--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/spec/util_tlsref_spec.lua	Fri Jun 12 13:01:56 2026 +0100
@@ -0,0 +1,168 @@
+local tlsref = require "prosody.util.tlsref";
+
+describe("util.tlsref", function()
+	local version_compare = require "prosody.util.human.io".simple_version_compare;
+
+	describe("default version", function()
+		it("is not greater than latest version", function ()
+			local default_version = tlsref.get_default_version();
+			local latest_version = tlsref.get_latest_version();
+			assert.equal(false, version_compare(latest_version, default_version));
+		end);
+
+		it("is a known version", function ()
+			assert.is_table(tlsref.get_profile(tlsref.get_default_version()));
+		end);
+	end);
+
+	describe("latest version", function ()
+		it("is a known version", function ()
+			assert.is_table(tlsref.get_profile("latest"));
+		end);
+
+		it("is the first entry of get_valid_versions()", function ()
+			local versions = tlsref.get_valid_versions();
+			assert.equal(tlsref.get_latest_version(), versions[1]);
+		end);
+	end);
+
+	describe("get_valid_versions()", function ()
+		it("returns versions in descending order", function ()
+			local versions = tlsref.get_valid_versions();
+			assert.is_true(#versions >= 1);
+			for i = 1, #versions-1 do
+				-- versions[i] must sort before versions[i+1]
+				assert.equal(false, version_compare(versions[i], versions[i+1]));
+			end
+		end);
+
+		it("contains the default version", function ()
+			local found = false;
+			for _, v in ipairs(tlsref.get_valid_versions()) do
+				if v == tlsref.get_default_version() then found = true; end
+			end
+			assert.is_true(found);
+		end);
+	end);
+
+	describe("get_valid_profile_names()", function ()
+		it("returns an error for unknown versions", function ()
+			local names, err = tlsref.get_valid_profile_names("0.0");
+			assert.is_nil(names);
+			assert.equal("unknown-version", err);
+		end);
+
+		it("uses the default version when none is given", function ()
+			assert.same(
+				tlsref.get_valid_profile_names(tlsref.get_default_version()),
+				tlsref.get_valid_profile_names()
+			);
+		end);
+
+		it("accepts 'latest' as a version", function ()
+			assert.same(
+				tlsref.get_valid_profile_names(tlsref.get_latest_version()),
+				tlsref.get_valid_profile_names("latest")
+			);
+		end);
+
+		it("lists the most-preferred profile first", function ()
+			for _, version in ipairs(tlsref.get_valid_versions()) do
+				local names = tlsref.get_valid_profile_names(version);
+				assert.equal("modern", names[1],
+					("most-preferred profile should be first for version %s"):format(version));
+			end
+		end);
+	end);
+
+	describe("get_profile()", function ()
+		it("returns the default profile of the default version when called with no arguments", function ()
+			assert.equal(
+				tlsref.get_profile(tlsref.get_default_version(), tlsref.get_default_profile_name()),
+				tlsref.get_profile()
+			);
+		end);
+
+		it("resolves 'latest' to the latest version", function ()
+			assert.equal(
+				tlsref.get_profile(tlsref.get_latest_version()),
+				tlsref.get_profile("latest")
+			);
+		end);
+
+		it("returns an error for unknown versions", function ()
+			local profile, err = tlsref.get_profile("0.0");
+			assert.is_nil(profile);
+			assert.equal("unknown-version", err);
+		end);
+
+		it("returns an error for unknown profile names", function ()
+			local profile, err = tlsref.get_profile(nil, "no-such-profile");
+			assert.is_nil(profile);
