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quantranhong1999 pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/james-jdkim.git
The following commit(s) were added to refs/heads/master by this push:
new d72e973 [ENHANCEMENT] Improve non-utf8 header char handling
d72e973 is described below
commit d72e973d15ff555d335a554c2efd71e345b2de2e
Author: Benoit TELLIER <[email protected]>
AuthorDate: Wed Oct 28 22:01:57 2026 +0100
[ENHANCEMENT] Improve non-utf8 header char handling
---
.../java/org/apache/james/jdkim/DKIMCommon.java | 19 ++++++++----
.../java/org/apache/james/jdkim/api/Headers.java | 10 +++++++
.../java/org/apache/james/jdkim/impl/Message.java | 4 ++-
.../test/java/org/apache/james/jdkim/DKIMTest.java | 34 ++++++++++++++++++++++
4 files changed, 61 insertions(+), 6 deletions(-)
diff --git a/main/src/main/java/org/apache/james/jdkim/DKIMCommon.java
b/main/src/main/java/org/apache/james/jdkim/DKIMCommon.java
index 853cdd1..919a679 100644
--- a/main/src/main/java/org/apache/james/jdkim/DKIMCommon.java
+++ b/main/src/main/java/org/apache/james/jdkim/DKIMCommon.java
@@ -26,6 +26,7 @@ import org.apache.james.jdkim.exceptions.PermFailException;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
+import java.nio.charset.StandardCharsets;
import java.security.Signature;
import java.security.SignatureException;
import java.util.HashMap;
@@ -37,6 +38,14 @@ public abstract class DKIMCommon {
private static final boolean DEEP_DEBUG = false;
+ /**
+ * Header fields are carried as Strings where each char is one raw octet
+ * (see {@link Headers}): ISO-8859-1 gives them back unchanged.
+ */
+ private static byte[] octets(String s) {
+ return s.getBytes(StandardCharsets.ISO_8859_1);
+ }
+
protected static void updateSignature(Signature signature,
boolean relaxed,
CharSequence header,
@@ -45,17 +54,17 @@ public abstract class DKIMCommon {
if (DEEP_DEBUG)
System.out
.println("#" + header.toString().toLowerCase() + ":-");
- signature.update(header.toString().toLowerCase().getBytes());
- signature.update(":".getBytes());
+ signature.update(octets(header.toString().toLowerCase(Locale.US)));
+ signature.update(octets(":"));
String headerValue = fv.substring(fv.indexOf(':') + 1);
headerValue = headerValue.replaceAll("\r\n[\t ]", " ");
headerValue = headerValue.replaceAll("[\t ]+", " ");
headerValue = headerValue.trim();
- signature.update(headerValue.getBytes());
+ signature.update(octets(headerValue));
if (DEEP_DEBUG)
System.out.println("#" + headerValue + "#");
} else {
- signature.update(fv.getBytes());
+ signature.update(octets(fv));
if (DEEP_DEBUG)
System.out.println("#" + fv + "#");
}
@@ -89,7 +98,7 @@ public abstract class DKIMCommon {
if (doneHeaders <= hl.size()) {
String fv = hl.get(hl.size() - doneHeaders);
updateSignature(signature, relaxedHeaders, header, fv);
- signature.update("\r\n".getBytes());
+ signature.update(octets("\r\n"));
processedHeader.put(lowerCaseHeader, doneHeaders);
}
}
diff --git a/main/src/main/java/org/apache/james/jdkim/api/Headers.java
b/main/src/main/java/org/apache/james/jdkim/api/Headers.java
index 3e07cff..b7d0106 100644
--- a/main/src/main/java/org/apache/james/jdkim/api/Headers.java
+++ b/main/src/main/java/org/apache/james/jdkim/api/Headers.java
@@ -21,6 +21,16 @@ package org.apache.james.jdkim.api;
import java.util.List;
+/**
+ * Raw header fields of a message, as used for DKIM header canonicalization.
+ * <p>
+ * Each returned field is the raw field (name, colon and value, folding
+ * included, without the trailing CRLF) where every char is one octet of the
+ * message, as decoded with ISO-8859-1. Implementations must not decode the
+ * field with any other charset: canonicalization works on the raw octets
+ * (RFC 6376 section 3.4) and a lossy decoding would let signed bytes be
+ * altered without breaking the signature.
