Is the congratulations.txt password not mslqvydyjkxgyrq ?
You are very close to the password. 'congratulations'.txt is the hint. It's a curveball!
If you encrypt 'APPLE' with vignere using the key 'KEYKE' the result should be 'KTNVI'. If you encrypt it with key 'KEWEE' the result is 'KTLPI'.* And I still can't figure out the password. *