+			assert.equal("unknown-profile", err);
+		end);
+
+		it("returns an error for profiles absent from a given version", function ()
+			-- 'old' was dropped from the 6.0 guidelines
+			local profile, err = tlsref.get_profile("6.0", "old");
+			assert.is_nil(profile);
+			assert.equal("unknown-profile", err);
+		end);
+
+		it("resolves every advertised version/profile combination", function ()
+			for _, version in ipairs(tlsref.get_valid_versions()) do
+				for _, name in ipairs(tlsref.get_valid_profile_names(version)) do
+					local profile, err = tlsref.get_profile(version, name);
+					assert.is_table(profile,
+						("get_profile(%q, %q) failed: %s"):format(version, name, err));
+				end
+			end
+		end);
+	end);
+
+	describe("get_default_profile_name()", function ()
+		it("returns an error for unknown versions", function ()
+			local name, err = tlsref.get_default_profile_name("0.0");
+			assert.is_nil(name);
+			assert.equal("unknown-version", err);
+		end);
+
+		it("accepts 'latest' as a version", function ()
+			assert.is_string(tlsref.get_default_profile_name("latest"));
+		end);
+
+		it("returns a profile name valid for every version", function ()
+			for _, version in ipairs(tlsref.get_valid_versions()) do
+				local name = tlsref.get_default_profile_name(version);
+				assert.is_string(name);
+				assert.is_table(tlsref.get_profile(version, name),
+					("default profile %q missing from version %s"):format(name, version));
+			end
+		end);
+	end);
+
+	describe("profile contents", function ()
+		it("every profile specifies a TLS protocol version", function ()
+			for _, version in ipairs(tlsref.get_valid_versions()) do
+				for _, name in ipairs(tlsref.get_valid_profile_names(version)) do
+					local profile = tlsref.get_profile(version, name);
+					assert.is_string(profile.protocol);
+					assert.truthy(profile.protocol:match("^tlsv1"),
+						("unexpected protocol %q in %s/%s"):format(profile.protocol, version, name));
+				end
+			end
+		end);
+
+		it("every profile specifies TLS 1.3 ciphersuites and curves", function ()
+			for _, version in ipairs(tlsref.get_valid_versions()) do
+				for _, name in ipairs(tlsref.get_valid_profile_names(version)) do
+					local profile = tlsref.get_profile(version, name);
+					assert.is_table(profile.ciphersuites);
+					assert.is_true(#profile.ciphersuites > 0);
+					assert.is_table(profile.curveslist);
+					assert.is_true(#profile.curveslist > 0);
+				end
+			end
+		end);
+	end);
+end);

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/util/tlsref.lua	Fri Jun 12 13:01:56 2026 +0100
@@ -0,0 +1,232 @@
+local array = require "prosody.util.array";
+local it = require "prosody.util.iterators";
+local version_compare = require "prosody.util.human.io".simple_version_compare;
+
+local latest_version = "6.0"
+local default_version = "5.7";
+local default_profile = "intermediate"; -- should exist in all profiles
+
+-- https://datatracker.ietf.org/doc/html/rfc7919#appendix-A.1
+local ffdhe2048 = [[
+-----BEGIN DH PARAMETERS-----
+MIIBCAKCAQEA//////////+t+FRYortKmq/cViAnPTzx2LnFg84tNpWp4TZBFGQz
++8yTnc4kmz75fS/jY2MMddj2gbICrsRhetPfHtXV/WVhJDP1H18GbtCFY2VVPe0a
+87VXE15/V8k1mE8McODmi3fipona8+/och3xWKE2rec1MKzKT0g6eXq8CrGCsyT7
+YdEIqUuyyOP7uWrat2DX9GgdT0Kj3jlN9K5W7edjcrsZCwenyO4KbXCeAvzhzffi
+7MA0BM0oNC9hkXL+nOmFg/+OTxIy7vKBg8P+OxtMb61zO7X8vC7CIAXFjvGDfRaD
+ssbzSibBsu/6iGtCOGEoXJf//////////wIBAg==
+-----END DH PARAMETERS-----
+]];
+
+local profiles = {
