Fix point length check.

crocs-muni · Jan 30, 2025 · 08623da · 08623da
1 parent 79a611a
commit 08623da
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Showing 4 changed files with 103 additions and 1 deletion.
diff --git a/common/src/main/java/cz/crcs/ectester/common/ec/EC_Data.java b/common/src/main/java/cz/crcs/ectester/common/ec/EC_Data.java
@@ -152,6 +152,7 @@ public boolean readBytes(byte[] bytes) {
                 return false;
             }
             short paramLength = ByteUtil.getShort(bytes, offset);
+            System.out.println("paramLength: " + paramLength);
             offset += 2;
             if (bytes.length < offset + paramLength) {
                 return false;

diff --git a/common/src/main/java/cz/crcs/ectester/common/ec/EC_Params.java b/common/src/main/java/cz/crcs/ectester/common/ec/EC_Params.java
@@ -1,6 +1,7 @@
 package cz.crcs.ectester.common.ec;
 
 import cz.crcs.ectester.common.util.ByteUtil;
+import cz.crcs.ectester.common.util.CardUtil;
 
 import java.io.ByteArrayOutputStream;
 import java.util.ArrayList;
@@ -202,6 +203,68 @@ public byte[] flatten(short params) {
         return (out.size() == 0) ? null : out.toByteArray();
     }
 
+    public boolean inflate(byte[] flattened) {
+        short paramMask = EC_Consts.PARAMETER_FP;
+        int i = 0;
+        int offset = 0;
+        while (paramMask <= EC_Consts.PARAMETER_S) {
+            short masked = (short) (this.params & paramMask);
+            if (masked != 0) {
+                short length = ByteUtil.getShort(flattened, offset);
+                offset += 2;
+                byte[] param = new byte[length];
+                System.arraycopy(flattened, offset, param, 0, length);
+                offset += length;
+                //System.out.println(CardUtil.getParams(masked) + " Length: " + length + " Param: " + ByteUtil.bytesToHex(param, false));
+                //System.out.println();
+                if (masked == EC_Consts.PARAMETER_F2M) {
+                    data[i] = new byte[2];
+                    data[i + 1] = new byte[2];
+                    data[i + 2] = new byte[2];
+                    data[i + 3] = new byte[2];
+                    if (length == 4) {
+                        // only m and e_1, other e are zero
+                        System.arraycopy(param, 0, data[i], 0, 2);
+                        System.arraycopy(param, 2, data[i + 1], 0, 2);
+                    } else if (length == 8) {
+                        // all m, e_1, e_2, e_3 are specified
+                        System.arraycopy(param, 0, data[i], 0, 2);
+                        System.arraycopy(param, 2, data[i + 1], 0, 2);
+                        System.arraycopy(param, 4, data[i + 2], 0, 2);
+                        System.arraycopy(param, 6, data[i + 3], 0, 2);
+                    }
+                } else if (masked == EC_Consts.PARAMETER_G || masked == EC_Consts.PARAMETER_W) {
+                    if ((length - 1) % 2 != 0) {
+                        return false;
+                    }
+                    int half = (length - 1) / 2;
+                    data[i] = new byte[half];
+                    data[i + 1] = new byte[half];
+                    System.arraycopy(param, 1, data[i], 0, half);
+                    System.arraycopy(param, 1 + half, data[i + 1], 0, half);
+                } else {
+                    data[i] = param;
+                }
+            }
+
+            if (masked == EC_Consts.PARAMETER_F2M) {
+                i += 4;
+            } else if (masked == EC_Consts.PARAMETER_G || masked == EC_Consts.PARAMETER_W) {
+                i += 2;
+            } else if (masked != 0) {
+                i++;
+            }
+            paramMask = (short) (paramMask << 1);
+        }
+        return true;
+    }
+
+    public static EC_Params inflate(short params, byte[] flattened) {
+        EC_Params p = new EC_Params(params);
+        p.inflate(flattened);
+        return p;
+    }
+
     @Override
     public String[] expand() {
         List<String> out = new ArrayList<>();

diff --git a/common/src/test/java/cz/crcs/ectester/common/ParamSerializationTests.java b/common/src/test/java/cz/crcs/ectester/common/ParamSerializationTests.java
@@ -0,0 +1,33 @@
+package cz.crcs.ectester.common;
+
+import cz.crcs.ectester.common.ec.EC_Category;
+import cz.crcs.ectester.common.ec.EC_Data;
+import cz.crcs.ectester.common.ec.EC_Params;
+import cz.crcs.ectester.data.EC_Store;
+import org.junit.jupiter.api.Test;
+
+import java.util.Map;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class ParamSerializationTests {
+
+    @Test
+    public void test() {
+        EC_Store store = EC_Store.getInstance();
+        Map<String, EC_Category> categories = store.getCategories();
+
+        for (EC_Category category : categories.values()) {
+            Map<String, EC_Data> objects = category.getObjects();
+            for (EC_Data object : objects.values()) {
+                if (object instanceof EC_Params) {
+                    EC_Params params = (EC_Params) object;
+                    byte[] serialized = params.flatten();
+                    EC_Params deserialized = new EC_Params(params.getId(), params.getParams());
+                    deserialized.inflate(serialized);
+                    assertEquals(params, deserialized, "Category: " + category.getName() + ", Params: " + params.getId());
+                }
+            }
+        }
+    }
+}
diff --git a/reader/src/main/java/cz/crcs/ectester/reader/command/Command.java b/reader/src/main/java/cz/crcs/ectester/reader/command/Command.java
@@ -373,13 +373,18 @@ public Set(CardMngr cardManager, byte keyPair, byte curve, short params, byte[]
                 System.arraycopy(external, 0, data, 2, external.length);
                 if ((params & EC_Consts.PARAMETER_FP) != 0) {
                     EC_Params par = new EC_Params(params);
-                    par.readBytes(external);
+                    boolean read = par.inflate(external);
+                    if (!read) {
+                        throw new IllegalArgumentException("External curve data does not match parameters.");
+                    }
                     byte[][] prime = par.getParam(EC_Consts.PARAMETER_FP);
                     byte[] p = prime[0];
                     int bytes = p.length;
                     if ((params & EC_Consts.PARAMETER_G) != 0) {
                         byte[][] generator = par.getParam(EC_Consts.PARAMETER_G);
                         if (generator[0].length != bytes || generator[1].length != bytes) {
+                            System.err.println("Generator x length: " + generator[0].length + " vs " + bytes);
+                            System.err.println("Generator y length: " + generator[1].length + " vs " + bytes);
                             throw new IllegalArgumentException("Generator point does not match prime field size.");
                         }
                     }