🎬决赛
回文
1、题目信息
=QfzEDO4YDNlBzN4gzN0YGM1QzYyUGZ3QDZzgDM7V2Sn52bI52Q=2、解题方法
base64解码，两种思路：
要么是去掉前面=号解码
QfzEDO4YDNlBzN4gzN0YGM1QzYyUGZ3QDZzgDM7V2Sn52bI52Q=要么去掉后面=号再翻转一下解码
Q25Ib25nS2V7MDgzZDQ3ZGUyYzQ1MGY0Nzg4NzBlNDY4ODEzfQ=显然试过后发现第二种是对的
CnHongKe{083d47de2c450f478870e468813}RSA2
1、题目信息
from Crypto.Util.number import*
import random
from gmpy2 import gcd ,invert
import os,random
from functools import reduce
flag = 'flag{*****}'
nbit = 2048
pbit = 658
qbit = nbit-pbit
def GCRT(mi, ai):
assert (isinstance(mi, list) and isinstance(ai, list))
curm, cura = mi[0], ai[0]
for (m, a) in zip(mi[1:], ai[1:]):
d = gcd(curm, m)
c = a - cura
assert (c % d == 0)
K = c / d * invert(curm / d, m / d)
cura += curm * K
curm = curm * m / d
return (cura % curm, curm)
def genkey():
p = getPrime(pbit)
q = getPrime(qbit)
assert(gcd(p-1,(q-1)//2) != 1 and q >= int(pow(p*q,qbit//nbit)))
n = p*q
while 1:
dp,dq = random.getrandbits(50), getPrime(50)
d = GCRT([p-1,q-1],[dp,dq])[0]
if(gcd(d, (p-1)*(q-1)) == 1):
break
e = invert(d,(p-1) * (q-1))
return n,e
n,e= genkey()
flag = flag + os.urandom(40)
flag = bytes_to_long(flag)
assert(flagprint n
#24520888125100345615044288264230762903878924272518571342713995342063192899124989891699091460914318368533612522321639660343147487234147817765379565866063142022911783047710228071012334390251457138278189863078398353697056081286846816500611712981402958876560909958985941278622099006464269427107124576069124593580390423932176305639686809675964840679026457045269910781753881177055233058940084858058581167930068081780478893848660425039669034700316924547379360271738374641525963541506226468912132334624110432284070298157810487695608530792082901545749959813831607311669250447276755584806773237811351439714525063949561215550447
print e
#11548167381567878954504039302995879760887384446160403678508673015926195316468675715911159300590761428446214638046840120602736300464514722774979925843178572277878822181099753174300465194145931556418080206026501299370963578262848611390583954955739032904548821443452579845787053497638128869038124506082956880448426261524733275521093477566421849134936014202472024600125629690903426235360356780817248587939756911284609010060687156927329496321413981116298392504514093379768896049697560475240887866765045884356249775891064190431436570827123388038801414013274666867432944085999838452709199063561463786334483612953109675470299
print pow(flag,e,n)
#7903942109284616971177039757063852086984176476936099228234294937286044560458869922921692962367056335407203285911162833729143727236259599183118544731181209893499971239166798975272362502847869401536913310597050934868114362409772188138668288760287305966467890063175096408668396691058313701210130473560756912616590509776003076415730640467731466851294845080825312579944440742910769345079740436037310725065646739277834041891837233390010487460412084089630786396822488869754420904734966722826157548254882580507819654527378643632759059506306290252851428488883937359516531613654502801727220504711666666550673928496325962262842 2、解题方法
这个题还是很难的，从大佬那里学到的方法。。。。
首先观察d的产生方式，而且发现p,q相差很大，因此想到Cryptanalysis of Unbalanced RSA with Small CRT-Exponent
这里讲了公私钥的产生方式，有个疑惑的点是论文里说了p-1和（q-1）/2must be coprime（互素），但是题目附件中
不是这样的。why？
然后网上搜索一番后找到了lazzzaro大神的脚本：https://lazzzaro.github.io/2020/05/06/crypto-RSA/index.html
#sage
N=
e=
n = 12 # 或n=5
beta = 0.32 # beta = 0.3212890625
delta = 0.02 # delta = 0.0244140625
X = int(N ** delta*(n+1)/2)
Y = int(N ** (delta + beta)*(n+1)/2)
def C(a,b):
ret=1
for i in range(b):
ret*=(a-i)
ret/=(b-i)
return ret
def get_Matrix(n,m):
MM=[[0 for __ in range(n)] for _ in range(n)]
for j in range(n):
pN=max(0,m-j)
for i in range(j+1):
MM[j][i]=pow(N,pN)*pow(X,n-i-1)*pow(Y,i)*pow(e,j-i)*C(j,i)*pow(-1,i)
MM=Matrix(ZZ,MM)
return MM
M=get_Matrix(n,n//2+1)
L=M.LLL()[0]
x,y = var('x'),var('y')
f=0
for i in range(n):
f+=x**(n-i-1) * y**i * (L[i] // pow(X,n-i-1) // pow(Y,i))#将x,y参数化
print(f.factor())参数beta：
参数delta：
参数n：n为格子的维度，大佬用下面的式子计算出n，对于本题来说，求得的n=3.408695
但是实际用脚本的过程中，发现n=4并不能得到想要的结果，n=5可能是一个最低值
beta =
delta =
n = round((1-2*beta-2*delta)/((1-beta)^2-2*delta-beta),6)
m = (1-beta)*n
print(m,n)结果得到：
...(603601239605461619719962824215850028370828276194986402520006784945171666555162381560306067089554862768237542295127706223128204911327713581268000464342787657534895446276895456449104343518846054862311913534953258511*x + 1115967702502739*y)从后往前， 第一个是dp，第二个是k
然后利用这两个式子求p
exp：
from Crypto.Util.number import *
import gmpy2
k = 603601239605461619719962824215850028370828276194986402520006784945171666555162381560306067089554862768237542295127706223128204911327713581268000464342787657534895446276895456449104343518846054862311913534953258511
dp = 1115967702502739
