A Clever RSA Attack Fooled a Hardware Vault—Here's What It Means for Crypto

In brief

• Researchers at UC San Diego and France's INRIA forged RSA signatures on a 1,024-bit key inside a hardware security module, the kind of device custodians use to guard crypto keys, without extracting the key.
• Bitcoin and Ethereum sign transactions with elliptic-curve signatures such as ECDSA rather than RSA, and the paper's claims cover RSA only.
• The attack needed about 2^32 signing requests (roughly 4 billion) and 1,380 CPU core-years, and the authors say it likely poses no immediate threat to most modern RSA deployments, which use padding.

Researchers at UC San Diego and France's Institute for Research in Computer Science impersonated a hardware security module—a tamper-resistant device that stores private keys and signs on request—without ever pulling the key out of it. They detailed the attack in a paper submitted to the IACR Cryptology ePrint Archive on September 20.

But don’t panic, crypto holders. This is not a Bitcoin or Ethereum break. Bitcoin uses an elliptic curve digital signature algorithm, or ECDSA. (Its curve also supports Schnorr signatures.) Ethereum, and most of the bigger blockchains, use the same. This paper is about Rivest-Shamir-Adlemen cryptography, or RSA, a different signature scheme.