot attacks.
The key insight is that these kinds of attacks are imperfect, i.e. the recovered data contains bitflips, or the attack only provides a probability for any given bit. Applied to cryptographic keys, these kind of imperfect attacks are enough to recover the actual key.
This implementation on the other hand, derives a sealing key from a large area of memory, the “pre-key”, using a key derivation function. Now, any single bitflip in the readout of the pre-key will avalanche through all the bits in the sealing key, rendering it unusable with no indication of where the error occurred.
This kind of protection was pioneered by OpenSSH. The commit adding it can be found here.