+ */
public interface Headers {
/**
diff --git a/main/src/main/java/org/apache/james/jdkim/impl/Message.java
b/main/src/main/java/org/apache/james/jdkim/impl/Message.java
index 8e84063..b41de81 100644
--- a/main/src/main/java/org/apache/james/jdkim/impl/Message.java
+++ b/main/src/main/java/org/apache/james/jdkim/impl/Message.java
@@ -33,6 +33,7 @@ import org.apache.james.mime4j.stream.MimeConfig;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
+import java.nio.charset.StandardCharsets;
import java.util.LinkedList;
import java.util.List;
@@ -100,8 +101,9 @@ public class Message implements Headers {
try {
mw.writeField(f, bos);
// writeField always ends with CRLF and we don't want it.
+ // ISO-8859-1 maps each raw octet to one char, losslessly.
byte[] fieldbytes = bos.toByteArray();
- field = new String(fieldbytes, 0, fieldbytes.length - 2);
+ field = new String(fieldbytes, 0, fieldbytes.length - 2,
StandardCharsets.ISO_8859_1);
} catch (IOException ignored) {
}
res2.add(field);
diff --git a/main/src/test/java/org/apache/james/jdkim/DKIMTest.java
b/main/src/test/java/org/apache/james/jdkim/DKIMTest.java
index 09f7441..5a176eb 100644
--- a/main/src/test/java/org/apache/james/jdkim/DKIMTest.java
+++ b/main/src/test/java/org/apache/james/jdkim/DKIMTest.java
@@ -20,6 +20,7 @@
package org.apache.james.jdkim;
import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
import static org.junit.Assert.assertEquals;
import java.io.ByteArrayInputStream;
@@ -41,6 +42,7 @@ import org.apache.james.jdkim.api.Headers;
import org.apache.james.jdkim.api.Result;
import org.apache.james.jdkim.api.SignatureRecord;
import org.apache.james.jdkim.api.VerifierOptions;
+import org.apache.james.jdkim.exceptions.PermFailException;
import org.apache.james.jdkim.impl.Message;
import org.junit.Test;
@@ -146,6 +148,38 @@ public class DKIMTest {
}
+ @Test
+ public void nonUtf8BytesOfASignedHeaderShouldVerify() throws Exception {
+ byte[] mail = "From: [email protected]\r\nSubject:
café\r\n\r\nbody\r\n".getBytes(StandardCharsets.ISO_8859_1);
+ String field = dkimSigner.sign(new ByteArrayInputStream(mail));
+
+ InputStream in = new SequenceInputStream(
+ new ByteArrayInputStream((field +
"\r\n").getBytes(StandardCharsets.US_ASCII)), new ByteArrayInputStream(mail));
+
+ assertThat(verifier.verify(in)).hasSize(1);
+ }
+
+ @Test
+ public void alteringNonUtf8BytesOfASignedHeaderShouldBreakTheSignature()
throws Exception {
+ assertTamperingNonUtf8HeaderBytesIsDetected(dkimSigner);
+ }
+
+ @Test
+ public void
alteringNonUtf8BytesOfASignedHeaderShouldBreakTheRelaxedSignature() throws
Exception {
+ DKIMSigner relaxedSigner = new
DKIMSigner(SIGNATURE_TEMPLATE.replace("c=simple", "c=relaxed"),
TestKeys.privateKey);
+ assertTamperingNonUtf8HeaderBytesIsDetected(relaxedSigner);
+ }
+
+ private void assertTamperingNonUtf8HeaderBytesIsDetected(DKIMSigner
signer) throws Exception {
+ byte[] mail = "From: [email protected]\r\nSubject:
café\r\n\r\nbody\r\n".getBytes(StandardCharsets.ISO_8859_1);
+ byte[] tampered = "From: [email protected]\r\nSubject:
cafè\r\n\r\nbody\r\n".getBytes(StandardCharsets.ISO_8859_1);
+ String field = signer.sign(new ByteArrayInputStream(mail));
+
+ InputStream in = new SequenceInputStream(
+ new ByteArrayInputStream((field +
"\r\n").getBytes(StandardCharsets.US_ASCII)), new
ByteArrayInputStream(tampered));
+
+ assertThatThrownBy(() ->
verifier.verify(in)).isInstanceOf(PermFailException.class);
+ }
private ByteArrayInputStream readFileToByteArrayInputStream(String
fileName) throws URISyntaxException, IOException {
URL resource = this.getClass().getResource(fileName);
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