From 0bc459385a67f0a0f09abda7c1c768fc14e20a5f Mon Sep 17 00:00:00 2001
From: J08nY
Date: Mon, 20 May 2024 13:37:35 +0200
Subject: Add check for a=-3 in tomcrypt.

---
 .../cz/crcs/ectester/standalone/libs/jni/tomcrypt.c      | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/standalone/src/main/resources/cz/crcs/ectester/standalone/libs/jni/tomcrypt.c b/standalone/src/main/resources/cz/crcs/ectester/standalone/libs/jni/tomcrypt.c
index 9593e9b..23f28ca 100644
--- a/standalone/src/main/resources/cz/crcs/ectester/standalone/libs/jni/tomcrypt.c
+++ b/standalone/src/main/resources/cz/crcs/ectester/standalone/libs/jni/tomcrypt.c
@@ -192,6 +192,22 @@ static ltc_ecc_set_type* create_curve(JNIEnv *env, jobject params) {
     jmethodID get_p = (*env)->GetMethodID(env, fp_field_class, "getP", "()Ljava/math/BigInteger;");
     jobject p = (*env)->CallObjectMethod(env, field, get_p);
 
+	jmethodID biginteger_valueof = (*env)->GetStaticMethodID(env, biginteger_class, "valueOf", "(J)Ljava/math/BigInteger;");
+	jobject three = (*env)->CallStaticObjectMethod(env, biginteger_class, biginteger_valueof, (jlong) 3);
+
+	jmethodID get_a = (*env)->GetMethodID(env, elliptic_curve_class, "getA", "()Ljava/math/BigInteger;");
+	jobject a = (*env)->CallObjectMethod(env, elliptic_curve, get_a);
+
+	jmethodID biginteger_add = (*env)->GetMethodID(env, biginteger_class, "add", "(Ljava/math/BigInteger;)Ljava/math/BigInteger;");
+	jobject a_3 = (*env)->CallObjectMethod(env, a, biginteger_add, three);
+
+	jmethodID biginteger_equals = (*env)->GetMethodID(env, biginteger_class, "equals", "(Ljava/lang/Object;)Z");
+	jboolean eq = (*env)->CallBooleanMethod(env, p, biginteger_equals, a_3);
+
+	if (!eq) {
+		return NULL;
+	}
+
     jmethodID get_g = (*env)->GetMethodID(env, ec_parameter_spec_class, "getGenerator", "()Ljava/security/spec/ECPoint;");
     jobject g = (*env)->CallObjectMethod(env, params, get_g);
 
-- 
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