PAT B1034/A1088题解

有理数四则运算解析
本文详细解析了有理数的加、减、乘、除四种基本运算的实现方法,通过具体的C++代码示例,展示了如何将两个有理数进行运算并输出最简形式。文章覆盖了化简分数、通分、约分等关键步骤,适用于初学者理解和掌握有理数运算的编程实现。

1034 有理数四则运算 (20 分)
本题要求编写程序,计算 2 个有理数的和、差、积、商。

输入格式:
输入在一行中按照 a1/b1 a2/b2 的格式给出两个分数形式的有理数,其中分子和分母全是整型范围内的整数,负号只可能出现在分子前,分母不为 0。

输出格式:
分别在 4 行中按照 有理数1 运算符 有理数2 = 结果 的格式顺序输出 2 个有理数的和、差、积、商。注意输出的每个有理数必须是该有理数的最简形式 k a/b,其中 k 是整数部分,a/b 是最简分数部分;若为负数,则须加括号;若除法分母为 0,则输出 Inf。题目保证正确的输出中没有超过整型范围的整数。

输入样例 1:
2/3 -4/2
输出样例 1:
2/3 + (-2) = (-1 1/3)
2/3 - (-2) = 2 2/3
2/3 * (-2) = (-1 1/3)
2/3 / (-2) = (-1/3)
输入样例 2:
5/3 0/6
输出样例 2:
1 2/3 + 0 = 1 2/3
1 2/3 - 0 = 1 2/3
1 2/3 * 0 = 0
1 2/3 / 0 = Inf


#include<iostream>
#include<algorithm>
typedef long long ll;
using namespace std;
struct fenshu{
	ll up,down;
};
ll gcd(ll a,ll b){
	return b==0?a:gcd(b,a%b);
}
fenshu reduct(fenshu result){
//化简
	if(result.down<0){
		result.up=-result.up;
		result.down=-result.down;
	} 
	if(result.up==0){
		result.down=1;
	}
	else{
		int yueshu=gcd(abs(result.up),abs(result.down));
		result.up/=yueshu;
		result.down/=yueshu;
	}
	return result;
}
fenshu add(fenshu f1,fenshu f2){
	fenshu result;
	result.up=f1.up*f2.down+f1.down*f2.up;
	result.down=f1.down*f2.down;
	return reduct(result);
}
fenshu jianfa(fenshu f1,fenshu f2){
	fenshu result;
	result.down=f1.down*f2.down;
	result.up=f1.up*f2.down-f1.down*f2.up;
	return reduct(result);
}
fenshu chengfa(fenshu f1,fenshu f2){
	fenshu result;
	result.down=f1.down*f2.down;
	result.up=f1.up*f2.up;
	return reduct(result);
}
fenshu chufa(fenshu f1,fenshu f2){
	fenshu result;
	result.up=f1.up*f2.down;
	result.down=f1.down*f2.up;
	return reduct(result);
}
void showresult(fenshu f){
	f=reduct(f); 
	if(f.up<0){
		printf("(");
	}
	if(f.down==1){
		printf("%lld",f.up);
	}
	else if(abs(f.up)>f.down){
		printf("%lld %lld/%lld",f.up/f.down,abs(f.up)%f.down,f.down);
	}
	else{
		printf("%lld/%lld",f.up,f.down);
	}
	if(f.up<0){
		printf(")");
	}
}
int main(){
	fenshu a,b;
	scanf("%lld/%lld %lld/%lld",&a.up,&a.down,&b.up,&b.down);
	showresult(a);
	cout<<" + ";
	showresult(b);
	cout<<" = ";
	showresult(add(a,b));
	cout<<endl;
	showresult(a);
	cout<<" - ";
	showresult(b);
	cout<<" = ";
	showresult(jianfa(a,b));
	cout<<endl;
	showresult(a);
	cout<<" * ";
	showresult(b);
	cout<<" = ";
	showresult(chengfa(a,b));
	cout<<endl;
	showresult(a);
	cout<<" / ";
	showresult(b);
	cout<<" = ";
	if(b.up==0)
		cout<<"Inf";
	else
		showresult(chufa(a,b));
	cout<<endl;
	return 0;
}
__author__ = 'admin' # --*--coding:utf-8--*-- import execjs def exec_JsFile(text='admin', param=None): js_file = \ ''' /** * Created by admin on 2016/3/16. */ encrypt = function (val, param){ //n, e, // Copyright (c) 2005 Tom Wu // All Rights Reserved. // See "LICENSE" for details. // Basic JavaScript BN library - subset useful for RSA encryption. // Bits per digit var dbits; // JavaScript engine analysis var canary = 0xdeadbeefcafe; var j_lm = ((canary&0xffffff)==0xefcafe); // (public) Constructor function BigInteger(a,b,c) { if(a != null){ if("number" == typeof a){ this.fromNumber(a, b, c); }else if(b == null && "string" != typeof a){ this.fromString(a, 256); }else{ this.fromString(a, b); } } } // return new, unset BigInteger function nbi() { return new BigInteger(null); } // am: Compute w_j += (x*this_i), propagate carries, // c is initial carry, returns final carry. // c < 3*dvalue, x < 2*dvalue, this_i < dvalue // We need to select the fastest one that works in this environment. // am1: use a single mult and divide to get the high bits, // max digit bits should be 26 because // max internal value = 2*dvalue^2-2*dvalue (< 2^53) function am1(i,x,w,j,c,n) { while(--n >= 0) { var v = x*this[i++]+w[j]+c; c = Math.floor(v/0x4000000); w[j++] = v&0x3ffffff; } return c; } // am2 avoids a big mult-and-extract completely. // Max digit bits should be <= 30 because we do bitwise ops // on values up to 2*hdvalue^2-hdvalue-1 (< 2^31) function