+	-- https://wiki.mozilla.org/Security/Server_Side_TLS
+	["6.0"] = {
+		-- Version 6.0 as of 2026-04-08
+		modern = {
+			protocol = "tlsv1_3";
+			options = { cipher_server_preference = false };
+			ciphers = "DEFAULT"; -- TLS 1.3 uses 'ciphersuites' rather than these
+			curveslist = { "X25519MLKEM768"; "X25519"; "prime256v1"; "secp384r1" };
+			ciphersuites = { "TLS_AES_128_GCM_SHA256"; "TLS_AES_256_GCM_SHA384"; "TLS_CHACHA20_POLY1305_SHA256" };
+		};
+		intermediate = {
+			protocol = "tlsv1_2+";
+			dhparam = ffdhe2048;
+			options = { cipher_server_preference = false };
+			ciphers = {
+				"ECDHE-ECDSA-AES128-GCM-SHA256";
+				"ECDHE-RSA-AES128-GCM-SHA256";
+				"ECDHE-ECDSA-AES256-GCM-SHA384";
+				"ECDHE-RSA-AES256-GCM-SHA384";
+				"ECDHE-ECDSA-CHACHA20-POLY1305";
+				"ECDHE-RSA-CHACHA20-POLY1305";
+			};
+			curveslist = { "X25519MLKEM768"; "X25519"; "prime256v1"; "secp384r1" };
+			ciphersuites = { "TLS_AES_128_GCM_SHA256"; "TLS_AES_256_GCM_SHA384"; "TLS_CHACHA20_POLY1305_SHA256" };
+		};
+	};
+
+	["5.8"] = {
+		-- Version 5.8 as of 2026-04-08
+		modern = {
+			protocol = "tlsv1_3";
+			options = { cipher_server_preference = false };
+			ciphers = "DEFAULT"; -- TLS 1.3 uses 'ciphersuites' rather than these
+			curveslist = { "X25519MLKEM768"; "X25519"; "prime256v1"; "secp384r1" };
+			ciphersuites = { "TLS_AES_128_GCM_SHA256"; "TLS_AES_256_GCM_SHA384"; "TLS_CHACHA20_POLY1305_SHA256" };
+		};
+		intermediate = {
+			protocol = "tlsv1_2+";
+			dhparam = ffdhe2048;
+			options = { cipher_server_preference = false };
+			ciphers = {
+				"ECDHE-ECDSA-AES128-GCM-SHA256";
+				"ECDHE-RSA-AES128-GCM-SHA256";
+				"ECDHE-ECDSA-AES256-GCM-SHA384";
+				"ECDHE-RSA-AES256-GCM-SHA384";
+				"ECDHE-ECDSA-CHACHA20-POLY1305";
+				"ECDHE-RSA-CHACHA20-POLY1305";
+			};
+			curveslist = { "X25519MLKEM768"; "X25519"; "prime256v1"; "secp384r1" };
+			ciphersuites = { "TLS_AES_128_GCM_SHA256"; "TLS_AES_256_GCM_SHA384"; "TLS_CHACHA20_POLY1305_SHA256" };
+		};
+		old = {
+			protocol = "tlsv1+";
+			dhparam = ffdhe2048;
+			options = { cipher_server_preference = true };
+			ciphers = {
+				"ECDHE-ECDSA-AES128-GCM-SHA256";
+				"ECDHE-RSA-AES128-GCM-SHA256";
+				"ECDHE-ECDSA-AES256-GCM-SHA384";
+				"ECDHE-RSA-AES256-GCM-SHA384";
+				"ECDHE-ECDSA-CHACHA20-POLY1305";
+				"ECDHE-RSA-CHACHA20-POLY1305";
+				"ECDHE-ECDSA-AES128-SHA256";
+				"ECDHE-RSA-AES128-SHA256";
+				"ECDHE-ECDSA-AES128-SHA";
+				"ECDHE-RSA-AES128-SHA";
+				"ECDHE-ECDSA-AES256-SHA384";
+				"ECDHE-RSA-AES256-SHA384";
+				"ECDHE-ECDSA-AES256-SHA";
+				"ECDHE-RSA-AES256-SHA";
+				"AES128-GCM-SHA256";
+				"AES256-GCM-SHA384";
+				"AES128-SHA256";
+				"AES256-SHA256";
+				"AES128-SHA";
+				"AES256-SHA";
+				"DES-CBC3-SHA";
+			};
+			curveslist = { "X25519MLKEM768"; "X25519"; "prime256v1"; "secp384r1" };
+			ciphersuites = { "TLS_AES_128_GCM_SHA256"; "TLS_AES_256_GCM_SHA384"; "TLS_CHACHA20_POLY1305_SHA256" };
+		};
+	};
+
+	["5.7"] = {
+		-- Version 5.7 as of 2023-07-09
+		modern = {
+			protocol = "tlsv1_3";
+			options = { cipher_server_preference = false };
+			ciphers = "DEFAULT"; -- TLS 1.3 uses 'ciphersuites' rather than these
+			curveslist = { "X25519"; "prime256v1"; "secp384r1" };
+			ciphersuites = { "TLS_AES_128_GCM_SHA256"; "TLS_AES_256_GCM_SHA384"; "TLS_CHACHA20_POLY1305_SHA256" };
+		};
+		intermediate = {
+			protocol = "tlsv1_2+";
+			dhparam = ffdhe2048;
+			options = { cipher_server_preference = false };
+			ciphers = {
