RSA:在iOS中加密,在Java中解密

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我有一个从Java服务器发送的公钥。在解码和去除ASN.1头部之前,base64编码的字符串相匹配。我将公钥存储在钥匙串中SecItemAdd

所以我试图用公钥加密数据,并用Java中的私钥解密。我SecKeyEncrypt在iOS端和CipherJava端使用。

我正在加密的是对称AES密钥,它可以加密我的实际数据,因此密钥长度为16个字节。只需对base64进行密钥编码,一切正常,所以我知道这个RSA加密有什么问题。

以下是我的iOS调用示例:

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

以下是我的Java调用的示例:

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;
}

我尝试了这么多组合,没有任何工作。

  • iOS:PKCS1,Java:RSA / ECB / PKCS1Padding
  • iOS:PKCS1,Java:RSA
  • iOS:PKCS1,Java:RSA / None / PKCS1Padding(引发org.bouncycastle.crypto.DataLengthException: input too large for RSA cipher.
  • iOS:OAEP,Java:RSA / ECB / OAEPWithSHA-1AndMGF1Padding
  • iOS:OAEP,Java:RSA / ECB / OAEPWithSHA-256AndMGF1Padding

我也尝试过使用内部Java提供程序以及BouncyCastle提供程序。在javax.crypto.BadPaddingException被抛出每一次,但消息是每个组合不同。有些展示Data must start with zero,而其他展示Message is larger than modulus

iOS: PKCS1, Java: RSA不抛出异常,但所得到的解密的byte[]阵列应该是长度16,但它的长度为256,这意味着填充未正确剥离出来。

有人可以帮忙吗?

当我做更多的测试时,我遇到了这个页面(http://javadoc.iaik.tugraz.at/iaik_jce/current/iaik/pkcs/pkcs1/RSACipher.html),它基本上告诉我这一点RSA == RSA/None/PKCS1Padding。解密的意义在于没有例外,但我仍然得到一个解密密钥,其字节[]长度为256而不是长度为16。

另一个有趣的地方。看起来,如果Java服务器具有从iOS设备生成并使用加密的公钥Cipher.getInstance("RSA"),则手机能够使用RSA / PKCS1正确解码消息。

我已经看过这些教程,并在iOS端再次查看我的代码:

据我所知,我的代码正在做的一切正确。一个显着的区别是我如何保存密钥,所以我试着用另一种方式保存它:

    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);

该保存是成功的,但最终结果是相同的:解密的AES密钥仍然是256字节长而不是16字节。

提问于
用户回答回答于

我有同样的问题。与Java代码中的任何组合一起工作kSecPaddingNone,但适用。kSecPaddingPKCS1PKCS1

但是,不使用填充来使用它并不是个好主意。

因此,在iOS上,替换kSecPaddingNonekSecPaddingOAEP,用RSA/NONE/OAEPWithSHA1AndMGF1Padding在Java代码中。这对我有用。

用户回答回答于

解决方案 RSA/None/NoPadding

好吧,所以我得到了它的工作,但没有填充。这部分令我非常沮丧,我将其留给其他人尝试帮忙。也许我最终会发布我作为github上的库,一个用于Obj-C,一个用于Java。这是我迄今发现的。

TL; DR:使用最小的属性将密钥保存到密钥链中以使检索更简单。加密SecKeyEncrypt但使用kSecPaddingNone。用BouncyCastle和算法解密Java端RSA/None/NoPadding

从Java发送RSA公钥到iOS

使用X.509证书

我想验证是否直接发送公钥,删除ASN.1头和保存实际上正在做它应该做的事情。所以我考虑将公钥作为证书发送。我想授予David Benko提供的帮助我进行证书转换的加密库(https://github.com/DavidBenko/DBTransitEncryption)。我没有真正使用他的库,因为1.我已经在使用RNCryptor/JNCryptor对于我的AES加密和2.他没有Java方面的组件,所以我需要在那里写我自己的AES解密,我不想这样做。对于那些有兴趣并想要采用这种方法的人,这里是我在Java端创建证书然后将该证书转换为iOS上的公钥的代码:

