CODEWITHSUNDEEP
pythonauthenticationhashfreeradius
Nicholas Lim
Nicholas Lim

Reputation: 137

Unable to compute FREERADIUS CHAP response based on ID + Password + Challenge in Python

I'm struggling to compute the response hash based on the CHAP ID + Plaintext Password + Challenge Hash.

Following is my code thus far :

def computeResponse(id_hex,password, challenge):
    #id_hex_result = id_hex.encode("hex")
    result = id_hex+password+challenge
    print result
    response = hashlib.md5(result).hexdigest()
    print "Generated: ",response
    print "Captured : ef53ae181830c4822f14ca826054cc8c"
computeResponse("1","SantaCruzpass","c8ec74267d0bbff78fe49abf756c211d")

The response generated was different as shown below the results :

Generated:  e6d0a07960e4d15153caf37fd06cdc8e
Captured : ef53ae181830c4822f14ca826054cc8c

Generated hash is the response computed by the program while the Captured hash is the actual response hash captured during authentication between HQ and Freeradius.

Am i doing it wrongly here ? The CHAP Id captured was "0x01" which yields the hexadecimal value of 1.

Upvotes: 0

Views: 1165

Answers (2)

p0gu
p0gu

Reputation: 26

I had the same problem. My solution is:

def check_chap_password(clear_text_password, chap_challenge, chap_password):
    chap_id = chap_password[0:2]
    check_chap_password = chap_id + hashlib.md5(bytearray.fromhex(chap_id) + password + bytearray.fromhex(chap_challenge)).hexdigest()
    return check_chap_password == chap_password

Example:

check_chap_password('hello', '2d8f0e32ee566a4f26a9dc46eefeafc0', '6db35db7cf22ecc964ccbb9e6fa8afef')

Upvotes: 0

Pwn Fire
Pwn Fire

Reputation: 74

Your password is already in binary form.

Try the following:

Just binascii.unhexlify the id_hex and challenge and you will get what you need.

def computeResponse(id_hex,password, challenge):

id_hex = binascii.unhexlify(id_hex)
challenge = binascii.unhexlify(challenge)
result = id_hex+password+challenge
print result
response = hashlib.md5(result).hexdigest()

Upvotes: 1

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