Minerva attack on ARM architecture about openssl HOT 7 OPEN

In the description:

OpenSSL in s390x architecture

Missing search and replace with Arm? :)

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There is a reason why an ECDH secret is usually not used in more than one key agreement.

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Depends on the use case. TLS doesn't because TLS uses signing keys for the long-lived credential, but there are plenty of protocols that are designed differently. HPKE, other ECIES schemes, Signal, the original QUIC handshake, etc.

Constant time ECDH isn't meaningfully harder than constant time ECDSA signing. Arguably easier. ECDSA is a point multiplication and then some. (Although they're not quite the same multiplication. ECDSA is a base point multiplication and ECDH is an arbitrary point. But that doesn't change how hard constant time is.)

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@GeorgePantelakis the signal is very small ~1ns and I would be very curious to see any real world attack scenario that could take an advantage of such small signal.

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@t8m That might be true, at least for now, but as you can see for Skylark in the deterministic path the signal is ~3ns so that could be an issue.

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@GeorgePantelakis the signal is very small ~1ns and I would be very curious to see any real world attack scenario that could take an advantage of such small signal.

Note that the leakage is most likely in scalar multiplication, which means ECDH is also most likely affected. So, anything that exposes a network API that uses static ECDH, for example, Json Web Encryption, can be attacked through this.

Confirming 1ns difference over the network is 100% possible, I've done that multiple times, it's just a question of persistence.

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There is a reason why an ECDH secret is usually not used in more than one key agreement.

that's why I wrote "static ECDH", not "ECDHE".

Yes, for ECDHE, like in TLS, IPsec or SSH, when the key is used once, or just few hundred times, a remote network timing attack is basically impossible with leakage this small.

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