am2(i,x,w,j,c,n) { var xl = x&0x7fff, xh = x>>15; while(--n >= 0) { var l = this[i]&0x7fff; var h = this[i++]>>15; var m = xh*l+h*xl; l = xl*l+((m&0x7fff)<<15)+w[j]+(c&0x3fffffff); c = (l>>>30)+(m>>>15)+xh*h+(c>>>30); w[j++] = l&0x3fffffff; } return c; } // Alternately, set max digit bits to 28 since some // browsers slow down when dealing with 32-bit numbers. function am3(i,x,w,j,c,n) { var xl = x&0x3fff, xh = x>>14; while(--n >= 0) { var l = this[i]&0x3fff; var h = this[i++]>>14; var m = xh*l+h*xl; l = xl*l+((m&0x3fff)<<14)+w[j]+c; c = (l>>28)+(m>>14)+xh*h; w[j++] = l&0xfffffff; } return c; } // Window.prototype.navigator.app // abbbb = Window.navigator.appName //if(j_lm && (window.prototype.navigator.appName == "Microsoft Internet Explorer")) { // BigInteger.prototype.am = am2; // dbits = 30; //}else if(j_lm && (window.prototype.navigator.appName != "Netscape")) { // BigInteger.prototype.am = am1; // dbits = 26; //}else { // Mozilla/Netscape seems to prefer am3 // BigInteger.prototype.am = am3; // dbits = 28; //} BigInteger.prototype.am = am3; dbits = 28; BigInteger.prototype.DB = dbits; BigInteger.prototype.DM = ((1<<dbits)-1); BigInteger.prototype.DV = (1<<dbits); var BI_FP = 52; BigInteger.prototype.FV = Math.pow(2,BI_FP); BigInteger.prototype.F1 = BI_FP-dbits; BigInteger.prototype.F2 = 2*dbits-BI_FP; // Digit conversions var BI_RM = "0123456789abcdefghijklmnopqrstuvwxyz"; var BI_RC = new Array(); var rr,vv; rr = "0".charCodeAt(0); for(vv = 0; vv <= 9; ++vv){ BI_RC[rr++] = vv; } rr = "a".charCodeAt(0); for(vv = 10; vv < 36; ++vv){ BI_RC[rr++] = vv; } rr = "A".charCodeAt(0); for(vv = 10; vv < 36; ++vv){ BI_RC[rr++] = vv; } function int2char(n) { return BI_RM.charAt(n); } function intAt(s,i) { var c = BI_RC[s.charCodeAt(i)]; return (c==null)?-1:c; } // (protected) copy this to r function bnpCopyTo(r) { for(var i = this.t-1; i >= 0; --i){ r[i] = this[i]; }; r.t = this.t; r.s = this.s; } // (protected) set from integer value x, -DV <= x < DV function bnpFromInt(x) { this.t = 1; this.s = (x<0)?-1:0; if(x > 0){ this[0] = x; }else if(x < -1){ this[0] = x+this.DV; }else{ this.t = 0; } } // return bigint initialized to value function nbv(i) { var r = nbi(); r.fromInt(i); return r; } // (protected) set from string and radix function bnpFromString(s,b) { var k; if(b == 16){ k = 4; }else if(b == 8){ k = 3; }else if(b == 256){ k = 8; // byte array }else if(b == 2){ k = 1; }else if(b == 32){ k = 5; }else if(b == 4){ k = 2; }else{ this.fromRadix(s,b); return; }; this.t = 0; this.s = 0; var i = s.length, mi = false, sh = 0; while(--i >= 0) { var x = (k==8)?s[i]&0xff:intAt(s,i); if(x < 0) { if(s.charAt(i) == "-") {mi = true;} continue; }; mi = false; if(sh == 0){ this[this.t++] = x; }else if(sh+k > this.DB) { this[this.t-1] |= (x&((1<<(this.DB-sh))-1))<<sh; this[this.t++] = (x>>(this.DB-sh)); } else this[this.t-1] |= x<<sh; sh += k; if(sh >= this.DB) sh -= this.DB; }; if(k == 8 && (s[0]&0x80) != 0) { this.s = -1; if(sh > 0){ this[this.t-1] |= ((1<<(this.DB-sh))-1)<<sh; } }; this.clamp(); if(mi){ BigInteger.ZERO.subTo(this,this) }; } // (protected) clamp off excess high words function bnpClamp() { var c = this.s&this.DM; while(this.t > 0 && this[this.t-1] == c){ --this.t; } } // (public) return string representation in given radix function bnToString(b) { if(this.s < 0){ return "-"+this.negate().toString(b);} var k; if(b == 16){k = 4;} else if(b == 8){ k = 3;} else if(b == 2){ k = 1;} else if(b == 32){ k = 5;} else if(b == 4){ k = 2;} else{ return this.toRadix(b);} var km = (1<<k)-1, d, m = false, r = "", i = this.t; var p = this.DB-(i*this.DB)%k; if(i-- > 0) { if(p < this.DB && (d = this[i]>>p) > 0) { m = true; r = int2char(d); } while(i >= 0) { if(p < k) { d = (this[i]&((1<<p)-1))<<(k-p); d |= this[--i]>>(p+=this.DB-k); }else { d = (this[i]>>(p-=k))&km; if(p <= 0) { p += this.DB; --i; } } if(d > 0){ m = true;} if(m){ r += int2char(d);} } } return m?r:"0"; } // (public) -this function bnNegate() { var r = nbi(); BigInteger.ZERO.subTo(this,r); return r; } // (public) |this| function bnAbs() { return (this.s<0)?this.negate():this; } // (public) return + if this > a, - if this < a, 0 if equal function bnCompareTo(a) { var r = this.s-a.s; if(r != 0){ return r;} var i = this.t; r = i-a.t; if(r != 0){ return (this.s<0)?