n = 24520888125100345615044288264230762903878924272518571342713995342063192899124989891699091460914318368533612522321639660343147487234147817765379565866063142022911783047710228071012334390251457138278189863078398353697056081286846816500611712981402958876560909958985941278622099006464269427107124576069124593580390423932176305639686809675964840679026457045269910781753881177055233058940084858058581167930068081780478893848660425039669034700316924547379360271738374641525963541506226468912132334624110432284070298157810487695608530792082901545749959813831607311669250447276755584806773237811351439714525063949561215550447
e = 11548167381567878954504039302995879760887384446160403678508673015926195316468675715911159300590761428446214638046840120602736300464514722774979925843178572277878822181099753174300465194145931556418080206026501299370963578262848611390583954955739032904548821443452579845787053497638128869038124506082956880448426261524733275521093477566421849134936014202472024600125629690903426235360356780817248587939756911284609010060687156927329496321413981116298392504514093379768896049697560475240887866765045884356249775891064190431436570827123388038801414013274666867432944085999838452709199063561463786334483612953109675470299
c = 7903942109284616971177039757063852086984176476936099228234294937286044560458869922921692962367056335407203285911162833729143727236259599183118544731181209893499971239166798975272362502847869401536913310597050934868114362409772188138668288760287305966467890063175096408668396691058313701210130473560756912616590509776003076415730640467731466851294845080825312579944440742910769345079740436037310725065646739277834041891837233390010487460412084089630786396822488869754420904734966722826157548254882580507819654527378643632759059506306290252851428488883937359516531613654502801727220504711666666550673928496325962262842
k = k + 1
p = (e * dp - 1) // k + 1
print(int(p).bit_length())
q = n // p
print(int(q).bit_length())
d = gmpy2.invert(e,(p-1)*(q-1))
m = pow(c,d,n)
print(long_to_bytes(int(m)))
#CnHongKe{1b35037a-a472-4e9c-bdba-768f7e84dd0e}根据
但是，这题不知道为什么k要加上1
总之，理解不太透彻，只能存下脚本了。。。
RSA3
1、题目信息
from Crypto.Util.number import *
from secret import flag
m = bytes_to_long(flag)
p1, q1 = getPrime(512), getPrime(512)
n1 = p1*q1
e = 65537
p2, q2 = getPrime(512), getPrime(512)
n2 = p2*q2
print(f'n1 = {n1}')
print(f'n2 = {n2}')
print(f'c1 = {pow(m,e,n2)}')
print(f'c2 = {pow(n1-m,e,n2)}')
# n1 = 52579135273678950581073020233998071974221658902576724000130040488018033110534210901239397446395736563148970863970460542205225993317478251099451639165369081820130823165642873594136020122857712288395352930384057524510346112486008850200845915783772351449146183974239444691330777565342525218070680067550270554767
# n2 = 68210568831848267339414957973218186686176324296418282565773310695862151827108036984694027795077376921170907068110296451176263520249799154781062517066423984526868547296781709439425857993705489037768605485740968600877866332458671029054092942851472208033494968784822459369206497698469167909174346042658361616469
# c1 = 42941712708129054668823891960764339394032538100909746015733801598044118605733969558717842106784388091495719003761324737091667431446354282990525549196642753967283958283202592037329821712755519455155110675327321252333824912095517427885925854391047828862338332559137577789387455868761466777370476884779752953853
# c2 = 627040432528616388953706748275598041846507086922277895328799415900389117998572328986923354297734808896240461677925738851259455113564560736884359119751610532315890199344271512309240049448472914341670679058031802071832098880822755831206334082327491193002005553278837194663491640621634593005189939520468737240052、解题方法
e太大了，对于Franklin攻击来说要跑很久，看到大佬WP后了解需要用到 half-gcd
参考文章：
脚本来源：
https://github.com/rkm0959/rkm0959_implements/blob/main/Half_GCD/code.sage
exp:
from Crypto.Util.number import *
import sys
def HGCD(a, b):
if 2 * b.degree() <= a.degree() or a.degree() == 1:
return 1, 0, 0, 1
m = a.degree() // 2
a_top, a_bot = a.quo_rem(x^m)
b_top, b_bot = b.quo_rem(x^m)
R00, R01, R10, R11 = HGCD(a_top, b_top)
c = R00 * a + R01 * b
d = R10 * a + R11 * b
q, e = c.quo_rem(d)
d_top, d_bot = d.quo_rem(x^(m // 2))
e_top, e_bot = e.quo_rem(x^(m // 2))
S00, S01, S10, S11 = HGCD(d_top, e_top)
RET00 = S01 * R00 + (S00 - q * S01) * R10
RET01 = S01 * R01 + (S00 - q * S01) * R11
RET10 = S11 * R00 + (S10 - q * S11) * R10
RET11 = S11 * R01 + (S10 - q * S11) * R11
return RET00, RET01, RET10, RET11
def GCD(a, b):
print(a.degree(), b.degree())
q, r = a.quo_rem(b)
if r == 0:
return b
R00, R01, R10, R11 = HGCD(a, b)
c = R00 * a + R01 * b
d = R10 * a + R11 * b
if d == 0:
return c.monic()
q, r = c.quo_rem(d)
if r == 0:
return d
return GCD(d, r)
sys.setrecursionlimit(500000)
e = 65537
n1 =
n2 =
c1 =
c2 =
R. = PolynomialRing(Zmod(n2))
f = x^e - c1
g = (n1 - x)^e - c2
res = GCD(f,g)
m = -res.monic().coefficients()[0]
print(m)
flag = long_to_bytes(int(m))
print(flag)
#CnHongKe{Fr4nkl1n_R31ter_4nd_gcD} GCD(f,g)返回ax-bM，a,b代表任意数字
用monic()使得上式变为x-M，再提取 M
RSA4
1、题目信息
from Crypto.Util.number import *
from os import *
from secret import flag
assert len(flag) <= 35
m = bytes_to_long(flag)
t = getPrime(32)
p = getPrime(512)
