Java 到 Objective-C RSA 实现

Question

我在Objective-C中实现RSA加密和解密时遇到了麻烦，我在Java中非常简单地实现了它，现在我尝试在objc中翻译这个java代码。这是我的 java 代码:

public static byte[] encryptRSA(byte[] text, PublicKey key) throws Exception {

byte[] cipherText = null;
// get an RSA cipher object and print the provider
Cipher cipher = Cipher.getInstance("RSA");

// encrypt the plaintext using the public key
cipher.init(Cipher.ENCRYPT_MODE, key);
cipherText = cipher.doFinal(text);
return cipherText;

}

public static byte[] decryptRSA(byte[] text, PrivateKey key) throws Exception {

byte[] dectyptedText = null;
// decrypt the text using the private key
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, key);
dectyptedText = cipher.doFinal(text);
return dectyptedText;

}

这就是我生成 key 对的方式

    String seed = "SOMERANDOMSEED"+Long.toString(System.currentTimeMillis());
    KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
    SecureRandom rand = new SecureRandom(seed.getBytes());

    keyGen.initialize(4096,rand);


    KeyPair keyPair = keyGen.generateKeyPair();
    PrivateKey privateKey = keyPair.getPrivate();
    PublicKey publicKey = keyPair.getPublic();

现在在 objC 中，我已经编写了一些可以工作的代码，但我不知道如何从种子生成 rsa，就像我在 java 中所做的那样，以及如何使用此方法导入我在 java 中保存的 key

   //for import
   public static byte[] hexStringToByteArray(String s) {
        byte[] b = new byte[s.length() / 2];
        for (int i = 0; i < b.length; i++) {
            int index = i * 2;
            int v = Integer.parseInt(s.substring(index, index + 2), 16);
            b[i] = (byte) v;
        }
        return b;
    }



//for export 
    public static String byteArrayToHexString(byte[] b) {
    StringBuilder sb = new StringBuilder(b.length * 2);
    for (int i = 0; i < b.length; i++) {
        int v = b[i] & 0xff;
        if (v < 16) {
            sb.append('0');
        }
        sb.append(Integer.toHexString(v));
    }
    return sb.toString().toUpperCase();
}

这是我的 objc 代码

//this works properly
+(NSString *)decryptRSA:(NSString *)cipherString key:(SecKeyRef) privateKey {
    size_t plainBufferSize = SecKeyGetBlockSize(privateKey);
    uint8_t *plainBuffer = malloc(plainBufferSize);
    NSData *incomingData = [cipherString decodeFromHexidecimal];
    uint8_t *cipherBuffer = (uint8_t*)[incomingData bytes];
    size_t cipherBufferSize = SecKeyGetBlockSize(privateKey);
    SecKeyDecrypt(privateKey,
                  kSecPaddingOAEPKey,
                  cipherBuffer,
                  cipherBufferSize,
                  plainBuffer,
                  &plainBufferSize);
    NSData *decryptedData = [NSData dataWithBytes:plainBuffer length:plainBufferSize];
    NSString *decryptedString = [[NSString alloc] initWithData:decryptedData encoding:NSUTF8StringEncoding];
    return decryptedString;
}
//this works properly
+(NSString *)encryptRSA:(NSString *)plainTextString key:(SecKeyRef)publicKey {
    size_t cipherBufferSize = SecKeyGetBlockSize(publicKey);
    uint8_t *cipherBuffer = malloc(cipherBufferSize);
    uint8_t *nonce = (uint8_t *)[plainTextString UTF8String];
    SecKeyEncrypt(publicKey,
                  kSecPaddingOAEPKey,
                  nonce,
                  strlen( (char*)nonce ),
                  &cipherBuffer[0],
                  &cipherBufferSize);
    NSData *encryptedData = [NSData dataWithBytes:cipherBuffer length:cipherBufferSize];

    return [encryptedData hexadecimalString];
}
//here i generate the key pair
#define kPublicKeyTag           "com.apple.sample.publickey"
#define kPrivateKeyTag          "com.apple.sample.privatekey"
//i should use these as seed!?!!?
- (void)generateKeyPair:(NSUInteger)keySize {
    OSStatus sanityCheck = noErr;
    publicKeyRef = NULL;
    privateKeyRef = NULL;


    // Container dictionaries.
    NSMutableDictionary * privateKeyAttr = [[NSMutableDictionary alloc] init];
    NSMutableDictionary * publicKeyAttr = [[NSMutableDictionary alloc] init];
    NSMutableDictionary * keyPairAttr = [[NSMutableDictionary alloc] init];

    // Set top level dictionary for the keypair.
    [keyPairAttr setObject:(id)kSecAttrKeyTypeRSA forKey:(id)kSecAttrKeyType];
    [keyPairAttr setObject:[NSNumber numberWithUnsignedInteger:keySize] forKey:(id)kSecAttrKeySizeInBits];

    // Set the private key dictionary.
    [privateKeyAttr setObject:[NSNumber numberWithBool:YES] forKey:(id)kSecAttrIsPermanent];
    [privateKeyAttr setObject:privateTag forKey:(id)kSecAttrApplicationTag];
    // See SecKey.h to set other flag values.

    // Set the public key dictionary.
    [publicKeyAttr setObject:[NSNumber numberWithBool:YES] forKey:(id)kSecAttrIsPermanent];
    [publicKeyAttr setObject:publicTag forKey:(id)kSecAttrApplicationTag];
    // See SecKey.h to set other flag values.

    // Set attributes to top level dictionary.
    [keyPairAttr setObject:privateKeyAttr forKey:(id)@kSecPrivateKeyAttrs];
    [keyPairAttr setObject:publicKeyAttr forKey:(id)@kSecPublicKeyAttrs];

    // SecKeyGeneratePair returns the SecKeyRefs just for educational purposes.
    sanityCheck = SecKeyGeneratePair((__bridge CFDictionaryRef)keyPairAttr, &publicKeyRef, &privateKeyRef);


}

这是我用来导出objc中的 key 的方法，它看起来就像java方法一样工作

+ (NSString *)fromPrivateKeyToString: (SecKeyRef) privateKey {
    size_t pkeySize = SecKeyGetBlockSize(privateKey);
    NSData* pkeyData = [NSData dataWithBytes:privateKey length:pkeySize];
    NSString* pkeyString = [pkeyData hexadecimalString];

    return pkeyString;

}

Answer 1

尽管从种子创建相同的 key 对并非不可能，但您需要确保 RNG 和生成的 key 对完全相同。此外，放入生成器中的种子也需要以相同的方式使用。 RNG 或 key 对生成通常在创建时都没有考虑到兼容性。实际上，默认的“SHA1PRNG”甚至在Java版本之间也发生了变化，并且算法没有描述。

如果您想使用相同的私钥，那么最好生成它并将其传输到其他运行时。有多种方法，但一种方法是使用(密码)加密的 PKCS#8 或 PKCS#12 格式。当然， key 或密码需要保密，但种子值也是如此。

有关详细信息，请参阅 this Q/A 。不要忘记投票赞成那里的问题和答案，我可以在加密方面使用更多点:)。