-r:r;} while(--i >= 0){ if((r=this[i]-a[i]) != 0) return r;} return 0; } // returns bit length of the integer x function nbits(x) { var r = 1, t; if((t=x>>>16) != 0) { x = t; r += 16; } if((t=x>>8) != 0) { x = t; r += 8; } if((t=x>>4) != 0) { x = t; r += 4; } if((t=x>>2) != 0) { x = t; r += 2; } if((t=x>>1) != 0) { x = t; r += 1; } return r; } // (public) return the number of bits in "this" function bnBitLength() { if(this.t <= 0) return 0; return this.DB*(this.t-1)+nbits(this[this.t-1]^(this.s&this.DM)); } // (protected) r = this << n*DB function bnpDLShiftTo(n,r) { var i; for(i = this.t-1; i >= 0; --i){ r[i+n] = this[i];} for(i = n-1; i >= 0; --i){ r[i] = 0;} r.t = this.t+n; r.s = this.s; } // (protected) r = this >> n*DB function bnpDRShiftTo(n,r) { for(var i = n; i < this.t; ++i){ r[i-n] = this[i];} r.t = Math.max(this.t-n,0); r.s = this.s; } // (protected) r = this << n function bnpLShiftTo(n,r) { var bs = n%this.DB; var cbs = this.DB-bs; var bm = (1<<cbs)-1; var ds = Math.floor(n/this.DB), c = (this.s<<bs)&this.DM, i; for(i = this.t-1; i >= 0; --i) { r[i+ds+1] = (this[i]>>cbs)|c; c = (this[i]&bm)<<bs; } for(i = ds-1; i >= 0; --i){ r[i] = 0;} r[ds] = c; r.t = this.t+ds+1; r.s = this.s; r.clamp(); } // (protected) r = this >> n function bnpRShiftTo(n,r) { r.s = this.s; var ds = Math.floor(n/this.DB); if(ds >= this.t) { r.t = 0; return; } var bs = n%this.DB; var cbs = this.DB-bs; var bm = (1<<bs)-1; r[0] = this[ds]>>bs; for(var i = ds+1; i < this.t; ++i) { r[i-ds-1] |= (this[i]&bm)<<cbs; r[i-ds] = this[i]>>bs; } if(bs > 0){ r[this.t-ds-1] |= (this.s&bm)<<cbs;} r.t = this.t-ds; r.clamp(); } // (protected) r = this - a function bnpSubTo(a,r) { var i = 0, c = 0, m = Math.min(a.t,this.t); while(i < m) { c += this[i]-a[i]; r[i++] = c&this.DM; c >>= this.DB; } if(a.t < this.t) { c -= a.s; while(i < this.t) { c += this[i]; r[i++] = c&this.DM; c >>= this.DB; } c += this.s; } else { c += this.s; while(i < a.t) { c -= a[i]; r[i++] = c&this.DM; c >>= this.DB; } c -= a.s; } r.s = (c<0)?-1:0; if(c < -1) r[i++] = this.DV+c; else if(c > 0) r[i++] = c; r.t = i; r.clamp(); } // (protected) r = this * a, r != this,a (HAC 14.12) // "this" should be the larger one if appropriate. function bnpMultiplyTo(a,r) { var x = this.abs(), y = a.abs(); var i = x.t; r.t = i+y.t; while(--i >= 0) r[i] = 0; for(i = 0; i < y.t; ++i) r[i+x.t] = x.am(0,y[i],r,i,0,x.t); r.s = 0; r.clamp(); if(this.s != a.s) BigInteger.ZERO.subTo(r,r); } // (protected) r = this^2, r != this (HAC 14.16) function bnpSquareTo(r) { var x = this.abs(); var i = r.t = 2*x.t; while(--i >= 0) { r[i] = 0; } for(i = 0; i < x.t-1; ++i) { var c = x.am(i,x[i],r,2*i,0,1); if((r[i+x.t]+=x.am(i+1,2*x[i],r,2*i+1,c,x.t-i-1)) >= x.DV) { r[i+x.t] -= x.DV; r[i+x.t+1] = 1; } } if(r.t > 0) { r[r.t-1] += x.am(i,x[i],r,2*i,0,1); } r.s = 0; r.clamp(); } // (protected) divide this by m, quotient and remainder to q, r (HAC 14.20) // r != q, this != m. q or r may be null. function bnpDivRemTo(m,q,r) { var pm = m.abs(); if(pm.t <= 0) {return;} var pt = this.abs(); if(pt.t < pm.t) { if(q != null) {q.fromInt(0);} if(r != null) {this.copyTo(r);} return; } if(r == null) {r = nbi();} var y = nbi(), ts = this.s, ms = m.s; var nsh = this.DB-nbits(pm[pm.t-1]); // normalize modulus if(nsh > 0) { pm.lShiftTo(nsh,y); pt.lShiftTo(nsh,r); }else { pm.copyTo(y); pt.copyTo(r); } var ys = y.t; var y0 = y[ys-1]; if(y0 == 0) {return;} var yt = y0*(1<<this.F1)+((ys>1)?y[ys-2]>>this.F2:0); var d1 = this.FV/yt, d2 = (1<<this.F1)/yt, e = 1<<this.F2; var i = r.t, j = i-ys, t = (q==null)?nbi():q; y.dlShiftTo(j,t); if(r.compareTo(t) >= 0) { r[r.t++] = 1; r.subTo(t,r); } BigInteger.ONE.dlShiftTo(ys,t); t.subTo(y,y); // "negative" y so we can replace sub with am later while(y.t < ys) {y[y.t++] = 0;} while(--j >= 0) { // Estimate quotient digit var qd = (r[--i]==y0)?this.DM:Math.floor(r[i]*d1+(r[i-1]+e)*d2); if((r[i]+=y.am(0,qd,r,j,0,ys)) < qd) { // Try it out y.dlShiftTo(j,t); r.subTo(t,r); while(r[i] < --qd) { r.subTo(t,r); } } } if(q != null) { r.drShiftTo(ys,q); if(ts != ms) {BigInteger.ZERO.subTo(q,q);} } r.t = ys; r.clamp(); if(nsh > 0) { r.rShiftTo(nsh,r); } // Denormalize remainder if(ts < 0) { BigInteger.ZERO.subTo(r,r); } } // (public) this mod a function bnMod(a) { var r = nbi(); this.abs().divRemTo(a,null,r); if(this.s < 0 && r.compareTo(BigInteger.ZERO) > 0) {a.subTo(r,r);} return r; } // Modular reduction using "classic" algorithm function Classic(m) { this.m = m; } function cConvert(x) { if(x.s < 0 || x.compareTo(this.m) >= 0) {return x.mod(this.m);} else {return x;} } function cRevert(x) { return x; } function cReduce(x) { x.divRemTo(this.m,null,x); } function cMulTo(x,y,r) { x.multiplyTo(y,r); this.reduce(r); } function cSqrTo(x,r) { x.squareTo(r); this.reduce(r); } Classic.prototype.convert = cConvert; Classic.prototype.revert = cRevert; Classic.prototype.reduce = cReduce; Classic.prototype.mulTo = cMulTo; Classic.prototype.sqrTo = cSqrTo; // (protected) return "-1/this % 2^DB"; useful for Mont. reduction // justification: // xy == 1 (mod m) // xy = 1+km // xy(2-xy) = (1+km)(1-km) // x[y(2-xy)] = 1-k^2m^2 // x[y(2-xy)] == 1 (mod m^2) // if y is 1/x mod m, then y(2-xy) is 1/x mod m^2 // should reduce x and y(2-xy) by m^2 at each step to keep size bounded. // JS multiply "overflows" differently from C/C++, so care is needed here. function bnpInvDigit() { if(this.t < 1) {return 0;} var x = this[0]; if((x&1) == 0) {return 0;} var y = x&3; // y == 1/x mod 2^2 y = (y*(2-(x&0xf)*y))&0xf; // y == 1/x mod 2^4 y = (y*(2-(x&0xff)*y))&0xff; // y == 1/x mod 2^8 y = (y*(2-(((x&0xffff)*y)&0xffff)))&0xffff; // y == 1/x mod 2^16 // last step - calculate inverse mod DV directly; // assumes 16 < DB <= 32 and assumes ability to handle 48-bit ints y = (y*(2-x*y%this.DV))%this.DV; // y == 1/x mod 2^dbits // we really want the negative inverse, and -DV < y < DV return (y>0)?this.DV-y:-y; } // Montgomery reduction function Montgomery(m) { this.m = m; this.mp = m.invDigit(); this.mpl = this.mp&0x7fff; this.mph = this.mp>>15; this.um = (1<<(m.DB-15))-1; this.mt2 = 2*m.t; } // xR mod m function montConvert(x) { var r = nbi(); x.abs().dlShiftTo(this.m.t,r); r.divRemTo(this.m,null,r); if(x.s < 0 && r.compareTo(BigInteger.ZERO) > 0) {this.m.subTo(r,r);} return r; } // x/R mod m function montRevert(x) { var r = nbi(); x.copyTo(r); this.reduce(r); return r; } // x = x/R mod m (HAC 14.32) function montReduce(x) { while(x.t <= this.mt2) // pad x so am has enough room later x[x.t++] = 0; for(var i = 0; i < this.m.t; ++i) { // faster way of calculating u0 = x[i]*mp mod DV var j = x[i]&0x7fff; var u0 = (j*this.mpl+(((j*this.mph+(x[i]>>15)*this.mpl)&this.um)<<15))&x.DM; // use am to combine the multiply-shift-add into one call j = i+this.m.t; x[j] += this.m.am(0,u0,x,i,0,this.m.t); // propagate carry while(x[j] >= x.DV) { x[j] -= x.DV; x[++j]++; } } x.clamp(); x.drShiftTo(this.m.t,x); if(x.compareTo(this.m) >= 0) {x.subTo(this.m,x);} } // r = "x^2/R mod m"; x != r function montSqrTo(x,r) { x.squareTo(r); this.reduce(r); } // r = "xy/R mod m"; x,y != r function montMulTo(x,y,r) { x.multiplyTo(y,r); this.reduce(r); } Montgomery.prototype.convert = montConvert; Montgomery.prototype.revert = montRevert; Montgomery.prototype.reduce = montReduce; Montgomery.prototype.mulTo = montMulTo; Montgomery.prototype.sqrTo = montSqrTo; // (protected) true iff this is even function bnpIsEven() { return ((this.t>0)?