1.题目需要下载一个压缩包，解压之后得到题目描述如下
Math is cool! Use the RSA algorithm to decode the secret message, c, p, q, and e are parameters for the RSA algorithm. p = 9648423029010515676590551740010426534945737639235739800643989352039852507298491399561035009163427050370107570733633350911691280297777160200625281665378483 q = 11874843837980297032092405848653656852760910154543380907650040190704283358909208578251063047732443992230647903887510065547947313543299303261986053486569407 e = 65537 c = 83208298995174604174773590298203639360540024871256126892889661345742403314929861939100492666605647316646576486526217457006376842280869728581726746401583705899941768214138742259689334840735633553053887641847651173776251820293087212885670180367406807406765923638973161375817392737747832762751690104423869019034 Use RSA to find the secret message
2.一开始我想到了用rsa算法工具，但是发现有些参数在工具中用不到，因此只能放弃工具，接下来就可以利用代码编写来实现
3.在pycharm中运行如下代码即可拿到flag
from gmpy2 import invert p = 9648423029010515676590551740010426534945737639235739800643989352039852507298491399561035009163427050370107570733633350911691280297777160200625281665378483 q = 11874843837980297032092405848653656852760910154543380907650040190704283358909208578251063047732443992230647903887510065547947313543299303261986053486569407 e = 65537 c = 83208298995174604174773590298203639360540024871256126892889661345742403314929861939100492666605647316646576486526217457006376842280869728581726746401583705899941768214138742259689334840735633553053887641847651173776251820293087212885670180367406807406765923638973161375817392737747832762751690104423869019034 n = p * q y = (p - 1) *(q - 1) d = invert(e, y) flag = pow(c, d, n) print(flag)
4.代码的解释如下
from gmpy2 import invert：这一行导入了 gmpy2 模块中的 invert 函数，用于计算模反函数。
e是指数的意思
c是密文
pow(c，d，n)是c和d的乘积模上n
d = invert(e, y)：这一行使用 invert 函数计算 e 在模 y 下的逆元，即私钥中的指数。
5.最终flag
flag{5577446633554466577768879988}
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