Is 256-bit BitLocker encryption really 256-bit?

[Piotr Urbańczyk]

It might sound like a silly question, but clearly I'm not getting something. I've enabled 256-bit encryption in group policy settings and encrypted a drive. manage-bde -status says Encryption Method: XTS-AES 256. But the recovery key is still 48 digits long. Since every sixth digit is a checksum, it gives us 10^40 (about 2^133) combinations. Doesn't this make the encryption key effectively 133 bits long?

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