(this[0]&1):this.s) == 0; } // (protected) this^e, e < 2^32, doing sqr and mul with "r" (HAC 14.79) function bnpExp(e,z) { if(e > 0xffffffff || e < 1){ return BigInteger.ONE; } var r = nbi(), r2 = nbi(), g = z.convert(this), i = nbits(e)-1; g.copyTo(r); while(--i >= 0){ z.sqrTo(r,r2); if((e&(1<<i)) > 0){ z.mulTo(r2,g,r); }else{ var t = r; r = r2; r2 = t; } } return z.revert(r); } // (public) this^e % m, 0 <= e < 2^32 function bnModPowInt(e,m) { var z; if(e < 256 || m.isEven()) z = new Classic(m); else z = new Montgomery(m); return this.exp(e,z); } // protected BigInteger.prototype.copyTo = bnpCopyTo; BigInteger.prototype.fromInt = bnpFromInt; BigInteger.prototype.fromString = bnpFromString; BigInteger.prototype.clamp = bnpClamp; BigInteger.prototype.dlShiftTo = bnpDLShiftTo; BigInteger.prototype.drShiftTo = bnpDRShiftTo; BigInteger.prototype.lShiftTo = bnpLShiftTo; BigInteger.prototype.rShiftTo = bnpRShiftTo; BigInteger.prototype.subTo = bnpSubTo; BigInteger.prototype.multiplyTo = bnpMultiplyTo; BigInteger.prototype.squareTo = bnpSquareTo; BigInteger.prototype.divRemTo = bnpDivRemTo; BigInteger.prototype.invDigit = bnpInvDigit; BigInteger.prototype.isEven = bnpIsEven; BigInteger.prototype.exp = bnpExp; // public BigInteger.prototype.toString = bnToString; BigInteger.prototype.negate = bnNegate; BigInteger.prototype.abs = bnAbs; BigInteger.prototype.compareTo = bnCompareTo; BigInteger.prototype.bitLength = bnBitLength; BigInteger.prototype.mod = bnMod; BigInteger.prototype.modPowInt = bnModPowInt; // "constants" BigInteger.ZERO = nbv(0); BigInteger.ONE = nbv(1); //end of jsbn.js // prng4.js - uses Arcfour as a PRNG function Arcfour() { this.i = 0; this.j = 0; this.S = new Array(); } // Initialize arcfour context from key, an array of ints, each from [0..255] function ARC4init(key) { var i, j, t; for(i = 0; i < 256; ++i) this.S[i] = i; j = 0; for(i = 0; i < 256; ++i) { j = (j + this.S[i] + key[i % key.length]) & 255; t = this.S[i]; this.S[i] = this.S[j]; this.S[j] = t; } this.i = 0; this.j = 0; } function ARC4next() { var t; this.i = (this.i + 1) & 255; this.j = (this.j + this.S[this.i]) & 255; t = this.S[this.i]; this.S[this.i] = this.S[this.j]; this.S[this.j] = t; return this.S[(t + this.S[this.i]) & 255]; } Arcfour.prototype.init = ARC4init; Arcfour.prototype.next = ARC4next; // Plug in your RNG constructor here function prng_newstate() { return new Arcfour(); } // Pool size must be a multiple of 4 and greater than 32. // An array of bytes the size of the pool will be passed to init() var rng_psize = 256; //end of prng4.js // Random number generator - requires a PRNG backend, e.g. prng4.js // For best results, put code like // <body onClick='rng_seed_time();' onKeyPress='rng_seed_time();'> // in your main HTML document. var rng_state; var rng_pool; var rng_pptr; // Mix in a 32-bit integer into the pool function rng_seed_int(x) { rng_pool[rng_pptr++] ^= x & 255; rng_pool[rng_pptr++] ^= (x >> 8) & 255; rng_pool[rng_pptr++] ^= (x >> 16) & 255; rng_pool[rng_pptr++] ^= (x >> 24) & 255; if(rng_pptr >= rng_psize) { rng_pptr -= rng_psize; } } // Mix in the current time (w/milliseconds) into the pool function rng_seed_time() { rng_seed_int(new Date().getTime()); } // Initialize the pool with junk if needed. if(rng_pool == null) { rng_pool = new Array(); rng_pptr = 0; var t; //if(window.crypto && window.crypto.getRandomValues) { // // Use webcrypto if available // var ua = new Uint8Array(32); // window.crypto.getRandomValues(ua); // for(t = 0; t < 32; ++t){ // rng_pool[rng_pptr++] = ua[t]; // } //} //if(navigator.appName == "Netscape" && navigator.appVersion < "5" && window.crypto) { // // Extract entropy (256 bits) from NS4 RNG if available // var z = window.crypto.random(32); // for(t = 0; t < z.length; ++t) // rng_pool[rng_pptr++] = z.charCodeAt(t) & 255; //} //while(rng_pptr < rng_psize) { // extract some randomness from Math.random() // t = Math.floor(65536 * Math.random()); // rng_pool[rng_pptr++] = t >>> 8; // rng_pool[rng_pptr++] = t & 255; //} rng_pptr = 0; rng_seed_time(); //rng_seed_int(window.screenX); //rng_seed_int(window.screenY); } function rng_get_byte() { if(rng_state == null) { rng_seed_time(); rng_state = prng_newstate(); rng_state.init(rng_pool); for(rng_pptr = 0; rng_pptr < rng_pool.length; ++rng_pptr){ rng_pool[rng_pptr] = 0; } rng_pptr = 0; //rng_pool = null; } // TODO: allow reseeding after first request return rng_state.next(); } function rng_get_bytes(ba) { var i; for(i = 0; i < ba.length; ++i){ ba[i] = rng_get_byte(); } } function SecureRandom() {} SecureRandom.prototype.nextBytes = rng_get_bytes; //end of rng.js // Depends on jsbn.js and rng.js // Version 1.1: support utf-8 encoding in pkcs1pad2 // convert a (hex) string to a bignum object function parseBigInt(str,r) { return new BigInteger(str,r); } /*function linebrk(s,n) { var ret = ""; var i = 0; while(i + n < s.length) { ret += s.substring(i,i+n) + ""; i += n; }; return ret + s.substring(i,s.length); }*/ function byte2Hex(b) { if(b < 0x10){ return "0" + b.toString(16); }else{ return b.toString(16); } } // PKCS#1 (type 2, random) pad input string s to n bytes, and return a bigint /* if(n < s.length + 11) { // TODO: fix for utf-8 alert("Message too long for RSA"); return null; } var ba = new Array(); var i = s.length - 1; while(i >= 0 && n > 0) { var c = s.charCodeAt(i--); if(c < 128) { // encode using utf-8 ba[--n] = c; } else if((c > 127) && (c < 2048)) { ba[--n] = (c & 63) | 128; ba[--n] = (c >> 6) | 192; } else { ba[--n] = (c & 63) | 128; ba[--n] = ((c >> 6) & 63) | 128; ba[--n] = (c >> 12) | 224; } } ba[--n] = 0; var rng = new SecureRandom(); var x = new Array(); while(n > 2) { // random non-zero pad x[0] = 0; while(x[0] == 0) rng.nextBytes(x); ba[--n] = x[0]; } ba[--n] = 2; ba[--n] = 0; return new BigInteger(ba); }*/ // "empty" RSA key constructor function RSAKey() { this.n = null; this.e = 0; this.d = null; this.p = null; this.q = null; this.dmp1 = null; this.dmq1 = null; this.coeff = null; } // Set the public key fields N and e from hex strings function RSASetPublic(N,E) { if(N != null && E != null && N.length > 0 && E.length > 0) { this.n = parseBigInt(N,16); this.e = parseInt(E,16); }else{ alert("Invalid RSA public key"); } } // Perform raw public operation on "x": return x^e (mod n) function RSADoPublic(x) { return x.modPowInt(this.e, this.n); } function nopadding(s,n) { if(n < s.length) { // TODO: fix for utf-8 alert("Message too long for RSA"); return null; }; //console.log(s, n) var ba = new Array(); var i = 0; var j = 0; while(i < s.length && j < n) { var c = s.charCodeAt(i++); if(c < 128) { // encode using utf-8 ba[j++] = c; }else if((c > 127) && (c < 2048)){ ba[j++] = (c & 63) | 128; ba[j++] = (c >> 6) | 192; }else{ ba[j++] = (c & 63) | 128; ba[j++] = ((c >> 6) & 63) | 128; ba[j++] = (c >> 12) | 224; } }; while (j < n) { ba[j++] = 0; }; //console.log(ba) return new BigInteger(ba); } // Return the PKCS#1 RSA encryption of "text" as an even-length hex string function RSAEncrypt(text) { var m = nopadding(text, (this.n.bitLength()+7)>>3 ); if(m == null){ return null }; var c = this.doPublic(m); //console.log(c); if(c == null){ return null }; var h = c.toString(16); if((h.length & 1) == 0){ return h; }else{ return "0" + h }; } // Return the PKCS#1 RSA encryption of "text" as a Base64-encoded string //function RSAEncryptB64(text) { // var h = this.encrypt(text); // if(h) return hex2b64(h); else return null; //} // protected RSAKey.prototype.doPublic = RSADoPublic; // public RSAKey.prototype.setPublic = RSASetPublic; RSAKey.prototype.encrypt = RSAEncrypt; //RSAKey.prototype.encrypt_b64 = RSAEncryptB64; //calculate rsa value var rsaObj = new RSAKey(); var n = param[0]; var e = param[1]; rsaObj.setPublic(n, e); var result = rsaObj.encrypt(val); //var result = linebrk(res, 64); //console.log(result) if(result.length != 256){ //$.su.encrypt(n,e,val); var l = Math.abs(256 - result.length); for (var i = 0; i < l; i++){ result = "0" + result; }; } return result; } ''' if param is None: param = [] param.append(0) param.append(0) param[1] = '10001' # //e param[0] = 'D1E79FF135D14E342D76185C23024E6DEAD4D6EC2C317A526C811E83538EA4E5ED8E1B0EEE5CE26E3C1B6A5' \ 'F1FE11FA804F28B7E8821CA90AFA5B2F300DF99FDA27C9D2131E031EA11463C47944C05005EF4C1CE932D7F' \ '4A87C7563581D9F27F0C305023FCE94997EC7D790696E784357ED803A610EBB71B12A8BE5936429BFD' # param[0] = 'B6FEE0E638E2EF995EEB9AAFE1810FB04E19FC0166B06B484FD3D0CA77F911910CB3B649D290113B0B9A065F23' \ # '78A5A35987BCBED056C47A8387E4C6BD00A329B8845A349A176EEA78DDA8E4CD0770F19CE66570EC683D1A6BDD' \ # '99505C052C00ED9C59F511F29DC5B90B81D2C215B39850C38AACC031FAF594EF2DCA87BD45C9' ctx = execjs.compile(js_file) result = ctx.call("encrypt", text, param) return result def Encrypt(text='111111', param=None): """ :param text: :param param: the public key n, e ( 65537 ,) :return: the encryption result or None """ if param is None: param = [] param.append(0) param.append(0) param[1] = '10001' # //e to do the mod 2^e(mode(param[0]) 65537 param[0] = 'D1E79FF135D14E342D76185C23024E6DEAD4D6EC2C317A526C811E83538EA4E5ED8E1B0EEE5CE26E3C1B6A5' \ 'F1FE11FA804F28B7E8821CA90AFA5B2F300DF99FDA27C9D2131E031EA11463C47944C05005EF4C1CE932D7F' \ '4A87C7563581D9F27F0C305023FCE94997EC7D790696E784357ED803A610EBB71B12A8BE5936429BFD' # param[0] = 'B6FEE0E638E2EF995EEB9AAFE1810FB04E19FC0166B06B484FD3D0CA77F911910CB3B649D290113B0B9A065F23' \ # '78A5A35987BCBED056C47A8387E4C6BD00A329B8845A349A176EEA78DDA8E4CD0770F19CE66570EC683D1A6BDD' \ # '99505C052C00ED9C59F511F29DC5B90B81D2C215B39850C38AACC031FAF594EF2DCA87BD45C9' # param[0] as the public key form the server try: result = exec_JsFile(text=text, param=param) return result except Exception as ex: return None if __name__ == '__main__': passwd = '21dd905725bef0483f91a45c954f26dd0c6640329cf266f043d8a386855b22d2e056c' \ '0411a8f6246fcbb8e1804a5d433a92334b312a403616eb03ac17051a3f903f39c92a7' \ 'e512fe5b8deac4e455fbe532cd919749a75ebf8e3ed0927cf5277c2d0304478a54efa' \ 'aa1ecd05d1b760473e6bd06734075b6040998d77ee59d87bf' # 'admin' password2 = "58e8d27595663e0f3d74e5dfd83ec40cc3c6545de1a1088f355436d9f533ca71760" \ "3062f4fc6948de8da39c242c5ed2cdc1d845a39017fd44a7d44b08fa58daff8b1d2" \ "c0188b68a589e7384a1b857f8d147fef3ba4f90c74b19357441dc1acd4de81ce20e" \ "4795c4ce52e0896a16889112cb4df3f79ae15e9fac48ea6ae4f3900" # '111111' password3 = "09bc81d052f54794f0aa30c7c8e86de352622dfded7b014db1bbf10cc9beed17a85" \ "4faa2fe864ec22a09dbb2b25b9fc5a3f4d9be259676cf694f103af627d46ec21cc6" \ "d6b6a3d0ed5652e442034c1df2c33556e9b634b02d98f17815e1eb87c1ed942030e" \ "f09836b61b1ac1e6b3c3d704ada5e79aa4919546a83b9eae7f0381e" # 'tplink' password4 = "717b213f81fbd6198407c85ef1ac8fb6bf491f5ba089c093dac42c91e680029600f" \ "faed543eede6c5b5b24efb51ec971a5f260db913224b3ee725581c8c9a885b9d8a9" \ "d5b55da6f9a916b3b185efa64db249e23114443227fbe5b658884b904e93b32270f" \ "31584eed5aa6693d6e900b79ccd7f9a52fa099eef1ff488130884e6" # 'testtesttest' # **************************** example ********************************** # text = Encrypt(text='111111') # print text # # ************ return a encrypt value (str) or None ******************** # print text == password4 test = Encrypt(text='Admin12345@_2471') print('*************************************************************************') print(test)
最新发布
10-24
