RSA加密算法

-------RSAUtils.java----------------


package my.tools.security;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.math.BigInteger;
import java.security.KeyPair;
import java.security.KeyFactory;
import java.security.KeyPairGenerator;
import java.security.Provider;
import java.security.PublicKey;
import java.security.PrivateKey;
import java.security.SecureRandom;
import java.security.NoSuchAlgorithmException;
import java.security.InvalidParameterException;
import java.security.interfaces.RSAPublicKey;
import java.security.interfaces.RSAPrivateKey;
import java.security.spec.RSAPublicKeySpec;
import java.security.spec.RSAPrivateKeySpec;
import java.security.spec.InvalidKeySpecException;

import javax.crypto.Cipher;

import org.apache.commons.io.IOUtils;
import org.apache.commons.io.FileUtils;
import org.apache.commons.codec.DecoderException;
import org.apache.commons.codec.binary.Hex;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.apache.commons.lang.StringUtils;
import org.apache.commons.lang.time.DateFormatUtils;

/**
 * RSA算法加密/解密工具类。
 * 
 * @author fuchun
 * @version 1.0.0, 2010-05-05
 */
public abstract class RSAUtils {

    private static final Logger LOGGER = LoggerFactory.getLogger(RSAUtils.class);

    /** 算法名称 */
    private static final String ALGORITHOM = "RSA";
    /**保存生成的密钥对的文件名称。 */
    private static final String RSA_PAIR_FILENAME = "/__RSA_PAIR.txt";
    /** 密钥大小 */
    private static final int KEY_SIZE = 1024;
    /** 默认的安全服务提供者 */
    private static final Provider DEFAULT_PROVIDER = new BouncyCastleProvider();

    private static KeyPairGenerator keyPairGen = null;
    private static KeyFactory keyFactory = null;
    /** 缓存的密钥对。 */
    private static KeyPair oneKeyPair = null;

    private static File rsaPairFile = null;

    static {
        try {
            keyPairGen = KeyPairGenerator.getInstance(ALGORITHOM, DEFAULT_PROVIDER);
            keyFactory = KeyFactory.getInstance(ALGORITHOM, DEFAULT_PROVIDER);
        } catch (NoSuchAlgorithmException ex) {
            LOGGER.error(ex.getMessage());
        }
        rsaPairFile = new File(getRSAPairFilePath());
    }

    private RSAUtils() {
    }

    /**
     * 生成并返回RSA密钥对。
     */
    private static synchronized KeyPair generateKeyPair() {
        try {
            keyPairGen.initialize(KEY_SIZE, new SecureRandom(DateFormatUtils.format("yyyyMMdd").getBytes()));
            oneKeyPair = keyPairGen.generateKeyPair();
            saveKeyPair(oneKeyPair);
            return oneKeyPair;
        } catch (InvalidParameterException ex) {
            LOGGER.error("KeyPairGenerator does not support a key length of " + KEY_SIZE + ".", ex);
        } catch (NullPointerException ex) {
            LOGGER.error("RSAUtils#KEY_PAIR_GEN is null, can not generate KeyPairGenerator instance.",
                    ex);
        }
        return null;
    }

    /**
     * 返回生成/读取的密钥对文件的路径。
     */
    private static String getRSAPairFilePath() {
        String urlPath = RSAUtils.class.getResource("/").getPath();
        return (new File(urlPath).getParent() + RSA_PAIR_FILENAME);
    }

    /**
     * 若需要创建新的密钥对文件，则返回 {@code true}，否则 {@code false}。
     */
    private static boolean isCreateKeyPairFile() {
        // 是否创建新的密钥对文件
        boolean createNewKeyPair = false;
        if (!rsaPairFile.exists() || rsaPairFile.isDirectory()) {
            createNewKeyPair = true;
        }
        return createNewKeyPair;
    }

    /**
     * 将指定的RSA密钥对以文件形式保存。
     * 
     * @param keyPair 要保存的密钥对。
     */
    private static void saveKeyPair(KeyPair keyPair) {
        FileOutputStream fos = null;
        ObjectOutputStream oos = null;
        try {
            fos = FileUtils.openOutputStream(rsaPairFile);
            oos = new ObjectOutputStream(fos);
            oos.writeObject(keyPair);
        } catch (Exception ex) {
            ex.printStackTrace();
        } finally {
        	IOUtils.closeQuietly(oos);
            IOUtils.closeQuietly(fos);
        }
    }

    /**
     * 返回RSA密钥对。
     */
    public static KeyPair getKeyPair() {
        // 首先判断是否需要重新生成新的密钥对文件
        if (isCreateKeyPairFile()) {
            // 直接强制生成密钥对文件，并存入缓存。
            return generateKeyPair();
        }
        if (oneKeyPair != null) {
            return oneKeyPair;
        }
        return readKeyPair();
    }
    
