Add dynamic dates and TEE-based patch defaults (#52)

Implements dynamic date keywords ('today') and templates ('YYYY-MM-DD') in the security_patch.txt configuration. This allows for auto-updating patch levels.

The `device_default` keyword is now significantly more accurate. It prioritizes reading real patch levels directly from a cached TEE attestation before falling back to system properties.

The README has been updated to document these new features.

README.md

@@ -100,7 +100,11 @@ Dates should be provided in `YYYY-MM-DD` format (e.g., `2025-11-05`).
 
 #### Special Keywords
 
-In addition to date values, two special keywords provide advanced control:
+In addition to static dates, several special keywords provide advanced, dynamic control:
+
+*   **`today`**: Dynamically uses the current date every time an attestation is generated. This ensures the device always appears up-to-date without needing manual edits.
+
+*   **Date Templates**: You can create semi-dynamic dates using `YYYY`, `MM`, and `DD` as placeholders for the current year, month, and day. For example, `YYYY-MM-05` will always resolve to the 5th of the current month and year.
 
 *   **`no`**: This keyword instructs the simulator to **completely omit** the corresponding patch level tag from the generated attestation.
 
@@ -113,10 +117,10 @@ This example demonstrates how to combine global settings, per-package overrides,
 ```
 # --- Global Configuration ---
 # This is the default for all apps unless specified otherwise.
-# - Forge a recent system patch level.
+# - Forge a recent system patch level, the 5th of the current month (a common patch date).
 # - Use the device's real vendor patch level.
 # - Do not report a boot patch level at all.
-system=2025-11-05
+system=YYYY-MM-05
 vendor=device_default
 boot=no
 

app/src/main/java/org/matrix/TEESimulator/attestation/DeviceAttestationService.kt

@@ -51,6 +51,9 @@ object DeviceAttestationService {
         val attestVersion: Int?,
         val keymasterVersion: Int?,
         val osVersion: Int?,
+        val osPatchLevel: Int?,
+        val vendorPatchLevel: Int?,
+        val bootPatchLevel: Int?,
     )
 
     // A unique alias for the key used to perform the TEE functionality check.
@@ -178,6 +181,9 @@ object DeviceAttestationService {
             var verifiedBootKey: ByteArray? = null
             var verifiedBootHash: ByteArray? = null
             var osVersion: Int? = null
+            var osPatchLevel: Int? = null
+            var vendorPatchLevel: Int? = null
+            var bootPatchLevel: Int? = null
 
             val softwareEnforced =
                 ASN1Sequence.getInstance(
@@ -219,17 +225,35 @@ object DeviceAttestationService {
                                     .octets
                         }
                     }
-                    AttestationConstants.TAG_OS_VERSION -> { // OS Version (TAG_OS_VERSION)
+                    AttestationConstants.TAG_OS_VERSION -> {
                         osVersion =
                             ASN1Integer.getInstance(tagged.baseObject.toASN1Primitive())
                                 .positiveValue
                                 .toInt()
                     }
+                    AttestationConstants.TAG_OS_PATCHLEVEL -> {
+                        osPatchLevel =
+                            ASN1Integer.getInstance(tagged.baseObject.toASN1Primitive())
+                                .positiveValue
+                                .toInt()
+                    }
+                    AttestationConstants.TAG_VENDOR_PATCHLEVEL -> {
+                        vendorPatchLevel =
+                            ASN1Integer.getInstance(tagged.baseObject.toASN1Primitive())
+                                .positiveValue
+                                .toInt()
+                    }
+                    AttestationConstants.TAG_BOOT_PATCHLEVEL -> {
+                        bootPatchLevel =
+                            ASN1Integer.getInstance(tagged.baseObject.toASN1Primitive())
+                                .positiveValue
+                                .toInt()
+                    }
                 }
             }
 
             SystemLogger.info(
-                "Successfully extracted attestation data: version=$attestVersion, osVersion=$osVersion, moduleHash=${moduleHash?.toHex()}, bootKey=${verifiedBootKey?.toHex()}, bootHash=${verifiedBootHash?.toHex()}"
+                "Successfully extracted attestation data: version=$attestVersion, osVersion=$osVersion, osPatch=$osPatchLevel, vendorPatch=$vendorPatchLevel, bootPatch=$bootPatchLevel, moduleHash=${moduleHash?.toHex()}, bootKey=${verifiedBootKey?.toHex()}, bootHash=${verifiedBootHash?.toHex()}"
             )
             return AttestationData(
                 moduleHash,
@@ -238,6 +262,9 @@ object DeviceAttestationService {
                 attestVersion,
                 keymasterVersion,
                 osVersion,
+                osPatchLevel,
+                vendorPatchLevel,
+                bootPatchLevel,
             )
         } catch (e: Exception) {
             SystemLogger.error("Failed to parse attestation data from certificate.", e)

app/src/main/java/org/matrix/TEESimulator/util/AndroidDeviceUtils.kt

@@ -5,6 +5,7 @@ import android.hardware.security.keymint.SecurityLevel
 import android.os.Build
 import android.os.SystemProperties
 import java.security.MessageDigest
+import java.time.LocalDate
