我向收件箱发送了一封带有签名的电子邮件。然后我使用Java Mail接收邮件并验证签名。但始终会出现错误消息"消息摘要属性值与计算值不匹配"。
org.bouncycastle.cms.CMSSignerDigestMismatchException: message-digest attribute value does not match calculated value
at org.bouncycastle.cms.SignerInformation.doVerify(SignerInformation.java:517)
at org.bouncycastle.cms.SignerInformation.verify(SignerInformation.java:601)
我使用maven
<dependency> <groupId>javax.mail</groupId> <artifactId>mail</artifactId> <version>1.4.5</version> </dependency> <!-- Bouncy Castle Provider --> <dependency> <groupId>org.bouncycastle</groupId> <artifactId>bcprov-jdk15on</artifactId> <version>1.54</version> </dependency> <!-- BC Mail --> <dependency> <groupId>org.bouncycastle</groupId> <artifactId>bcmail-jdk15on</artifactId> <version>1.54</version> </dependency>
这一行我得到了一个例外：
verify = signer.verify(new JcaSimpleSignerInfoVerifierBuilder().setProvider("BC").build(certificate));
这是我的代码：
public static void receiveSignedMail(Message msg) throws MessagingException {
try {
SMIMESigned signed = new SMIMESigned((MimeMultipart) msg.getContent());
if (isValid(signed)) {
System.out.println("verification succeeded");
} else {
System.out.println("verification failed");
}
signed = new SMIMESigned((MimeMultipart) msg.getContent());
MimeBodyPart content = signed.getContent();
System.out.println("Content: " + content.getContent());
} catch (Exception e) {
e.printStackTrace(System.out);
}
}
public static boolean isValid(CMSSignedData signedData) {
try {
SignerInformationStore signers = signedData.getSignerInfos();
Iterator<SignerInformation> it = signers.getSigners().iterator();
boolean verify = false;
while (it.hasNext()) {
SignerInformation signer = it.next();
org.bouncycastle.util.Store store = (org.bouncycastle.util.Store) signedData.getCertificates();
Collection certCollection = ((org.bouncycastle.util.Store) store).getMatches(signer.getSID());
Iterator certIt = certCollection.iterator();
X509CertificateHolder certHolder = (X509CertificateHolder) certIt.next();
X509Certificate certificate = new JcaX509CertificateConverter().setProvider("BC").getCertificate(certHolder);
verify = signer.verify(new JcaSimpleSignerInfoVerifierBuilder().setProvider("BC").build(certificate));
}
return verify;
} catch (Exception e) {
e.printStackTrace(System.out);
return false;
}
}
public static Folder getFolder(String folderName) {
try {
String host = "your mail server";
boolean auth = true;
/* You must use SSL for incoming mail, SSL ports are 993 for IMAP and 995 for POP3 */
/* To support SSL, using protocl 'pop3s' or 'imaps' */
String port = "993";
String receivingProtocol = "imaps";
String username = "your email address";
String password = "your email password";
Properties props = System.getProperties();
props.put("mail.smtp.host", host);
props.put("mail.smtp.port", port);
props.put("mail.smtp.auth", auth);
props.put("mail.store.protocol", receivingProtocol);
Session session = Session.getDefaultInstance(props, null);
Store store = session.getStore(receivingProtocol);
store.connect(host, username, password);
Folder folder = store.getFolder(folderName);
folder.open(Folder.READ_WRITE);
return folder;
} catch (Exception e) {
e.printStackTrace(System.out);
return null;
}
}
以及运行的主要方法
public static void main(String args[]) {
Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
try {
String inbox = "Your Inbox";
Folder folder = getFolder(inbox);
SearchTerm st = new OrTerm(new FromStringTerm("search condition"), new SubjectTerm("search condition"));
Message[] messages = folder.search(st);
int mailCounts = messages.length;
