TLS_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA

What each component means

A cipher suite names the algorithms a client and server agree on in one handshake. TLS_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA combines DHE key exchange, DSS authentication, DES40-CBC encryption and SHA1 integrity protection. Each part is explained below with its known weaknesses; for the bigger picture see how cipher suites work.

Key exchange: DHE, ephemeral finite-field Diffie-Hellman. A new DH key pair per handshake gives forward secrecy, but in TLS 1.2 the server alone picks the group and the client cannot ask for a stronger one; RFC 7919 (2016) added negotiated FFDHE groups, which saw little uptake. Logjam (CVE-2015-4000, 2015) broke servers that still accepted 512-bit export groups and showed that huge numbers of sites shared the same few 1024-bit primes, and the Raccoon timing attack (2020) exploits how TLS 1.2 strips leading zero bytes from the DH secret. Those are the reasons RFC 9325 (2022) gives for telling TLS 1.2 implementations not to negotiate TLS_DHE_* suites.

This is a 1990s EXPORT suite: the cipher is cut to 40 bits and the Diffie-Hellman group to 512 bits to meet old US export rules. Logjam (CVE-2015-4000, May 2015) showed that a man-in-the-middle could downgrade a normal DHE handshake to DHE_EXPORT on servers that still accepted it and then break the 512-bit group within minutes, because most servers used the same few primes and the expensive precomputation only had to be done once per prime.

Authentication: DSS, meaning DSA certificates. Publicly trusted CAs only issue RSA and ECDSA certificates under the CA/Browser Forum Baseline Requirements, TLS 1.3 has no DSA signature scheme, and NIST's FIPS 186-5 (2023) no longer approves DSA for creating signatures, so DSS suites only survive in legacy private PKIs.

Encryption: DES reduced to 40 bits of secret key, an export-grade cipher that ordinary hardware brute-forces quickly. RFC 9325 (2022) forbids any suite with less than 112 bits of security and names export-level 40- and 56-bit ciphers explicitly.

Mode: CBC with MAC-then-encrypt. TLS 1.2 and earlier compute the HMAC over the plaintext, then pad and encrypt, so a receiver has to decrypt before it can check integrity. That ordering produced a long run of padding-oracle attacks: BEAST (CVE-2011-3389) against TLS 1.0's predictable IVs, Lucky Thirteen (CVE-2013-0169, 2013), which times the MAC check, and POODLE (CVE-2014-3566, 2014) against SSL 3.0's unchecked padding. RFC 9325 (2022) says CBC suites SHOULD NOT be used unless the encrypt_then_mac extension (RFC 7366) is also negotiated.

Integrity: HMAC-SHA1. SHA-1 collisions are practical (SHAttered, 2017), but HMAC does not rely on collision resistance, so HMAC-SHA1 record MACs are not considered broken; this suite's weak points lie elsewhere.

Why this rating

ssl.sh rating: Insecure. The reasons:

• Export-grade cryptography (40/56-bit keys), broken since the 1990s and exploited by FREAK and Logjam.
• Uses single DES, whose 56-bit key can be brute-forced; RFC 5246 removed DES suites from TLS 1.2.

How ssl.sh rates cipher suites

Which TLS libraries support it

Support for TLS_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA as read from each library's own source code or official documentation on 2026-11-10. “Enabled by default” means the library negotiates it with no configuration; “off by default” means it is implemented but has to be switched on.

None of the 9 libraries tracked here enables it by default. Supported but off by default in: Java 21 (SunJSSE).

NSS shows the library's own defaults; Firefox switches every NSS suite off at start-up and re-enables only those with a security.ssl3.* or security.tls13.* preference. Java defaults are derived from the jdk.tls.disabledAlgorithms value Oracle documents for JDK 21, which later updates may extend. The OpenSSL and GnuTLS rows only show whether the suite is implemented.

History and standards status

TLS_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA (0x00,0x11) is registered in the IANA TLS Cipher Suites registry with RFC 4346, “The Transport Layer Security (TLS) Protocol Version 1.1” (April 2006, Historic) as its specification. RFC 4346 has since been obsoleted by RFC 5246 (2008). As early as 2006, the TLS 1.1 specification RFC 4346 said TLS 1.1 implementations MUST NOT negotiate the export suites, which include this one. It can only be negotiated in SSL 3.0, TLS 1.0. RFC 7568 (2015) deprecated SSL 3.0 and RFC 8996 (2021) deprecated TLS 1.0 and TLS 1.1, so no protocol version still in good standing allows it. RFC 10015 (2026) now says clients MUST NOT offer and servers MUST NOT select FFDHE suites in (D)TLS 1.2, and IANA changed this entry's Recommended value to D.

Enable or disable it in Nginx and Apache

OpenSSL 3.5 doesn't implement this suite, so stock Nginx and Apache httpd builds can't offer it and you don't need to disable it.

How to test whether a server accepts it

OpenSSL 3.5 cannot offer TLS_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA, so openssl s_client can't test it directly; use a scanner that implements the suite itself.

nmap's ssl-enum-ciphers script connects repeatedly, trying one suite at a time, and lists every suite the server accepts with a grade from A to F. Look for TLS_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA in its output:

nmap --script ssl-enum-ciphers -p 443 example.com

To decode a name or hex code, use the cipher suite lookup; the SSL checker shows which protocol versions a live server accepts and the cipher suite it negotiates.