4 files changed, 67 insertions, 4 deletions

diff --git a/standalone/src/main/java/cz/crcs/ectester/standalone/libs/MbedTLSLib.java b/standalone/src/main/java/cz/crcs/ectester/standalone/libs/MbedTLSLib.java
index e44598c..efc8cad 100644
--- a/standalone/src/main/java/cz/crcs/ectester/standalone/libs/MbedTLSLib.java
+++ b/standalone/src/main/java/cz/crcs/ectester/standalone/libs/MbedTLSLib.java
@@ -17,4 +17,10 @@ public class MbedTLSLib extends NativeECLibrary {
 
     @Override
     public native Set<String> getCurves();
+
+    @Override
+    public native boolean supportsDeterministicPRNG();
+
+    @Override
+    public native boolean setupDeterministicPRNG(byte[] seed);
 }
diff --git a/standalone/src/main/resources/cz/crcs/ectester/standalone/libs/jni/mbedtls.c b/standalone/src/main/resources/cz/crcs/ectester/standalone/libs/jni/mbedtls.c
index 5fc879b..8f5e0fb 100644
--- a/standalone/src/main/resources/cz/crcs/ectester/standalone/libs/jni/mbedtls.c
+++ b/standalone/src/main/resources/cz/crcs/ectester/standalone/libs/jni/mbedtls.c
@@ -16,7 +16,8 @@
 
 
 static mbedtls_ctr_drbg_context ctr_drbg;
-static mbedtls_entropy_context entropy;
+static mbedtls_entropy_context urandom_entropy;
+static mbedtls_entropy_context fixed_entropy;
 static jclass provider_class;
 
 
@@ -62,6 +63,17 @@ static int dev_urandom(void *data, unsigned char *output, size_t len, size_t *ol
     return 0;
 }
 
+static unsigned char seed_store[32] = {0};
+
+static int fixed_random(void *data, unsigned char *output, size_t len, size_t *olen) {
+	for (size_t i = 0; i < len; ++i) {
+		output[i] = seed_store[i % 32];
+	}
+	*olen = len;
+	return 0;
+}
+
+
 static int ctr_drbg_wrapper(void *ctx, unsigned char *buf, size_t len) {
     native_timing_pause();
     int result = mbedtls_ctr_drbg_random(ctx, buf, len);
@@ -77,9 +89,9 @@ JNIEXPORT void JNICALL Java_cz_crcs_ectester_standalone_libs_jni_NativeProvider_
     ADD_SIG(env, this, "NONEwithECDSA", "MbedTLSECDSAwithNONE");
 
     mbedtls_ctr_drbg_init(&ctr_drbg);
-    mbedtls_entropy_init(&entropy);
-    mbedtls_entropy_add_source(&entropy, dev_urandom, NULL, 32, MBEDTLS_ENTROPY_SOURCE_STRONG);
-    mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &entropy, NULL, 0);
+    mbedtls_entropy_init(&urandom_entropy);
+    mbedtls_entropy_add_source(&urandom_entropy, dev_urandom, NULL, 32, MBEDTLS_ENTROPY_SOURCE_STRONG);
+    mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &urandom_entropy, NULL, 0);
 
     init_classes(env, "MbedTLS");
 }
@@ -101,6 +113,32 @@ JNIEXPORT jobject JNICALL Java_cz_crcs_ectester_standalone_libs_MbedTLSLib_getCu
     return result;
 }
 
