Padding of the R and S components in case they are smaller than 31 by…

…tes for SECP256r1 (#52) * code modified to allow 30 bytes signature and test added Signed-off-by: Miguel Rojo <[email protected]>
hyperledger · Jan 26, 2022 · 0353a6f · 0353a6f
1 parent 6a73c7d
commit 0353a6f
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Showing 2 changed files with 24 additions and 4 deletions.
diff --git a/secp256r1/src/main/java/org/hyperledger/besu/nativelib/secp256r1/LibSECP256R1.java b/secp256r1/src/main/java/org/hyperledger/besu/nativelib/secp256r1/LibSECP256R1.java
@@ -113,13 +113,13 @@ private byte[] convertToNativeRepresentation(final byte[] signature) {
             return nativeSignature;
         }
 
-        // the first byte in the native representation was 0, but in the Java representation this is ignored.
+        // the first bytes in the native representation were 0, but in the Java representation this is ignored.
         // the signature needs to be shifted to the right for the native representation
-        if (signature.length == CURVE_BYTE_LENGTH - 1) {
+        if (signature.length < CURVE_BYTE_LENGTH) {
             byte[] nativeSignature = new byte[CURVE_BYTE_LENGTH];
 
-            // copy signature to nativeSignature, shifting it one to the right
-            System.arraycopy(signature, 0, nativeSignature, 1, signature.length);
+            // copy signature to nativeSignature, shifting it to the right
+            System.arraycopy(signature, 0, nativeSignature, CURVE_BYTE_LENGTH - signature.length, signature.length);
 
             return nativeSignature;
         }

diff --git a/secp256r1/src/test/java/org/hyperledger/besu/nativelib/secp256r1/LibSECP256R1Test.java b/secp256r1/src/test/java/org/hyperledger/besu/nativelib/secp256r1/LibSECP256R1Test.java
@@ -16,9 +16,11 @@
 package org.hyperledger.besu.nativelib.secp256r1;
 
 import org.apache.tuweni.bytes.Bytes;
+import org.assertj.core.util.Hexadecimals;
 import org.junit.Before;
 import org.junit.Test;
 
+import java.math.BigInteger;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 
@@ -93,6 +95,24 @@ public void keyRecovery_should_return_expected_public_key() {
 
     }
 
+    @Test
+    public void keyRecovery_should_return_expected_public_key_if_r_is_less_than_32_bytes_long() {
+        final BigInteger r = new BigInteger("607232317131644998607993399928086035368869502933999419429470745918733484");
+        final BigInteger s = new BigInteger("909326537358980219114547956988636184748037502936154044628658501523731230682");
+        final byte v = (byte) 1;
+        final Bytes dataHash = Bytes.fromHexString("0x5d2a686cbe81873192db62f069cc1f0c10a1580c89d19c21407dcd1cde48ad06");
+
+
+        byte[] actualPublicKey = libSecp256r1.keyRecovery(
+                dataHash.toArrayUnsafe(),
+                r.toByteArray(),
+                s.toByteArray(),
+                v
+        );
+
+        assertThat(Hexadecimals.toHexString(actualPublicKey)).isEqualTo("33F004F357282E13036385D3F52A90F5E62FA0D51C39DFF99CB72FD06CB5FAB72F2DC5E05786154DD7A349DC3FDD9BE2F0B9665C4E08FA6CDC1FD447112ACF3F");
+    }
+
     @Test(expected = IllegalArgumentException.class)
     public void keyRecovery_should_throw_exception_if_parameter_is_invalid() {
         libSecp256r1.keyRecovery(