q = getPrime(512)
n = p * q
hint = ((t+q)**4+(t+q)**3+(t+q)**2+(t+q)+2023) % n
r = 11779674470989201650533406519886591289516202072957618550910646323186300227953911
c = pow(t,m,r)
print(c)
print(n)
print(hint)
# 6580860405834148836110773014414875358234621644983930335529135801623195480368832
# 139415227833650606627481949032630333904915784502498383402775795770352459104117035911044614539656661779065034631025979910419387363425628162982061251276669112098757186870838748231794731153245273066810769109396532311364451556967782895742561287251234088360088678874714586399626016737310602036235187097500522638791
# 436919096205145539073370847478776131257701809147255602316728221900470482686543230149098570871171015555508725816809760376736096450728166881794309211134111897756811862826529131022074734042673613388451282287501911288283479790582117931919117955389176875090921403311148672173147322257419630901581571189569583616672、解题方法
展开后发现
在Coppersmith下模n，会把q全部模完，所以可以直接求出t
hint = 43691909620514553907337084747877613125770180914725560231672822190047048268654323014909857087117101555550872581680976037673609645072816688179430921113411189775681186282652913102207473404267361338845128228750191128828347979058211793191911795538917687509092140331114867217314732225741963090158157118956958361667
n = 139415227833650606627481949032630333904915784502498383402775795770352459104117035911044614539656661779065034631025979910419387363425628162982061251276669112098757186870838748231794731153245273066810769109396532311364451556967782895742561287251234088360088678874714586399626016737310602036235187097500522638791
R. = PolynomialRing(Zmod(n))
f = x^4 + x^3 + x^2 + x + 2023 - hint
res = f.small_roots(X=2^32,beta=0.4)
print(res)
# res = [4000655279] 
发现m一直出不来
接着就是爆破k
exp:
from Crypto.Util.number import *
c = 6580860405834148836110773014414875358234621644983930335529135801623195480368832
n = 139415227833650606627481949032630333904915784502498383402775795770352459104117035911044614539656661779065034631025979910419387363425628162982061251276669112098757186870838748231794731153245273066810769109396532311364451556967782895742561287251234088360088678874714586399626016737310602036235187097500522638791
hint = 43691909620514553907337084747877613125770180914725560231672822190047048268654323014909857087117101555550872581680976037673609645072816688179430921113411189775681186282652913102207473404267361338845128228750191128828347979058211793191911795538917687509092140331114867217314732225741963090158157118956958361667
r = 11779674470989201650533406519886591289516202072957618550910646323186300227953911
R. = PolynomialRing(Zmod(n))
f = x^4 + x^3 + x^2 + x + 2023 - hint
res = f.small_roots(X=2^32,beta=0.4)
# print(res)
t = res[0]
# print(t)
t = 4000655279
m = discrete_log(mod(c,r),mod(t,r))
print(int(m).bit_length())
order = []
for i in factor(r-1):
if pow(t,(r-1)//i[0],r) == 1:
order.append(i[0])
# print(order)
# [2, 17]
phi = (r - 1) // 34
for k in range(2^22):
temp = m + k*phi
flag = long_to_bytes(temp)
try:
if len(flag.decode()) <= 35:
print(flag)
break
except:
continue
# CnHongKe{cp_smith_with_pollard_p-1} 🎬复赛
asr
1、题目信息
from Crypto.Util.number import *
from secret import flag
def genprime():
while True:
r = getRandomNBitInteger(64)
p = r**6 + 8*r**4 - 41*r**3 + 14*r**2 - 116*r + 31387
q = r**5 - 9*r**4 + 17*r**3 - 311*r**2 - 16*r + 14029
if isPrime(p) and isPrime(q):
return p, q
def enc(flag, n):
m = bytes_to_long(flag)
return pow(m, 31387, n)
p, q = genprime()
n = p * q
c = enc(flag, n)
print(n)
print(c)2、解题方法
把n开11次方，得到的r'会略大于或者略小于r
爆破一下
exp:
from Crypto.Util.number import *
import gmpy2
n = 73553176031506251642448229714220151174734540964434813056145000616720019024269982417494553771890010861489245572362590935764438928110836109730139595790550323300572059713433794357690270439325805603980903813396260703
c = 6035303231100318215656164353047198868742763055193754611914191674005776329646395050293747516587004104241717689072827492745628156828285466831779549229513115371571798719567117034735830671759951028004405762435531685
e = 31387
r = gmpy2.iroot(n,11)[0]
for i in range(100000):
p = r**6 + 8*r**4 - 41*r**3 + 14*r**2 - 116*r + 31387
q = r**5 - 9*r**4 + 17*r**3 - 311*r**2 - 16*r + 14029
r = r+1
if isPrime(p) and isPrime(q) and n==p*q:
print(p)
q = n // p
d = gmpy2.invert(e,(p-1)*(q-1))
m = pow(c,d,n)
print(long_to_bytes(m))
break
# b'CnHongKe{m0re_fuN_RSA!!!}'结果发现，只需要r+1就行了
脚本来源：2023 江苏领航杯
ezrsa
1、题目信息
from Crypto.Util.number import *
from gmpy2 import invert
#from secret import flag,e
e=11299
flag="CnHongKe{xxxxx}"
def enc(key, p):
e, n = key
cipher = [pow(ord(char), e, n) for char in p]
return cipher
def dec(pk, c):
key, n = pk
plain = [chr(pow(char, key, n)) for char in c]
return ''.join(plain)
p = getPrime(512)
q = getPrime(512)
n = p*q
pubkey = (e,n)
assert(e < 20000)
print("Public key:")
print(pubkey[1])
cipher = (enc(pubkey, flag))
print("Encrypted flag:")
print(cipher)
"""
