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  • Given d and e, factorize N to attack RSA

    题目如下:

    RSA算法的使用一般要求每个不同的用户有一个独立的模数N。有天,Bob脑洞大开,认为似乎没有必要这样做。只需要一个模数N,然后给不同的用户分发不同的e和d就好了。可惜这种做法有严重的安全漏洞。

    给定Alice的公钥(e1,N),Adv为了破解Alice的密文,他也注册一个公私钥对,得到(e2, d2, N),然后他就可以巧妙地计算出Alice的解密私钥。注意:Adv得到的私钥不一定与Alice的相同,只是它确实可以解密。

    (e1 =

    44379563805854841580307748547737435172564831877127303051909203409873174780389273150966396080375621148040275710628408649117613085199533826455458312376264659153842853015345496268736337902730232293424031775369541079662258443836020140399047886828048837071536578243295077689245549921524765222192270061081366989243

    N = 

    188115669939527035644766943794256836704505079895306601119938518634078379404429524926183546093986493443422022468844644307633083886388295943602507953702360632321739073592477683222131866451975315695813478098524853358977564134499058448438525811837376172990710150323209055804682074564005014776547535959114226010493

    (e2 =

    112465763139808984065405993827008716763974555200543206549100182421914260511395374512318119557311872118857352370325610769529155517454000609905909538235321637165438962672069969201523246380106126889874030417878823876408727390390051948217715186480658609481138938023687641185709391304878382079926539531855678365763

     d2 =

    55881649455902117785162844948995531081646760354831350250450328774662614334096209227124014992837725793190883247171284132768863157972472923057215962250425474753160669444247876851199006665484502793278672692761545198268608005712388135980371518592854149756626148424994498979112285655516912703587302199972664162731

     N = 

    188115669939527035644766943794256836704505079895306601119938518634078379404429524926183546093986493443422022468844644307633083886388295943602507953702360632321739073592477683222131866451975315695813478098524853358977564134499058448438525811837376172990710150323209055804682074564005014776547535959114226010493

    )

    求解(e1, N)加密得到的密文(没有编码,是一个整数):

    166834578157098529809222592291594342260836191039081705782260506690911922650094691879568641873546447862853989518762075081785381252999566333779425586950217410876199240677942391128773211264433855236931134494842223272683014826519273429450763047329625425561073729238027952900168036140503255431512655421527963913597

    请解释过程,给出明文及其解密用的私钥。

    一开始想,给定的N相同,是不是共模攻击,看并不满足共模攻击的条件

    后来看到一篇博客(http://jackyc.top/2018/10/27/RSA-3/#more),里面有个参考文档(https://www.di-mgt.com.au/rsa_factorize_n.html),看完后知道原来知道(e,d,N)可以分解N,但是原理还不是很理解

    找到了一个PDF,里面有原理的讲解,不过里面有些小地方和我的理解有出入,要么我错了,要么PDF出现小错误,最后还是按自己的理解和各种参考资料用python写了一下

    e1 = 44379563805854841580307748547737435172564831877127303051909203409873174780389273150966396080375621148040275710628408649117613085199533826455458312376264659153842853015345496268736337902730232293424031775369541079662258443836020140399047886828048837071536578243295077689245549921524765222192270061081366989243
    N = 188115669939527035644766943794256836704505079895306601119938518634078379404429524926183546093986493443422022468844644307633083886388295943602507953702360632321739073592477683222131866451975315695813478098524853358977564134499058448438525811837376172990710150323209055804682074564005014776547535959114226010493
    e2 = 112465763139808984065405993827008716763974555200543206549100182421914260511395374512318119557311872118857352370325610769529155517454000609905909538235321637165438962672069969201523246380106126889874030417878823876408727390390051948217715186480658609481138938023687641185709391304878382079926539531855678365763
    d2 = 55881649455902117785162844948995531081646760354831350250450328774662614334096209227124014992837725793190883247171284132768863157972472923057215962250425474753160669444247876851199006665484502793278672692761545198268608005712388135980371518592854149756626148424994498979112285655516912703587302199972664162731
    c = 166834578157098529809222592291594342260836191039081705782260506690911922650094691879568641873546447862853989518762075081785381252999566333779425586950217410876199240677942391128773211264433855236931134494842223272683014826519273429450763047329625425561073729238027952900168036140503255431512655421527963913597
    
    from random import randint
    import gmpy2
    def oddR(r):
        while r%2==0:
            r=r//2
        return r
        
    def bits(b):
        k=[]
        while b:
            if b%2!=0:
                k.append(1)
            else:
                k.append(0)
            b>>=1
        k.reverse()      #对于List等Sequence等类型的变量,比如此处的List变量,其内置函数reverse,是直接操作变量本身,调用reverse后,变量本身的值就是reverse后的值了,所以不能出现:kk=k.reverse()这样的操作
        return k
        
    def quickmod(a,b,n):      #a^b mod n 快速幂模n运算
        f=1
        k=bits(b)
        for i in range(len(k)):
            f=(f*f)%n
            if k[i]:
                f=(f*a)%n
        return f
    
    def gcd(m,n):
        while(n!=0):
            m,n=n,m%n
        return m
    
    def func(e,d,N):
        k=e*d-1             #k是一个even number
        r=oddR(k)           #求出k=2^t*r中的r
        
        while True:
            b=randint(2,N-1)    #获取区间(2,N-1)的一个随机数
            a=quickmod(b,r,N)   #求解出b^r mod N的值
            if a==1:            #如果求得的a=1,则需要重新获取一个随机数b
                continue    
            y=gcd(a-1,N)
            if a>1 and y>1:     #a要大于1,
                q=N//y
                return q
            else:
                r=r*2         #如果不满足的话,b就平方 a0 = br, a1 = (a0)^2, a2 = (a1)^2,…, ak = (ak-1)^2
        
    #print(func(3,16971,25777))
    def deciphering(e1,e2,d,N,c):    #e1用来求解p和q,e2用来求解e2*d=1 (mod)
        p=func(e1,d,N)
        q=N//p
        phi=N-(p+q)+1          #N和phi之间的关系
        
        d=gmpy2.invert(e2,phi)    #得到e2对应的私钥d
        m=gmpy2.powmod(c,d,N)
        return d,m
    
    d,m=deciphering(e2,e1,d2,N,c)
    print("The private key is:",d)
    print("The message is:",m)    
    View Code

    结果:

    明文为:131

    密钥为:72818963105077629740558410461847080457967247911531271148355717844840007560618118158503931879141520737129717539191898962908710378608064897528018640573684648011556192613882739251759874374669201358126911422986850885586463283920904391451268159684723197972233648239891580239064904439566608991520126027809037410483

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  • 原文地址:https://www.cnblogs.com/Guhongying/p/10148996.html
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