serverinfoview

Tests/SCRAMDowngradeProtectionTests.swift

@@ -0,0 +1,91 @@
+import XCTest
+@testable import Luma
+
+final class SCRAMDowngradeProtectionTests: XCTestCase {
+    /// Reference vector from XEP-0474 §6.3: the server's `h` attribute is
+    /// base64(SHA-1('SCRAM-SHA-1\u{1E}SCRAM-SHA-1-PLUS\u{1F}tls-exporter\u{1E}tls-server-end-point')).
+    func testHashMatchesXEP0474Example() {
+        let hash = SCRAMDowngradeProtection.hash(
+            mechanisms: ["SCRAM-SHA-1", "SCRAM-SHA-1-PLUS"],
+            channelBindingTypes: ["tls-exporter", "tls-server-end-point"],
+            using: .sha1
+        )
+        XCTAssertEqual(hash.base64EncodedString(), "G6k/rBLDqgOhRRaCuuatSDFkJ08=")
+    }
+
+    func testHashSortsListsPerIOctetCollation() {
+        // XEP-0474 §5.1 requires i;octet-sorted lists, so advertisement order
+        // must not affect the hash.
+        let advertisedOrder = SCRAMDowngradeProtection.hash(
+            mechanisms: ["SCRAM-SHA-1", "SCRAM-SHA-1-PLUS"],
+            channelBindingTypes: ["tls-exporter", "tls-server-end-point"],
+            using: .sha1
+        )
+        let reordered = SCRAMDowngradeProtection.hash(
+            mechanisms: ["SCRAM-SHA-1-PLUS", "SCRAM-SHA-1"],
+            channelBindingTypes: ["tls-server-end-point", "tls-exporter"],
+            using: .sha1
+        )
+        XCTAssertEqual(advertisedOrder, reordered)
+    }
+
+    func testHashOmitsBindingSectionWhenNoTypesAdvertised() {
+        let withBindings = SCRAMDowngradeProtection.hash(
+            mechanisms: ["SCRAM-SHA-1"],
+            channelBindingTypes: ["tls-exporter"],
+            using: .sha1
+        )
+        let withoutBindings = SCRAMDowngradeProtection.hash(
+            mechanisms: ["SCRAM-SHA-1"],
+            channelBindingTypes: [],
+            using: .sha1
+        )
+        XCTAssertNotEqual(withBindings, withoutBindings)
+        // Without bindings the input is exactly the sorted mechanisms with no
+        // trailing 0x1F delimiter.
+        let expected = SCRAMHash.sha1.hash(data: Data("SCRAM-SHA-1".utf8))
+        XCTAssertEqual(withoutBindings, expected)
+    }
+
+    func testServerFirstParsesDowngradeProtectionHash() throws {
+        let message = "r=12C4CD5C-E38E-4A98-8F6D-15C38F51CCC6a09117a6-ac50-4f2f-93f1-93799c2bddf6,s=QSXCR+Q6sek8bf92,i=4096,h=G6k/rBLDqgOhRRaCuuatSDFkJ08="
+        let parsed = try SCRAMSHA512.parseServerFirst(
+            message,
+            expectedNoncePrefix: "12C4CD5C-E38E-4A98-8F6D-15C38F51CCC6"
+        )
+        XCTAssertEqual(parsed.downgradeProtectionHash, "G6k/rBLDqgOhRRaCuuatSDFkJ08=")
+    }
+
+    func testServerFirstWithoutHashParsesCleanly() throws {
+        let message = "r=fyko+d2lbbFgONRv9qkxdawL3rfcNHYJY1ZVvWVs7j,s=W22ZaJ0SNY7soEsUEjb6gQ==,i=4096"
+        let parsed = try SCRAMSHA512.parseServerFirst(
+            message,
+            expectedNoncePrefix: "fyko+d2lbbFgONRv9qkxdawL"
+        )
+        XCTAssertNil(parsed.downgradeProtectionHash)
+    }
+
+    func testClientFinalIncludesXAttributeWhenHashPresent() throws {
+        let exchange = SCRAMPlusExchange(
+            hash: .sha1,
+            username: "user",
+            password: "pencil",
+            channelBindingType: "tls-server-end-point",
+            channelBindingData: Data(0..<32),
+            clientNonce: "fyko+d2lbbFgONRv9qkxdawL"
+        )
+        let serverFirst = "r=fyko+d2lbbFgONRv9qkxdawL3rfcNHYJY1ZVvWVs7j,s=W22ZaJ0SNY7soEsUEjb6gQ==,i=4096,h=G6k/rBLDqgOhRRaCuuatSDFkJ08="
+        let final = try exchange.clientFinalMessage(
+            serverFirst: serverFirst,
+            downgradeProtectionHashBase64: "G6k/rBLDqgOhRRaCuuatSDFkJ08="
+        )
+        XCTAssertTrue(final.contains(",x=G6k/rBLDqgOhRRaCuuatSDFkJ08=,"))
+        // The same x-attribute must be part of the expected signature's
+        // auth message (server reconstructs client-final-without-proof).
+        let expected = try exchange.expectedServerSignature(
+            serverFirst: serverFirst,
+            downgradeProtectionHashBase64: "G6k/rBLDqgOhRRaCuuatSDFkJ08="
+        )
+        XCTAssertFalse(expected.isEmpty)
+    }
+}