我有一个openssl生成的smime文件的问题。我需要解析（在BouncyCastle的帮助下）使用openssl生成的smime SignedData包。我用这个命令创建了一个例子：
openssl smime -sign -inkey Signer/signer_key.pem -in Signer/message.txt -text -out SMIME/signed.data -signer Signer/signer_cert.pem -certfile cacert.pem -outform smime
问题是我需要在流程中填写pkcs7 ASN.1结构，然后应用标准中描述的算法，可以在此处找到：pkcs7 signedData
ASN.1结构如下：
SignedData ::= SEQUENCE { version Version,
digestAlgorithms DigestAlgorithmIdentifiers,
contentInfo ContentInfo,
certificates [0] IMPLICIT ExtendedCertificatesAndCertificates OPTIONAL,
crls [1] IMPLICIT CertificateRevocationLists OPTIONAL,
signerInfos SignerInfos }
SignerInfo ::= SEQUENCE { version Version,
issuerAndSerialNumber IssuerAndSerialNumber,
digestAlgorithm DigestAlgorithmIdentifier,
authenticatedAttributes [0] IMPLICIT Attributes OPTIONAL,
digestEncryptionAlgorithm DigestEncryptionAlgorithmIdentifier,
encryptedDigest EncryptedDigest,
unauthenticatedAttributes [1] IMPLICIT Attributes OPTIONAL }
签名验证中出现问题。在标准中说是
消息摘要计算过程的结果取决于 signedAttrs字段是否存在。当田地不存在时 结果只是所描述的内容的消息摘要 以上。但是，当字段存在时，结果就是消息 摘要SignedAttrs值的完整DER编码 包含在signedAttrs字段中。
在smime包中我有明文，我正在计算它的摘要，并与从smime文件中读取encryptedDigest的结果进行比较，然后对其进行解密。假设它没有属性。但是对我来说很明显，不知何故，smime包中包含的签名不仅基于明文计算，还基于某些属性计算。我想知道的是通过在cleantext中附加必要的属性来使这项工作成为一种方法，以便两者的摘要等于从SMIME包中读取的encryptedDigest字段。
以下是我正在使用的主要内容。为了简化，我删除了（大量）调试部分，并放置了一些英文评论，取代了葡萄牙语。我认为理解它很简单，但如果有人对此感兴趣，我可以发布我的整个代码。
package signedData;
import PKCS7.SignedData;
import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.ObjectOutputStream;
import java.security.MessageDigest;
import java.security.Security;
import java.security.cert.CertStore;
import java.security.cert.X509Certificate;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.Properties;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.mail.Session;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMultipart;
import org.bouncycastle.cms.SignerInformation;
import org.bouncycastle.cms.SignerInformationStore;
import org.bouncycastle.mail.smime.SMIMESigned;
import org.bouncycastle.util.Store;
import sun.misc.BASE64Encoder;
public class Main {
public static void main(String[] args) {
String ksFile = "Recipient/ks_recipient", ks_type = "JCEKS", key_alias = "recipient_pkcs12", cert_alias = "cacert", algorithm, provider = "BC";
byte[] encrypted, encrypted2, decrypted, digest;
Cifra cipher;
Digest dgst;
X509Certificate cert;
Properties props;
Session session;
MimeMessage msg;
SMIMESigned signed;
SignerInformationStore signers;
SignerInformation s;
CertStore certs;
Collection c;
Iterator it, certIt;
ByteArrayOutputStream baos;
ObjectOutputStream oos;
if( args.length == 1) {
/**
* args[0] - SMIME's Path file
*/
try {
props = System.getProperties();
session = Session.getDefaultInstance(props);
msg = new MimeMessage(session, new FileInputStream(args[0]));
signed = new SMIMESigned((MimeMultipart) msg.getContent());
/* Putting information from various parties ( contained in the SMIME package) in a Collection, in order to process the information from each individually */
signers = signed.getSignerInfos();
c = signers.getSigners();
/* Read certificates from SMIME package */
certs = (CertStore) signed.getCertificatesAndCRLs("Collection", provider);
/* Iterate through the signers */
it = c.iterator();
while(it.hasNext()) {
/* Isolate each signer information */
s = (SignerInformation) it.next();
Collection certCollection = certs.getCertificates(s.getSID());
/* Iterate through this chain's certificates */
certIt = certCollection.iterator();
cert = (X509Certificate) certIt.next();
/* Verify signer certificate with CA */
if(Certificate_Handler.verifyCertificate( RW_KeyStore.getCertificate(ksFile, ks_type, cert_alias), cert, Security.getProvider(provider))) {
/* Read encryption algorithm identifier from SMIME package */
algorithm = Gadgets.getBC_Algorithm(s.getEncryptionAlgOID());
