如何創建或純Java打開libsodium兼容的密封箱

Question

libsodium提供了一個API來創建或打開此文檔一個密封箱https://download.libsodium.org/doc/public-key_cryptography/sealed_boxes.html

我怎樣才能實現在純Java一樣的，這樣可以讓我打開由libsodium創建的一個框或創建一個libsodium可以打開的框？

Answer 1

以下示例代碼可以創建並打開libsodium密封框。

它需要從https://github.com/InstantWebP2P/tweetnacl-java TweetNaclFast和Blake2b散列實現中，例如從https://github.com/alphazero/Blake2b

import java.security.GeneralSecurityException; 
import java.util.Arrays; 
import ove.crypto.digest.Blake2b; 
import com.iwebpp.crypto.TweetNaclFast; 


/** 
* Example how to open sealed boxes in pure java (libsodium sealed boxes according to 
* https://download.libsodium.org/doc/public-key_cryptography/sealed_boxes.html) 
* 
* Has a dependency on TweetNaclFast and Blake2B, for example 
* 
* https://github.com/alphazero/Blake2b 
* and 
* https://github.com/InstantWebP2P/tweetnacl-java 
* 
*/ 
public class SealedBoxUtility { 


public static final int crypto_box_NONCEBYTES = 24; 
public static final int crypto_box_PUBLICKEYBYTES = 32; 
public static final int crypto_box_MACBYTES = 16; 
public static final int crypto_box_SEALBYTES = (crypto_box_PUBLICKEYBYTES + crypto_box_MACBYTES); 

// libsodium 
// int crypto_box_seal(unsigned char *c, const unsigned char *m, 
//   unsigned long long mlen, const unsigned char *pk); 


/** 
* Encrypt in a sealed box 
* 
* @param clearText clear text 
* @param receiverPubKey receiver public key 
* @return encrypted message 
* @throws GeneralSecurityException 
*/ 
public static byte[] crypto_box_seal(byte[] clearText, byte[] receiverPubKey) throws GeneralSecurityException { 

    // create ephemeral keypair for sender 
    TweetNaclFast.Box.KeyPair ephkeypair = TweetNaclFast.Box.keyPair(); 
    // create nonce 
    byte[] nonce = crypto_box_seal_nonce(ephkeypair.getPublicKey(), receiverPubKey); 
    TweetNaclFast.Box box = new TweetNaclFast.Box(receiverPubKey, ephkeypair.getSecretKey()); 
    byte[] ciphertext = box.box(clearText, nonce); 
    if (ciphertext == null) throw new GeneralSecurityException("could not create box"); 

    byte[] sealedbox = new byte[ciphertext.length + crypto_box_PUBLICKEYBYTES]; 
    byte[] ephpubkey = ephkeypair.getPublicKey(); 
    for (int i = 0; i < crypto_box_PUBLICKEYBYTES; i ++) 
     sealedbox[i] = ephpubkey[i]; 

    for(int i = 0; i < ciphertext.length; i ++) 
     sealedbox[i+crypto_box_PUBLICKEYBYTES]=ciphertext[i]; 

    return sealedbox; 
} 

// libsodium: 
//  int 
//  crypto_box_seal_open(unsigned char *m, const unsigned char *c, 
//       unsigned long long clen, 
//       const unsigned char *pk, const unsigned char *sk) 

/** 
* Decrypt a sealed box 
* 
* @param c ciphertext 
* @param pk receiver public key 
* @param sk receiver secret key 
* @return decrypted message 
* @throws GeneralSecurityException 
*/ 
public static byte[] crypto_box_seal_open(byte[]c, byte[] pk, byte[]sk) throws GeneralSecurityException{ 
    if (c.length < crypto_box_SEALBYTES) throw new IllegalArgumentException("Ciphertext too short"); 

    byte[] pksender = Arrays.copyOfRange(c, 0, crypto_box_PUBLICKEYBYTES); 
    byte[] ciphertextwithmac = Arrays.copyOfRange(c, crypto_box_PUBLICKEYBYTES , c.length); 
    byte[] nonce = crypto_box_seal_nonce(pksender,pk); 

    TweetNaclFast.Box box = new TweetNaclFast.Box(pksender, sk); 
    byte[] cleartext = box.open(ciphertextwithmac, nonce); 
    if (cleartext == null) throw new GeneralSecurityException("could not open box"); 
    return cleartext; 
} 


/** 
* hash the combination of senderpk + mypk into nonce using blake2b hash 
* @param senderpk the senders public key 
* @param mypk my own public key 
* @return the nonce computed using Blake2b generic hash 
*/ 
public static byte[] crypto_box_seal_nonce(byte[] senderpk, byte[] mypk){ 
// C source ported from libsodium 
//  crypto_generichash_state st; 
// 
//  crypto_generichash_init(&st, NULL, 0U, crypto_box_NONCEBYTES); 
//  crypto_generichash_update(&st, pk1, crypto_box_PUBLICKEYBYTES); 
//  crypto_generichash_update(&st, pk2, crypto_box_PUBLICKEYBYTES); 
//  crypto_generichash_final(&st, nonce, crypto_box_NONCEBYTES); 
// 
//  return 0; 
    final Blake2b blake2b = Blake2b.Digest.newInstance(crypto_box_NONCEBYTES); 
    blake2b.update(senderpk); 
    blake2b.update(mypk); 
    byte[] nonce = blake2b.digest(); 
    if (nonce == null || nonce.length!=crypto_box_NONCEBYTES) throw new IllegalArgumentException("Blake2b hashing failed"); 
    return nonce; 


} 

} 

所述一個