Firefox added some new signature constants with missing definitions signature_algs Unknown[0x8]_Unknown[0x4], Unknown[0x8]_Unknown[0x5], Unknown[0x8]_Unknown[0x6],
http://www.iana.org/assignments/tls-parameters/tls-parameters.xhtml#tls-parameters-18
Oops. These are in Chrome too. https://tlswg.github.io/tls13-spec/#rfc.section.4.2.3 /* RSASSA-PSS algorithms */ rsa_pss_sha256 (0x0804), rsa_pss_sha384 (0x0805), rsa_pss_sha512 (0x0806),