RSA：在iOS中加密，在Java中解密

我有一个从Java服务器发送的公钥。base64编码的字符串在我解码并去掉ASN.1头之前匹配。我使用

SecItemAdd

将公钥存储在钥匙链中

因此，我尝试使用公钥对数据进行加密，并使用Java中的私钥对其进行解密。我在iOS端使用

SecKeyEncrypt

，在Java端使用

Cipher

我加密的是对称AES密钥，它加密我的实际数据，所以密钥长度是16字节。当简单地对密钥进行base64编码时，一切正常，因此我知道这种RSA加密有问题

以下是我的iOS呼叫示例：

OSStatus sanityCheck = SecKeyEncrypt(publicKey,
        kSecPaddingPKCS1,
        (const uint8_t *) [incomingData bytes],
        keyBufferSize,
        cipherBuffer,
        &cipherBufferSize
);

下面是我的Java调用示例：

public static byte[] decryptMessage (byte[] message, PrivateKey privateKey, String algorithm) {
    if (message == null || privateKey == null) {
        return null;
    }
    Cipher cipher = createCipher(Cipher.DECRYPT_MODE, privateKey, algorithm, false);
    if (cipher == null) {
        return null;
    }

    try {
        return cipher.doFinal(message);
    }
    catch (IllegalBlockSizeException e) {
        e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.
        return null;
    }
    catch (BadPaddingException e) {
        e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.
        return null;
    }
}

private static Cipher createCipher (int mode, Key encryptionKey, String algorithm, boolean useBouncyCastle) {
    Cipher cipher;

    try {
        if (useBouncyCastle) {
            Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
            cipher = Cipher.getInstance(algorithm, "BC");
        }
        else {
            cipher = Cipher.getInstance(algorithm);
        }
    }
    catch (NoSuchAlgorithmException e) {
        e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.
        return null;
    }
    catch (NoSuchPaddingException e) {
        e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.
        return null;
    }
    catch (NoSuchProviderException e) {
        e.printStackTrace();
        return null;
    }

    try {
        cipher.init(mode, encryptionKey);
    }
    catch (InvalidKeyException e) {
        e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.
        return null;
    }

    return cipher;
}

我尝试了这么多的组合，但都没有效果

• iOS:PKCS1，Java:RSA/ECB/pkcs1p
• iOS:PKCS1，Java:RSA
• iOS:PKCS1，Java:RSA/None/PKCS1Padding（抛出

  org.bounchycastle.crypto.datalength异常：输入太大，不适合RSA密码。

  ）
• iOS:OAEP，Java:RSA/ECB/OAEPWITHHA-1和MGF1
• iOS:OAEP，Java:RSA/ECB/OAEPHA-256和MGF1

我还尝试使用内部Java提供程序和BouncyCastle提供程序。每次都会抛出

javax.crypto.BadPaddingException

，但每个组合的消息都不同。一些显示<代码>数据必须以零开始，而另一些显示<代码>消息大于模数

iOS:PKCS1，Java:RSA

不会抛出异常，但是得到的解密的

byte[]

数组的长度应该是16，但长度是256，这意味着填充没有正确地去除

有人能帮忙吗

***编辑***

在进行更多测试时，我看到了这个页面（），它本质上告诉我

RSA==RSA/None/PKCS1Padding

。解密工作的意义是没有例外，但我仍然得到一个解密密钥，其字节[]长度为256，而不是16

另一个有趣的问题。如果Java服务器具有从iOS设备生成的公钥，并使用

Cipher.getInstance（“RSA”）

进行加密，则手机可以使用RSA/PKCS1正确解码消息

***编辑2***

我已经阅读了这些教程，并在iOS端再次阅读了我的代码：

据我所知，我的代码做的一切都是正确的。一个显著的区别在于我如何保存密钥，因此我尝试以另一种方式保存它：

    OSStatus error = noErr;
    CFTypeRef persistPeer = NULL;

    NSMutableDictionary * keyAttr = [[NSMutableDictionary alloc] init];

    keyAttr[(__bridge id) kSecClass] = (__bridge id) kSecClassKey;
    keyAttr[(__bridge id) kSecAttrKeyType] = (__bridge id) kSecAttrKeyTypeRSA;
    keyAttr[(__bridge id) kSecAttrApplicationTag] = [secKeyWrapper getKeyTag:serverPublicKeyTag];
    keyAttr[(__bridge id) kSecValueData] = strippedServerPublicKey;
    keyAttr[(__bridge id) kSecReturnPersistentRef] = @YES;

    error = SecItemAdd((__bridge CFDictionaryRef) keyAttr, (CFTypeRef *)&persistPeer);

    if (persistPeer == nil || ( error != noErr && error != errSecDuplicateItem)) {
        NSLog(@"Problem adding public key to keychain");
        return;
    }

