feat: Signer settings and CAWG signing

library/src/androidTest/kotlin/org/contentauth/c2pa/AndroidSignerTests.kt

@@ -1,4 +1,4 @@
-/* 
+/*
 This file is licensed to you under the Apache License, Version 2.0
 (http://www.apache.org/licenses/LICENSE-2.0) or the MIT license
 (http://opensource.org/licenses/MIT), at your option.
@@ -103,4 +103,16 @@ class AndroidSignerTests : SignerTests() {
         val result = testStrongBoxAvailability()
         assertTrue(result.success, "StrongBox Availability test failed: ${result.message}")
     }
+
+    @Test
+    fun runTestSignerFromSettingsToml() = runBlocking {
+        val result = testSignerFromSettingsToml()
+        assertTrue(result.success, "Signer From Settings (TOML) test failed: ${result.message}")
+    }
+
+    @Test
+    fun runTestSignerFromSettingsJson() = runBlocking {
+        val result = testSignerFromSettingsJson()
+        assertTrue(result.success, "Signer From Settings (JSON) test failed: ${result.message}")
+    }
 }

library/src/androidTest/kotlin/org/contentauth/c2pa/ResourceTestHelper.kt

@@ -1,4 +1,4 @@
-/* 
+/*
 This file is licensed to you under the Apache License, Version 2.0
 (http://www.apache.org/licenses/LICENSE-2.0) or the MIT license
 (http://opensource.org/licenses/MIT), at your option.
@@ -22,6 +22,8 @@ object ResourceTestHelper {
             TestBase.loadSharedResourceAsBytes("$resourceName.jpg")
                 ?: TestBase.loadSharedResourceAsBytes("$resourceName.pem")
                 ?: TestBase.loadSharedResourceAsBytes("$resourceName.key")
+                ?: TestBase.loadSharedResourceAsBytes("$resourceName.toml")
+                ?: TestBase.loadSharedResourceAsBytes("$resourceName.json")
 
         return sharedResource ?: throw IllegalArgumentException("Resource not found: $resourceName")
     }
@@ -31,6 +33,8 @@ object ResourceTestHelper {
             TestBase.loadSharedResourceAsString("$resourceName.jpg")
                 ?: TestBase.loadSharedResourceAsString("$resourceName.pem")
                 ?: TestBase.loadSharedResourceAsString("$resourceName.key")
+                ?: TestBase.loadSharedResourceAsString("$resourceName.toml")
+                ?: TestBase.loadSharedResourceAsString("$resourceName.json")
 
         return sharedResource ?: throw IllegalArgumentException("Resource not found: $resourceName")
     }

library/src/main/jni/c2pa_jni.c

@@ -1020,6 +1020,16 @@ JNIEXPORT jbyteArray JNICALL Java_org_contentauth_c2pa_Builder_signDataHashedEmb
 }
 
 // Signer native methods
+JNIEXPORT jlong JNICALL Java_org_contentauth_c2pa_Signer_nativeFromSettings(JNIEnv *env, jclass clazz) {
+    struct C2paSigner *signer = c2pa_signer_from_settings();
+
+    if (signer == NULL) {
+        return 0;
+    }
+
+    return (jlong)(uintptr_t)signer;
+}
+
 JNIEXPORT jlong JNICALL Java_org_contentauth_c2pa_Signer_nativeFromInfo(JNIEnv *env, jclass clazz, jstring algorithm, jstring certificatePEM, jstring privateKeyPEM, jstring tsaURL) {
     if (algorithm == NULL || certificatePEM == NULL || privateKeyPEM == NULL) {
         (*env)->ThrowNew(env, (*env)->FindClass(env, "java/lang/IllegalArgumentException"), 

library/src/main/kotlin/org/contentauth/c2pa/C2PA.kt

@@ -1,4 +1,4 @@
-/* 
+/*
 This file is licensed to you under the Apache License, Version 2.0
 (http://www.apache.org/licenses/LICENSE-2.0) or the MIT license
 (http://opensource.org/licenses/MIT), at your option.
@@ -40,6 +40,13 @@ object C2PA {
     @JvmStatic
     private external fun loadSettingsNative(settings: String, format: String): Int
 
+    /**
+     * Load settings from a string.
+     * Returns the result code from the native call (0 for success).
+     */
+    @JvmStatic
+    fun loadSettingsResult(settings: String, format: String): Int = loadSettingsNative(settings, format)
+
     /**
      * Load settings from a string
      */

library/src/main/kotlin/org/contentauth/c2pa/Signer.kt

@@ -1,4 +1,4 @@
-/* 
+/*
 This file is licensed to you under the Apache License, Version 2.0
 (http://www.apache.org/licenses/LICENSE-2.0) or the MIT license
 (http://opensource.org/licenses/MIT), at your option.
@@ -54,6 +54,132 @@ class Signer internal constructor(internal var ptr: Long) : Closeable {
             if (handle == 0L) null else Signer(handle)
         }
 
