from Crypto.Random import random
import binascii
import hashlib
import challenge39
decryptedHashes = set()
pub, priv = challenge39.genKey(128)
def encrypt(plaintext):
return challenge39.encryptbytes(pub, plaintext)
def decryptOnce(ciphertext):
sha1 = hashlib.sha1()
sha1.update(ciphertext)
digest = sha1.digest()
if digest in decryptedHashes:
raise ValueError('Already decrypted')
decryptedHashes.add(digest)
return challenge39.decryptbytes(priv, ciphertext)
if __name__ == '__main__':
plaintext = b'secret text'
ciphertext = encrypt(plaintext)
plaintext2 = decryptOnce(ciphertext)
if plaintext2 != plaintext:
raise ValueError(plaintext2 + b' != ' + plaintext)
import challenge39 import binascii import math (pub0, priv0) = challenge39.genKey(256) (pub1, priv1) = challenge39.genKey(256) (pub2, priv2) = challenge39.genKey(256) plaintext = b'This is a plaintext string' plainnum = challenge39.bytestonum(plaintext) c0 = challenge39.encryptnum(pub0, plainnum) c1 = challenge39.encryptnum(pub1, plainnum) c2 = challenge39.encryptnum(pub2, plainnum) n0 = pub0[1] n1 = pub1[1] n2 = pub2[1] ms0 = n1 * n2 ms1 = n0 * n2 ms2 = n0 * n1 N = n0 * n1 * n2 r0 = (c0 * ms0 * challenge39.invmod(ms0, n0)) r1 = (c1 * ms1 * challenge39.invmod(ms1, n1)) r2 = (c2 * ms2 * challenge39.invmod(ms2, n2)) r = (r0 + r1 + r2) % N
import challenge39
import challenge47
import itertools
import re
pub, priv = challenge39.genKey(768)
def parityOracle(c):
_, n = pub
k = (n.bit_length() + 7) // 8
p = challenge39.decryptnum(priv, c)
pbytes = challenge39.numtobytes(p)
pbytes = (b'\x00' * (k - len(pbytes))) + pbytes
return pbytes[0:2] == b'\x00\x02'
def computeNextS(e, n, M, s, B, c0):
if len(M) > 1:
while True:
s += 1
c = (c0 * pow(s, e, n)) % n
if parityOracle(c):
return (s, c)
else:
a, b = M[0]
r = (2 * (b * s - 2 * B) + n - 1) // n
while True:
sLow = (2 * B + r * n + b - 1) // b
sHigh = (3 * B + r * n + a - 1) // a
for s in range(sLow, sHigh):
from Crypto.Random import random
import challenge39
import re
pub, priv = challenge39.genKey(256)
def parityOracle(c):
_, n = pub
k = (n.bit_length() + 7) // 8
p = challenge39.decryptnum(priv, c)
pbytes = challenge39.numtobytes(p)
pbytes = (b'\x00' * (k - len(pbytes))) + pbytes
return pbytes[0:2] == b'\x00\x02'
def randnonzerobytes(k):
return bytes(random.sample(range(1, 256), k))
def padPKCS15(s, n):
if len(s) < 8:
raise Exception('unexpected')
k = (n.bit_length() + 7) // 8
padding = randnonzerobytes(k - 3 - len(s))
return b'\x00\x02' + padding + b'\x00' + s
def computeFirstS(e, n, B, c0, parityOracle):
s = (n + 3*B - 1) // (3*B)
while True:
c = (c0 * pow(s, e, n)) % n
if parityOracle(c):
return (s, c)
s += 1
from Crypto.Random import random
import binascii
import hashlib
import challenge39
decryptedHashes = set()
pub, priv = challenge39.genKey(128)
def encrypt(plaintext):
return challenge39.encryptbytes(pub, plaintext)
def decryptOnce(ciphertext):
sha1 = hashlib.sha1()
sha1.update(ciphertext)
digest = sha1.digest()
if digest in decryptedHashes:
raise ValueError('Already decrypted')
decryptedHashes.add(digest)
return challenge39.decryptbytes(priv, ciphertext)
if __name__ == '__main__':
plaintext = b'secret text'
ciphertext = encrypt(plaintext)
plaintext2 = decryptOnce(ciphertext)
if plaintext2 != plaintext:
raise ValueError(plaintext2 + b' != ' + plaintext)