    // 同步读出保存的密钥对
    private static KeyPair readKeyPair() {
        FileInputStream fis = null;
        ObjectInputStream ois = null;
        try {
            fis = FileUtils.openInputStream(rsaPairFile);
            ois = new ObjectInputStream(fis);
            oneKeyPair = (KeyPair) ois.readObject();
            return oneKeyPair;
        } catch (Exception ex) {
            ex.printStackTrace();
        } finally {
            IOUtils.closeQuietly(ois);
            IOUtils.closeQuietly(fis);
        }
        return null;
    }

    /**
     * 根据给定的系数和专用指数构造一个RSA专用的公钥对象。
     * 
     * @param modulus 系数。
     * @param publicExponent 专用指数。
     * @return RSA专用公钥对象。
     */
    public static RSAPublicKey generateRSAPublicKey(byte[] modulus, byte[] publicExponent) {
        RSAPublicKeySpec publicKeySpec = new RSAPublicKeySpec(new BigInteger(modulus),
                new BigInteger(publicExponent));
        try {
            return (RSAPublicKey) keyFactory.generatePublic(publicKeySpec);
        } catch (InvalidKeySpecException ex) {
            LOGGER.error("RSAPublicKeySpec is unavailable.", ex);
        } catch (NullPointerException ex) {
            LOGGER.error("RSAUtils#KEY_FACTORY is null, can not generate KeyFactory instance.", ex);
        }
        return null;
    }

    /**
     * 根据给定的系数和专用指数构造一个RSA专用的私钥对象。
     * 
     * @param modulus 系数。
     * @param privateExponent 专用指数。
     * @return RSA专用私钥对象。
     */
    public static RSAPrivateKey generateRSAPrivateKey(byte[] modulus, byte[] privateExponent) {
        RSAPrivateKeySpec privateKeySpec = new RSAPrivateKeySpec(new BigInteger(modulus),
                new BigInteger(privateExponent));
        try {
            return (RSAPrivateKey) keyFactory.generatePrivate(privateKeySpec);
        } catch (InvalidKeySpecException ex) {
            LOGGER.error("RSAPrivateKeySpec is unavailable.", ex);
        } catch (NullPointerException ex) {
            LOGGER.error("RSAUtils#KEY_FACTORY is null, can not generate KeyFactory instance.", ex);
        }
        return null;
    }
    
    /**
     * 根据给定的16进制系数和专用指数字符串构造一个RSA专用的私钥对象。
     * 
     * @param modulus 系数。
     * @param privateExponent 专用指数。
     * @return RSA专用私钥对象。
     */
    public static RSAPrivateKey getRSAPrivateKey(String hexModulus, String hexPrivateExponent) {
        if(StringUtils.isBlank(hexModulus) || StringUtils.isBlank(hexPrivateExponent)) {
            if(LOGGER.isDebugEnabled()) {
                LOGGER.debug("hexModulus and hexPrivateExponent cannot be empty. RSAPrivateKey value is null to return.");
            }
            return null;
        }
        byte[] modulus = null;
        byte[] privateExponent = null;
        try {
            modulus = Hex.decodeHex(hexModulus.toCharArray());
            privateExponent = Hex.decodeHex(hexPrivateExponent.toCharArray());
        } catch(DecoderException ex) {
            LOGGER.error("hexModulus or hexPrivateExponent value is invalid. return null(RSAPrivateKey).");
        }
        if(modulus != null && privateExponent != null) {
            return generateRSAPrivateKey(modulus, privateExponent);
        }
        return null;
    }
    
    /**
     * 根据给定的16进制系数和专用指数字符串构造一个RSA专用的公钥对象。
     * 
     * @param modulus 系数。
     * @param publicExponent 专用指数。
     * @return RSA专用公钥对象。
     */
    public static RSAPublicKey getRSAPublidKey(String hexModulus, String hexPublicExponent) {
        if(StringUtils.isBlank(hexModulus) || StringUtils.isBlank(hexPublicExponent)) {
            if(LOGGER.isDebugEnabled()) {
                LOGGER.debug("hexModulus and hexPublicExponent cannot be empty. return null(RSAPublicKey).");
            }
            return null;
        }
        byte[] modulus = null;
        byte[] publicExponent = null;
        try {
            modulus = Hex.decodeHex(hexModulus.toCharArray());
            publicExponent = Hex.decodeHex(hexPublicExponent.toCharArray());
        } catch(DecoderException ex) {
            LOGGER.error("hexModulus or hexPublicExponent value is invalid. return null(RSAPublicKey).");
        }
        if(modulus != null && publicExponent != null) {
            return generateRSAPublicKey(modulus, publicExponent);
        }
        return null;
    }

    /**
     * 使用指定的公钥加密数据。
     * 
     * @param publicKey 给定的公钥。
     * @param data 要加密的数据。
     * @return 加密后的数据。
     */
    public static byte[] encrypt(PublicKey publicKey, byte[] data) throws Exception {
        Cipher ci = Cipher.getInstance(ALGORITHOM, DEFAULT_PROVIDER);
        ci.init(Cipher.ENCRYPT_MODE, publicKey);
        return ci.doFinal(data);
    }