System.out.println("Found: " + mailCounts + " mails matched with the condition.");
if (messages.length == 0) {
System.out.println("No Message!");
}
for (int i = 0; i < messages.length; i++) {
System.out.println("the " + (i + 1) + " mail" + "------------------------------------------------");
MimeMessage mail = (MimeMessage) messages[i];
String out_from = ((InternetAddress) messages[i].getFrom()[0]).getAddress();
System.out.println("From:" + out_from);
System.out.println("Subject:" + messages[i].getSubject());
System.out.println("Type: " + mail.getContentType());
if (mail.isMimeType("multipart/signed")) {
System.out.println("a signed mail");
receiveSignedMail(mail);
}
}
folder.close(true);
} catch (Exception e) {
e.printStackTrace(System.out);
}
}
我对所有其他电子邮件客户端（Thunderbird、Outlook等）都有同样的问题，但我能够解决它。我认为这个问题是由javax.mail库中的一个错误引起的。
我正在使用以下Maven依赖项：
<dependency>
<groupId>com.sun.mail</groupId>
<artifactId>javax.mail</artifactId>
<version>1.6.2</version>
</dependency>
<dependency>
<groupId>org.bouncycastle</groupId>
<artifactId>bcprov-jdk15on</artifactId>
<version>1.62</version>
</dependency>
<dependency>
<groupId>org.bouncycastle</groupId>
<artifactId>bcmail-jdk15on</artifactId>
<version>1.62</version>
</dependency>
解决方案：
当通过IMAP从电子邮件服务器轮询电子邮件时，您会将其作为消息对象数组接收：
Message[] messages = pollFolder.getMessages();
现在，您将对这个数组进行迭代，并分别处理每条消息。这意味着您直接使用Message对象。
但是，如果您想使用Bouncy Castle验证邮件的签名，则需要使用MimeMessage对象（请参阅Bouncy Castle的官方示例代码；代码行93）
要将消息转换为MimeMessage，通常需要以以下方式投射对象：
MimeMessage mimeMsg = (MimeMessage) message;
但由于某种原因，这没有正确工作，所以我后来在使用Bouncy Castle验证电子邮件签名时出现了以下异常：org.bouncycastle.cms.CMSSignerDigestMismatchException: message-digest attribute value does not match calculated value
作为一种变通方法，我所做的是，在MimeMessage构造函数的使用下复制已经广播的MimeMessage对象！！！
所以这解决了我的问题：
MimeMessage mimeMsg = new MimeMessage((MimeMessage) message);
这是完整的工作代码：
Message message = // get Message from folder...
MimeMessage mimeMsg = new MimeMessage((MimeMessage) message);
boolean emailSignatureValid = verifySignature(mimeMsg);
// code from Bouncy Castle
public boolean verifySignature(MimeMessage signedMimeMessage) {
try {
if (signedMimeMessage.isMimeType("multipart/signed")) {
SMIMESignedParser s = new SMIMESignedParser(new JcaDigestCalculatorProviderBuilder().build(), (MimeMultipart) signedMimeMessage.getContent());
return verify(s);
} else if (signedMimeMessage.isMimeType("application/pkcs7-mime")) {
SMIMESignedParser s = new SMIMESignedParser(new JcaDigestCalculatorProviderBuilder().build(), signedMimeMessage);
return verify(s);
} else {
throw new IllegalArgumentException("This mimeMessage is not signed: " + EmailPrinter.printMessage(signedMimeMessage));
}
} catch (Exception e) {
log.error("Could not verify signature of mimeMessage", e);
return false;
}
}
// code from Bouncy Castle
private static boolean verify(SMIMESignedParser s) throws Exception {
Store certs = s.getCertificates();
SignerInformationStore signers = s.getSignerInfos();
Collection c = signers.getSigners();
Iterator it = c.iterator();
while (it.hasNext()) {
SignerInformation signer = (SignerInformation) it.next();
Collection certCollection = certs.getMatches(signer.getSID());
Iterator certIt = certCollection.iterator();
X509Certificate cert = new JcaX509CertificateConverter().setProvider(BC).getCertificate((X509CertificateHolder) certIt.next());
try {
return signer.verify(new JcaSimpleSignerInfoVerifierBuilder().setProvider(BC).build(cert));
} catch (Exception e) {
log.error("Error occured during verification",e);
}
}
return false;
}
我知道这是一个奇怪的解决办法，但这是唯一的办法，我可以解决这个问题。我希望你也觉得它有用。
欢呼！
BEEveloper