*重要说明:请e.printStackTrace()用真实的日志记录替换。我只用它进行测试而不是用于生产。

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;
}

Obj-C

- (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

请注意,您不需要将公钥作为证书发送。事实上,在发现公钥被错误地保存后(见下文),我恢复了这段代码并将公钥保存到了我的设备中。您需要删除ASN.1其中一篇博文中提到的标题。该代码在此处转贴(为清楚起见,格式化)。

+ (NSData *)stripPublicKeyHeader:(NSData *)keyBits {
    // Skip ASN.1 public key header
    if (keyBits == nil) {
        return nil;
    }

    unsigned int len = [keyBits length];
    if (!len) {
        return nil;
    }

    unsigned char *c_key = (unsigned char *)[keyBits bytes];
    unsigned int  idx    = 0;

    if (c_key[idx++] != 0x30) {
        return nil;
    }

    if (c_key[idx] > 0x80) {
        idx += c_key[idx] - 0x80 + 1;
    }
    else {
        idx++;
    }

    if (idx >= len) {
        return nil;
    }

    if (c_key[idx] != 0x30) {
        return nil;
    }

    idx += 15;

    if (idx >= len - 2) {
        return nil;
    }

    if (c_key[idx++] != 0x03) {
        return nil;
    }

    if (c_key[idx] > 0x80) {
        idx += c_key[idx] - 0x80 + 1;
    }
    else {
        idx++;
    }

    if (idx >= len) {
        return nil;
    }

    if (c_key[idx++] != 0x00) {
        return nil;
    }

    if (idx >= len) {
        return nil;
    }

    // Now make a new NSData from this buffer
    return([NSData dataWithBytes:&c_key[idx] length:len - idx]);
}

所以我会简单地保存这样的密钥:

- (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公钥保存至钥匙串

它很生气。事实证明,即使我将钥匙保存在钥匙链中,我所检索的并不是我放入的!当我将保存的base64密钥与我用来加密AES密钥的base64密钥进行比较时,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。这就是我最终的结果:

- (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;
}

在一天结束时,我只能在没有填充的情况下工作。我不确定为什么BouncyCastle无法删除填充,所以如果有人有任何见解,请告诉我。

这是我的加密代码(由David Benko修改):

- (NSData *)encryptData:(NSData *)content usingPublicKey:(NSString *)publicKeyTag {
    SecKeyRef publicKey = [self getKeyRef:publicKeyTag isPrivate:NO];
    NSData *keyBits = [self getKeyBitsFromKey:publicKey];
    NSString *keyString = [keyBits base64EncodedStringWithOptions:0];
    NSAssert(publicKey != nil,@"Public key can not be nil");

    size_t cipherLen = SecKeyGetBlockSize(publicKey); // convert to byte
    void *cipher = malloc(cipherLen);
    size_t maxPlainLen = cipherLen - 12;

    size_t plainLen = [content length];
    if (plainLen > maxPlainLen) {
        NSLog(@"content(%ld) is too long, must < %ld", plainLen, maxPlainLen);
        return nil;
    }

    void *plain = malloc(plainLen);
    [content getBytes:plain
               length:plainLen];

    OSStatus returnCode = SecKeyEncrypt(publicKey, kSecPaddingNone, plain,
            plainLen, cipher, &cipherLen);

    NSData *result = nil;
    if (returnCode != errSecSuccess) {
        NSLog(@"SecKeyEncrypt fail. Error Code: %d", (int)returnCode);
    }
    else {
        result = [NSData dataWithBytes:cipher
                                length:cipherLen];
    }

    free(plain);
    free(cipher);

    return result;
}

以下是我在Java方面解密的方式:

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;
    }
}

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