because they make it for living • Independent from large corporations, government, etc. And some of them are large corporations Except, some of them ARE government
because they make it for living • Independent from large corporations, government, etc. • Pursuing their interests as trusted third parties • Corporations and government always tend to elevate their own interests
by domain owner • Allowed using non-privileged ports (>50,000) to verify domain control • Allowed using subdomains to verify 2nd level domain • Allowed using arbitrary files to verify ownership
by domain owner • Allowed using non-privileged ports (>50,000) to verify domain control • Allowed using subdomains to verify 2nd level domain • Allowed using arbitrary files to verify ownership • Allowed to issue certificates for arbitrary domains without verification
by domain owner • Allowed using non-privileged ports (>50,000) to verify domain control • Allowed using subdomains to verify 2nd level domain • Allowed using arbitrary files to verify ownership • Allowed to issue certificates for arbitrary domains without verification • Issued backdated SHA-1 certificates
by domain owner • Allowed using non-privileged ports (>50,000) to verify domain control • Allowed using subdomains to verify 2nd level domain • Allowed using arbitrary files to verify ownership • Allowed to issue certificates for arbitrary domains without verification • Issued backdated SHA-1 certificates • Used unpatched software (such as dig) on the validation server
by domain owner • Allowed using non-privileged ports (>50,000) to verify domain control • Allowed using subdomains to verify 2nd level domain • Allowed using arbitrary files to verify ownership • Allowed to issue certificates for arbitrary domains without verification • Issued backdated SHA-1 certificates • Used unpatched software (such as dig) on the validation server • Purchased other CA (StartCom) and attempted to suppress information about the ownership transfer
Bonus points if it provides some kind of API • Pick multiple CAs • “Extended validity” certificates are a security theater (don’t bother if you are not a bank and auditor doesn’t force you to)
Bonus points if it provides some kind of API • Pick multiple CAs • “Extended validity” certificates are a security theater (don’t bother if you are not a bank and auditor doesn’t force you to) • Prefer short-lived certificates
#^$ updating all the certs Cons: • Soft-fail CRL and OCSP are not reliable • Hard-fail CRL and OCSP are never used (you may do it in your app though) • Certificate deployment and management must be automated anyway
Certificate deployment and management must be automated Long-lived cert is a technical debt. It wouldn’t punish you immediately. It will hurt you eventually.
certificates real quick • Manage certificates properly: short lifetime, multiple keys • Set up a clientside TLS auth • Quickly work around obscure issues like “Intermediate CA was revoked”
revoked its own certificate • Used CDN (Cloudflare) for CRL and OCSP • Undid revocation, but it’s got cached on CDN • Four days before cached response will expire in a browser • Wikipedia, Dropbox, Spotify, Financial Times affected • Large sites affected more because CRL got cached everywhere immediately
CRL got cached everywhere immediately • “All is good and yet traffic dropped by 30%” • Really hard to troubleshoot • The issue is of distributed nature • You depend on a vendor
CRL got cached everywhere immediately • “All is good and yet traffic dropped by 30%” • Really hard to troubleshoot • The issue is of distributed nature • You depend on a vendor • Multiple different certs from different vendors helped to track down • tcpdump also of a great help: sessions got stuck at TLS Server Hello
The issue is of distributed nature • You depend on a vendor • Multiple different certs from different vendors will help to track down • tcpdump also of a great help: sessions got stuck at TLS Server Hello TLS is still bleeding edge of technology. Unsufficient tools, unsufficient knowledge.
Security • “Opportunistic encryption” simply doesn’t work • Most users won’t notice if HTTPS is absent • HTTPS only makes sense if it’s enforced • Public Key Pinning • Pin all end-entity public keys • Create a backup • Include future leafs • Rotate often => use automated tools to generate the header
Army • Military required three distinct security levels, with less sensitive data to be encrypted using the most weak method and vice versa • Crypto designers implemented three key sizes (128, 192, 256), with the most weak still unbreakable in foreseeable future (except quantum computers)
Army • Military required three distinct security levels, with less sensitive data to be encrypted using the most weak method and vice versa • Crypto designers implemented three key sizes (128, 192, 256), with the most weak still unbreakable in foreseeable future (except quantum computers) • So, AES-128 is still good enough • Not that it matters much with modern AES-NI
Diffie-Hellman ciphers • Makes out-of-path analysis impossible • Makes historic data analysis impossible • Good catch for an out-of-path DPI and/or WAF 70% HTTPS requests come and go without analysis
impossible • Makes historic data analysis impossible • Good catch for an out-of-path DPI and/or WAF 70% HTTP requests go without analysis The story of Perfect Forward Secrecy 60% legitimate 90% malicious
impossible • Makes historic data analysis impossible • Good catch for an out-of-path DPI and/or WAF 70% HTTP requests go without analysis Oh boy, ciphers are tough. The story of Perfect Forward Secrecy 60% legitimate 90% malicious
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