RSA加密算法-前端(JS)加密,后端(JAVA)解密

简述一下:

RSA非对称加密算法, 简单理解就是: 准备两把钥匙-公钥, 私钥.

加密的时候使用公钥进行加密, 解密的时候使用私钥进行解密, 这两把钥匙是不同的.

js里面包含了解密和加密方法, 我们需要做的就是使用方法的时候传递 钥匙和数据进去.

RSA工具类里面也包含 解密js端传递来的密文方法, 以及在后台进行数据的加密解密方法.

直接开始:

1. 准备前端需要的js

jquery.js 这个满大街都有,随便找一个

security.js,下面贴出内容.

(function($w) {

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

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










    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);



    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;
    };


    var lr10 = RSAUtils.biFromNumber(1000000000000000);

    RSAUtils.biFromDecimal = function(s) {
        var isNeg = s.charAt(0) == '-';
        var i = isNeg ? 1 : 0;
        var result;

        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) {
        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;
        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;

                if (result.digits[i] < 0) result.digits[i] += biRadix;
                c = 0 - Number(n < 0);
            }

            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;

                    if (result.digits[i] < 0) result.digits[i] += biRadix;
                    c = 0 - Number(n < 0);
                }

                result.isNeg = !x.isNeg;
            } else {

                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;

            }
            result.digits[i + n + 1] = c;
        }

        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;

        }
        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) {

            if (x.isNeg) {
                q = RSAUtils.biCopy(bigOne);
                q.isNeg = !y.isNeg;
                x.isNeg = false;
                y.isNeg = false;
                r = biSubtract(y, x);

                x.isNeg = true;
                y.isNeg = origYIsNeg;
            } else {
                q = new BigInt();
                r = RSAUtils.biCopy(x);
            }
            return [q, r];
        }

        q = new BigInt();
        r = x;


        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;
        }


        r = RSAUtils.biShiftLeft(r, lambda);
        nb += lambda;
        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);

        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);
        }

        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;
        this.mu = RSAUtils.biDivide(b2k, this.modulus);
        this.bkplus1 = new BigInt();
        this.bkplus1.digits[this.k + 1] = 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) {

        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);




        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);
        };
    }




    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);
    };

    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);
            }
        }

        if (result.charCodeAt(result.length - 1) == 0) {
            result = result.substring(0, result.length - 1);
        }
        return result;
    };

    RSAUtils.setMaxDigits(130);

})(window);

 

 

2.准备一个简单的jsp页面,这里面有我从自己写的控制层里面拿到的数据, 之后你自己换成你的就行,注释都有写

<%@ page contentType="text/html;charset=UTF-8" language="java" %>




    


JavaScript RSA Encryption Demo
需要加密的字符串：




<%--获取公钥信息--%>

    公钥系数-我这里是通过控制层传递过来,在工具类中已经注明了系数获取,读RSA工具类的main方法注释即可:
    
    

    公钥指数-同:
    

 

 

3.java端需要的RSA工具类.

注意点:

该工具类中需要 org.bouncycastle..包,自行百度也是轻松能找得到, 其余RSA需要的jar包都是java自带了

package encryptionanddecryption;

import java.io.UnsupportedEncodingException;
import java.math.BigInteger;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.security.InvalidParameterException;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.Provider;
import java.security.SecureRandom;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import javax.crypto.Cipher;

import org.apache.commons.lang3.StringUtils;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.util.encoders.Hex;

/**
 * RSA算法加密/解密工具类。
 * 以下代码可以使用,唯一需要注意的是: org.bouncycastle...这个jar包需要找一到放到项目中,RSA所需jar包在java中已经自带了.
 *
 * @author liuyan
 */
public class RSAUtils {
    /**
     * 算法名称
     */
    private static final String ALGORITHOM = "RSA";
    /**
     * 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;

    //密文种子, 当想更换RSA钥匙的时候,只需要修改密文种子,即可更换
    private static final String radamKey = "你自己随便写上数字或者英文即可";

    //类加载后进行初始化数据
    static {
        try {
            keyPairGen = KeyPairGenerator.getInstance(ALGORITHOM,
                    DEFAULT_PROVIDER);
            keyFactory = KeyFactory.getInstance(ALGORITHOM, DEFAULT_PROVIDER);
        } catch (NoSuchAlgorithmException ex) {
            ex.printStackTrace();
        }
    }

    /**
     * 根据指定的密文种子,生成并返回RSA密钥对。
     */
    private static synchronized KeyPair generateKeyPair() {
        try {
            keyPairGen.initialize(KEY_SIZE,
                    new SecureRandom(radamKey.getBytes()));
            oneKeyPair = keyPairGen.generateKeyPair();
            return oneKeyPair;
        } catch (InvalidParameterException ex) {
            ex.printStackTrace();
        } catch (NullPointerException ex) {
            ex.printStackTrace();
        }
        return null;
    }

