我在那里!
我的 openssl 生成的 smime 文件有问题。我需要解析(在 BouncyCaSTLe 的帮助下)使用 openssl 生成的 smime SignedData 包。我使用此命令创建了一个示例:
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
问题是我需要在过程中填充一个pkcs7 ASN.1结构，然后应用标准中描述的算法，可以在这里找到: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 }
问题出现在签名验证中。标准中说
The result of the message digest calculation process depends on whether the signedAttrs field is present. When the field is absent, the result is just the message digest of the content as described above. When the field is present, however, the result is the message digest of the complete DER encoding of the SignedAttrs value contained in the signedAttrs field.
在 smime 包中，我有明文，我正在计算其摘要，并与从 smime 文件中读取加密摘要的结果进行比较，然后解密它。假设它没有属性。但在我看来，很明显，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。我想知道的是一种实现此功能的方法，通过在干净文本中附加必要的属性，以便两者的摘要等于从 SMIME 包中读取的加密摘要字段。
下面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，并放置了一些英文注释，替换了葡萄牙语注释。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 SMIME 文件的示例，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--
最佳答案
我已经解决了。 (pkcs7)标准在计算摘要后创建一个辅助结构(DigestInfo)。
DigestInfo ::= SEQUENCE { digestAlgorithm DigestAlgorithmIdentifier,
digest Digest }
解密我从SMIME包中读取的EncryptedDigest后，结果是一个DigestInfo。
然后我计算签名属性的摘要(对于每个签名者):
SignerInformation.getSignedAttributes()
最后将结果放入 DigestInfo 中。然后我才检查签名的有效性。瞧，它正在工作!
希望这可以帮助任何和我有同样问题的人，因为这确实是一个耗时的问题......
关于cryptography - bouncycaSTLe 中的 PKCS #7 SignedData 问题，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/9203177/