n = 72247494519029483967034760366376786853061601103300157813759661775953565912596351092287547406601293830981872918918938736057259213906558022493243888210973589378711150746378675386713286364059548872717761789465830532496818860955952848759604076974545518597370294034234115061042965941759696027120414108241913315823
c = [23086568633766027889700149282556028601873588133389538577048220777519629053893020835596785887647597774272630671514043075789089166339490664485821551265008072526985961605709337174865785620861795518368806256695564549352791382917399957127324333828822855864895189216581775972150143373812919138450624070271563605781, 61424780590998716668669522879005833894226611068988736111090847848564952203683192799647992306556603909310758923465682857752771528865725336620979965796403804180726836508128298963907214867637490978049881021200499605597084724400813056262536028860369819412653602159130062278358850923752212354694875260742761085298, 48972347185727309580275811398968322398732292284718613286033964656750569533816676490768122129969818200823106363038086076716848785261859085349544695714346759435389253954398744742706972731080540025437559712419376172012608552755595256980994587437212314607911439680754158685958213442852345610886117149808132016667, 61900034054386621130587335874165191153789670659043111868368913383427388843553828977951515166753531254554889530123861241679942156133394477844988559568261609121966239636746106844585498882352452796587012169345091313195906669668187972481122815780919799898784783071380231308771760678158462462371463688337980966056, 61424780590998716668669522879005833894226611068988736111090847848564952203683192799647992306556603909310758923465682857752771528865725336620979965796403804180726836508128298963907214867637490978049881021200499605597084724400813056262536028860369819412653602159130062278358850923752212354694875260742761085298, 9450415868171579852265098054119152648200942770623210086786809222084784959844945630371248180007508011953947300816820109987312423346559505226253550792399518771112488858163511513111841198409634670818742944088825363946933893952656072580401498319136121912520261916028145167846733858193149171599064970439268199783, 10035734578627344969947375235594072983851319696847209997368331158831147669149961069031833471519627366504594153020437204571060611428623914456969214997923532068856482468179965518854707629794312716955250557912419773434419097161023559262564458848063915219346903480654597328232422644596377103117825829328614075690, 5651041338136387965270707005514495599960051787842260459297309665876049923224924292148523058126335232362070965833156272480917510429785778533039914573874120321092901286353688478193761623313802721160582545556066963078690764669931722358118104123077318311422846797054759255064946480668759913078778113387444436772, 14271259146328702790695772784067429851163342737347538777950741762508946650827944617931146968866218980425939274541815935964077603794848153188731356254177631333208035026728310408767228380734867744475231330055609453484352384922899766458129175972076865172633564831188088602907146780176603278159798710852150155253, 62406194652765011605245085350409728452067228284594736543030951188813141827047471129688563874017873401654027493958313799538667190622125421268982329762449606129199279688989354341511243792985075002044026442461088633434402762089223231979549393979184803396697173744411798858018768084174805247172995100258785744206, 63709385155465577684045832627013714734477675077145869296144855691101040965871249828804609100346204070983371062590273336734564969020068052618256509773408613924173909751351554561064586129837540954337160904415625404892669592986127801019807989827319368290273765648256480872195493742292667971088647173453059033806, 48977318868316177241868377840886234518379318740788414464335149639789241373564334219732049732484152649864293157598629604567238775720288389168177046142209467079549232009426147052416900999957014084019576693027561825654624690272350264451017869825303585254430358271190141844081570800201723992346171314406386674943, 48977318868316177241868377840886234518379318740788414464335149639789241373564334219732049732484152649864293157598629604567238775720288389168177046142209467079549232009426147052416900999957014084019576693027561825654624690272350264451017869825303585254430358271190141844081570800201723992346171314406386674943, 565104133813638796527070700551449559996005178784226045,
