I recently reinstalled my OS (Linux), planning to recover from the regular backups I make (through Pika, a graphical interface for the Borg frontend).
To my surprise, the backup is encrypted and because it was stored in my keyring, I never had to enter a password so I completely forgot what it is (and the keyring is stored inside the encrypted password 🥲).

First, I tried remembering the password and trying out different passwords I could have used. No luck.

Then I tried recovering files from the computers storage, in hope to find the keyrings, but no luck either. (Although I admit that I have only limited knowledge about these practices so there could still be hope ?)

I looked through the files contained along with the backed up data, and there is this config file that looks interesting:

[repository]
version = 1
segments_per_dir = 1000
max_segment_size = 524288000
append_only = 0
storage_quota = 0
additional_free_space = 2G
id = b6b5c29e6bc0eec2b017670ae7f784c7e7806d6f77c9604fe5d44cef173c6d19
key = hqlhbGdvcml0aG2mc2hhMjU2pGRhdGHaAZ45kv7irZY7JbZN0LGfkag7UOSFi2gJ0Uk4qA
    nMW2OeaDESsvllGefCQL2P/SIXgyil0HlZqQ+rftdNfDEwIvUj3CjY/p4YTJV024rXi3XG
    tkIkK2SCbJo3cFtW3ZFjWIv+4R5Oevlpj6tAJCoKkioQB6gcaImag9jZS7bR7F3QHwJbVE
    KzaD5iMbItCq39KRR1zXgHwbpXdBwwzTF0SoK3zejMgqR6UXxLh9TgrzoBkIrtXkePRGMM
    FpFDoguAZ43DXLnlVW1Om+b++5l1q1r4bR98syDA86wSdQiYpHetClK1xU7u5K1/zbAs5y
    HuXMlKXvyuPJzFL5EhQBXwZfDE/rwir5+8AO+aQY4dTAV3hOsU1wyein83i5h0oEpo/k5e
    r8niXsSkY9ZEVLWKGVj/puCiJ0Ua0KxG7ziNLcM2QHS//hWXDGGIqH5z1Alc3oOOUpN+mK
    DNEN3GaXCCipHgq+PmdrlELbIrCfsDx/j8aEXgH5ARkNCOBihcuENyUbqSdjBY/AQfsiAi
    rqDmOcgZI7tqgkeSCBKnJo52d2GkaGFzaNoAIIdOHmzthmCAIVQ/LJbV6nGj6FsQQ/ktd5
    mH0hEGPOwOqml0ZXJhdGlvbnPOAAGGoKRzYWx02gAgjTXJTU7dSrPHAkOVriHHZFOay3mc
    8AornHgfdeDMXbWndmVyc2lvbgE=

Whilst I don’t know what it is, I have the feeling it could be used to bruteforce the password. (The information stored on the backup isn’t vital, I’d just like to recover it’s contents someday).
How would I go about writing/finding a program that can do that ? I would put it on a raspberry pi and leave it running for weeks or even months.

There are also other files: hints.378, index.378, integrity.378, nonce and a README that links to https://borgbackup.readthedocs.io/, but I don’t know if these files are important. I’ve also read that Borg uses AES-256 in CTR mode and HMAC-SHA256 encryption.

Any explanations, solutions or other ideas on how to approach the issue would be appreciated.