微信小程序rsa分段加密

前段时间公司要开发app配套的微信小程序，而app的接口是使用rsa加密的。

找了很多资料，发现rsa的秘钥长度限制了加密时明文的长度。又不能重新写一套接口。纠结了三天，终于集合各方资料弄出了一个微信小程序试用的rsa分段加密程序.

详见rsa.js
demo下载地址http://download.csdn.net/detail/u011731544/9908595

里面有好几种加密
这个是导出的签名方法，注释的两行是不分段的。不过我测试过，分段的encryptLong也可以兼容不分段的encrypt。

function sign(text) {   //var encStr = encrypt_rsa.encrypt(text);//不分段的加密  //encStr = hex2b64(encStr);//不分段加密需要base64一下  var encStr = encrypt_rsa.encryptLong(text);//分段加密  console.log(text)  console.log("加密结果：" + encStr)  return encStr;}

配套的java端解密的代码如下：

import java.io.ByteArrayInputStream;import java.io.ByteArrayOutputStream;import java.io.InputStream;import java.security.KeyFactory;import java.security.PrivateKey;import java.security.interfaces.RSAPublicKey;import java.security.spec.PKCS8EncodedKeySpec;import java.security.spec.X509EncodedKeySpec;import javax.crypto.Cipher;import org.apache.commons.codec.binary.Base64;/** * RSA算法 *  */public class RSA {    /**     * SIGN_ALGORITHMS     */    public static final String SIGN_ALGORITHMS = "SHA1WithRSA";    /**     * 公钥加密     *      * @param content     * @param public_key     * @return     * @throws Exception     */    public static String signWithPublicKey(String content, String public_key) throws Exception {        byte[] buffer = Base64.decodeBase64(public_key);        KeyFactory keyFactory = KeyFactory.getInstance("RSA");        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer);        RSAPublicKey publicKey = (RSAPublicKey) keyFactory.generatePublic(keySpec);        Cipher cipher = Cipher.getInstance(publicKey.getAlgorithm());        cipher.init(1, publicKey);        byte[] data = content.getBytes("utf-8");        int inputLen = data.length;        ByteArrayOutputStream out = new ByteArrayOutputStream();        int offSet = 0;        int key_len = publicKey.getModulus().bitLength() / 8 - 11;        for (int i = 0; inputLen - offSet > 0; offSet = i * key_len) {            byte[] cache;            if (inputLen - offSet > key_len) {                cache = cipher.doFinal(data, offSet, key_len);            } else {                cache = cipher.doFinal(data, offSet, inputLen - offSet);            }            out.write(cache, 0, cache.length);            ++i;        }        byte[] encryptedData = out.toByteArray();        out.close();        return new String(Base64.encodeBase64(encryptedData));    }    public static PrivateKey getPrivateKey(String key) throws Exception {        byte[] keyBytes;        keyBytes = Base64.decodeBase64(key);        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);        KeyFactory keyFactory = KeyFactory.getInstance("RSA");        PrivateKey privateKey = keyFactory.generatePrivate(keySpec);        return privateKey;    }    /**     * 私钥解密     *      * @param content     * @param private_key     * @param input_charset     * @return     * @throws Exception     */    public static String decryptByPrivateKey(String content, String private_key, String input_charset)            throws Exception {        PrivateKey prikey = getPrivateKey(private_key);        Cipher cipher = Cipher.getInstance("RSA");        cipher.init(Cipher.DECRYPT_MODE, prikey);        InputStream ins = new ByteArrayInputStream(Base64.decodeBase64(content));        ByteArrayOutputStream writer = new ByteArrayOutputStream();        // rsa解密的字节大小最多是128，将需要解密的内容，按128位拆开解密        byte[] buf = new byte[128];        int bufl;        while ((bufl = ins.read(buf)) != -1) {            byte[] block = null;            if (buf.length == bufl) {                block = buf;            } else {                block = new byte[bufl];                for (int i = 0; i < bufl; i++) {                    block[i] = buf[i];                }            }            writer.write(cipher.doFinal(block));        }        return new String(writer.toByteArray(), input_charset);    }}

参考资料http://download.csdn.net/detail/yubin2009m/9862378
http://blog.csdn.net/ufo00001/article/details/72822907