Is American Express quantum-safe?
Partly. 6 of 19 public servers under americanexpress.com use post-quantum key exchange, the protection against traffic recorded today being decrypted once a large quantum computer exists. Grade C. Scanned October 18, 2026, a partial scan while the certificate logs were unavailable.
Fix first
Production login, API, VPN, payment and developer servers that still rely on key exchange scheduled for retirement.
- accounts.americanexpress.com
- api.americanexpress.com
- pay.americanexpress.com
- payments.americanexpress.com
9 other servers without post-quantum key exchange
- analytics.americanexpress.com
- ci.americanexpress.com
- dev.americanexpress.com
- link.americanexpress.com
- open.americanexpress.com
- referral.americanexpress.com
- sandbox.americanexpress.com
- shop.americanexpress.com
- stream.americanexpress.com
6 servers already protected
- americanexpress.com
- careers.americanexpress.com
- developer.americanexpress.com
- m.americanexpress.com
- secure.americanexpress.com
- www.americanexpress.com
What this means
NIST has scheduled the key exchange most servers still use for retirement: deprecated after 2030, disallowed after 2035 (NIST IR 8547). Traffic recorded today can be decrypted once a large quantum computer exists. A server that offers hybrid ML-KEM key exchange closes that today; a server that does not is still open to harvest now, decrypt later.
Hostnames come from public certificate logs plus common service names, kept where the name resolves to a public address, and each is tested from the outside with post-quantum-only TLS 1.3 handshakes. A hostname shows what a server is called, not what traffic it carries; internal systems are out of scope. Method.
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<a href="https://latticescan.com/readiness/americanexpress.com"><img src="https://latticescan.com/badge/readiness/americanexpress.com" alt="quantum readiness"></a>