    /**
     * 使用指定的私钥解密数据。
     * 
     * @param privateKey 给定的私钥。
     * @param data 要解密的数据。
     * @return 原数据。
     */
    public static byte[] decrypt(PrivateKey privateKey, byte[] data) throws Exception {
        Cipher ci = Cipher.getInstance(ALGORITHOM, DEFAULT_PROVIDER);
        ci.init(Cipher.DECRYPT_MODE, privateKey);
        return ci.doFinal(data);
    }

    /**
     * 使用给定的公钥加密给定的字符串。
     * <p />
     * 若 {@code publicKey} 为 {@code null}，或者 {@code plaintext} 为 {@code null} 则返回 {@code
     * null}。
     * 
     * @param publicKey 给定的公钥。
     * @param plaintext 字符串。
     * @return 给定字符串的密文。
     */
    public static String encryptString(PublicKey publicKey, String plaintext) {
        if (publicKey == null || plaintext == null) {
            return null;
        }
        byte[] data = plaintext.getBytes();
        try {
            byte[] en_data = encrypt(publicKey, data);
            return new String(Hex.encodeHex(en_data));
        } catch (Exception ex) {
            LOGGER.error(ex.getCause().getMessage());
        }
        return null;
    }
    
    /**
     * 使用默认的公钥加密给定的字符串。
     * <p />
     * 若{@code plaintext} 为 {@code null} 则返回 {@code null}。
     * 
     * @param plaintext 字符串。
     * @return 给定字符串的密文。
     */
    public static String encryptString(String plaintext) {
        if(plaintext == null) {
            return null;
        }
        byte[] data = plaintext.getBytes();
        KeyPair keyPair = getKeyPair();
        try {
            byte[] en_data = encrypt((RSAPublicKey)keyPair.getPublic(), data);
            return new String(Hex.encodeHex(en_data));
        } catch(NullPointerException ex) {
            LOGGER.error("keyPair cannot be null.");
        } catch(Exception ex) {
            LOGGER.error(ex.getCause().getMessage());
        }
        return null;

    }

    /**
     * 使用给定的私钥解密给定的字符串。
     * <p />
     * 若私钥为 {@code null}，或者 {@code encrypttext} 为 {@code null}或空字符串则返回 {@code null}。
     * 私钥不匹配时，返回 {@code null}。
     * 
     * @param privateKey 给定的私钥。
     * @param encrypttext 密文。
     * @return 原文字符串。
     */
    public static String decryptString(PrivateKey privateKey, String encrypttext) {
        if (privateKey == null || StringUtils.isBlank(encrypttext)) {
            return null;
        }
        try {
            byte[] en_data = Hex.decodeHex(encrypttext.toCharArray());
            byte[] data = decrypt(privateKey, en_data);
            return new String(data);
        } catch (Exception ex) {
            LOGGER.error(String.format("\"%s\" Decryption failed. Cause: %s", encrypttext, ex.getCause().getMessage()));
        }
        return null;
    }
    
    /**
     * 使用默认的私钥解密给定的字符串。
     * <p />
     * 若{@code encrypttext} 为 {@code null}或空字符串则返回 {@code null}。
     * 私钥不匹配时，返回 {@code null}。
     * 
     * @param encrypttext 密文。
     * @return 原文字符串。
     */
    public static String decryptString(String encrypttext) {
        if(StringUtils.isBlank(encrypttext)) {
            return null;
        }
        KeyPair keyPair = getKeyPair();
        try {
            byte[] en_data = Hex.decodeHex(encrypttext.toCharArray());
            byte[] data = decrypt((RSAPrivateKey)keyPair.getPrivate(), en_data);
            return new String(data);
        } catch(NullPointerException ex) {
            LOGGER.error("keyPair cannot be null.");
        } catch (Exception ex) {
            LOGGER.error(String.format("\"%s\" Decryption failed. Cause: %s", encrypttext, ex.getMessage()));
        }
        return null;
    }
    
    /**
     * 使用默认的私钥解密由JS加密（使用此类提供的公钥加密）的字符串。
     * 
     * @param encrypttext 密文。
     * @return {@code encrypttext} 的原文字符串。
     */
    public static String decryptStringByJs(String encrypttext) {
        String text = decryptString(encrypttext);
        if(text == null) {
            return null;
        }
        return StringUtils.reverse(text);
    }
    
    /** 返回已初始化的默认的公钥。*/
    public static RSAPublicKey getDefaultPublicKey() {
        KeyPair keyPair = getKeyPair();
        if(keyPair != null) {
            return (RSAPublicKey)keyPair.getPublic();
        }
        return null;
    }
    
    /** 返回已初始化的默认的私钥。*/
    public static RSAPrivateKey getDefaultPrivateKey() {
        KeyPair keyPair = getKeyPair();
        if(keyPair != null) {
            return (RSAPrivateKey)keyPair.getPrivate();
        }
        return null;
    }
}