    CFRelease(persistPeer);

该保存成功，但最终结果相同：解密的AES密钥仍然是256字节长，而不是16字节。

解决方案使用

RSA/None/NoPadding

好的，我让它工作了，但是没有填充。这一部分真的让我很沮丧，我把它留给其他人来帮助我。也许我最终会在github上发布我的库，一个用于Obj-C，一个用于Java。这是我到目前为止发现的

TL；DR：使用最少的属性将密钥保存到密钥链，以简化检索。使用

SecKeyEncrypt

加密，但使用

kSecPaddingNone

。使用BouncyCastle和算法在Java端解密

RSA/None/NoPadding

从Java向iOS发送RSA公钥 使用X.509证书 我想验证是否直接发送公钥，去掉ASN.1头并保存实际上是在做它应该做的事情。因此，我考虑将公钥作为证书发送。我想感谢David Benko提供了一个加密库（）来帮助我进行证书转换。实际上我没有使用他的图书馆，因为1。我已经在使用

RNCryptor

/

jncyptor

进行AES加密和2。他没有Java端组件，所以我需要在那里编写自己的AES解密，我不想这样做。对于那些感兴趣并希望采用这种方法的人，下面是我的代码，用于在Java端创建证书，然后在iOS上将该证书转换为公钥：

*重要提示：请将

e.printStackTrace（）

替换为真实的日志记录语句。我只在测试时使用它，而不是在生产中使用它

Java：

public static X509Certificate generateCertificate (KeyPair newKeys) {
    Security.addProvider(new BouncyCastleProvider());
    Date startDate = new Date();
    Date expiryDate = new DateTime().plusYears(100).toDate();

    BigInteger serialNumber = new BigInteger(10, new Random());
    try {
        ContentSigner sigGen = new JcaContentSignerBuilder("SHA1withRSA").setProvider("BC").build(newKeys
                                                                                                          .getPrivate());
        SubjectPublicKeyInfo subjectPublicKeyInfo = new SubjectPublicKeyInfo(ASN1Sequence.getInstance(newKeys
                                                                                                              .getPublic().getEncoded()
                                                                                                              ));
        X500Name dnName = new X500Name("CN=FoodJudge API Certificate");
        X509v1CertificateBuilder builder = new X509v1CertificateBuilder(dnName,
                                                                        serialNumber,
                                                                        startDate, expiryDate,
                                                                        dnName,
                                                                        subjectPublicKeyInfo);
        X509CertificateHolder holder = builder.build(sigGen);
        return new JcaX509CertificateConverter().setProvider("BC").getCertificate(holder);
    }
    catch (OperatorCreationException e) {
        e.printStackTrace();
    }
    catch (CertificateException e) {
        e.printStackTrace();
    }
    return null;
}

- (SecKeyRef)extractPublicKeyFromCertificate:(NSData *)certificateBytes {
    if (certificateBytes == nil) {
        return nil;
    }

    SecCertificateRef certificate = SecCertificateCreateWithData(kCFAllocatorDefault, ( __bridge CFDataRef) certificateBytes);
    if (certificate == nil) {
        NSLog(@"Can not read certificate from data");
        return false;
    }

    SecTrustRef trust;
    SecPolicyRef policy = SecPolicyCreateBasicX509();
    OSStatus returnCode = SecTrustCreateWithCertificates(certificate, policy, &trust);

    // release the certificate as we're done using it
    CFRelease(certificate);
    // release the policy
    CFRelease(policy);

    if (returnCode != errSecSuccess) {
        NSLog(@"SecTrustCreateWithCertificates fail. Error Code: %d", (int)returnCode);
        return nil;
    }

    SecTrustResultType trustResultType;
    returnCode = SecTrustEvaluate(trust, &trustResultType);
    if (returnCode != errSecSuccess) {
        // TODO log
        CFRelease(trust);
        return nil;
    }