+        /**
+         * Creates a signer from JSON settings configuration.
+         *
+         * This method creates a signer from a JSON settings object that can include certificate
+         * paths, private keys, algorithm selection, and other configuration options. This is useful
+         * for loading signer configuration from external sources, configuration files, or for CAWG
+         * (Creator Assertions Working Group) signers.
+         *
+         * @param settingsJson A JSON string containing signer configuration.
+         * @return A new [Signer] instance configured according to the settings.
+         * @throws C2PAError if the settings are invalid or the signer cannot be created.
+         *
+         * Example JSON for a CAWG signer:
+         * ```json
+         * {
+         *     "version": 1,
+         *     "signer": {
+         *         "local": {
+         *             "alg": "es256",
+         *             "sign_cert": "-----BEGIN CERTIFICATE-----\n...",
+         *             "private_key": "-----BEGIN PRIVATE KEY-----\n...",
+         *             "tsa_url": "http://timestamp.digicert.com"
+         *         }
+         *     },
+         *     "cawg_x509_signer": {
+         *         "local": {
+         *             "alg": "es256",
+         *             "sign_cert": "-----BEGIN CERTIFICATE-----\n...",
+         *             "private_key": "-----BEGIN PRIVATE KEY-----\n...",
+         *             "tsa_url": "http://timestamp.digicert.com",
+         *             "referenced_assertions": ["cawg.training-mining"]
+         *         }
+         *     }
+         * }
+         * ```
+         */
+        @JvmStatic
+        @Throws(C2PAError::class)
+        fun fromSettingsJson(settingsJson: String): Signer =
+            fromSettings(settingsJson, "json")
+
+        /**
+         * Creates a signer from TOML settings configuration.
+         *
+         * This method creates a signer from a TOML settings string. TOML format supports additional
+         * features like CAWG (Creator Assertions Working Group) X.509 signers that generate identity
+         * assertions.
+         *
+         * @param settingsToml A TOML string containing signer configuration.
+         * @return A new [Signer] instance configured according to the settings.
+         * @throws C2PAError if the settings are invalid or the signer cannot be created.
+         *
+         * Example TOML for a CAWG signer:
+         * ```toml
+         * version = 1
+         *
+         * [signer.local]
+         * alg = "es256"
+         * sign_cert = """-----BEGIN CERTIFICATE-----
+         * ...certificate chain...
+         * -----END CERTIFICATE-----
+         * """
+         * private_key = """-----BEGIN PRIVATE KEY-----
+         * ...private key...
+         * -----END PRIVATE KEY-----
+         * """
+         * tsa_url = "http://timestamp.digicert.com"
+         *
+         * [cawg_x509_signer.local]
+         * alg = "es256"
+         * sign_cert = """-----BEGIN CERTIFICATE-----
+         * ...certificate chain...
+         * -----END CERTIFICATE-----
+         * """
+         * private_key = """-----BEGIN PRIVATE KEY-----
+         * ...private key...
+         * -----END PRIVATE KEY-----
+         * """
+         * tsa_url = "http://timestamp.digicert.com"
+         * referenced_assertions = ["cawg.training-mining"]
+         * ```
+         */
+        @JvmStatic
+        @Throws(C2PAError::class)
+        fun fromSettingsToml(settingsToml: String): Signer =
+            fromSettings(settingsToml, "toml")
+
+        /**
+         * Creates a signer from settings configuration in the specified format.
+         *
+         * @param settings The settings string in the specified format.
+         * @param format The format of the settings string ("json" or "toml").
+         * @return A new [Signer] instance configured according to the settings.
+         * @throws C2PAError if the settings are invalid or the signer cannot be created.
+         */
+        @JvmStatic
+        @Throws(C2PAError::class)
+        private fun fromSettings(settings: String, format: String): Signer =
+            executeC2PAOperation("Failed to create signer from settings") {
+                val loadResult = C2PA.loadSettingsResult(settings, format)
+                if (loadResult != 0) {
+                    throw C2PAError.Api(C2PA.getError() ?: "Failed to load settings")
+                }
+                val handle = nativeFromSettings()
+                if (handle == 0L) null else Signer(handle)
+            }
+
+        /**
+         * Loads global C2PA settings without creating a signer.
+         *
+         * This method loads settings that will be used by subsequent signing operations. Use this
+         * to load CAWG identity assertion settings separately from the main signer.
+         *
+         * @param settings The settings string in the specified format.
+         * @param format The format of the settings string ("json" or "toml").
+         * @throws C2PAError if the settings are invalid.
+         */
+        @JvmStatic
+        @Throws(C2PAError::class)
+        fun loadSettings(settings: String, format: String) {
+            val result = C2PA.loadSettingsResult(settings, format)
+            if (result != 0) {
+                throw C2PAError.Api(C2PA.getError() ?: "Failed to load settings")
+            }
+        }
+
         /** Create signer with custom signing callback */
         @JvmStatic
         @Throws(C2PAError::class)
@@ -92,6 +218,9 @@ class Signer internal constructor(internal var ptr: Long) : Closeable {
             tsaURL: String?,
             callback: SignCallback,
         ): Long
+
+        @JvmStatic
+        private external fun nativeFromSettings(): Long
     }
 
     /** Get the reserve size for this signer */