(e, n) = pub
s = random.randint(2, n - 1)
c = challenge39.bytestonum(ciphertext)
import challenge39
import challenge47
import itertools
import re
pub, priv = challenge39.genKey(768)
def parityOracle(c):
_, n = pub
k = (n.bit_length() + 7) // 8
p = challenge39.decryptnum(priv, c)
pbytes = challenge39.numtobytes(p)
pbytes = (b'\x00' * (k - len(pbytes))) + pbytes
return pbytes[0:2] == b'\x00\x02'
def computeNextS(e, n, M, s, B, c0):
if len(M) > 1:
while True:
s += 1
c = (c0 * pow(s, e, n)) % n
if parityOracle(c):
return (s, c)
else:
a, b = M[0]
r = (2 * (b * s - 2 * B) + n - 1) // n
while True:
sLow = (2*B + r*n + b - 1) // b
sHigh = (3*B + r*n + a - 1) // a
for s in range(sLow, sHigh):
c = (c0 * pow(s, e, n)) % n
if parityOracle(c):
return False
digest = m.group(1)
sha1 = hashlib.sha1()
sha1.update(message)
return digest == sha1.digest()
def forgeSignature(pub, message):
sha1 = hashlib.sha1()
sha1.update(message)
digest = sha1.digest()
block = b'\x00\x01\xff\x00' + digest + (b'\x00' * (128 - len(digest) - 4))
(d, n) = pub
blocknum = challenge39.bytestonum(block)
signaturenum = challenge40.floorRoot(blocknum, 3) + 1
signature = challenge39.numtobytes(signaturenum)
return signature
if __name__ == '__main__':
message = b'hi mom'
pub, priv = challenge39.genKey(1024)
signature = generateSignature(priv, message)
print(signature)
if not verifySignature(pub, message, signature):
raise Exception(message + b' has invalid signature ' + signature)
forgedSignature = forgeSignature(pub, message)
print(forgedSignature)
if not verifySignature(pub, message, forgedSignature):
raise Exception(message + b' has invalid signature ' + forgedSignature)
import challenge39 import binascii import math (pub0, priv0) = challenge39.genKey(256) (pub1, priv1) = challenge39.genKey(256) (pub2, priv2) = challenge39.genKey(256) plaintext = b'This is a plaintext string' plainnum = challenge39.bytestonum(plaintext) c0 = challenge39.encryptnum(pub0, plainnum) c1 = challenge39.encryptnum(pub1, plainnum) c2 = challenge39.encryptnum(pub2, plainnum) n0 = pub0[1] n1 = pub1[1] n2 = pub2[1] ms0 = n1 * n2 ms1 = n0 * n2 ms2 = n0 * n1 N = n0 * n1 * n2 r0 = (c0 * ms0 * challenge39.invmod(ms0, n0)) r1 = (c1 * ms1 * challenge39.invmod(ms1, n1)) r2 = (c2 * ms2 * challenge39.invmod(ms2, n2)) r = (r0 + r1 + r2) % N
block = b'\x00' + challenge39.encryptbytes(pub, signature)
r = re.compile(b'\x00\x01\xff+?\x00(.{20})', re.DOTALL)
m = r.match(block)
if not m:
return False
digest = m.group(1)
sha1 = hashlib.sha1()
sha1.update(message)
return digest == sha1.digest()
def forgeSignature(pub, message):
sha1 = hashlib.sha1()
sha1.update(message)
digest = sha1.digest()
block = b'\x00\x01\xff\x00' + digest + (b'\x00' * (128 - len(digest) - 4))
(d, n) = pub
blocknum = challenge39.bytestonum(block)
signaturenum = challenge40.floorRoot(blocknum, 3) + 1
signature = challenge39.numtobytes(signaturenum)
return signature
if __name__ == '__main__':
message = b'hi mom'
pub, priv = challenge39.genKey(1024)
signature = generateSignature(priv, message)
if not verifySignature(pub, message, signature):
raise Exception(message + b' has invalid signature ' + signature)
forgedSignature = forgeSignature(pub, message)
if not verifySignature(pub, message, forgedSignature):
raise Exception(message + b' has invalid signature ' + forgedSignature)