Re: Search through the string's space for find the target string whose md5sum matches the required condition.

[Hongyi Zhao]

On Tue, Oct 12, 2021 at 4:42 PM Hongyi Zhao <hongyi.zhao@gmail.com> wrote:
>
> Suppose we have a string represented as follows, where `?' represents
> arbitrary uppercase letters:
>
> TASC?O3RJMV?WDJKX?ZM
>
> We also know that its md5sum has the following form:
>
> E903???4DAB????08?????51?80??8A?
>
> Based on the above information, find out the string and its
> corresponding md5sum.
>
> I've done the work with the following python code:
>
> ```python
> import re
> from hashlib import md5
> from string import ascii_uppercase
>
> alphabet_uppercase=ascii_uppercase
> re_md5_str=re.compile(r'^E903[A-F0-9]{3}4DAB[A-F0-9]{4}08[A-F0-9]{5}51[A-F0-9]80[A-F0-9]{2}8A[A-F0-9]')
>
> #result_str=[]
> for i in alphabet_uppercase:
>     i_str= 'TASC' + i
>     for j in alphabet_uppercase:
>         j_str = i_str + 'O3RJMV' + j
>         for k in alphabet_uppercase:
>             k_str = j_str + 'WDJKX' + k + 'ZM'
>             #result_str.append(k_str)
>             md5_str=md5(k_str.encode('utf-8')).hexdigest().upper()
>             if re_md5_str.match(md5_str):
>                 md5_str = re_md5_str.match(md5_str)[0]
>                 print('The string: ' + k_str + '\n' + 'md5sum: ' + md5_str)
> ```

The following is an improved version:

```python
import re
from hashlib import md5
from string import ascii_uppercase

alphabet_uppercase = ascii_uppercase
re_md5_str = re.compile(r"""^E903[A-F0-9]{3}
                4DAB[A-F0-9]{4}
                08[A-F0-9]{5}
                51[A-F0-9]
                80[A-F0-9]{2}
                8A[A-F0-9]""", re.X)

for i in alphabet_uppercase:
    i_str = 'TASC' + i
    for j in alphabet_uppercase:
        j_str = i_str + 'O3RJMV' + j
        for k in alphabet_uppercase:
            _str = j_str + 'WDJKX' + k + 'ZM'
            md5_str = md5(_str.encode('utf-8')).hexdigest().upper()
            if re_md5_str.match(md5_str):
                print('string: ' + _str + '\n' + 'md5sum: ' + md5_str)
```
HZ