+				"ECDHE-ECDSA-AES128-GCM-SHA256";
+				"ECDHE-RSA-AES128-GCM-SHA256";
+				"ECDHE-ECDSA-AES256-GCM-SHA384";
+				"ECDHE-RSA-AES256-GCM-SHA384";
+				"ECDHE-ECDSA-CHACHA20-POLY1305";
+				"ECDHE-RSA-CHACHA20-POLY1305";
+				"DHE-RSA-AES128-GCM-SHA256";
+				"DHE-RSA-AES256-GCM-SHA384";
+				"DHE-RSA-CHACHA20-POLY1305";
+			};
+			curveslist = { "X25519"; "prime256v1"; "secp384r1" };
+			ciphersuites = { "TLS_AES_128_GCM_SHA256"; "TLS_AES_256_GCM_SHA384"; "TLS_CHACHA20_POLY1305_SHA256" };
+		};
+		old = {
+			protocol = "tlsv1+";
+			dhparam = nil; -- openssl dhparam 1024
+			options = { cipher_server_preference = true };
+			ciphers = {
+				"ECDHE-ECDSA-AES128-GCM-SHA256";
+				"ECDHE-RSA-AES128-GCM-SHA256";
+				"ECDHE-ECDSA-AES256-GCM-SHA384";
+				"ECDHE-RSA-AES256-GCM-SHA384";
+				"ECDHE-ECDSA-CHACHA20-POLY1305";
+				"ECDHE-RSA-CHACHA20-POLY1305";
+				"DHE-RSA-AES128-GCM-SHA256";
+				"DHE-RSA-AES256-GCM-SHA384";
+				"DHE-RSA-CHACHA20-POLY1305";
+				"ECDHE-ECDSA-AES128-SHA256";
+				"ECDHE-RSA-AES128-SHA256";
+				"ECDHE-ECDSA-AES128-SHA";
+				"ECDHE-RSA-AES128-SHA";
+				"ECDHE-ECDSA-AES256-SHA384";
+				"ECDHE-RSA-AES256-SHA384";
+				"ECDHE-ECDSA-AES256-SHA";
+				"ECDHE-RSA-AES256-SHA";
+				"DHE-RSA-AES128-SHA256";
+				"DHE-RSA-AES256-SHA256";
+				"AES128-GCM-SHA256";
+				"AES256-GCM-SHA384";
+				"AES128-SHA256";
+				"AES256-SHA256";
+				"AES128-SHA";
+				"AES256-SHA";
+				"DES-CBC3-SHA";
+			};
+			curveslist = { "X25519"; "prime256v1"; "secp384r1" };
+			ciphersuites = { "TLS_AES_128_GCM_SHA256"; "TLS_AES_256_GCM_SHA384"; "TLS_CHACHA20_POLY1305_SHA256" };
+		};
+	};
+};
+
+local function get_valid_versions()
+	return array.collect(it.keys(profiles)):sort(version_compare):reverse();
+end
+
+local pref_order = { modern = 100, intermediate = 50, old = 0 };
+
+local function sort_profile_by_pref(a, b)
+	local pref_a, pref_b = pref_order[a] or 0, pref_order[b] or 0;
+	return pref_a > pref_b; -- Best first
+end
+
+local function get_valid_profile_names(version)
+	if version == "latest" then
+		version = latest_version;
+	end
+	local version_profiles = profiles[version or default_version];
+	if not version_profiles then
+		return nil, "unknown-version";
+	end
+	return array.collect(it.keys(version_profiles)):sort(sort_profile_by_pref);
+end
+
+local function get_profile(version, profile_name)
+	if version == "latest" then
+		version = latest_version;
+	end
+	local version_profiles = profiles[version or default_version];
+	if not version_profiles then
+		return nil, "unknown-version";
+	end
+	local profile = version_profiles[profile_name or default_profile];
+	if not profile then
+		return nil, "unknown-profile";
+	end
+	return profile;
+end
+
+local function get_default_version()
+	return default_version;
+end
+
+local function get_latest_version()
+	return latest_version;
+end
+
+local function get_default_profile_name(version)
+	-- Default profile name is currently the same across all versions,
+	-- but can't guarantee this in the future - ensure valid version
+	if version ~= "latest" and not profiles[version or default_version] then
+		return nil, "unknown-version";
+	end
+	return default_profile;
+end
+
+return {
+	profiles = profiles;
+	get_default_version = get_default_version;
+	get_latest_version = get_latest_version;
+	get_default_profile_name = get_default_profile_name;
+	get_valid_versions = get_valid_versions;
+	get_valid_profile_names = get_valid_profile_names;
+	get_profile = get_profile;
+};