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AES / CBCでファイルを暗号化しようとしています。キーはランダムであり、RSAで暗号化されている必要があります。「対称暗号化に適していないアルゴリズムRSAのキー」を取得しています...何が問題になっているようですか？

これは私のコードの一部です：

    Security.addProvider(new BouncyCastleProvider());
    byte[] input = "Encryption Test".getBytes();
    Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding", "BC"); // init Cipher to use AES/CBC
    SecureRandom random = new SecureRandom(); // IV is random 
    KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA", "BC"); // Key will be generated with RSA

    generator.initialize(512, random);
    KeyPair pair = generator.generateKeyPair();
    Key pubKey = pair.getPublic();
    //Key privKey = pair.getPrivate();

    cipher.init(Cipher.ENCRYPT_MODE, pubKey, random);
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2 に答える 2

1

鍵交換に鍵交換暗号を使用したいということでおめでとうございます! インターネット上で RSA をストリーム暗号に変えようとする人がこれほど多いのはなぜかと思うことがあります。

以下のサンプル コードは、これを行う方法を示しています。

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

import java.io.*;
import java.security.*;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

public class Test {

    /**
     * Generate an RSA key pair and save it to the file
     */
    public static KeyPair genKeys(File keyFile) throws Exception {
        System.out.println("Generating RSA keys");

        KeyFactory factory = KeyFactory.getInstance("RSA");
        KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
        kpg.initialize(2048);
        KeyPair kp = kpg.generateKeyPair();
        X509EncodedKeySpec pubSpec = factory.getKeySpec(kp.getPublic(),
                X509EncodedKeySpec.class);
        PKCS8EncodedKeySpec privSpec = factory.getKeySpec(kp.getPrivate(),
                PKCS8EncodedKeySpec.class);

        FileOutputStream out = new FileOutputStream(keyFile);
        DataOutputStream dat = new DataOutputStream(out);

        byte[] enc = pubSpec.getEncoded();
        dat.writeInt(enc.length);
        dat.write(enc);

        enc = privSpec.getEncoded();
        dat.writeInt(enc.length);
        dat.write(enc);
        dat.flush();
        dat.close();

        System.out.println("RSA keys saved to " + keyFile.getPath());

        return kp;
    }


    /**
     * Load an RSA key pair from the file
     */
    public static KeyPair loadKeys(File keyFile) throws Exception {
        System.out.println("Loading RSA keys");

        FileInputStream in = new FileInputStream(keyFile);
        DataInputStream dat = new DataInputStream(in);

        int len = dat.readInt();
        byte[] enc = new byte[len];
        dat.readFully(enc);
        X509EncodedKeySpec pubSpec = new X509EncodedKeySpec(enc);

        len = dat.readInt();
        enc = new byte[len];
        dat.readFully(enc);
        PKCS8EncodedKeySpec privSpec = new PKCS8EncodedKeySpec(enc);

        dat.close();

        KeyFactory factory = KeyFactory.getInstance("RSA");
        PublicKey pub = factory.generatePublic(pubSpec);
        PrivateKey priv = factory.generatePrivate(privSpec);

        System.out.println("RSA keys loaded from " + keyFile.getPath());
        return new KeyPair(pub, priv);
    }


    /**
     * Decrypt a file
     */
    public static void decrypt(KeyPair kp, File inFile, File outFile) throws Exception {
        Cipher rsa = Cipher.getInstance("RSA/ECB/OAEPWithSHA1AndMGF1Padding");

        FileInputStream in = new FileInputStream(inFile);
        DataInputStream dat = new DataInputStream(in);

        // read RSA encrypted AES key
        int len = dat.readInt();
        byte[] buf = new byte[len];
        dat.readFully(buf);
        rsa.init(Cipher.DECRYPT_MODE, kp.getPrivate());

        SecretKeySpec key = new SecretKeySpec(rsa.doFinal(buf), "AES");

        // read the AES IV
        len = dat.readInt();
        buf = new byte[len];
        dat.readFully(buf);
        IvParameterSpec iv = new IvParameterSpec(buf);

        Cipher aes = Cipher.getInstance("AES/CBC/PKCS5Padding");
        aes.init(Cipher.DECRYPT_MODE, key, iv);

        // process the rest of the file to get the original back
        FileOutputStream out = new FileOutputStream(outFile);

        buf = new byte[1000];
        int r = -1;
        while( (r = dat.read(buf)) != -1 ) {
            byte[] sec = aes.update(buf, 0, r);
            if (sec != null) out.write(sec);
        }
        out.write(aes.doFinal());
        out.flush();
        out.close();
        in.close();
    }


    public static void encrypt(KeyPair kp, File inFile, File outFile) throws Exception {
        Cipher rsa = Cipher.getInstance("RSA/ECB/OAEPWithSHA1AndMGF1Padding");

        // create new AES key
        KeyGenerator gen = KeyGenerator.getInstance("AES");
        gen.init(256);
        SecretKey key = gen.generateKey();

        // RSA encrypt AES key
        byte[] keyEnc = key.getEncoded();
        rsa.init(Cipher.ENCRYPT_MODE, kp.getPublic());
        byte[] keySec = rsa.doFinal(keyEnc);

        // Create AES cipher
        Cipher aes = Cipher.getInstance("AES/CBC/PKCS5Padding");
        aes.init(Cipher.ENCRYPT_MODE, key);
        byte[] iv = aes.getIV();

        FileOutputStream out = new FileOutputStream(outFile);
        DataOutputStream dat = new DataOutputStream(out);

        // save encrypted AES key and IV
        dat.writeInt(keySec.length);
        dat.write(keySec);
        dat.writeInt(iv.length);
        dat.write(iv);

        // save the encrypted file
        FileInputStream in = new FileInputStream(inFile);
        byte[] buf = new byte[1000];
        int r = -1;
        while( (r = in.read(buf)) != -1 ) {
            byte[] sec = aes.update(buf, 0, r);
            if (sec != null) dat.write(sec);
        }
        dat.write(aes.doFinal());
        dat.flush();
        dat.close();
        in.close();
    }


    /**
     * @param args
     */
    public static void main(String[] args) throws Exception {
        if (args.length != 4) {
            System.out.println("Usage: java Test (encrpyt|decrypt) keyFile inFile outFile");
            return;
        }
        KeyPair kp;
        File keyFile = new File(args[0]);
        if (!keyFile.canRead()) {
            kp = genKeys(keyFile);
        } else {
            kp = loadKeys(keyFile);
        }

        boolean isEnc = args[1].equalsIgnoreCase("encrypt");
        boolean isDec = args[1].equalsIgnoreCase("decrypt");
        File inFile = new File(args[2]);
        File outFile = new File(args[3]);
        if (!(isEnc || isDec) || !inFile.canRead()) {
            System.out.println("Usage: java Test (encrpyt|decrypt) keyFile inFile outFile");
            return;
        }

        if (isEnc) {
            encrypt(kp, inFile, outFile);
        } else {
            decrypt(kp, inFile, outFile);
        }
    }
}
于 2013-01-05T00:48:29.940 に答える
1

AES暗号でRSAキーを使用することはできません...

代わりにこれを使用してください：

 KeyGenerator keyGen = KeyGenerator.getInstance("AES", "BC");
 keyGen.init(256);
 Key key = keyGen.generateKey();

ここでコード例を見つけることができます。

于 2013-01-04T22:59:42.233 に答える