[terminaluzer1]

Can someone help me with what this is

chall.py
```
from random import getrandbits
from Crypto.Util.number import getPrime, bytes_to_long
from SECRET import FLAG
e = 2
p = getPrime(256)
q = getPrime(256)
n = p * q
m = bytes_to_long(FLAG)
cor_m = m - getrandbits(160)
if __name__ == "__main__":
    c = pow(m, e, n)
    print("n = {}\nc = {}\ncor_m = {}".format(n, c, cor_m))
```

out.txt
```
n = 5113166966960118603250666870544315753374750136060769465485822149528706374700934720443689630473991177661169179462100732951725871457633686010946951736764639
c = 329402637167950119278220170950190680807120980712143610290182242567212843996710001488280098771626903975534140478814872389359418514658167263670496584963653
cor_m = 724154397787031699242933363312913323086319394176220093419616667612889538090840511507392245976984201647543870740055095781645802588721
```

[babuji101]

what is the name of the machine

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[mazafaka555]

crypto RSA challenge with very small public exponent e = 2
find appropriate attack on RSA crypto where public exponent is too small.

[tenebrae]

from Crypto.Util.number import bytes_to_long, long_to_bytes, getPrime
from sympy import mod_sqrt
from random import getrandbits

# Given values (these would be the actual output from the script)
n = <value_of_n>
c = <value_of_c>
cor_m = <value_of_cor_m>

# Function to find square root modulo n
def modular_sqrt(a, p):
""" Find a quadratic residue (mod p) of 'a'. """
return mod_sqrt(a, p)

# Calculate possible m values
possible_m = modular_sqrt(c, n)
if possible_m is None:
print("No solution exists")
else:
# Since e=2, there might be two solutions
m1 = possible_m
m2 = n - possible_m

# Check which one matches the range for cor_m
if cor_m <= m1 < cor_m + (1 << 160):
recovered_m = m1
else:
recovered_m = m2

# Convert back to bytes
recovered_flag = long_to_bytes(recovered_m)
print("Recovered FLAG:", recovered_flag)

[mbaker5159]

thanks so much i was hoping to get pointed in the right or any direction.

[elena83]

from Crypto.Util.number import bytes_to_long, long_to_bytes, getPrime
from sympy import mod_sqrt
from random import getrandbits

# Given values (these would be the actual output from the script)
n = <value_of_n>
c = <value_of_c>
cor_m = <value_of_cor_m>

# Function to find square root modulo n
def modular_sqrt(a, p):
    """ Find a quadratic residue (mod p) of 'a'. """
    return mod_sqrt(a, p)

# Calculate possible m values
possible_m = modular_sqrt(c, n)
if possible_m is None:
    print("No solution exists")
else:
    # Since e=2, there might be two solutions
    m1 = possible_m
    m2 = n - possible_m

    # Check which one matches the range for cor_m
    if cor_m <= m1 < cor_m + (1 << 160):
        recovered_m = m1
    else:
        recovered_m = m2

    # Convert back to bytes
    recovered_flag = long_to_bytes(recovered_m)
    print("Recovered FLAG:", recovered_flag)

Thanks, can you tell me what is the name of the chall ?

[redbaby]

from Crypto.Util.number import bytes_to_long, long_to_bytes, getPrime
from sympy import mod_sqrt
from random import getrandbits

# Given values (these would be the actual output from the script)
n = <value_of_n>
c = <value_of_c>
cor_m = <value_of_cor_m>

# Function to find square root modulo n
def modular_sqrt(a, p):
""" Find a quadratic residue (mod p) of 'a'. """
return mod_sqrt(a, p)

# Calculate possible m values
possible_m = modular_sqrt(c, n)
if possible_m is None:
print("No solution exists")
else:
# Since e=2, there might be two solutions
m1 = possible_m
m2 = n - possible_m

# Check which one matches the range for cor_m
if cor_m <= m1 < cor_m + (1 << 160):
recovered_m = m1
else:
recovered_m = m2

# Convert back to bytes
recovered_flag = long_to_bytes(recovered_m)
print("Recovered FLAG:", recovered_flag)

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