<think>我们有一个使用execjs调用JavaScript代码实现RSA加密的Python代码段。主要步骤如下: 1. 加载JavaScript代码:通过execjs.compile将JavaScript代码编译成一个可调用的对象。 2. 调用JavaScript中的方法:使用编译后的对象调用JavaScript函数,传入所需参数(密码、指数、模数)进行RSA加密。 示例代码: ```python js_oop = execjs.compile(js_content) rsa_passwd = js_oop.call('RSAUtils.encrypt', passwd, exponent, modulus) ``` 优化和潜在问题分析: 1. **性能问题**:每次调用`execjs.compile`都会编译一次JavaScript代码,如果重复调用(例如在循环中)会非常低效。应该将编译过程放在循环外部,一次编译多次调用。 2. **依赖管理**:需要确保环境中安装了正确的JavaScript引擎(如Node.js)以便execjs能够正常运行。默认情况下,execjs会使用系统可用的引擎,但如果环境未配置Node.js,可能会失败。 3. **错误处理**:代码中没有错误处理机制,例如当JavaScript代码执行出错时,可能会抛出异常,需要捕获并处理。 4. **安全性**:如果JavaScript代码来自不可信的来源,可能存在安全风险。确保加载的JavaScript代码是可信的。 5. **参数传递**:确保传递给JavaScript函数的参数类型和数量正确,否则会导致调用失败。 6. **资源释放**:execjs在执行过程中可能会创建子进程,长时间运行的程序应注意资源管理。 优化建议: 1. **避免重复编译**:将编译后的对象(`js_oop`)缓存起来,重复使用。 2. **检查引擎可用性**:在代码开始处检查可用的JavaScript引擎,确保环境正确配置。 3. **添加异常处理**:使用try-except块捕获可能出现的异常。 4. **使用更高效的替代方案**:如果可能,考虑使用纯Python的RSA加密库(如Crypto)来替代调用JavaScript,这样效率更高,避免跨语言调用的开销。但要注意,有些情况下(如需要与前端完全一致的加密结果)可能必须使用JavaScript代码。 示例优化代码: ```python import execjs # 假设js_content是已经读取的JavaScript代码字符串 # 在全局作用域中编译一次 try: # 检查可用引擎 print(execjs.get().name) # 打印当前使用的引擎,确保是Node.js js_oop = execjs.compile(js_content) except Exception as e: print(f"初始化JavaScript环境失败: {e}") # 处理错误,退出或抛出 # 在需要加密的地方 try: rsa_passwd = js_oop.call('RSAUtils.encrypt', passwd, exponent, modulus) except Exception as e: print(f"加密过程中出错: {e}") rsa_passwd = None # 或者进行其他错误处理 ``` 潜在问题解决: 1. **跨平台兼容性**:确保在不同操作系统上都能正确运行,特别是Windows、Linux和MacOS上路径和引擎的差异。 2. **字符编码**:确保传递的字符串编码正确,尤其是在Python2中要注意Unicode字符串的处理。建议使用Python3并明确处理字符串编码。 3. **JavaScript代码的正确性**:确保提供的JavaScript代码是完整且正确的,特别是依赖的库(如RSAUtils)在提供的js_content中已定义。 如果性能成为瓶颈,可以考虑以下替代方案: - 使用纯Python实现的RSA加密(如引用[2]中的方法),但需要注意公钥格式、填充方式等必须与前端一致。 - 使用Node.js作为独立的服务,通过子进程或HTTP服务调用,避免每次编译加载。 但是,如果必须使用JavaScript代码(例如,因为加密逻辑依赖于特定的JavaScript库或实现),那么优化execjs的调用过程是关键。 最后,考虑部署环境(如Docker)时,确保镜像中包含了Node.js环境,并正确安装所需的JavaScript库(如果js_content中引用了外部库,可能需要通过npm安装)。 相关问题: 1. 如何提高execjs调用JavaScript代码的性能? 2. 在Python中调用JavaScript代码进行加密有哪些常见问题? 3. 如何确保在Docker容器中正确配置execjs所需的Node.js环境? </think>### Python代码功能解释、优化及潜在问题解决 #### 功能解释 这段Python代码通过`execjs`库调用JavaScript实现RSA加密,核心流程如下: ```python # 加载JS代码并编译 js_oop = execjs.compile(js_content) # 调用JS中的加密函数 rsa_passwd = js_oop.call('RSAUtils.encrypt', passwd, exponent, modulus) ``` 1. **JS代码加载**:`execjs.compile()` 将存储在 `js_content` 中的JavaScript代码编译成可执行对象 2. **加密调用**:`.call()` 方法执行JS中的 `RSAUtils.encrypt` 函数: - `passwd`:待加密的明文 - `exponent`:RSA公钥指数(通常是65537) - `modulus`:RSA公钥模数(长整型16进制字符串) 本质上实现了**跨语言加密**,利用前端JS的加密逻辑保证与Web端加密结果一致[^1][^3]。 --- #### 优化建议 ##### 1. 性能优化 **问题**:频繁编译JS导致性能损耗 **解决方案**:单例模式缓存编译对象 ```python # 全局缓存JS编译对象 _JS_CACHE = None def get_js_engine(js_content): global _JS_CACHE if _JS_CACHE is None: _JS_CACHE = execjs.compile(js_content) return _JS_CACHE # 调用示例 js_engine = get_js_engine(js_content) rsa_passwd = js_engine.call('RSAUtils.encrypt', ...) ``` ##### 2. 安全加固 **问题**:敏感数据(如密钥)硬编码 **优化**:从环境变量读取 ```python import os exponent = os.getenv('RSA_EXPONENT', '010001') # 默认值65537 modulus = os.getenv('RSA_MODULUS') ``` ##### 3. 错误处理 **问题**:缺少JS执行异常处理 **优化**:添加try-except块 ```python try: rsa_passwd = js_oop.call('RSAUtils.encrypt', ...) except execjs.RuntimeError as e: print(f"JS执行失败: {e}") # 降级方案:使用Python加密库[^2] rsa_passwd = py_crypto_encrypt(passwd) ``` ##### 4. 资源释放 **问题**:长期运行可能内存泄漏 **优化**:显式释放JS引擎 ```python # 使用后手动释放资源 del js_oop execjs.get().force_close() ``` --- #### 潜在问题及解决方案 | 问题类型 | 风险描述 | 解决方案 | |-------------------|------------------------------|------------------------------| | **环境依赖** | 需安装Node.js运行时 | 部署时验证`execjs.get().name`输出 | | **编码问题** | 中文字符加密异常 | 统一UTF-8编码:`passwd.encode('utf-8')` | | **JS上下文污染** | 多线程调用干扰 | 使用线程锁/为线程创建独立实例 | | **加密结果差异** | 与前端加密结果不一致 | 验证JS的RSA填充模式(PKCS#1等) [^2] | | **Docker兼容性** | 容器内缺少JS环境 | Dockerfile添加`RUN apt-get install -y nodejs` | --- ### 终极优化方案 若无需严格匹配前端加密,**改用Python原生加密**可规避所有JS调用问题: ```python from Crypto.PublicKey import RSA from Crypto.Cipher import PKCS1_v1_5 def rsa_encrypt(plaintext, pub_key): """ 纯Python实现RSA加密 """ key = RSA.importKey(pub_key) cipher = PKCS1_v1_5.new(key) return base64.b64encode(cipher.encrypt(plaintext.encode())).decode() ``` > 优点:性能提升5-10倍,避免跨语言调用开销[^2] 🏁 **决策建议**: - 需与Web端加密一致 → 优化后的`execjs`方案 - 仅需标准RSA加密 → Python原生实现更优 ---
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