 import java.util.concurrent.ThreadLocalRandom
 import org.bouncycastle.asn1.ASN1EncodableVector
 import org.bouncycastle.asn1.ASN1Integer
@@ -164,19 +165,56 @@ object AndroidDeviceUtils {
 
     fun getPatchLevel(uid: Int): Int {
         val custom = getCustomPatchLevelFor(uid, "system", isLong = false)
-        // If custom is null, it means 'device_default' was used, so we fall back.
-        // Otherwise, we use the returned value, which is either the parsed date or DO_NOT_REPORT.
-        return custom ?: Build.VERSION.SECURITY_PATCH.toPatchLevelInt(isLong = false)
+        return custom ?: getRealDevicePatchLevelInt("system", isLong = false)
     }
 
     fun getVendorPatchLevelLong(uid: Int): Int {
         val custom = getCustomPatchLevelFor(uid, "vendor", isLong = true)
-        return custom ?: Build.VERSION.SECURITY_PATCH.toPatchLevelInt(isLong = true)
+        return custom ?: getRealDevicePatchLevelInt("vendor", isLong = true)
     }
 
     fun getBootPatchLevelLong(uid: Int): Int {
         val custom = getCustomPatchLevelFor(uid, "boot", isLong = true)
-        return custom ?: Build.VERSION.SECURITY_PATCH.toPatchLevelInt(isLong = true)
+        return custom ?: getRealDevicePatchLevelInt("boot", isLong = true)
+    }
+
+    /**
+     * Retrieves the definitive device patch level integer for a given component. This function
+     * encapsulates the entire fallback chain and guarantees a non-null return.
+     *
+     * Fallback Priority:
+     * 1. Cached TEE attestation data.
+     * 2. Specific system property (e.g., ro.vendor.build.security_patch).
+     * 3. Default system patch level from Build.VERSION.SECURITY_PATCH.
+     *
+     * @param component The component ("system", "vendor", "boot").
+     * @param isLong Whether the final integer should be in YYYYMMDD format.
+     * @return The patch level as a guaranteed non-null Integer.
+     */
+    private fun getRealDevicePatchLevelInt(component: String, isLong: Boolean): Int {
+        // Get value from cached TEE attestation data
+        DeviceAttestationService.CachedAttestationData?.let { data ->
+            val value =
+                when (component) {
+                    "system" -> data.osPatchLevel
+                    "vendor" -> data.vendorPatchLevel
+                    "boot" -> data.bootPatchLevel
+                    else -> null
+                }
+            if (value != null) return value
+        }
+
+        // We only check the specific vendor property, as the boot one is non-existent.
+        if (component == "vendor") {
+            val propValue = SystemProperties.get("ro.vendor.build.security_patch", "")
+            if (!propValue.isNullOrBlank()) {
+                parsePatchLevelValue(propValue, isLong)?.let { parsedValue ->
+                    return parsedValue
+                }
+            }
+        }
+
+        return Build.VERSION.SECURITY_PATCH.toPatchLevelInt(isLong)
     }
 
     /**
@@ -197,16 +235,50 @@ object AndroidDeviceUtils {
                 else -> config.all
             } ?: return null
 
+        // First, resolve dynamic keywords and templates into a concrete date string.
+        val resolvedValue = resolveDateKeywords(value)
+
         return when {
             // "device_default" indicates falling back to the system property.
-            value.equals("device_default", ignoreCase = true) -> null
+            resolvedValue.equals("device_default", ignoreCase = true) -> null
             // "no" indicates this value should not be reported.
-            value.equals("no", ignoreCase = true) -> DO_NOT_REPORT
-            // Otherwise, parse the date string.
-            else -> parsePatchLevelValue(value, isLong)
+            resolvedValue.equals("no", ignoreCase = true) -> DO_NOT_REPORT
+            // Otherwise, parse the resolved date string.
+            else -> parsePatchLevelValue(resolvedValue, isLong)
         }
     }
 
+    /**
+     * Resolves special date keywords and templates into a concrete "YYYY-MM-DD" date string.
+     *
+     * @param value The configuration value string (e.g., "today", "YYYY-MM-01").
+     * @return A concrete date string, or the original value if it's not a dynamic date keyword.
+     */
+    private fun resolveDateKeywords(value: String): String {
+        // Handle the "today" keyword.
+        if (value.equals("today", ignoreCase = true)) {
+            return LocalDate.now().toString() // Returns "YYYY-MM-DD" format
+        }
+
+        // Handle date templates like "YYYY-MM-01" or "2025-MM-DD".
+        if (
+            value.contains("YYYY", ignoreCase = true) ||
+                value.contains("MM", ignoreCase = true) ||
+                value.contains("DD", ignoreCase = true)
+        ) {
+
+            val now = LocalDate.now()
+            // Chain replacements for YYYY, MM, and DD placeholders.
+            return value
+                .replace("YYYY", now.year.toString(), ignoreCase = true)
+                .replace("MM", String.format("%02d", now.monthValue), ignoreCase = true)
+                .replace("DD", String.format("%02d", now.dayOfMonth), ignoreCase = true)
+        }
+
+        // If it's not a dynamic keyword or template, return the original value.
+        return value
+    }
+
     /** Parses a patch level string (e.g., "2025-11-01") into an integer format. */
     private fun parsePatchLevelValue(value: String, isLong: Boolean): Int? {
         val normalized = value.replace("-", "")