Egg 24: Spam Hash

Challenge:

Crypto Chiefs Ltd. developed a new hash function, which takes a ‘divide and conquer’ approach and combines several well-known hash functions (“Split, Hash, And Merge”). The inventors claim that with this approach, their function becomes more secure. Can you prove they are wrong?

Create a string which produces the following hash: 757c479895d6845b2b0530cd9a2b11

Specification:

Solution:

From the specification we see we need to find a 30-character string such that:

MD2( inputString[0-5] ) = targetString[0-5] (= 757c47)
MD5( inputString[6-11] ) = targetString[6-11] (= 9895d6)
SHA1(  inputString[12-27] ) = targetString[12-17] (= 845b2b)
SHA256( inputString[18-23] ) = targetString[18-23] (= 0530cd)
SHA512( inputString[24-29] ) = targetString[24-29] (= 9a2b11)

So we need to find 5 6-character strings which when hashed produce the desired outcome, and then concatenate them.

We bruteforce 6-character strings until we find a matching input for each hash type:

import itertools
from Crypto.Hash import MD2,MD5,SHA,SHA256,SHA512

charset = 'abcdefghijklmnopqrstuvwxyz0123456789'

for i in itertools.product(charset, repeat=6):
    MD2hash = MD2.new(''.join(i)).hexdigest()
    MD5hash = MD5.new(''.join(i)).hexdigest()
    SHA1hash = SHA.new(''.join(i)).hexdigest()
    SHA256hash = SHA256.new(''.join(i)).hexdigest()
    SHA512hash = SHA512.new(''.join(i)).hexdigest()

    if MD2hash.startswith('757c47'):
        print 'MD2: '+''.join(i)+' '+MD2hash

    if MD5hash[6:].startswith('9895d6'):
        print 'MD5: '+''.join(i)+' '+MD5hash

    if SHA1hash[12:].startswith('845b2b'):
        print 'SHA1: '+''.join(i)+' '+SHA1hash

    if SHA256hash[18:].startswith('0530cd'):
        print 'SHA256: '+''.join(i)+' '+SHA256hash

    if SHA512hash[24:].startswith('9a2b11'):
        print 'SHA512: '+''.join(i)+' '+SHA512hash

We let this run for a couple minutes until one hit for each hash algorithm is found:

output:
MD5: aaqidt 46e0109895d6278b858d2161a53d6163
MD2: afpmqt 757c47d05a0d3effdd7102323912fed7
SHA512: af9pt3 112cace752c20eaa6cd66ab29a2b1195ffd375a7a0f80a7cf0aa5bb295119d6e9f251f61be772dc848f9a21fdaeabf122128b54d13b2f200fb513a3c1c69caf7
MD5: ahaelu 6b02a89895d63a26836b34d9e041520d
SHA512: aick61 fe59ce23a7860e0f87d898849a2b111d938010054ac505bc428eb1ed134f5a337025cfe47be2272585a239fe85d4390e1b86fd1393ddcdd0ec32c549058129cb
MD2: albkyq 757c47edf09c10f213f8a8028d8b2fa1
MD5: amlp1i 5546e09895d684095e0993da825520cd
SHA256: angeca e77a4a14b3946679280530cd08ed8843265b07d7828d411c06359bfc7113bc1c
MD5: aor7e3 6db1079895d69d81efc0fb41200a8731
MD2: ao45aq 757c4778d66b2936ec81b46f6f0a41bd
SHA256: apt877 8084b4b49e86b5b5ab0530cd320762fc21ef339b2d66c1df72ebaf6c6086ed30
SHA256: arlh5t ca6d3501b11a2b6e910530cd17c3c47a97980097e2ae87f3ceea52af504a6ae7
MD5: awbzbv 71e2d99895d6492b26585cb718228f82
SHA1: aww8nt c9f3a96a6c2f845b2b24a61cad2ade37528bca39
...

we concatenate an answer for each hash type MD2-MD5-SHA1-SHA256-SHA512, for example: afpmqtaaqidtaww8ntangecaaick61. We enter this in the password box and get our egg:

Egg 24: Spam Hash

Challenge:

Solution:

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