文档：

// Struts2 Action方法中：

// 将公钥的 modulus 和 exponent 传给页面。

// Hex -> apache commons-codec

RSAPublicKey publicKey = RSAUtils.getDefaultPublicKey();

ActionContext.getContext().put("modulus", new String(Hex.encodeHex(publicKey.getModulus().toByteArray())));

ActionContext.getContext().put("exponent", new String(Hex.encodeHex(publicKey.getPublicExponent().toByteArray())));

 

// 页面里，Javascript对明文进行加密：

var modulus = $('#hid_modulus').val(), exponent = $('#hid_exponent').val();

var key = RSAUtils.getKeyPair(exponent, '', modulus);

pwd1 = RSAUtils.encryptedString(key, pwd1);

pwd2 = RSAUtils.encryptedString(key, pwd2);

13

14 // 服务器端，使用RSAUtils工具类对密文进行解密

15 RSAUtils.decryptStringByJs(password1);

所需的jar包 及 js文件 ：

                     

 

 

-------------security.js-------------------

/*
* RSA, a suite of routines for performing RSA public-key computations in JavaScript.
* Copyright 1998-2005 David Shapiro.
* Dave Shapiro
* dave@ohdave.com
* changed by Fuchun, 2010-05-06
* fcrpg2005@gmail.com
*/

(function($w) {

if(typeof $w.RSAUtils === 'undefined')
var RSAUtils = $w.RSAUtils = {};

var biRadixBase = 2;
var biRadixBits = 16;
var bitsPerDigit = biRadixBits;
var biRadix = 1 << 16; // = 2^16 = 65536
var biHalfRadix = biRadix >>> 1;
var biRadixSquared = biRadix * biRadix;
var maxDigitVal = biRadix - 1;
var maxInteger = 9999999999999998;

//maxDigits:
//Change this to accommodate your largest number size. Use setMaxDigits()
//to change it!
//
//In general, if you're working with numbers of size N bits, you'll need 2*N
//bits of storage. Each digit holds 16 bits. So, a 1024-bit key will need
//
//1024 * 2 / 16 = 128 digits of storage.
//
var maxDigits;
var ZERO_ARRAY;
var bigZero, bigOne;

var BigInt = $w.BigInt = function(flag) {
if (typeof flag == "boolean" && flag == true) {
this.digits = null;
} else {
this.digits = ZERO_ARRAY.slice(0);
}
this.isNeg = false;
};

RSAUtils.setMaxDigits = function(value) {
maxDigits = value;
ZERO_ARRAY = new Array(maxDigits);
for (var iza = 0; iza < ZERO_ARRAY.length; iza++) ZERO_ARRAY[iza] = 0;
bigZero = new BigInt();
bigOne = new BigInt();
bigOne.digits[0] = 1;
};
RSAUtils.setMaxDigits(20);

//The maximum number of digits in base 10 you can convert to an
//integer without JavaScript throwing up on you.
var dpl10 = 15;

RSAUtils.biFromNumber = function(i) {
var result = new BigInt();
result.isNeg = i < 0;
i = Math.abs(i);
var j = 0;
while (i > 0) {
result.digits[j++] = i & maxDigitVal;
i = Math.floor(i / biRadix);
}
return result;
};

//lr10 = 10 ^ dpl10
var lr10 = RSAUtils.biFromNumber(1000000000000000);

RSAUtils.biFromDecimal = function(s) {
var isNeg = s.charAt(0) == '-';
var i = isNeg ? 1 : 0;
var result;
// Skip leading zeros.
while (i < s.length && s.charAt(i) == '0') ++i;
if (i == s.length) {
result = new BigInt();
}
else {
var digitCount = s.length - i;
var fgl = digitCount % dpl10;
if (fgl == 0) fgl = dpl10;
result = RSAUtils.biFromNumber(Number(s.substr(i, fgl)));
i += fgl;
while (i < s.length) {
result = RSAUtils.biAdd(RSAUtils.biMultiply(result, lr10),
RSAUtils.biFromNumber(Number(s.substr(i, dpl10))));
i += dpl10;
}
result.isNeg = isNeg;
}
return result;
};

RSAUtils.biCopy = function(bi) {
var result = new BigInt(true);
result.digits = bi.digits.slice(0);
result.isNeg = bi.isNeg;
return result;
};

RSAUtils.reverseStr = function(s) {
var result = "";
for (var i = s.length - 1; i > -1; --i) {
result += s.charAt(i);
}
return result;
};

var hexatrigesimalToChar = [
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',
'u', 'v', 'w', 'x', 'y', 'z'
];

