Rating:
## Solution
`speech.dat` is a binary file without any obvious structure. Given the clue of the challenge name, and the name of the file, we can guess that `speech.dat` may be the text of Martin Luther King Jr's "I Have a Dream" speech. We can also guess that the encryption method may be XOR. If we XOR the beginning of the "I Have a Dream" speech with the given ciphertext, we recover a key that makes sense:
```python
>>> from pwn import *
>>> plaintext = b"I am happy to join with you today in what will go down in history"
>>> ciphertext = open("speech.dat", "rb").read()
>>> xor(plaintext, ciphertext[:len(plaintext)])
b'BlackLivesMatterBlackLivesMatterBlackLivesMatterBlackLivesMatterB'
```
The XOR key is `BlackLivesMatter`. We can XOR this with the entire ciphertext to get the plaintext:
```python
>>> from pwn import *
>>> speech = xor(ciphertext, b"BlackLivesMatter").decode("windows-1252").replace("\n", "")
```
We choose `windows-1252` as the decoding because the plaintext from XORing resulted in characters that are point codes in [Windows-1252](https://en.wikipedia.org/wiki/Windows-1252). We also replaced the newlines on a hunch because the last step of the flag recovery doesn't work if you don't.
Finally, the challenge gave us a list of integers. These are offsets into the resulting plaintext. This allows us to reconstruct the flag:
```python
>>> indexes = [8337,669,8972,3621,8898,5581,8720,1900,5208]
>>> flag = ""
>>> for i in indexes:
... flag += speech[i]
...
>>> print(flag)
ROsAParkS
```
## Flag
**flag{ROsAParkS}**
