在java中加密和解密一个字符串 [英] Encrypt and decrypt a String in java

问题描述

我是密码学的新手.我想学习如何加密和解密文件中的文本……当我参考 net 中的相关文章时.我怀疑当对同一文本进行多次加密时，单个文本的加密文本是否相同?谁能解开我的疑惑?

I am new to cryptography. I wish to learn how to encrypt and decrypt the text in a file... when I refer the related articles in net. I had a doubt that whether the encrypted text will be same for single text when encryption is done multiple times on the same text? Can anyone please clear my doubt?

推荐答案

    public String encrypt(String str) {
        try {
            // Encode the string into bytes using utf-8
            byte[] utf8 = str.getBytes("UTF8");

            // Encrypt
            byte[] enc = ecipher.doFinal(utf8);

            // Encode bytes to base64 to get a string
            return new sun.misc.BASE64Encoder().encode(enc);
        } catch (javax.crypto.BadPaddingException e) {
        } catch (IllegalBlockSizeException e) {
        } catch (UnsupportedEncodingException e) {
        } catch (java.io.IOException e) {
        }
        return null;
    }

    public String decrypt(String str) {
        try {
            // Decode base64 to get bytes
            byte[] dec = new sun.misc.BASE64Decoder().decodeBuffer(str);

            // Decrypt
            byte[] utf8 = dcipher.doFinal(dec);

            // Decode using utf-8
            return new String(utf8, "UTF8");
        } catch (javax.crypto.BadPaddingException e) {
        } catch (IllegalBlockSizeException e) {
        } catch (UnsupportedEncodingException e) {
        } catch (java.io.IOException e) {
        }
        return null;
    }
}

以下是使用该类的示例:

Here's an example that uses the class:

try {
    // Generate a temporary key. In practice, you would save this key.
    // See also Encrypting with DES Using a Pass Phrase.
    SecretKey key = KeyGenerator.getInstance("DES").generateKey();

    // Create encrypter/decrypter class
    DesEncrypter encrypter = new DesEncrypter(key);

    // Encrypt
    String encrypted = encrypter.encrypt("Don't tell anybody!");

    // Decrypt
    String decrypted = encrypter.decrypt(encrypted);
} catch (Exception e) {
}

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