9297309665876049923224924292148523058126335232362070965833156272480917510429785778533039914573874120321092901286353688478193761623313802721160582545556066963078690764669931722358118104123077318311422846797054759255064946480668759913078778113387444436772, 3956140276099962408524811644378665260926195324627931125735919417604617330787900581903522720016806707086965650313838135840992580442876605474811383818108244966337270671303251812771008272858935652243561913687651063565007930291142413707811828393424201379693530423289355865533076364121921469892110296393354892615, 64940238786056387401400208343541494710106569145648776253264921960848871998112873944735053044143142466740886274718484463159497520574083206269832189589919893550520334911490391957266450195041949757369417242568602992393025242097901450113737739057611554182495438506865992404354942119595468005771945393932589768474, 64940238786056387401400208343541494710106569145648776253264921960848871998112873944735053044143142466740886274718484463159497520574083206269832189589919893550520334911490391957266450195041949757369417242568602992393025242097901450113737739057611554182495438506865992404354942119595468005771945393932589768474, 26352444581944643830963227423429946980811236174292159142870560906116668786800921081108266494217634934060542948019867625299869944900083383044563948756655507024025376518773098977036898176798319228360435941463124583821154981070698271384027340432620539761424919238056654209894138660851835259359180413998571510866, 40143952866342512113851528831224840428508359508863486720333430314639020044892359484055175960350878532212164045297142804890441825145732613460997839927190176844605217276182528040788352071676527553305037569493706223713078036314819975031692707790811142576347096406283580538840499698900522007082050790381461432333, 3956140276099962408524811644378665260926195324627931125735919417604617330787900581903522720016806707086965650313838135840992580442876605474811383818108244966337270671303251812771008272858935652243561913687651063565007930291142413707811828393424201379693530423289355865533076364121921469892110296393354892615, 64940238786056387401400208343541494710106569145648776253264921960848871998112873944735053044143142466740886274718484463159497520574083206269832189589919893550520334911490391957266450195041949757369417242568602992393025242097901450113737739057611554182495438506865992404354942119595468005771945393932589768474, 63709385155465577684045832627013714734477675077145869296144855691101040965871249828804609100346204070983371062590273336734564969020068052618256509773408613924173909751351554561064586129837540954337160904415625404892669592986127801019807989827319368290273765648256480872195493742292667971088647173453059033806, 48888685774691755361314428123012470903274435407919121739086146641066936108772671897622273617773466901370666579985825990735116909193505734002962914749300893402294987407241465624548368394059300582991374404299605248595530416820237532082552535859877438232561386581747696852665114096889765422722443550622873560905, 48888685774691755361314428123012470903274435407919121739086146641066936108772671897622273617773466901370666579985825990735116909193505734002962914749300893402294987407241465624548368394059300582991374404299605248595530416820237532082552535859877438232561386581747696852665114096889765422722443550622873560905, 38583572018907364214647900005166742548285199585572254326541125387795789224923544225334386246655335740938100752554849888600258201438026409196139322439518308323982209353504064739859448757230608480631399883893401220790226127149746215151900805996489931009866529965548635227695192170717058032494324346363053930619, 64940238786056387401400208343541494710106569145648776253264921960848871998112873944735053044143142466740886274718484463159497520574083206269832189589919893550520334911490391957266450195041949757369417242568602992393025242097901450113737739057611554182495438506865992404354942119595468005771945393932589768474, 39561402760999624085248116443786652609261953246279311257359194176046173307879005819035227200168067070869656503,
13838135840992580442876605474811383818108244966337270671303251812771008272858935652243561913687651063565007930291142413707811828393424201379693530423289355865533076364121921469892110296393354892615, 64940238786056387401400208343541494710106569145648776253264921960848871998112873944735053044143142466740886274718484463159497520574083206269832189589919893550520334911490391957266450195041949757369417242568602992393025242097901450113737739057611554182495438506865992404354942119595468005771945393932589768474, 48977318868316177241868377840886234518379318740788414464335149639789241373564334219732049732484152649864293157598629604567238775720288389168177046142209467079549232009426147052416900999957014084019576693027561825654624690272350264451017869825303585254430358271190141844081570800201723992346171314406386674943, 5651041338136387965270707005514495599960051787842260459297309665876049923224924292148523058126335232362070965833156272480917510429785778533039914573874120321092901286353688478193761623313802721160582545556066963078690764669931722358118104123077318311422846797054759255064946480668759913078778113387444436772, 48977318868316177241868377840886234518379318740788414464335149639789241373564334219732049732484152649864293157598629604567238775720288389168177046142209467079549232009426147052416900999957014084019576693027561825654624690272350264451017869825303585254430358271190141844081570800201723992346171314406386674943, 