def checkPadding(rawCipher, rawIV):
rawOutput = aes_cbc_dec(rawCipher, aeskey, rawIV);
try:
checkAndRemovePKCS7Padding(rawOutput);
return True;
except:
return False;
def message5_5_gp1(state):
# (p-1) is essentially (-1)
# B's secret is (-1)^b which is either (+1) or (-1) (and also B)
# A's secret is (-1)^b^a, which is either (+1) or (-1),
# but not necessarily the same as B's secret
# thus, we may need to modify cipher
# use CBC padding to check validity of key
# check validity of cbc padding to determine which
# B's secret
cipherkey_plus1, mackey_plus1 = secretToKeys(intToBytes(1));
cipherkey_minus1, mackey_minus1 = secretToKeys(intToBytes(state["p"]-1));
plain_plus1 = aes_cbc_dec(state["a_cipher"], cipherkey_plus1, state["a_iv"])
plain_minus1 = aes_cbc_dec(state["a_cipher"], cipherkey_minus1, state["a_iv"])
plain = None;
try:
plain = checkAndRemovePKCS7Padding(plain_plus1)
state["m_key_a"] = cipherkey_plus1
except ValueError:
plain = checkAndRemovePKCS7Padding(plain_minus1)
state["m_key_a"] = cipherkey_minus1
state["m_plain_a"] = plain;
# encrypt to B's key
state["m_key_b"], b_mackey = secretToKeys(intToBytes(state["B"]))
state["a_cipher"] = aes_cbc_enc(addPKCS7Padding(plain, 16), state["m_key_b"], state["a_iv"]);
return state;
def message5_5_gp1(state):
# (p-1) is essentially (-1)
# B's secret is (-1)^b which is either (+1) or (-1) (and also B)
# A's secret is (-1)^b^a, which is either (+1) or (-1),
# but not necessarily the same as B's secret
# thus, we may need to modify cipher
# use CBC padding to check validity of key
# check validity of cbc padding to determine which
# B's secret
cipherkey_plus1, mackey_plus1 = secretToKeys(intToBytes(1))
cipherkey_minus1, mackey_minus1 = secretToKeys(intToBytes(state["p"] - 1))
plain_plus1 = aes_cbc_dec(state["a_cipher"], cipherkey_plus1,
state["a_iv"])
plain_minus1 = aes_cbc_dec(state["a_cipher"], cipherkey_minus1,
state["a_iv"])
plain = None
try:
plain = checkAndRemovePKCS7Padding(plain_plus1)
state["m_key_a"] = cipherkey_plus1
except ValueError:
plain = checkAndRemovePKCS7Padding(plain_minus1)
state["m_key_a"] = cipherkey_minus1
state["m_plain_a"] = plain
# encrypt to B's key
state["m_key_b"], b_mackey = secretToKeys(intToBytes(state["B"]))
state["a_cipher"] = aes_cbc_enc(addPKCS7Padding(plain, 16),
state["m_key_b"], state["a_iv"])
return state
def decryptAndCheckAdmin(cip):
rawPlain = checkAndRemovePKCS7Padding(aes_cbc_dec(cip, global_aes_key, global_iv));
strPlain = str(rawPlain).rstrip("b'");
print(strPlain)
if ";admin=true;" in strPlain:
return True;
return False;
def decryptAndCheckAdmin(cip):
rawPlain = checkAndRemovePKCS7Padding(
aes_cbc_dec(cip, global_aes_key, global_iv))
strPlain = str(rawPlain).rstrip("b'")
print(strPlain)
if ";admin=true;" in strPlain:
return True
return False
