Obsolete key exchange mechanisms alias crypto wars part eleven

Obsolete key exchange mechanisms alias crypto wars part eleven

Especially weak key exchange mechanisms indicated by the cipher suite include those designated as EXPORT or ANON;  cipher suites using these key exchange mechanisms should not be used. Even if the cipher suite used in a TLS session is acceptable, a key exchange mechanism may use weak keys that allow exploitation. TLS key exchange methods include RSA key transport and DH or ECDH key establishment. DH and ECDH include static as well as ephemeral mechanisms. NSA recommends RSA key transport and ephemeral DH (DHE) or ECDH (ECDHE) mechanisms, with RSA or DHE key exchange using at least 3072-bit keys and ECDHE key exchanges using the secp384r1 elliptic curve. For RSA key transport and DH/DHE key exchange,  keys less than 2048 bits should not be used,  and ECDH/ECDHE using custom curves should not be used. The use of custom public key parameters in key exchange messages is deprecated per RFC 8422 Section 5.1.1

The recommended configuration is the following

Header always set Strict-Transport-Security "max-age=15553000; preload"
SSLUseStapling On
SSLSessionCache shmcb:/opt/apache2/logs/ssl_gcache_data(512000)
SSLStaplingCache shmcb:/opt/apache2/logs/ssl_stapling_data(512000)
SSLOptions +StrictRequire +StdEnvVars -ExportCertData
SSLProtocol -all +TLSv1.2 +TLSv1.3
SSLCompression Off
SSLHonorCipherOrder On
SSLCipherSuite TLSv1.3 TLS_CHACHA20_POLY1305_SHA256:TLS_AES_256_GCM_SHA384

SSLOpenSSLConfCmd ECDHParameters secp521r1
SSLOpenSSLConfCmd Curves sect571r1:sect571k1:secp521r1:sect409k1:sect409r1:secp384r1

H2Direct On

SSLOpenSSLConfCmd SignatureAlgorithms rsa_pss_rsae_sha512:rsa_pss_rsae_sha256:ECDSA+SHA512:ECDSA+SHA256:RSA+SHA512:RSA+SHA256
SSLOpenSSLConfCmd ClientSignatureAlgorithms rsa_pss_rsae_sha512:rsa_pss_rsae_sha256:ECDSA+SHA512:ECDSA+SHA256:RSA+SHA512:RSA+SHA256

2 thoughts on “Obsolete key exchange mechanisms alias crypto wars part eleven

  1. openssl ecparam -list_curves \
    | grep -v “wap” \
    | grep -v “brainpool” \
    | grep -v “X9” \
    | grep -v “11” \
    | grep -v “12” \
    | grep -v “16” \
    | grep -v “19” \
    | grep -v “28” \
    | grep -v “22” \
    | grep -v “25” \
    | grep -v “23” \
    | grep -v “13” \
    | grep -v “Oak” \
    | grep -v “Question” \
    | grep -v “Not suitable”

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