RSAUtils.biToString = function(x, radix) { // 2 <= radix <= 36
var b = new BigInt();
b.digits[0] = radix;
var qr = RSAUtils.biDivideModulo(x, b);
var result = hexatrigesimalToChar[qr[1].digits[0]];
while (RSAUtils.biCompare(qr[0], bigZero) == 1) {
qr = RSAUtils.biDivideModulo(qr[0], b);
digit = qr[1].digits[0];
result += hexatrigesimalToChar[qr[1].digits[0]];
}
return (x.isNeg ? "-" : "") + RSAUtils.reverseStr(result);
};

RSAUtils.biToDecimal = function(x) {
var b = new BigInt();
b.digits[0] = 10;
var qr = RSAUtils.biDivideModulo(x, b);
var result = String(qr[1].digits[0]);
while (RSAUtils.biCompare(qr[0], bigZero) == 1) {
qr = RSAUtils.biDivideModulo(qr[0], b);
result += String(qr[1].digits[0]);
}
return (x.isNeg ? "-" : "") + RSAUtils.reverseStr(result);
};

var hexToChar = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'a', 'b', 'c', 'd', 'e', 'f'];

RSAUtils.digitToHex = function(n) {
var mask = 0xf;
var result = "";
for (i = 0; i < 4; ++i) {
result += hexToChar[n & mask];
n >>>= 4;
}
return RSAUtils.reverseStr(result);
};

RSAUtils.biToHex = function(x) {
var result = "";
var n = RSAUtils.biHighIndex(x);
for (var i = RSAUtils.biHighIndex(x); i > -1; --i) {
result += RSAUtils.digitToHex(x.digits[i]);
}
return result;
};

RSAUtils.charToHex = function(c) {
var ZERO = 48;
var NINE = ZERO + 9;
var littleA = 97;
var littleZ = littleA + 25;
var bigA = 65;
var bigZ = 65 + 25;
var result;

if (c >= ZERO && c <= NINE) {
result = c - ZERO;
} else if (c >= bigA && c <= bigZ) {
result = 10 + c - bigA;
} else if (c >= littleA && c <= littleZ) {
result = 10 + c - littleA;
} else {
result = 0;
}
return result;
};

RSAUtils.hexToDigit = function(s) {
var result = 0;
var sl = Math.min(s.length, 4);
for (var i = 0; i < sl; ++i) {
result <<= 4;
result |= RSAUtils.charToHex(s.charCodeAt(i));
}
return result;
};

RSAUtils.biFromHex = function(s) {
var result = new BigInt();
var sl = s.length;
for (var i = sl, j = 0; i > 0; i -= 4, ++j) {
result.digits[j] = RSAUtils.hexToDigit(s.substr(Math.max(i - 4, 0), Math.min(i, 4)));
}
return result;
};

RSAUtils.biFromString = function(s, radix) {
var isNeg = s.charAt(0) == '-';
var istop = isNeg ? 1 : 0;
var result = new BigInt();
var place = new BigInt();
place.digits[0] = 1; // radix^0
for (var i = s.length - 1; i >= istop; i--) {
var c = s.charCodeAt(i);
var digit = RSAUtils.charToHex(c);
var biDigit = RSAUtils.biMultiplyDigit(place, digit);
result = RSAUtils.biAdd(result, biDigit);
place = RSAUtils.biMultiplyDigit(place, radix);
}
result.isNeg = isNeg;
return result;
};

RSAUtils.biDump = function(b) {
return (b.isNeg ? "-" : "") + b.digits.join(" ");
};

RSAUtils.biAdd = function(x, y) {
var result;

if (x.isNeg != y.isNeg) {
y.isNeg = !y.isNeg;
result = RSAUtils.biSubtract(x, y);
y.isNeg = !y.isNeg;
}
else {
result = new BigInt();
var c = 0;
var n;
for (var i = 0; i < x.digits.length; ++i) {
n = x.digits[i] + y.digits[i] + c;
result.digits[i] = n % biRadix;
c = Number(n >= biRadix);
}
result.isNeg = x.isNeg;
}
return result;
};

RSAUtils.biSubtract = function(x, y) {
var result;
if (x.isNeg != y.isNeg) {
y.isNeg = !y.isNeg;
result = RSAUtils.biAdd(x, y);
y.isNeg = !y.isNeg;
} else {
result = new BigInt();
var n, c;
c = 0;
for (var i = 0; i < x.digits.length; ++i) {
n = x.digits[i] - y.digits[i] + c;
result.digits[i] = n % biRadix;
// Stupid non-conforming modulus operation.
if (result.digits[i] < 0) result.digits[i] += biRadix;
c = 0 - Number(n < 0);
}
// Fix up the negative sign, if any.
if (c == -1) {
c = 0;
for (var i = 0; i < x.digits.length; ++i) {
n = 0 - result.digits[i] + c;
result.digits[i] = n % biRadix;
// Stupid non-conforming modulus operation.
if (result.digits[i] < 0) result.digits[i] += biRadix;
c = 0 - Number(n < 0);
}
// Result is opposite sign of arguments.
result.isNeg = !x.isNeg;
} else {
// Result is same sign.
result.isNeg = x.isNeg;
}
}
return result;
};