/* Read encrypted signature bytes */
encrypted = s.toASN1Structure().getEncryptedDigest().getOctets();
/* Create an instance of Digest, which is responsible for computing message digests */
dgst = new Digest(Gadgets.getBC_DigestAlgorithm(s.getDigestAlgOID()), provider);
/* Specify the encryption algorithm */
cipher = new Cifra(algorithm, provider);
// decrypt digest
decrypted = cipher.decifrar(encrypted2, cert.getPublicKey());
/* Compute plaintext digest */
digest = dgst.computeMessageDigest(((String) signed.getContent().getContent()).getBytes());
/* Verify signature */
if( MessageDigest.isEqual(decrypted, digest) )
System.out.println("check");
else
System.out.println("fail");
}
else
throw new Exception("Invalid Certificate");
}
}
catch (Exception ex) {
Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
}
}
else
System.err.println("Invalid parameter number: " + args.length);
}
}
现在是一个SMIME文件的例子，这是我实际使用的文件：
MIME-Version: 1.0
Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg="sha1"; boundary="----BF337FE7381F86CE88DBE2ED7A24396E"
This is an S/MIME signed message
------BF337FE7381F86CE88DBE2ED7A24396E
Content-Type: text/plain
Executive Mansion,
Washington, August 22, 1862.
Hon. Horace Greeley:
Dear Sir.
I have just read yours of the 19th. addressed to myself through the New-York Tribune. If there be in it any statements, or assumptions of fact, which I may know to be erroneous, I do not, now and here, controvert them. If there be in it any inferences which I may believe to be falsely drawn, I do not now and here, argue against them. If there be perceptable in it an impatient and dictatorial tone, I waive it in deference to an old friend, whose heart I have always supposed to be right.
As to the policy I "seem to be pursuing" as you say, I have not meant to leave any one in doubt.
I would save the Union. I would save it the shortest way under the Constitution. The sooner the national authority can be restored; the nearer the Union will be "the Union as it was." If there be those who would not save the Union, unless they could at the same time save slavery, I do not agree with them. If there be those who would not save the Union unless they could at the same time destroy slavery, I do not agree with them. My paramount object in this struggle is to save the Union, and is not either to save or to destroy slavery. If I could save the Union without freeing any slave I would do it, and if I could save it by freeing all the slaves I would do it; and if I could save it by freeing some and leaving others alone I would also do that. What I do about slavery, and the colored race, I do because I believe it helps to save the Union; and what I forbear, I forbear because I do not believe it would help to save the Union. I shall do less whenever I shall believe what I am doing hurts the cause, and I shall do more whenever I shall believe doing more will help the cause. I shall try to correct errors when shown to be errors; and I shall adopt new views so fast as they shall appear to be true views.
I have here stated my purpose according to my view of official duty; and I intend no modification of my oft-expressed personal wish that all men every where could be free.
Yours,
A. Lincoln.
------BF337FE7381F86CE88DBE2ED7A24396E
Content-Type: application/pkcs7-signature; name="smime.p7s"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="smime.p7s"
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------BF337FE7381F86CE88DBE2ED7A24396E--
答案 0 :(得分：2)
我解决了。 （pkcs7）标准在计算摘要后创建一个辅助结构（DigestInfo）。
DigestInfo ::= SEQUENCE { digestAlgorithm DigestAlgorithmIdentifier,
digest Digest }
在解密我从SMIME包中读取的EncryptedDigest后，结果是DigestInfo。
然后我计算signedAttributes的摘要（对于每个签名者）：
SignerInformation.getSignedAttributes()
最后将结果放入DigestInfo。只有这样我才能检查签名的有效性。瞧，它正在发挥作用！
希望这可以帮助任何遇到与我相同问题的人，因为这真的是一个耗时的问题......