    /**
     * 返回初始化时默认的公钥。
     */
    public static RSAPublicKey getDefaultPublicKey() {
        KeyPair keyPair = generateKeyPair();
        if (keyPair != null) {
            return (RSAPublicKey) keyPair.getPublic();
        }
        return null;
    }

    /**
     * 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);
    }

    /**
     * 使用默认的私钥解密给定的字符串。
     * @param encryptText 密文。
     * @return 原文字符串。
     */
    public static String decryptString(String encryptText) {
        if (StringUtils.isBlank(encryptText)) {
            return null;
        }
        KeyPair keyPair = generateKeyPair();
        try {
            byte[] en_data = Hex.decode(encryptText);
            byte[] data = decrypt((RSAPrivateKey) keyPair.getPrivate(), en_data);
            return new String(data);
        } catch (NullPointerException ex) {
            ex.printStackTrace();
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return null;
    }

    /**
     * 使用秘钥 - 对js端传递过来密文进行解密
     *
     * @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;
        }
        String reverse = StringUtils.reverse(text);
        String decode = null;
        try {
            //这里需要进行编码转换.注:在前端js对明文加密前需要先进行转码-可自行百度"编码转换"
            decode = URLDecoder.decode(reverse, "UTF-8");
            System.out.println("解密后文字：" + decode);
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        return decode;
    }

    //java端 - 使用公钥进行加密
    public static byte[] encrypt(String plaintext) throws Exception {
        // 获取公钥及参数e,n
        RSAPublicKey publicKey = RSAUtils.getDefaultPublicKey();
        //获取公钥指数 e
        BigInteger e = publicKey.getPublicExponent();
        //获取公钥系数 n
        BigInteger n = publicKey.getModulus();
        //先将明文进行编码
        String encode = URLEncoder.encode(plaintext);
        // 获取明文字节数组 m
        BigInteger m = new BigInteger(encode.getBytes());
        // 进行明文加密 c
        BigInteger c = m.modPow(e, n);
        //返回密文字节数组
        return c.toByteArray();
    }

    //java端 - 使用私钥进行解密
    public static String decrypt(byte[] cipherText) throws Exception {
        // 读取私钥
        KeyPair keyPair = generateKeyPair();
        RSAPrivateKey prk = (RSAPrivateKey) keyPair.getPrivate();
        // 获取私钥参数-指数/系数
        BigInteger d = prk.getPrivateExponent();
        BigInteger n = prk.getModulus();
        // 读取密文
        BigInteger c = new BigInteger(cipherText);
        // 进行解密
        BigInteger m = c.modPow(d, n);
        // 解密结果-字节数组
        byte[] mt = m.toByteArray();
        //转成String,此时是乱码
        String en = new String(mt);
        //再进行编码
        String result = java.net.URLDecoder.decode(en, "UTF-8");
        //最后返回解密后得到的明文
        return result;
    }


    public static void main(String[] args) {
        /*解密js端传递过来的密文*/
        //获取公钥对象--注意:前端那边需要用到公钥系数和指数
        RSAPublicKey publicKey = RSAUtils.getDefaultPublicKey();
        //公钥-系数(n)
        System.out.println("public key modulus:" + new String(Hex.encode(publicKey.getModulus().toByteArray())));
        //公钥-指数(e1)
        System.out.println("public key exponent:" + new String(Hex.encode(publicKey.getPublicExponent().toByteArray())));
        //JS加密后的字符串
        String param = "8c49dfb92a0c8d15b0187b1eabc343a80f340962ebecc497205f83f6a4792141d4e711b6d439388ecf691df4eda2cae1e6431573b61e3f564ffe1c757e32f3e846b5983e5939ddeb28c9570001d7f208ffbaa069677d363cc73e4c78c0d508e8b0b9f6205473269bbfbc22e7fb9413be4c449520eb6cfb4fbbff4e7e189a005a";
        //解密后的字符串
        String param1 = RSAUtils.decryptStringByJs(param);

//        /*后端的加密和解密-在加密的方法中已经使用了公钥指数和系数*/

//        try {
//            //加密
//            byte[] param3 = encrypt("你好> @# !!# #");
//            //解密
//            String decrypt = RSAUtils.decrypt(param3);
//            System.out.println(decrypt);
//        } catch (Exception e) {
//            e.printStackTrace();
//        }

    }
}

工具类拿到之后, 把你本地少的jar包补上, 然后写一个控制层方法,把公钥信息传给页面即可.

感谢各位愿意花时间写csdn博客的朋友们, 纯看RSA原理完全看不懂啊!