RSAUtils.biHighIndex = function(x) {
var result = x.digits.length - 1;
while (result > 0 && x.digits[result] == 0) --result;
return result;
};

RSAUtils.biNumBits = function(x) {
var n = RSAUtils.biHighIndex(x);
var d = x.digits[n];
var m = (n + 1) * bitsPerDigit;
var result;
for (result = m; result > m - bitsPerDigit; --result) {
if ((d & 0x8000) != 0) break;
d <<= 1;
}
return result;
};

RSAUtils.biMultiply = function(x, y) {
var result = new BigInt();
var c;
var n = RSAUtils.biHighIndex(x);
var t = RSAUtils.biHighIndex(y);
var u, uv, k;

for (var i = 0; i <= t; ++i) {
c = 0;
k = i;
for (j = 0; j <= n; ++j, ++k) {
uv = result.digits[k] + x.digits[j] * y.digits[i] + c;
result.digits[k] = uv & maxDigitVal;
c = uv >>> biRadixBits;
//c = Math.floor(uv / biRadix);
}
result.digits[i + n + 1] = c;
}
// Someone give me a logical xor, please.
result.isNeg = x.isNeg != y.isNeg;
return result;
};

RSAUtils.biMultiplyDigit = function(x, y) {
var n, c, uv;

result = new BigInt();
n = RSAUtils.biHighIndex(x);
c = 0;
for (var j = 0; j <= n; ++j) {
uv = result.digits[j] + x.digits[j] * y + c;
result.digits[j] = uv & maxDigitVal;
c = uv >>> biRadixBits;
//c = Math.floor(uv / biRadix);
}
result.digits[1 + n] = c;
return result;
};

RSAUtils.arrayCopy = function(src, srcStart, dest, destStart, n) {
var m = Math.min(srcStart + n, src.length);
for (var i = srcStart, j = destStart; i < m; ++i, ++j) {
dest[j] = src[i];
}
};

var highBitMasks = [0x0000, 0x8000, 0xC000, 0xE000, 0xF000, 0xF800,
0xFC00, 0xFE00, 0xFF00, 0xFF80, 0xFFC0, 0xFFE0,
0xFFF0, 0xFFF8, 0xFFFC, 0xFFFE, 0xFFFF];

RSAUtils.biShiftLeft = function(x, n) {
var digitCount = Math.floor(n / bitsPerDigit);
var result = new BigInt();
RSAUtils.arrayCopy(x.digits, 0, result.digits, digitCount,
result.digits.length - digitCount);
var bits = n % bitsPerDigit;
var rightBits = bitsPerDigit - bits;
for (var i = result.digits.length - 1, i1 = i - 1; i > 0; --i, --i1) {
result.digits[i] = ((result.digits[i] << bits) & maxDigitVal) |
((result.digits[i1] & highBitMasks[bits]) >>>
(rightBits));
}
result.digits[0] = ((result.digits[i] << bits) & maxDigitVal);
result.isNeg = x.isNeg;
return result;
};

var lowBitMasks = [0x0000, 0x0001, 0x0003, 0x0007, 0x000F, 0x001F,
0x003F, 0x007F, 0x00FF, 0x01FF, 0x03FF, 0x07FF,
0x0FFF, 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF];

RSAUtils.biShiftRight = function(x, n) {
var digitCount = Math.floor(n / bitsPerDigit);
var result = new BigInt();
RSAUtils.arrayCopy(x.digits, digitCount, result.digits, 0,
x.digits.length - digitCount);
var bits = n % bitsPerDigit;
var leftBits = bitsPerDigit - bits;
for (var i = 0, i1 = i + 1; i < result.digits.length - 1; ++i, ++i1) {
result.digits[i] = (result.digits[i] >>> bits) |
((result.digits[i1] & lowBitMasks[bits]) << leftBits);
}
result.digits[result.digits.length - 1] >>>= bits;
result.isNeg = x.isNeg;
return result;
};

RSAUtils.biMultiplyByRadixPower = function(x, n) {
var result = new BigInt();
RSAUtils.arrayCopy(x.digits, 0, result.digits, n, result.digits.length - n);
return result;
};

RSAUtils.biDivideByRadixPower = function(x, n) {
var result = new BigInt();
RSAUtils.arrayCopy(x.digits, n, result.digits, 0, result.digits.length - n);
return result;
};

RSAUtils.biModuloByRadixPower = function(x, n) {
var result = new BigInt();
RSAUtils.arrayCopy(x.digits, 0, result.digits, 0, n);
return result;
};

RSAUtils.biCompare = function(x, y) {
if (x.isNeg != y.isNeg) {
return 1 - 2 * Number(x.isNeg);
}
for (var i = x.digits.length - 1; i >= 0; --i) {
if (x.digits[i] != y.digits[i]) {
if (x.isNeg) {
return 1 - 2 * Number(x.digits[i] > y.digits[i]);
} else {
return 1 - 2 * Number(x.digits[i] < y.digits[i]);
}
}
}
return 0;
};

