encrypt By RSA Public Key - Android java.security

Android examples for java.security:RSA

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Description

encrypt By RSA Public Key

Demo Code


//package com.java2s;

import java.security.interfaces.RSAPublicKey;

import javax.crypto.Cipher;

public class Main {

    public static String encryptByPublicKey(String data,
            RSAPublicKey publicKey) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        // ??/*w w w. java2s. c  o m*/
        int key_len = publicKey.getModulus().bitLength() / 8;
        // ? <= ??-11
        String[] datas = splitString(data, key_len - 11);
        String mi = "";
        // ???-11
        for (String s : datas) {
            mi += bcd2Str(cipher.doFinal(s.getBytes()));
        }
        return mi;
    }

    public static String[] splitString(String string, int len) {
        int x = string.length() / len;
        int y = string.length() % len;
        int z = 0;
        if (y != 0) {
            z = 1;
        }
        String[] strings = new String[x + z];
        String str = "";
        for (int i = 0; i < x + z; i++) {
            if (i == x + z - 1 && y != 0) {
                str = string.substring(i * len, i * len + y);
            } else {
                str = string.substring(i * len, i * len + len);
            }
            strings[i] = str;
        }
        return strings;
    }

    public static String bcd2Str(byte[] bytes) {
        char temp[] = new char[bytes.length * 2], val;

        for (int i = 0; i < bytes.length; i++) {
            val = (char) (((bytes[i] & 0xf0) >> 4) & 0x0f);
            temp[i * 2] = (char) (val > 9 ? val + 'A' - 10 : val + '0');

            val = (char) (bytes[i] & 0x0f);
            temp[i * 2 + 1] = (char) (val > 9 ? val + 'A' - 10 : val + '0');
        }
        return new String(temp);
    }
}

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