Alright .NET gurus, solve this one Options

[Hartmann]

I have been scraping data off of a site (300KB) and they recently changed their URI string so that the date parameter has a hash of a date instead of the date itself.

The piece of the string I am looking at looks like this:

CODE

FDate=ZVbeOGQGDBnVmWDrJ6901w==&RDiret=Status

And more exactly the FDate parameter. Any ideas on the hashing mechanism? I know it can't be one way encryption because there would be no way to interpret that as a date (and they have to interpret it as a date).

[impala454]

I guess I'd have to know what the site is to undersand the meaning of those querystrings.

If the MD5 hash is just an encoded date and you have a reasonable idea of the format of the date, you can set up a quick program like this:

(obviously pseudocode)

CODE

string hashtodecode = ytghdgadoghdlurgh9438gh48hg
datettime date = startdate

while(date < enddate)
{
  date = date.adddays(1)
  if(getmd5hash(date.tostring) == hashtodecode)
        break
}

edit: you can do a quick google search for MD5 get hash C# or whatever language you're using to get the standard method everyone uses
edit2: you'll also have to play around with the date.tostring("yyyy/MM/dd"), with different formats until you guess it correctly

[Hartmann]

I guess I'd have to know what the site is to undersand the meaning of those querystrings.

If the MD5 hash is just an encoded date and you have a reasonable idea of the format of the date, you can set up a quick program like this:

(obviously pseudocode)

CODE

string hashtodecode = ytghdgadoghdlurgh9438gh48hg
datettime date = startdate

while(date < enddate)
{
  date = date.adddays(1)
  if(getmd5hash(date.tostring) == hashtodecode)
        break
}

edit: you can do a quick google search for MD5 get hash C# or whatever language you're using to get the standard method everyone uses

Well the issue is more the format of the date (MM/DD/YYYY, YYYMMDD, etc.) as each of those have a different representation when hashed by MD5.

Basically, the query string takes this parameter and compares it to a field in the database that holds a replica of it next to its actual value. It verifies that the data coming in is valid.

[impala454]

Well the issue is more the format of the date (MM/DD/YYYY, YYYMMDD, etc.) as each of those have a different representation when hashed by MD5.

right, you could just come up with about 10-15 different formats and run the loop for each. once you have the format you're set. that .net MD5 hash class is pretty damn fast so it shouldn't take long.