    SecKeyRef publicKey = SecTrustCopyPublicKey(trust);
    CFRelease(trust);

    if (publicKey == nil) {
        NSLog(@"SecTrustCopyPublicKey fail");
        return nil;
    }

    return publicKey;
}

Obj-C：

public static X509Certificate generateCertificate (KeyPair newKeys) {
    Security.addProvider(new BouncyCastleProvider());
    Date startDate = new Date();
    Date expiryDate = new DateTime().plusYears(100).toDate();

    BigInteger serialNumber = new BigInteger(10, new Random());
    try {
        ContentSigner sigGen = new JcaContentSignerBuilder("SHA1withRSA").setProvider("BC").build(newKeys
                                                                                                          .getPrivate());
        SubjectPublicKeyInfo subjectPublicKeyInfo = new SubjectPublicKeyInfo(ASN1Sequence.getInstance(newKeys
                                                                                                              .getPublic().getEncoded()
                                                                                                              ));
        X500Name dnName = new X500Name("CN=FoodJudge API Certificate");
        X509v1CertificateBuilder builder = new X509v1CertificateBuilder(dnName,
                                                                        serialNumber,
                                                                        startDate, expiryDate,
                                                                        dnName,
                                                                        subjectPublicKeyInfo);
        X509CertificateHolder holder = builder.build(sigGen);
        return new JcaX509CertificateConverter().setProvider("BC").getCertificate(holder);
    }
    catch (OperatorCreationException e) {
        e.printStackTrace();
    }
    catch (CertificateException e) {
        e.printStackTrace();
    }
    return null;
}

- (SecKeyRef)extractPublicKeyFromCertificate:(NSData *)certificateBytes {
    if (certificateBytes == nil) {
        return nil;
    }

    SecCertificateRef certificate = SecCertificateCreateWithData(kCFAllocatorDefault, ( __bridge CFDataRef) certificateBytes);
    if (certificate == nil) {
        NSLog(@"Can not read certificate from data");
        return false;
    }

    SecTrustRef trust;
    SecPolicyRef policy = SecPolicyCreateBasicX509();
    OSStatus returnCode = SecTrustCreateWithCertificates(certificate, policy, &trust);

    // release the certificate as we're done using it
    CFRelease(certificate);
    // release the policy
    CFRelease(policy);

    if (returnCode != errSecSuccess) {
        NSLog(@"SecTrustCreateWithCertificates fail. Error Code: %d", (int)returnCode);
        return nil;
    }

    SecTrustResultType trustResultType;
    returnCode = SecTrustEvaluate(trust, &trustResultType);
    if (returnCode != errSecSuccess) {
        // TODO log
        CFRelease(trust);
        return nil;
    }

    SecKeyRef publicKey = SecTrustCopyPublicKey(trust);
    CFRelease(trust);

    if (publicKey == nil) {
        NSLog(@"SecTrustCopyPublicKey fail");
        return nil;
    }

    return publicKey;
}

使用RSA公钥 需要注意的是，不需要将公钥作为证书发送。事实上，在发现公钥保存不正确（见下文）后，我还原了此代码并将公钥保存到我的设备中。你需要去掉其中一篇博文中提到的

ASN.1

标题。该代码在此处重新发布（格式清晰）

因此，我只需像这样保存密钥：

- (void)storeServerPublicKey:(NSString *)serverPublicKey {
    if (!serverPublicKey) {
        return;
    }
    SecKeyWrapper *secKeyWrapper = [SecKeyWrapper sharedWrapper];
    NSData *decryptedServerPublicKey = [[NSData alloc] initWithBase64EncodedString:serverPublicKey options:0];

    NSData *strippedServerPublicKey = [SecKeyWrapper stripPublicKeyHeader:decryptedServerPublicKey];
    if (!strippedServerPublicKey) {
        return;
    }
    [secKeyWrapper savePublicKeyToKeychain:strippedServerPublicKey tag:@"com.sampleapp.publickey"];
}

将RSA公钥保存到密钥链 真让人发疯。结果证明，即使我把钥匙保存在钥匙链上，我找回的东西也不是我放进去的！当我比较保存的base64密钥和用于加密AES密钥的base64密钥时，我意外地发现了这一点。所以我发现最好简化保存密钥时使用的NSDictionary。以下是我最终得到的结果：

- (void)savePublicKeyToKeychain:(NSData *)key tag:(NSString *)tagString {
    NSData *tag = [self getKeyTag:tagString];

