FIPS 140-3 and the TLS KDF

There has been a little turmoil between the CAVP and the FIPS community regarding the TLS KDF. The CAVP deprecated testing of the kdf-component-tls-1.0 at the beginning of the year. The community wasn’t ready and it was temporarily un-deprecated. wolfSSL and our wolfCrypt cryptography library are ready for the transition to the RFC7627 TLS KDF.

The kdf-component-tls-1.0 KDF is the standard TLSv1.2 KDF described in RFC5246. The preferred algorithm is the KDF described in RFC7627, also know as Extended Master Secret. This uses the TLSv1.2 KDF and replaces the client and master random values with hashes of the handshake messages up to the key exchange. This cryptographically ties the TLS master secret to the handshake. wolfSSL has enabled Extended Master Secret as a default since 2016.

If you want an up to date cryptography library and TLS stack that is ready for FIPS 140-3, send a message to for more information.