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RSA(中国剩余定理)

November 15, 2020 • Read: 638 • CTF阅读设置

题目:RSA-e与φ(n)不互素时
n1=0xcfc59d54b4b2e9ab1b5d90920ae88f430d39fee60d18dddbc623d15aae645e4e50db1c07a02d472b2eebb075a547618e1154a15b1657fbf66ed7e714d23ac70bdfba4c809bbb1e27687163cb09258a07ab2533568192e29a3b8e31a5de886050b28b3ed58e81952487714dd7ae012708db30eaf007620cdeb34f150836a4b723L
e1=0xfae3aL
c1=0x81523a330fb15125b6184e4461dadac7601340960840c5213b67a788c84aecfcdc3caf0bf3e27e4c95bb3c154db7055376981972b1565c22c100c47f3fa1dd2994e56090067b4e66f1c3905f9f780145cdf8d0fea88a45bae5113da37c8879c9cdb8ee9a55892bac3bae11fbbabcba0626163d0e2e12c04d99f4eeba5071cbeaL
n2=0xd45304b186dc82e40bd387afc831c32a4c7ba514a64ae051b62f483f27951065a6a04a030d285bdc1cb457b24c2f8701f574094d46d8de37b5a6d55356d1d368b89e16fa71b6603bd037c7f329a3096ce903937bb0c4f112a678c88fd5d84016f745b8281aea8fd5bcc28b68c293e4ef4a62a62e478a8b6cd46f3da73fa34c63L
e2=0x1f9eaeL
c2=0x4d7ceaadf5e662ab2e0149a8d18a4777b4cd4a7712ab825cf913206c325e6abb88954ebc37b2bda19aed16c5938ac43f43966e96a86913129e38c853ecd4ebc89e806f823ffb802e3ddef0ac6c5ba078d3983393a91cd7a1b59660d47d2045c03ff529c341f3ed994235a68c57f8195f75d61fc8cac37e936d9a6b75c4bd2347L
assert pow(flag,e1,n1)==c1
assert pow(flag,e2,n2)==c2
assert gcd(e1,(p1-1)*(q1-1))==14
assert gcd(e2,(p2-1)*(q2-1))==14

0x表示16进制,最后L表示为long型

WP:
import libnum
from Crypto.PublicKey import RSA
from Crypto.Cipher import PKCS1_OAEP
import gmpy2

n1=0xcfc59d54b4b2e9ab1b5d90920ae88f430d39fee60d18dddbc623d15aae645e4e50db1c07a02d472b2eebb075a547618e1154a15b1657fbf66ed7e714d23ac70bdfba4c809bbb1e27687163cb09258a07ab2533568192e29a3b8e31a5de886050b28b3ed58e81952487714dd7ae012708db30eaf007620cdeb34f150836a4b723
e1=0xfae3a
c1=0x81523a330fb15125b6184e4461dadac7601340960840c5213b67a788c84aecfcdc3caf0bf3e27e4c95bb3c154db7055376981972b1565c22c100c47f3fa1dd2994e56090067b4e66f1c3905f9f780145cdf8d0fea88a45bae5113da37c8879c9cdb8ee9a55892bac3bae11fbbabcba0626163d0e2e12c04d99f4eeba5071cbea
n2=0xd45304b186dc82e40bd387afc831c32a4c7ba514a64ae051b62f483f27951065a6a04a030d285bdc1cb457b24c2f8701f574094d46d8de37b5a6d55356d1d368b89e16fa71b6603bd037c7f329a3096ce903937bb0c4f112a678c88fd5d84016f745b8281aea8fd5bcc28b68c293e4ef4a62a62e478a8b6cd46f3da73fa34c63
e2=0x1f9eae
c2=0x4d7ceaadf5e662ab2e0149a8d18a4777b4cd4a7712ab825cf913206c325e6abb88954ebc37b2bda19aed16c5938ac43f43966e96a86913129e38c853ecd4ebc89e806f823ffb802e3ddef0ac6c5ba078d3983393a91cd7a1b59660d47d2045c03ff529c341f3ed994235a68c57f8195f75d61fc8cac37e936d9a6b75c4bd2347

p=libnum.gcd(n1,n2)
q1=gmpy2.mpz(n1//p)
q2=gmpy2.mpz(n2//p)#注意要用//整除不然计算出的结果会有误
fn1=(p-1)*(q1-1)
fn2=(p-1)*(q2-1)
e1=gmpy2.mpz(e1//14)
e2=gmpy2.mpz(e2//14)
d1 = gmpy2.invert(e1,fn1)
d2 = gmpy2.invert(e2,fn2)

m1=pow(c1,d1,n1)
m2=pow(c2,d2,n2)
c=libnum.solve_crt([m1,m1,m2],[p,q1,q2])#求解中国剩余定理

#print(libnum.gcd(14,(q1-1)*(q2-1)))
#由于存在公约数2,所以整个问题就化简为了e=7,c=...,n=...的新问题
e=7
n=q1*q2
fn=(q1-1)*(q2-1)
d=gmpy2.invert(e,fn)
m=pow(c,d,n)
t=gmpy2.iroot(m, 2)[0]
print(libnum.n2s(t))
Last Modified: November 9, 2021