#438·sjcl

Security issue: Library is vulnerable to timing attacks

Author: paulmillrCreated May 13, 2023Updated Sep 7, 2026

sjcl elliptic curve public key calculation time depends on private key bits, effectively leaking all the timings:

sjcl private key A x 7,624 ops/sec @ 131μs/op
sjcl private key B x 117 ops/sec @ 8ms/op
sjcl private key C x 56 ops/sec @ 17ms/op

Reproducible with this code:

javascript

// mkdir a && cd a && npm init -y && npm install micro-bmark sjcl-including-ecc
const bmark = require('micro-bmark');
const sjcl = require('sjcl-including-ecc');
const curve = sjcl.ecc.curves.k256;
const privA = '1000000000000000000000000000000000000000000000000000000000000000';
const privB = '0000000000000000000000000000010000000000000000000000000000000000';
const privC = '0000000000000000000000000000000000000000000000000000000000000001';
bmark.run(async () => {
  console.log(curve.G.mult(privA).isIdentity);
  await bmark.mark('sjcl private key A', 110, () => curve.G.mult(privA));
  await bmark.mark('sjcl private key B', 110, () => curve.G.mult(privB));
  await bmark.mark('sjcl private key C', 110, () => curve.G.mult(privC));
})

Source: bitwiseshiftleft/sjcl

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