What causes "SUITE_B_INVALID_ALGORITHM" in oven-sh/bun?

Find the offending cert: openssl x509 -noout -text | grep 'Public Key Algorithm' across the chain

oven-sh/bun · error · TypeError

SUITE_B_INVALID_ALGORITHM

SUITE_B_INVALID_ALGORITHM

Error message

SUITE_B_INVALID_ALGORITHM

What it means

CertError::SUITE_B_INVALID_ALGORITHM maps BoringSSL X509_V_ERR_SUITE_B_INVALID_ALGORITHM (verify code 57). Suite B verification requires ECDSA public keys throughout the chain; a certificate in the chain uses another algorithm (RSA, DSA, Ed25519). Message: "Suite B: invalid public key algorithm".

Source

Thrown at src/http/error.rs:233

    #[error("PERMITTED_VIOLATION")]
    PERMITTED_VIOLATION,
    #[error("EXCLUDED_VIOLATION")]
    EXCLUDED_VIOLATION,
    #[error("SUBTREE_MINMAX")]
    SUBTREE_MINMAX,
    #[error("APPLICATION_VERIFICATION")]
    APPLICATION_VERIFICATION,
    #[error("UNSUPPORTED_CONSTRAINT_TYPE")]
    UNSUPPORTED_CONSTRAINT_TYPE,
    #[error("UNSUPPORTED_CONSTRAINT_SYNTAX")]
    UNSUPPORTED_CONSTRAINT_SYNTAX,
    #[error("UNSUPPORTED_NAME_SYNTAX")]
    UNSUPPORTED_NAME_SYNTAX,
    #[error("CRL_PATH_VALIDATION_ERROR")]
    CRL_PATH_VALIDATION_ERROR,
    #[error("SUITE_B_INVALID_VERSION")]
    SUITE_B_INVALID_VERSION,
    #[error("SUITE_B_INVALID_ALGORITHM")]
    SUITE_B_INVALID_ALGORITHM,
    #[error("SUITE_B_INVALID_CURVE")]
    SUITE_B_INVALID_CURVE,
    #[error("SUITE_B_INVALID_SIGNATURE_ALGORITHM")]
    SUITE_B_INVALID_SIGNATURE_ALGORITHM,
    #[error("SUITE_B_LOS_NOT_ALLOWED")]
    SUITE_B_LOS_NOT_ALLOWED,
    #[error("SUITE_B_CANNOT_SIGN_P_384_WITH_P_256")]
    SUITE_B_CANNOT_SIGN_P_384_WITH_P_256,
    #[error("HOSTNAME_MISMATCH")]
    HOSTNAME_MISMATCH,
    #[error("EMAIL_MISMATCH")]
    EMAIL_MISMATCH,
    #[error("IP_ADDRESS_MISMATCH")]
    IP_ADDRESS_MISMATCH,
    #[error("INVALID_CALL")]
    INVALID_CALL,
    #[error("STORE_LOOKUP")]

View on GitHub (pinned to 8c5296ac45)

Solutions

Find the offending cert: openssl x509 -noout -text | grep 'Public Key Algorithm' across the chain
Reissue every chain certificate with ECDSA keys (P-256 or P-384)
Or disable Suite B flags on the verifying stack if the profile is not mandated

Example fix

# before
openssl req -x509 -newkey rsa:2048 ...

# after: ECDSA per Suite B
openssl ecparam -name prime256v1 -genkey -out key.pem
openssl req -x509 -key key.pem ...

Defensive patterns

Strategy: validation

Validate before calling

// Assert all chain certs use ECDSA when a Suite B verifier will connect
import tls from "node:tls";
import { X509Certificate } from "node:crypto";
export function chainIsAllEcdsa(host, port = 443) {
  return new Promise((resolve, reject) => {
    const s = tls.connect({ host, port, servername: host, rejectUnauthorized: false }, () => {
      let c = s.getPeerCertificate(true), ok = true;
      do { ok = ok && new X509Certificate(c.raw).keyObject.asymmetricKeyType === "ec"; } while (c.issuerCertificate && (c = c.issuerCertificate) && !Object.is(c, s.getPeerCertificate(true)));
      s.end(); resolve(ok);
    });
    s.on("error", reject);
  });
}

Type guard

export function isSuiteBInvalidAlgorithm(e): e is Error & { code: "SUITE_B_INVALID_ALGORITHM" } {
  return e instanceof Error && (e as any).code === "SUITE_B_INVALID_ALGORITHM";
}

Try / catch

try {
  await fetch(url);
} catch (e) {
  if (e?.code === "SUITE_B_INVALID_ALGORITHM") {
    // an RSA (or other non-ECDSA) cert is in the chain under Suite B - reissue with ECDSA
    planReissueToEcdsa(new URL(url).hostname);
  } else throw e;
}

Prevention

Finish ECDSA migrations end-to-end: root, intermediates, leaf - partial migration fails Suite B
Set ECDSA as the default key type in your CA issuance pipeline if Suite B clients exist
Grep public-key algorithms across the served chain monthly: openssl s_client -showcerts | grep 'Public Key Algorithm'

When it happens

Trigger: Suite B flags enabled on the verifier and any chain certificate carries an RSA key - typically a legacy RSA intermediate or leaf in front of an ECDSA-rooted hierarchy.

Common situations: Mixed-algorithm chains during incremental ECDSA migration; Suite B gateways in defense networks; default RSA certs (many CAs' default issuance) hitting a Suite B-verifying endpoint.

Related errors

AI-assisted analysis of oven-sh/bun@8c5296ac45 (2026-08-16). Data as JSON: /api/errors/29e065787fe2fc21. Report an issue: GitHub.