Rating:
We can bruteforce shift of each word (separated by `_`, `,` and `.`) then choose the most meaningful words for each word. The corresponding shift of each word reveal part of the flag.
```python
import string
def caesar(msg, shift):
return ''.join(chars[(chars.index(c) - shift) % len(chars)] for c in msg)
chars = string.ascii_letters + string.digits + '+/='
ct = "AtvDxK lAopjz /i + vhw c6 uwnshnuqjx ymfy kymhi Kyv 47+3l/eh Bs kpfkxkfwcnu Als 9phdgj9 +ka ymzuBGxmFq 6fdglk8i CICDowC, sjxir bjme+pfwfkd 6li=fj=kp, nCplEtGtEJ, lyo qeb INKLNBM vm ademb7697. ollqba lq DitCmA xzhm fx ef7dd7ii, wIvv eggiww GB kphqtocvkqp, 3d6 MAx ilsplm /d rpfkd vnloov hc nruwtAj xDxyjrx vexliv KyrE +3hc Gurz, jcemgt ixlmgw 9f7gmj5/9k obpmlkpf/ib mzp 8k/=64c ECo sj qb=eklildv. =k loGznlEpD qzC qo+kpm+obk=v, vHEEtuHKtMBHG, huk h7if75j/d9 mofs+=v, zkloh lqAkwCzioqvo rfqnhntzx fhynAnynjx b/a7 JKvrCzEx hexe BE ecwukpi 63c397. MAxLx wypujpwslz 3/c ql irvwhu 9bbcj1h9cb fsi f tswmxmzi zDGrtK ed FBpvrGL vjtqwij ixlmgep 5f8 =lkpqor=qfsb tmowuzs."
ct = ct.replace(' ', ']').replace(',', ']').replace('.', ']')
ct = ct.split(']')
ct = [x for x in ct if x != '']
for block in ct:
for i in range(len(chars)):
val = caesar(block, i)
if any(x not in string.ascii_lowercase for x in val[1:]):
continue
if val[0] not in string.ascii_letters:
continue
print(val, chars[i])
print()
# th3_d1ffer3nce5_m4ke_4ll_th3_diff3renc3
```
