android rsa数据加密,Android中的RSA加密

Frank..

5

这里有一个如何做到的例子,但在实践中,

您不能仅使用RSA加密和解密整个文件.RSA算法只能加密单个块,并且执行整个文件的速度相当慢.

您可以使用3DES或AES加密文件,然后使用预期收件人的RSA公钥加密AES密钥.

一些代码:

public static void main(String[] args) throws Exception {

KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");

Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");

kpg.initialize(1024);

KeyPair keyPair = kpg.generateKeyPair();

PrivateKey privKey = keyPair.getPrivate();

PublicKey pubKey = keyPair.getPublic();

// Encrypt

cipher.init(Cipher.ENCRYPT_MODE, pubKey);

String test = "My test string";

String ciphertextFile = "ciphertextRSA.txt";

InputStream fis = new ByteArrayInputStream(test.getBytes("UTF-8"));

FileOutputStream fos = new FileOutputStream(ciphertextFile);

CipherOutputStream cos = new CipherOutputStream(fos, cipher);

byte[] block = new byte[32];

int i;

while ((i = fis.read(block)) != -1) {

cos.write(block, 0, i);

}

cos.close();

// Decrypt

String cleartextAgainFile = "cleartextAgainRSA.txt";

cipher.init(Cipher.DECRYPT_MODE, privKey);

fis = new FileInputStream(ciphertextFile);

CipherInputStream cis = new CipherInputStream(fis, cipher);

fos = new FileOutputStream(cleartextAgainFile);

while ((i = cis.read(block)) != -1) {

fos.write(block, 0, i);

}

fos.close();

}