我有一个从Java服务器发送的公钥 . 在解码和删除ASN.1标头之前，base64编码的字符串匹配 . 我使用 SecItemAdd 将公钥存储在钥匙串中 .

所以我在iOS端使用 SecKeyEncrypt ，在Java端使用 Cipher .

我正在加密的是加密我的实际数据的对称AES密钥，因此密钥长度为16个字节 . 当简单地对base64进行编码时，一切正常，所以我知道这个RSA加密有问题 .

这是我的iOS调用示例：

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

这是我的Java调用的一个例子：

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;
}

我尝试了很多组合，但没有任何效果 .

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

我也尝试使用内部Java提供程序以及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 . 有些显示 Data must start with zero ，有些显示 Message is larger than modulus .

iOS: PKCS1, Java: RSA 不会抛出异常，但生成的解密 byte[] 数组应该是长度为16，但它正确地被删除了.1563378_t .

有人可以帮忙吗？

*** EDIT ***

当我进行更多测试时，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 RSA == RSA/None/PKCS1Padding . 解密工作的意义是没有异常，但我仍然得到一个解密密钥，其byte []长度为256而不是长度为16 .

另一个兴趣点 . 似乎如果Java服务器具有从iOS设备生成并使用 Cipher.getInstance("RSA") 加密的公钥，则电话能够使用RSA / PKCS1正确解码消息 .

*** EDIT 2 ***

我查看了这些教程，并在iOS端再次查看了我的代码：

据我所知，我的代码正在做正确的事情 . 一个显着的区别在于我如何保存密钥，所以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);

保存成功，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 .

2 回答

5

我有同样的问题 . 使用 kSecPaddingNone ，但 doesn't 与 kSecPaddingPKCS1 一起使用，Java代码中的任何 PKCS1 组合 .

但是，没有填充使用它并不是一个好主意 .

因此，在iOS上，将 kSecPaddingNone 替换为 kSecPaddingOAEP 并在Java代码中使用 RSA/NONE/OAEPWithSHA1AndMGF1Padding . 这对我有用 .

回复于 2024-04-27T10:37:39+08:00

使用RSA / None / NoPadding的解决方案

好的，所以我让它工作但 WITHOUT PADDING . 这部分让我非常沮丧，我将其留给其他人试图帮助 . 也许我到目前为止发现了什么 .

TL;DR ：使用最少的属性将密钥保存到钥匙串，以使检索更简单 . 使用 SecKeyEncrypt 进行加密，但使用 kSecPaddingNone . 用BouncyCastle和算法 RSA/None/NoPadding 解密Java端 .

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，剥离ASN.1标头并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 . 我想赞扬David Benko提供的加密库（https://github.com/DavidBenko/DBTransitEncryption）帮助我进行了证书转换 . 我没有't actually use his library because 1. I'已经使用 RNCryptor / JNCryptor 进行我的AES加密和2.他没有想要这样做 . 对于那些感兴趣并希望采用这种方法的人，这是我在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：请将 e.printStackTrace() 替换为真实的日志记录 . 我只用它来测试和生产环境中的 NOT .

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

它_1163412_ t需要将公钥作为证书发送 . 实际上，在发现公钥被错误保存后（见下文），我还原了这段代码并将公钥保存到我的设备中 . 您需要删除其中一篇博文中提到的 ASN.1 Headers . 该代码在此处重新发布（为清晰起见而格式化） .

+ (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公钥保存到钥匙串

这令人抓狂 . 原来，即使我将钥匙保存到钥匙串中，我检索到的不是我放入的钥匙！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 . 这是我最终得到的：

- (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使其工作 . 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;
}

这是我在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;
    }
}

回复于 2024-04-27T10:37:39+08:00

RSA：在iOS中加密，用Java解密