    NSDictionary *saveDict = @{
            (__bridge id) kSecClass : (__bridge id) kSecClassKey,
            (__bridge id) kSecAttrKeyType : (__bridge id) kSecAttrKeyTypeRSA,
            (__bridge id) kSecAttrApplicationTag : tag,
            (__bridge id) kSecAttrKeyClass : (__bridge id) kSecAttrKeyClassPublic,
            (__bridge id) kSecValueData : key
    };
    [self saveKeyToKeychain:saveDict tag:tagString];
}

- (void)saveKeyToKeychain:(NSDictionary *)saveDict tag:(NSString *)tagString {
    OSStatus sanityCheck = SecItemAdd((__bridge CFDictionaryRef) saveDict, NULL);
    if (sanityCheck != errSecSuccess) {
        if (sanityCheck == errSecDuplicateItem) {
            // delete the duplicate and save again
            sanityCheck = SecItemDelete((__bridge CFDictionaryRef) saveDict);
            sanityCheck = SecItemAdd((__bridge CFDictionaryRef) saveDict, NULL);
        }
        if (sanityCheck != errSecSuccess) {
            NSLog(@"Problem saving the key to keychain, OSStatus == %d.", (int) sanityCheck);
        }
    }
    // remove from cache
    [keyCache removeObjectForKey:tagString];
}

要检索我的密钥，我使用以下方法：

 - (SecKeyRef)getKeyRef:(NSString *)tagString isPrivate:(BOOL)isPrivate {
     NSData *tag = [self getKeyTag:tagString];

     id keyClass = (__bridge id) kSecAttrKeyClassPublic;
     if (isPrivate) {
         keyClass = (__bridge id) kSecAttrKeyClassPrivate;
     }

     NSDictionary *queryDict = @{
             (__bridge id) kSecClass : (__bridge id) kSecClassKey,
             (__bridge id) kSecAttrKeyType : (__bridge id) kSecAttrKeyTypeRSA,
             (__bridge id) kSecAttrApplicationTag : tag,
             (__bridge id) kSecAttrKeyClass : keyClass,
             (__bridge id) kSecReturnRef : (__bridge id) kCFBooleanTrue
     };
     return [self getKeyRef:queryDict tag:tagString];
 }

- (SecKeyRef)getKeyRef:(NSDictionary *)query tag:(NSString *)tagString {
    SecKeyRef keyReference = NULL;
    OSStatus sanityCheck = SecItemCopyMatching((__bridge CFDictionaryRef) query, (CFTypeRef *) &keyReference);
    if (sanityCheck != errSecSuccess) {
        NSLog(@"Error trying to retrieve key from keychain. tag: %@. sanityCheck: %li", tagString, sanityCheck);
        return nil;
    }
    return keyReference;
}

一天结束时，我只能在没有填充物的情况下让它工作。我不知道为什么

BouncyCastle

无法删除填充，因此如果有人有任何见解，请告诉我

以下是我的加密代码（由David Benko修改）：

---

我也有同样的问题。可以使用

kSecPaddingNone

，但是不能使用

kSecPaddingPKCS1

和Java代码中的任何

PKCS1

组合

但是，不使用填充物是不好的

因此，在iOS上，将

kSecPaddingNone

替换为

kSecPaddingOAEP
private Response authenticate (String encryptedSymmetricString) {
    byte[] encryptedSymmetricKey = Base64.decodeBase64(encryptedSymmetricKeyString);
    String privateKey = Server.getServerPrivateKey();
    byte[] decryptedSymmetricKey = KeyHandler.decryptMessage(encryptedSymmetricKey, privateKey,
                                                             KeyHandler.ASYMMETRIC_CIPHER_ALGORITHM);
}

public static byte[] decryptMessage (byte[] message, String privateKeyString, String algorithm) {
    if (message == null || privateKeyString == null) {
        return null;
    }
    PrivateKey privateKey = getPrivateKey(privateKeyString);
    return decryptMessage(message, privateKey, algorithm);
}

public static byte[] decryptMessage (byte[] message, PrivateKey privateKey, String algorithm) {
    if (message == null || privateKey == null) {
        return null;
    }
    Cipher cipher = createCipher(Cipher.DECRYPT_MODE, privateKey, algorithm, true);
    if (cipher == null) {
        return null;
    }

    try {
        return cipher.doFinal(message);
    }
    catch (IllegalBlockSizeException e) {
        e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.
        return null;
    }
    catch (BadPaddingException e) {
        e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.
        return null;
    }
}