Custom solution for MD5?

[DigestMyHash]

Hey everyone, wasn't sure where to post this but i figured i'd give it a shot. I'm trying to solve for some MD5 Hashes but not in the typical
sense.

I have an equation where i need to solve for a variable, it goes sort of like this:

StringaStringbStringc = Stringd(md5 hash of concatenation of Stringa+Stringb+Stringc)


We know the values of Stringa, Stringc, Stringd. We try to solve for Stringb

So with example values substituted we have,

1234(UNKNOWN_STRING_MD5_UPPERCASE)5678 = 4bd16ac7d6af4a922109bfffb0f6564d

Stringa=1234
Stringb=(UNKNOWN_STRING_MD5_UPPERCASE), which is the uppercase MD5 digest of a lowercase alphanumeric string, 8char max.
Stringc=5678
Stringd=4bd16ac7d6af4a922109bfffb0f6564d


We need to solve for Stringb, we know that Stringb is the (UPPERCASE)md5 result of a lowercase alphanumeric string, that has an 8 character limit.

We know that Stringd(4bd16ac7d6af4a922109bfffb0f6564d) is the md5 result of the concatenation of Stringa+Stringb+Stringc.

So in this case, solving for Stringb eventually provides us with the uppercase MD5 Value of "AE2B1FCA515949E5D54FB22B8ED95575", which is "testing" in plaintext, and it fits in the equation

So, we have:

Stringa=1234
Stringb=AE2B1FCA515949E5D54FB22B8ED95575
Stringc=5678
Stringd=4bd16ac7d6af4a922109bfffb0f6564d



MD5(1234AE2B1FCA515949E5D54FB22B8ED955755678) = 4bd16ac7d6af4a922109bfffb0f6564d


What i'm looking to do is have a script created that solves for stringb in this exact format.


Stringa, Stringc, Stringd would all be known constants, and it would try to solve for stringb in the way i outlined above. Obviously i am paying for someones time and effort in creating an efficient script / addon to do just this.

[atom]

doesn't look untypical for me. it's the opposite, it looks more like a typical custom algorithm used in a php app or so. in this case its simply md5(salt1.md5(pass).salt2)?

[DigestMyHash]

I am not too experienced in this field, actually. But i *think* you have it right. There's 3 constants, and 1 variable to solve for. I will gladly pay for anyones consultation on this, and perhaps an extension is needed to process it my way? Maybe the uppercase conversion in the middle of the cracking can cause a problem...

[DigestMyHash]

Still looking for this. Can provide some real examples that need cracking.