63709385155465577684045832627013714734477675077145869296144855691101040965871249828804609100346204070983371062590273336734564969020068052618256509773408613924173909751351554561064586129837540954337160904415625404892669592986127801019807989827319368290273765648256480872195493742292667971088647173453059033806, 21643731734484252696109953515687478013118937715056061520976924340371395968660338303624558633862679263768843575243426341986847599097591917653435606042602095144570247241757302533523905744626606836773661026140082883368820615972739914083417816255913686820936373857254933361629603081613492930030281179652207492149, 48888685774691755361314428123012470903274435407919121739086146641066936108772671897622273617773466901370666579985825990735116909193505734002962914749300893402294987407241465624548368394059300582991374404299605248595530416820237532082552535859877438232561386581747696852665114096889765422722443550622873560905, 64940238786056387401400208343541494710106569145648776253264921960848871998112873944735053044143142466740886274718484463159497520574083206269832189589919893550520334911490391957266450195041949757369417242568602992393025242097901450113737739057611554182495438506865992404354942119595468005771945393932589768474, 40143952866342512113851528831224840428508359508863486720333430314639020044892359484055175960350878532212164045297142804890441825145732613460997839927190176844605217276182528040788352071676527553305037569493706223713078036314819975031692707790811142576347096406283580538840499698900522007082050790381461432333, 40143952866342512113851528831224840428508359508863486720333430314639020044892359484055175960350878532212164045297142804890441825145732613460997839927190176844605217276182528040788352071676527553305037569493706223713078036314819975031692707790811142576347096406283580538840499698900522007082050790381461432333, 63709385155465577684045832627013714734477675077145869296144855691101040965871249828804609100346204070983371062590273336734564969020068052618256509773408613924173909751351554561064586129837540954337160904415625404892669592986127801019807989827319368290273765648256480872195493742292667971088647173453059033806, 63709385155465577684045832627013714734477675077145869296144855691101040965871249828804609100346204070983371062590273336734564969020068052618256509773408613924173909751351554561064586129837540954337160904415625404892669592986127801019807989827319368290273765648256480872195493742292667971088647173453059033806, 395614027609996240852481164437866526092619532462793112573591941760461733078790058190352272001680670708696565031383813584099258044287660547481138381810824496633727067,
1303251812771008272858935652243561913687651063565007930291142413707811828393424201379693530423289355865533076364121921469892110296393354892615, 48977318868316177241868377840886234518379318740788414464335149639789241373564334219732049732484152649864293157598629604567238775720288389168177046142209467079549232009426147052416900999957014084019576693027561825654624690272350264451017869825303585254430358271190141844081570800201723992346171314406386674943, 20593313344992264722474643208232460904729585942331327945281307002575544045487870568637031063784433406096326172788745559326479291854636106027597680333110098010128235038952685620360851399518780967171732233524825381055879695801401425059095441692301391956163400460584139637380367489591078077440142620116997434358]
"""2、解题方法
直接爆破
exp:
e = 11299
n =
c = [...]
flag = ''
for j in range(len(c)):
for i in range(32,128):
if pow(i,e,n) == c[j]:
flag += chr(i)
print(flag)
#CnHongKe{a8cc755d375811f55cec82153388c}prng
1、题目信息
from Crypto.Util.number import *
from secret import flag
import random
def base(n, l):
bb = []
while n > 0:
n, r = divmod(n, l)
bb.append(r)
return ''.join(str(d) for d in bb[::-1])
def prng(secret):
seed = base(secret, 5)
seed = [int(i) for i in list(seed)]
length = len(seed)
R = [[ random.randint(0,4) for _ in range(length)] for _ in range(length*2)]
S = []
for r in R:
s = 0
for index in range(length):
s += (r[index] * seed[index]) % 5
s %= 5
S.append(s)
return R, S
m = bytes_to_long(flag)
R, S = prng(m)
with open('output.txt', 'w') as f:
f.write(f'R = {R}\nS = {S}')2、解题方法
divmod(n,l)返回(n // l,n % l)
base(n,l)就是把n，写成l进制
分析代码知道
上面代码自己生成数据
在GF(5)下解这个矩阵方程
exp:
#sage
from Crypto.Util.number import *
R = [[] , ... , []]
S = []
r = Matrix(GF(5),R)
s = vector(GF(5),S)
seed = r.solve_right(s)
m = list(seed)
flag = ""
# flag="".join(map(str,m))
for i in m:
flag += str(i)
flag = long_to_bytes(int(flag,5))
print(flag)
# CnHongKe{l1ne4r_prng_1s_d4ngr0s~~!d9uxdj9223}bd
1、题目信息
from Crypto.Util.number import *
from secret import flag
p = getPrime(512)
q = getPrime(512)
n = p * q
d = getPrime(299)
e = inverse(d,(p-1)*(q-1))
m = bytes_to_long(flag)
c = pow(m,e,n)
hint1 = p >> (512-70)
hint2 = q >> (512-70)
print(f"n = {n}")
print(f"e = {e}")
print(f"c = {c}")
