feature: new compatibility-focused security policy preferring ECDSA (#…

…4579)

tls/s2n_cipher_preferences.c

@@ -2014,6 +2014,63 @@ const struct s2n_cipher_preferences cipher_preferences_20210816_gcm = {
     .allow_chacha20_boosting = false,
 };
 
+/* Cipher suite options for backwards compatibility with older clients,
+ * while prioritizing forward secret key exchange and ECDSA certificates.
+ */
+struct s2n_cipher_suite *cipher_suites_20240603[] = {
+    /* TLS1.3 suites */
+    &s2n_tls13_aes_128_gcm_sha256,
+    &s2n_tls13_aes_256_gcm_sha384,
+    &s2n_tls13_chacha20_poly1305_sha256,
+
+    /* Preferred ECDHE + ECDSA suites */
+    &s2n_ecdhe_ecdsa_with_aes_128_gcm_sha256,
+    &s2n_ecdhe_ecdsa_with_aes_128_cbc_sha256,
+    &s2n_ecdhe_ecdsa_with_aes_256_gcm_sha384,
+    &s2n_ecdhe_ecdsa_with_aes_256_cbc_sha384,
+    &s2n_ecdhe_ecdsa_with_chacha20_poly1305_sha256,
+
+    /* Preferred ECDHE + RSA suites */
+    &s2n_ecdhe_rsa_with_aes_128_gcm_sha256,
+    &s2n_ecdhe_rsa_with_aes_128_cbc_sha256,
+    &s2n_ecdhe_rsa_with_aes_256_gcm_sha384,
+    &s2n_ecdhe_rsa_with_aes_256_cbc_sha384,
+    &s2n_ecdhe_rsa_with_chacha20_poly1305_sha256,
+
+    /* Legacy ECDHE suites */
+    &s2n_ecdhe_ecdsa_with_aes_128_cbc_sha,
+    &s2n_ecdhe_ecdsa_with_aes_256_cbc_sha,
+    &s2n_ecdhe_rsa_with_aes_128_cbc_sha,
+    &s2n_ecdhe_rsa_with_aes_256_cbc_sha,
+
+    /* DHE suites */
+    &s2n_dhe_rsa_with_aes_128_gcm_sha256,
+    &s2n_dhe_rsa_with_aes_128_cbc_sha256,
+    &s2n_dhe_rsa_with_aes_256_gcm_sha384,
+    &s2n_dhe_rsa_with_aes_256_cbc_sha256,
+    &s2n_dhe_rsa_with_aes_128_cbc_sha,
+    &s2n_dhe_rsa_with_aes_256_cbc_sha,
+
+    /* 3DES suites */
+    &s2n_ecdhe_rsa_with_3des_ede_cbc_sha,
+    &s2n_dhe_rsa_with_3des_ede_cbc_sha,
+
+    /* RSA kex suites */
+    &s2n_rsa_with_aes_128_gcm_sha256,
+    &s2n_rsa_with_aes_128_cbc_sha256,
+    &s2n_rsa_with_aes_256_gcm_sha384,
+    &s2n_rsa_with_aes_256_cbc_sha256,
+    &s2n_rsa_with_aes_128_cbc_sha,
+    &s2n_rsa_with_aes_256_cbc_sha,
+    &s2n_rsa_with_3des_ede_cbc_sha,
+};
+
+const struct s2n_cipher_preferences cipher_preferences_20240603 = {
+    .count = s2n_array_len(cipher_suites_20240603),
+    .suites = cipher_suites_20240603,
+    .allow_chacha20_boosting = true,
+};
+
 struct s2n_cipher_suite *cipher_suites_rfc9151[] = {
     /* TLS1.2 */
     &s2n_ecdhe_ecdsa_with_aes_256_gcm_sha384,

tls/s2n_cipher_preferences.h

@@ -58,6 +58,7 @@ extern const struct s2n_cipher_preferences cipher_preferences_20210825_gcm;
 extern const struct s2n_cipher_preferences cipher_preferences_20210831;
 extern const struct s2n_cipher_preferences cipher_preferences_20231213;
 extern const struct s2n_cipher_preferences cipher_preferences_20231214;
+extern const struct s2n_cipher_preferences cipher_preferences_20240603;
 
 extern const struct s2n_cipher_preferences cipher_preferences_default_fips;
 

tls/s2n_ecc_preferences.c

@@ -70,6 +70,16 @@ const struct s2n_ecc_named_curve *const s2n_ecc_pref_list_20201021[] = {
     &s2n_ecc_curve_secp521r1,
 };
 