+JNIEXPORT jboolean JNICALL Java_cz_crcs_ectester_standalone_libs_MbedTLSLib_supportsDeterministicPRNG(JNIEnv *env, jobject this) {
+	return JNI_TRUE;
+}
+
+JNIEXPORT jboolean JNICALL Java_cz_crcs_ectester_standalone_libs_MbedTLSLib_setupDeterministicPRNG(JNIEnv *env, jobject this, jbyteArray seed) {
+	jsize seed_length = (*env)->GetArrayLength(env, seed);
+	if (seed_length > 32) {
+		fprintf(stderr, "Error setting seed, needs to be at most 32 bytes, is %i.\n", seed_length);
+		return JNI_FALSE;
+	}
+	jbyte *seed_data = (*env)->GetByteArrayElements(env, seed, NULL);
+	memcpy(seed_store, seed_data, seed_length);
+	(*env)->ReleaseByteArrayElements(env, seed, seed_data, JNI_ABORT);
+
+	memset(&ctr_drbg, 0, sizeof(ctr_drbg));
+    mbedtls_ctr_drbg_init(&ctr_drbg);
+
+    mbedtls_entropy_init(&fixed_entropy);
+    // This is NASTY! We are accessing something the library does not want us to.
+    fixed_entropy.private_source_count = 0;
+    mbedtls_entropy_add_source(&fixed_entropy, fixed_random, NULL, 32, MBEDTLS_ENTROPY_SOURCE_STRONG);
+    mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &fixed_entropy, NULL, 0);
+
+    return JNI_TRUE;
+}
+
 JNIEXPORT jboolean JNICALL Java_cz_crcs_ectester_standalone_libs_jni_NativeKeyPairGeneratorSpi_00024MbedTLS_keysizeSupported(JNIEnv *env, jobject this, jint keysize) {
     for (const mbedtls_ecp_curve_info *curve_info = mbedtls_ecp_curve_list();
          curve_info->grp_id != MBEDTLS_ECP_DP_NONE;
diff --git a/standalone/src/main/resources/cz/crcs/ectester/standalone/libs/jni/native.h b/standalone/src/main/resources/cz/crcs/ectester/standalone/libs/jni/native.h
index 627f38f..287b450 100644
--- a/standalone/src/main/resources/cz/crcs/ectester/standalone/libs/jni/native.h
+++ b/standalone/src/main/resources/cz/crcs/ectester/standalone/libs/jni/native.h
@@ -1389,6 +1389,22 @@ JNIEXPORT jobject JNICALL Java_cz_crcs_ectester_standalone_libs_MbedTLSLib_creat
 JNIEXPORT jobject JNICALL Java_cz_crcs_ectester_standalone_libs_MbedTLSLib_getCurves
   (JNIEnv *, jobject);
 
+/*
+ * Class:     cz_crcs_ectester_standalone_libs_MbedTLSLib
+ * Method:    supportsDeterministicPRNG
+ * Signature: ()Z
+ */
+JNIEXPORT jboolean JNICALL Java_cz_crcs_ectester_standalone_libs_MbedTLSLib_supportsDeterministicPRNG
+  (JNIEnv *, jobject);
+
+/*
+ * Class:     cz_crcs_ectester_standalone_libs_MbedTLSLib
+ * Method:    setupDeterministicPRNG
+ * Signature: ([B)Z
+ */
+JNIEXPORT jboolean JNICALL Java_cz_crcs_ectester_standalone_libs_MbedTLSLib_setupDeterministicPRNG
+  (JNIEnv *, jobject, jbyteArray);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/standalone/src/test/java/cz/crcs/ectester/standalone/AppTests.java b/standalone/src/test/java/cz/crcs/ectester/standalone/AppTests.java
index 6072e68..8693b7b 100644
--- a/standalone/src/test/java/cz/crcs/ectester/standalone/AppTests.java
+++ b/standalone/src/test/java/cz/crcs/ectester/standalone/AppTests.java
@@ -106,6 +106,9 @@ public class AppTests {
             case "BoringSSL":
                 args = new String[]{"generate", "-ps", "123412341234123412341234123412341234123412341234123412341234123412341234123412341234123412341234", "-n", "10", "-cn", "prime256v1", libName};
                 break;
+            case "mbedTLS":
+                args = new String[]{"generate", "-ps", "12345678", "-n", "10", "-nc", "secg/secp256r1", libName};
+                break;
         }
         ECTesterStandalone.main(args);
         String out1 = out.capturedString();