print(f"hint1 = {hint1}")
print(f"hint2 = {hint2}")
"""
n = 73337798113265277242402875272164983073482378701520700321577706460042584510776095519204866950129951930143711572581533177043149866218358557626070702546982947219557280493881836314492046745063916644418320245218549690820002504737756133747743286301499039227014032044403571945455215839074583290324966069724343874361
e = 42681919079074901709680276679968298324860328305878264036188155781983964226653746568102282190906458519960811259171162918944726137301701132135900454469634110653076655027353831375989861927565774719655974876907429954299669710134188543166679161864800926130527741511760447090995444554722545165685959110788876766283
c = 35616516401097721876690503261383371143934066789806504179229622323608172352486702183654617788750099596415052166506074598646146147151595929618406796332682042252530491640781065608144381326123387506000855818316664510273026302748073274714692374375426255513608075674924804166600192903250052744024508330641045908599
hint1 = 740477612377832718425
hint2 = 767891335159501447918
"""2、解题方法
根据大佬师傅WP，需要利用上高位的boneh_durfee攻击
参考论文：https://eprint.iacr.org/2023/367.pdf
他们实验时的脚本：https://pastebin.com/zpUkrfDh
论文中提到：
对于1024bit的模，当m = 7, t = 3的时候，至少需要27位p的高位，才能成功
exp:
import time
time.clock = time.time
debug = True
strict = False
helpful_only = True
dimension_min = 7 # 如果晶格达到该尺寸，则停止移除
# 显示有用矢量的统计数据
def helpful_vectors(BB, modulus):
nothelpful = 0
for ii in range(BB.dimensions()[0]):
if BB[ii,ii] >= modulus:
nothelpful += 1
print (nothelpful, "/", BB.dimensions()[0], " vectors are not helpful")
# 显示带有 0 和 X 的矩阵
def matrix_overview(BB, bound):
for ii in range(BB.dimensions()[0]):
a = ('%02d ' % ii)
for jj in range(BB.dimensions()[1]):
a += '0' if BB[ii,jj] == 0 else 'X'
if BB.dimensions()[0] < 60:
a += ' '
if BB[ii, ii] >= bound:
a += '~'
#print (a)
# 尝试删除无用的向量
# 从当前 = n-1（最后一个向量）开始
def remove_unhelpful(BB, monomials, bound, current):
# 我们从当前 = n-1（最后一个向量）开始
if current == -1 or BB.dimensions()[0] <= dimension_min:
return BB
# 开始从后面检查
for ii in range(current, -1, -1):
# 如果它没有用
if BB[ii, ii] >= bound:
affected_vectors = 0
affected_vector_index = 0
# 让我们检查它是否影响其他向量
for jj in range(ii + 1, BB.dimensions()[0]):
# 如果另一个向量受到影响：
# 我们增加计数
if BB[jj, ii] != 0:
affected_vectors += 1
affected_vector_index = jj
# 等级：0
# 如果没有其他载体最终受到影响
# 我们删除它
if affected_vectors == 0:
#print ("* removing unhelpful vector", ii)
BB = BB.delete_columns([ii])
BB = BB.delete_rows([ii])
monomials.pop(ii)
BB = remove_unhelpful(BB, monomials, bound, ii-1)
return BB
# 等级：1
#如果只有一个受到影响，我们会检查
# 如果它正在影响别的向量
elif affected_vectors == 1:
affected_deeper = True
for kk in range(affected_vector_index + 1, BB.dimensions()[0]):
# 如果它影响哪怕一个向量
# 我们放弃这个
if BB[kk, affected_vector_index] != 0:
affected_deeper = False
# 如果没有其他向量受到影响，则将其删除，并且
# 这个有用的向量不够有用
#与我们无用的相比
if affected_deeper and abs(bound - BB[affected_vector_index, affected_vector_index]) < abs(bound - BB[ii, ii]):
#print ("* removing unhelpful vectors", ii, "and", affected_vector_index)
BB = BB.delete_columns([affected_vector_index, ii])
BB = BB.delete_rows([affected_vector_index, ii])
monomials.pop(affected_vector_index)
monomials.pop(ii)
BB = remove_unhelpful(BB, monomials, bound, ii-1)
return BB
# nothing happened
return BB
"""
Returns:
* 0,0 if it fails
* -1，-1 如果 "strict=true"，并且行列式不受约束
* x0,y0 the solutions of `pol`
"""
def boneh_durfee(pol, modulus, mm, tt, XX, YY):
"""
Boneh and Durfee revisited by Herrmann and May
在以下情况下找到解决方案：
* d < N^delta
* |x|< e^delta
* |y|< e^0.5
每当 delta < 1 - sqrt（2）/2 ~ 0.292
"""
# substitution (Herrman and May)
PR. = PolynomialRing(ZZ) #多项式环
Q = PR.quotient(x*y + 1 - u) # u = xy + 1
polZ = Q(pol).lift()
UU = XX*YY + 1
# x-移位
gg = []
for kk in range(mm + 1):
for ii in range(mm - kk + 1):
xshift = x^ii * modulus^(mm - kk) * polZ(u, x, y)^kk
gg.append(xshift)
gg.sort()
# 单项式 x 移位列表
monomials = []
for polynomial in gg:
for monomial in polynomial.monomials(): #对于多项式中的单项式。单项式（）：
if monomial not in monomials: # 如果单项不在单项中
monomials.append(monomial)
monomials.sort()
# y-移位
for jj in range(1, tt + 1):
for kk in range(floor(mm/tt) * jj, mm + 1):
yshift = y^jj * polZ(u, x, y)^kk * modulus^(mm - kk)
yshift = Q(yshift).lift()
gg.append(yshift) # substitution
# 单项式 y 移位列表
for jj in range(1, tt + 1):
for kk in range(floor(mm/tt) * jj, mm + 1):
monomials.append(u^kk * y^jj)
# 构造格 B
nn = len(monomials)
BB = Matrix(ZZ, nn)
for ii in range(nn):
BB[ii, 0] = gg[ii](0, 0, 0)
for jj in range(1, ii + 1):
if monomials[jj] in gg[ii].monomials():
BB[ii, jj] = gg[ii].monomial_coefficient(monomials[jj]) * monomials[jj](UU,XX,YY)
#约化格的原型
if helpful_only:
# #自动删除
BB = remove_unhelpful(BB, monomials, modulus^mm, nn-1)
# 重置维度
nn = BB.dimensions()[0]
if nn == 0:
print ("failure")
return 0,0
# 检查向量是否有帮助
if debug:
helpful_vectors(BB, modulus^mm)
# 检查行列式是否正确界定
det = BB.det()
bound = modulus^(mm*nn)
if det >= bound:
print ("We do not have det < bound. Solutions might not be found.")