RSAUtils.biDivideModulo = function(x, y) {
var nb = RSAUtils.biNumBits(x);
var tb = RSAUtils.biNumBits(y);
var origYIsNeg = y.isNeg;
var q, r;
if (nb < tb) {
// |x| < |y|
if (x.isNeg) {
q = RSAUtils.biCopy(bigOne);
q.isNeg = !y.isNeg;
x.isNeg = false;
y.isNeg = false;
r = biSubtract(y, x);
// Restore signs, 'cause they're references.
x.isNeg = true;
y.isNeg = origYIsNeg;
} else {
q = new BigInt();
r = RSAUtils.biCopy(x);
}
return [q, r];
}

q = new BigInt();
r = x;

// Normalize Y.
var t = Math.ceil(tb / bitsPerDigit) - 1;
var lambda = 0;
while (y.digits[t] < biHalfRadix) {
y = RSAUtils.biShiftLeft(y, 1);
++lambda;
++tb;
t = Math.ceil(tb / bitsPerDigit) - 1;
}
// Shift r over to keep the quotient constant. We'll shift the
// remainder back at the end.
r = RSAUtils.biShiftLeft(r, lambda);
nb += lambda; // Update the bit count for x.
var n = Math.ceil(nb / bitsPerDigit) - 1;

var b = RSAUtils.biMultiplyByRadixPower(y, n - t);
while (RSAUtils.biCompare(r, b) != -1) {
++q.digits[n - t];
r = RSAUtils.biSubtract(r, b);
}
for (var i = n; i > t; --i) {
var ri = (i >= r.digits.length) ? 0 : r.digits[i];
var ri1 = (i - 1 >= r.digits.length) ? 0 : r.digits[i - 1];
var ri2 = (i - 2 >= r.digits.length) ? 0 : r.digits[i - 2];
var yt = (t >= y.digits.length) ? 0 : y.digits[t];
var yt1 = (t - 1 >= y.digits.length) ? 0 : y.digits[t - 1];
if (ri == yt) {
q.digits[i - t - 1] = maxDigitVal;
} else {
q.digits[i - t - 1] = Math.floor((ri * biRadix + ri1) / yt);
}

var c1 = q.digits[i - t - 1] * ((yt * biRadix) + yt1);
var c2 = (ri * biRadixSquared) + ((ri1 * biRadix) + ri2);
while (c1 > c2) {
--q.digits[i - t - 1];
c1 = q.digits[i - t - 1] * ((yt * biRadix) | yt1);
c2 = (ri * biRadix * biRadix) + ((ri1 * biRadix) + ri2);
}

b = RSAUtils.biMultiplyByRadixPower(y, i - t - 1);
r = RSAUtils.biSubtract(r, RSAUtils.biMultiplyDigit(b, q.digits[i - t - 1]));
if (r.isNeg) {
r = RSAUtils.biAdd(r, b);
--q.digits[i - t - 1];
}
}
r = RSAUtils.biShiftRight(r, lambda);
// Fiddle with the signs and stuff to make sure that 0 <= r < y.
q.isNeg = x.isNeg != origYIsNeg;
if (x.isNeg) {
if (origYIsNeg) {
q = RSAUtils.biAdd(q, bigOne);
} else {
q = RSAUtils.biSubtract(q, bigOne);
}
y = RSAUtils.biShiftRight(y, lambda);
r = RSAUtils.biSubtract(y, r);
}
// Check for the unbelievably stupid degenerate case of r == -0.
if (r.digits[0] == 0 && RSAUtils.biHighIndex(r) == 0) r.isNeg = false;

return [q, r];
};

RSAUtils.biDivide = function(x, y) {
return RSAUtils.biDivideModulo(x, y)[0];
};

RSAUtils.biModulo = function(x, y) {
return RSAUtils.biDivideModulo(x, y)[1];
};

RSAUtils.biMultiplyMod = function(x, y, m) {
return RSAUtils.biModulo(RSAUtils.biMultiply(x, y), m);
};

RSAUtils.biPow = function(x, y) {
var result = bigOne;
var a = x;
while (true) {
if ((y & 1) != 0) result = RSAUtils.biMultiply(result, a);
y >>= 1;
if (y == 0) break;
a = RSAUtils.biMultiply(a, a);
}
return result;
};

RSAUtils.biPowMod = function(x, y, m) {
var result = bigOne;
var a = x;
var k = y;
while (true) {
if ((k.digits[0] & 1) != 0) result = RSAUtils.biMultiplyMod(result, a, m);
k = RSAUtils.biShiftRight(k, 1);
if (k.digits[0] == 0 && RSAUtils.biHighIndex(k) == 0) break;
a = RSAUtils.biMultiplyMod(a, a, m);
}
return result;
};

