encryption – I have a hex string and hex key, but I’m not sure how it was encrypted. It may be a puzzle

I found the following message written by a developer in a video game:

{"msg":{
"key": "0xa6",
"txt":"eb82e98cacc5b696e28aefcf9ce999eb8ee386a6e58ae78aeb85e184f6d6b9dfff8be386a6f585e487e2c296ff92f7d794fb95e188e693e68ba585c2a7c9acdebfd3bfc6e687a7c9a0c3a686e78be7caabd9b6c3adc9e98efb82ac"}}

The “txt” string is obviously hexadecimal, and the key is only a single byte. I’ve tried the XOR cipher (and several others), but haven’t been able to get the bytes to decode to any legible string. I’ve tried all the common character encodings.

It’s a 91 byte array, and one interesting thing to note is that no byte is repeated more than 3 times, which leads me to believe it’s not a straight “byte to char” conversion and is most likely encrypted in some way (plus, I mean there’s a key).

As for the key itself, I’m unaware of many encryption algorithms that use 8 bit keys. I’ve tried using 0xA6 (166) as the ordinal position in the string, which curiously enough takes the final 16 characters of the message (c3adc9e98efb82ac) but I haven’t been able to find out what to do with that either.