print ("Try with highers m and t.")
if debug:
diff = (log(det) - log(bound)) / log(2)
print ("size det(L) - size e^(m*n) = ", floor(diff))
if strict:
return -1, -1
else:
print ("det(L) < e^(m*n) (good! If a solution exists < N^delta, it will be found)")
# display the lattice basis
if debug:
matrix_overview(BB, modulus^mm)
# LLL
if debug:
print ("optimizing basis of the lattice via LLL, this can take a long time")
#BB = BB.BKZ(block_size=25)
BB = BB.LLL()
if debug:
print ("LLL is done!")
# 替换向量 i 和 j ->多项式 1 和 2
if debug:
print ("在格中寻找线性无关向量")
found_polynomials = False
for pol1_idx in range(nn - 1):
for pol2_idx in range(pol1_idx + 1, nn):
# 对于i and j, 构造两个多项式
PR. = PolynomialRing(ZZ)
pol1 = pol2 = 0
for jj in range(nn):
pol1 += monomials[jj](w*z+1,w,z) * BB[pol1_idx, jj] / monomials[jj](UU,XX,YY)
pol2 += monomials[jj](w*z+1,w,z) * BB[pol2_idx, jj] / monomials[jj](UU,XX,YY)
# 结果
PR. = PolynomialRing(ZZ)
rr = pol1.resultant(pol2)
if rr.is_zero() or rr.monomials() == [1]:
continue
else:
print ("found them, using vectors", pol1_idx, "and", pol2_idx)
found_polynomials = True
break
if found_polynomials:
break
if not found_polynomials:
print ("no independant vectors could be found. This should very rarely happen...")
return 0, 0
rr = rr(q, q)
# solutions
soly = rr.roots()
if len(soly) == 0:
print ("Your prediction (delta) is too small")
return 0, 0
soly = soly[0][0]
ss = pol1(q, soly)
solx = ss.roots()[0][0]
return solx, soly
def example():
############################################
# 随机生成数据
##########################################
#start_time =time.perf_counter
start =time.clock()
size=512
length_N = 2*size;
ss=0
s=70;
M=1 # the number of experiments
delta = 299/1024
# p = random_prime(2^512,2^511)
for i in range(M):
# p = random_prime(2^size,None,2^(size-1))
# q = random_prime(2^size,None,2^(size-1))
# if(p
# temp=p
# p=q
# q=temp
N =
e =
c =
hint1 = # p高位
hint2 = # q高位
# print ("p真实高",s,"比特：", int(p/2^(512-s)))
# print ("q真实高",s,"比特：", int(q/2^(512-s)))
# N = p*q;
# 解密指数d的指数( 最大0.292)
m = 7 # 格大小（越大越好/越慢）
t = round(((1-2*delta) * m)) # 来自 Herrmann 和 May 的优化
X = floor(N^delta) #
Y = floor(N^(1/2)/2^s) # 如果 p、 q 大小相同，则正确
for l in range(int(hint1),int(hint1)+1):
print('\n\n\n l=',l)
pM=l;
p0=pM*2^(size-s)+2^(size-s)-1;
q0=N/p0;
qM=int(q0/2^(size-s))
A = N + 1-pM*2^(size-s)-qM*2^(size-s);
#A = N+1
P. = PolynomialRing(ZZ)
pol = 1 + x * (A + y) #构建的方程
# Checking bounds
#if debug:
#print ("=== 核对数据 ===")
#print ("* delta:", delta)
#print ("* delta < 0.292", delta < 0.292)
#print ("* size of e:", ceil(log(e)/log(2))) # e的bit数
# print ("* size of N:", len(bin(N))) # N的bit数
#print ("* size of N:", ceil(log(N)/log(2))) # N的bit数
#print ("* m:", m, ", t:", t)
# boneh_durfee
if debug:
##print ("=== running algorithm ===")
start_time = time.time()
solx, soly = boneh_durfee(pol, e, m, t, X, Y)
if solx > 0:
#print ("=== solution found ===")
if False:
print ("x:", solx)
print ("y:", soly)
d_sol = int(pol(solx, soly) / e)
ss=ss+1
print ("=== solution found ===")
print ("p的高比特为：",l)
print ("q的高比特为：",qM)
print ("d=",d_sol)
if debug:
print("=== %s seconds ===" % (time.time() - start_time))
#break
print("ss=",ss)
#end=time.process_time
end=time.clock()
print('Running time: %s Seconds'%(end-start))
if __name__ == "__main__":
example()
题目给出了p的高70位，所以exp中把s由27改为了70，得出：
d=783087701705468761679148299766995936398557044101882919430819055852416479930185217204358163
from Crypto.Util.number import *
n =
d =
c =
m = pow(c,d,n)
print(long_to_bytes(m))
#CnHongKe{Y0u_m4d3_n3w_rec0rd!!!1113dsd2et}另外一种解法参考：2023 江苏领航杯 misc密码wp
_沐小琪_ CTF技术类博客
__EOF__