传输RSA公钥,javaME,充气城堡的问题

Question

我正在致力于将实例消息传递应用程序从Java移植到JavaME,它还实现了加密.问题是我想将我的公钥发送到服务器.桌面客户端具有此作业的代码:

byte[] encoded_public_key=publick_key.getEncoded();

并且服务器具有此代码来检索密钥:

EncodedKeySpec publicKeySpec = new X509EncodedKeySpec(encoded_public_key);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
PublicKey puKey = keyFactory.generatePublic(publicKeySpec);

现在我看了getEncoded的API,它说它以字节数组的形式返回密钥的DER编码形式(http://www.docjar.com/docs/api/sun/s...tml #getEncoded)

我在JavaME中的实现是这样的:

RSAPublicKeyStructure public_key_JAVAME=new RSAPublicKeyStructure(modulus,exponent);
byte[] DER_encoded_public_key_JAVAME=public_key_JAVAME.getDEREncoded();

//the getEncoded functions returns exact the same byte array.

但是,当我尝试使用服务器代码检索JavaME创建的DER编码密钥时,换句话说,当我尝试这样做时:

EncodedKeySpec publicKeySpec = new X509EncodedKeySpec(DER_encoded_public_key_JAVAME);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
PublicKey puKey = keyFactory.generatePublic(publicKeySpec);

我明白了

java.security.spec.InvalidKeySpecException: java.security.InvalidKeyException: IOException: algid parse error, not a sequence
at sun.security.rsa.RSAKeyFactory.engineGeneratePublic(RSAKeyFactory.java:188)
at java.security.KeyFactory.generatePublic(KeyFactory.java:304)

Caused by: java.security.InvalidKeyException: IOException: algid parse error, not a sequence
at sun.security.x509.X509Key.decode(X509Key.java:380)
at sun.security.x509.X509Key.decode(X509Key.java:386)
at sun.security.rsa.RSAPublicKeyImpl.<init>(RSAPublicKeyImpl.java:66)
at sun.security.rsa.RSAKeyFactory.generatePublic(RSAKeyFactory.java:281)
at sun.security.rsa.RSAKeyFactory.engineGeneratePublic(RSAKeyFactory.java:184)

有趣的是:来自普通Java的DER编码密钥(使用getencoded()函数)是一个162字节长的字节数组,而使用充气城堡在JavaME中编码的SAME密钥DER是140字节长.这些2 DER编码密钥不应该具有相同的长度吗？我的意思是它与DER编码格式中的密钥相同,因此它们应该是相同的.

我究竟做错了什么？

---

真的我没注意到.问题是你知道如何从bouncyCastle中的PublicKey创建一个subjectPublickeyInfo对象吗？我试过了:

ByteArrayInputStream bIn = new ByteArrayInputStream(RSApublickey.toString().getbytes()); SubjectPublicKeyInfo info = new SubjectPublicKeyInfo((ASN1Sequence)new ASN1InputStream(bIn).readObject());

但它没有用.我也尝试过:

ByteArrayInputStream(RSApublicKeyStructure.getEncoded()); SubjectPublicKeyInfo info = new SubjectPublicKeyInfo((ASN1Sequence)new ASN1InputStream(bIn).readObject());

实际上我确实希望不工作,但我必须尝试.那么我怎样才能从RSAkeyparameters创建一个Subjectpublickeyinfo？(这是有弹性的城堡API默默无闻的点之一)

再次感谢您的回复,您已经给了我很大的帮助.您已经让我走上了正确的道路.

Answer 1

DER编码只是编码的标准.说,一个关键是DER编码相当于说是XML编码:您需要在同意怎么就DER-/XML编码,以便能够解码.

在这种情况下,您RSAPublicKeyStructure.getEncoded()将密钥作为ASN.1的DER编码返回RSAPublicKey:

RSAPublicKey ::= SEQUENCE {
  modulus INTEGER, -- n
  publicExponent INTEGER -- e 
}

在X509EncodedKeySpec另一方面预计要切换DER编码的ASN.1的PublicKeyInfo:

PublicKeyInfo ::= SEQUENCE {
  algorithm AlgorithmIdentifier,
  PublicKey BIT STRING
}

要创建一个PublicKeyInfo使用BouncyCastle这样做(由GregS提供):

RSAPublicKeyStructure rsaPublicKey = /* ... */
AlgorithmIdentifier rsaEncryption = new AlgorithmIdentifier(PKCSObjectIdentifiers.rsaEncryption, DERNull.INSTANCE); 
SubjectPublicKeyInfo publicKeyInfo = new SubjectPublicKeyInfo(rsaEncryption, rsaPublicKey);
byte[] encodedPublicKeyInfo = publicKeyInfo.getEncoded();