$w.BarrettMu = function(m) {
this.modulus = RSAUtils.biCopy(m);
this.k = RSAUtils.biHighIndex(this.modulus) + 1;
var b2k = new BigInt();
b2k.digits[2 * this.k] = 1; // b2k = b^(2k)
this.mu = RSAUtils.biDivide(b2k, this.modulus);
this.bkplus1 = new BigInt();
this.bkplus1.digits[this.k + 1] = 1; // bkplus1 = b^(k+1)
this.modulo = BarrettMu_modulo;
this.multiplyMod = BarrettMu_multiplyMod;
this.powMod = BarrettMu_powMod;
};

function BarrettMu_modulo(x) {
var $dmath = RSAUtils;
var q1 = $dmath.biDivideByRadixPower(x, this.k - 1);
var q2 = $dmath.biMultiply(q1, this.mu);
var q3 = $dmath.biDivideByRadixPower(q2, this.k + 1);
var r1 = $dmath.biModuloByRadixPower(x, this.k + 1);
var r2term = $dmath.biMultiply(q3, this.modulus);
var r2 = $dmath.biModuloByRadixPower(r2term, this.k + 1);
var r = $dmath.biSubtract(r1, r2);
if (r.isNeg) {
r = $dmath.biAdd(r, this.bkplus1);
}
var rgtem = $dmath.biCompare(r, this.modulus) >= 0;
while (rgtem) {
r = $dmath.biSubtract(r, this.modulus);
rgtem = $dmath.biCompare(r, this.modulus) >= 0;
}
return r;
}

function BarrettMu_multiplyMod(x, y) {
/*
x = this.modulo(x);
y = this.modulo(y);
*/
var xy = RSAUtils.biMultiply(x, y);
return this.modulo(xy);
}

function BarrettMu_powMod(x, y) {
var result = new BigInt();
result.digits[0] = 1;
var a = x;
var k = y;
while (true) {
if ((k.digits[0] & 1) != 0) result = this.multiplyMod(result, a);
k = RSAUtils.biShiftRight(k, 1);
if (k.digits[0] == 0 && RSAUtils.biHighIndex(k) == 0) break;
a = this.multiplyMod(a, a);
}
return result;
}

var RSAKeyPair = function(encryptionExponent, decryptionExponent, modulus) {
var $dmath = RSAUtils;
this.e = $dmath.biFromHex(encryptionExponent);
this.d = $dmath.biFromHex(decryptionExponent);
this.m = $dmath.biFromHex(modulus);
// We can do two bytes per digit, so
// chunkSize = 2 * (number of digits in modulus - 1).
// Since biHighIndex returns the high index, not the number of digits, 1 has
// already been subtracted.
this.chunkSize = 2 * $dmath.biHighIndex(this.m);
this.radix = 16;
this.barrett = new $w.BarrettMu(this.m);
};

RSAUtils.getKeyPair = function(encryptionExponent, decryptionExponent, modulus) {
return new RSAKeyPair(encryptionExponent, decryptionExponent, modulus);
};

if(typeof $w.twoDigit === 'undefined') {
$w.twoDigit = function(n) {
return (n < 10 ? "0" : "") + String(n);
};
}

// Altered by Rob Saunders (rob@robsaunders.net). New routine pads the
// string after it has been converted to an array. This fixes an
// incompatibility with Flash MX's ActionScript.
RSAUtils.encryptedString = function(key, s) {
var a = [];
var sl = s.length;
var i = 0;
while (i < sl) {
a[i] = s.charCodeAt(i);
i++;
}

while (a.length % key.chunkSize != 0) {
a[i++] = 0;
}

var al = a.length;
var result = "";
var j, k, block;
for (i = 0; i < al; i += key.chunkSize) {
block = new BigInt();
j = 0;
for (k = i; k < i + key.chunkSize; ++j) {
block.digits[j] = a[k++];
block.digits[j] += a[k++] << 8;
}
var crypt = key.barrett.powMod(block, key.e);
var text = key.radix == 16 ? RSAUtils.biToHex(crypt) : RSAUtils.biToString(crypt, key.radix);
result += text + " ";
}
return result.substring(0, result.length - 1); // Remove last space.
};

RSAUtils.decryptedString = function(key, s) {
var blocks = s.split(" ");
var result = "";
var i, j, block;
for (i = 0; i < blocks.length; ++i) {
var bi;
if (key.radix == 16) {
bi = RSAUtils.biFromHex(blocks[i]);
}
else {
bi = RSAUtils.biFromString(blocks[i], key.radix);
}
block = key.barrett.powMod(bi, key.d);
for (j = 0; j <= RSAUtils.biHighIndex(block); ++j) {
result += String.fromCharCode(block.digits[j] & 255,
block.digits[j] >> 8);
}
}
// Remove trailing null, if any.
if (result.charCodeAt(result.length - 1) == 0) {
result = result.substring(0, result.length - 1);
}
return result;
};

RSAUtils.setMaxDigits(130);

})(window);