+/* Prefer x25519 over p256 for performance */
+const struct s2n_ecc_named_curve *const s2n_ecc_pref_list_20240603[] = {
+#if EVP_APIS_SUPPORTED
+    &s2n_ecc_curve_x25519,
+#endif
+    &s2n_ecc_curve_secp256r1,
+    &s2n_ecc_curve_secp384r1,
+    &s2n_ecc_curve_secp521r1,
+};
+
 const struct s2n_ecc_named_curve *const s2n_ecc_pref_list_20210816[] = {
     &s2n_ecc_curve_secp384r1,
 };
@@ -118,6 +128,11 @@ const struct s2n_ecc_preferences s2n_ecc_preferences_20210816 = {
     .ecc_curves = s2n_ecc_pref_list_20210816,
 };
 
+const struct s2n_ecc_preferences s2n_ecc_preferences_20240603 = {
+    .count = s2n_array_len(s2n_ecc_pref_list_20240603),
+    .ecc_curves = s2n_ecc_pref_list_20240603,
+};
+
 const struct s2n_ecc_preferences s2n_ecc_preferences_test_all = {
     .count = s2n_array_len(s2n_ecc_pref_list_test_all),
     .ecc_curves = s2n_ecc_pref_list_test_all,

tls/s2n_ecc_preferences.h

@@ -33,6 +33,7 @@ extern const struct s2n_ecc_preferences s2n_ecc_preferences_20230623;
 extern const struct s2n_ecc_preferences s2n_ecc_preferences_default_fips;
 extern const struct s2n_ecc_preferences s2n_ecc_preferences_20201021;
 extern const struct s2n_ecc_preferences s2n_ecc_preferences_20210816;
+extern const struct s2n_ecc_preferences s2n_ecc_preferences_20240603;
 extern const struct s2n_ecc_preferences s2n_ecc_preferences_test_all;
 extern const struct s2n_ecc_preferences s2n_ecc_preferences_null;
 

tls/s2n_security_policies.c

@@ -59,6 +59,15 @@ const struct s2n_security_policy security_policy_20240503 = {
     },
 };
 
+const struct s2n_security_policy security_policy_20240603 = {
+    .minimum_protocol_version = S2N_TLS12,
+    .cipher_preferences = &cipher_preferences_20240603,
+    .kem_preferences = &kem_preferences_null,
+    .signature_preferences = &s2n_signature_preferences_20240501,
+    .certificate_signature_preferences = &s2n_certificate_signature_preferences_20201110,
+    .ecc_preferences = &s2n_ecc_preferences_20240603,
+};
+
 const struct s2n_security_policy security_policy_20170210 = {
     .minimum_protocol_version = S2N_TLS10,
     .cipher_preferences = &cipher_preferences_20170210,
@@ -1228,6 +1237,7 @@ struct s2n_security_policy_selection security_policy_selection[] = {
     { .version = "20201021", .security_policy = &security_policy_20201021, .ecc_extension_required = 0, .pq_kem_extension_required = 0 },
     { .version = "20210816", .security_policy = &security_policy_20210816, .ecc_extension_required = 0, .pq_kem_extension_required = 0 },
     { .version = "20210816_GCM", .security_policy = &security_policy_20210816_gcm, .ecc_extension_required = 0, .pq_kem_extension_required = 0 },
+    { .version = "20240603", .security_policy = &security_policy_20240603, .ecc_extension_required = 0, .pq_kem_extension_required = 0 },
     { .version = "rfc9151", .security_policy = &security_policy_rfc9151, .ecc_extension_required = 0, .pq_kem_extension_required = 0 },
     { .version = "test_all", .security_policy = &security_policy_test_all, .ecc_extension_required = 0, .pq_kem_extension_required = 0 },
     { .version = "test_all_fips", .security_policy = &security_policy_test_all_fips, .ecc_extension_required = 0, .pq_kem_extension_required = 0 },

tls/s2n_security_policies.h

@@ -122,6 +122,8 @@ extern const struct s2n_security_policy security_policy_20230317;
 extern const struct s2n_security_policy security_policy_20240331;
 extern const struct s2n_security_policy security_policy_20240417;
 extern const struct s2n_security_policy security_policy_20240416;
+extern const struct s2n_security_policy security_policy_20240603;
+
 extern const struct s2n_security_policy security_policy_rfc9151;
 extern const struct s2n_security_policy security_policy_test_all;