如何使用SunMSCAPI密钥解密RSA-OAEP

Posted 2023-02-08

我有一个带有私钥的证书存储在Windows证书存储区中。如何使用此密钥解密使用OAEP填充的消息？我可以使用Bouncycastle提供程序和pfx文件（PKCS12密钥存储库）解密消息，但不能使用Windows存储库（SunMSCAPI）解密消息。

我基本上使用此代码

KeyStore keyStore = java.security.KeyStore.getInstance("Windows-MY");
keyStore.load(null, null);
PrivateKey privateKey = (PrivateKey) keyStore.getKey("keyalias", null);

java.security.Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());

JceKeyTransRecipient jceKeyTransEnvelopedRecipient = new JceKeyTransEnvelopedRecipient(privateKey);
CMSEnvelopedData envelopedData = new CMSEnvelopedData(Base64.getDecoder().decode(encryptedData));
RecipientInformationStore recipientInfos = envelopedData.getRecipientInfos();
RecipientInformation recipient = recipientInfos.getRecipients().iterator().next();
byte[] decrypted = recipient.getContent(jceKeyTransEnvelopedRecipient);

结果为

Caused by: java.security.InvalidKeyException: No installed provider supports this key: sun.security.mscapi.RSAPrivateKey
    at javax.crypto.Cipher.chooseProvider(Cipher.java:892)
    at javax.crypto.Cipher.init(Cipher.java:1248)
    at javax.crypto.Cipher.init(Cipher.java:1185)
    at org.bouncycastle.operator.jcajce.JceAsymmetricKeyUnwrapper.generateUnwrappedKey(JceAsymmetricKeyUnwrapper.java:148)

如果我这样指定提供者：

JceKeyTransRecipient jceKeyTransEnvelopedRecipient = new JceKeyTransEnvelopedRecipient(privateKey).setProvider("SunMSCAPI");

然后我收到错误消息（不支持OAEP）

Caused by: java.security.NoSuchAlgorithmException: No such algorithm: 1.2.840.113549.1.1.7
    at javax.crypto.Cipher.getInstance(Cipher.java:687)
    at javax.crypto.Cipher.getInstance(Cipher.java:595)
    at org.bouncycastle.jcajce.util.NamedJcaJceHelper.createCipher(NamedJcaJceHelper.java:47)
    at org.bouncycastle.operator.jcajce.OperatorHelper.createAsymmetricWrapper(OperatorHelper.java:267)

简短地说，java不支持OAEP，即使BC支持OAEP，它也不能将其用于“外部”键。如果是这样，还有其他选择吗？

答案

我认为詹姆斯是correct with his comment。即使是Windows平台，也只是SunMSCAPI桥doesn't support OAEP。 SunMSCAPI不会释放私钥值，所以发生的事情是Java将搜索任何支持OAEP 和私钥对象的提供程序，然后找不到任何提供程序。这解释了最初的异常：No installed provider supports this key: sun.security.mscapi.RSAPrivateKey。

注意，由于OAEP为even included as required algorithm，因此语句“ Java不支持OAEP”显然是错误的。换句话说，如果没有OAEP，您甚至都不能call it Java，实际上SunJCE提供程序确实支持该功能，包括支持更多的散列函数和其他位大小，而不仅仅是1024位和2048位。但是，这确实需要与软件实现兼容的密钥。