With the help of Bitlocker I encrypted an external hard disk. The first time I tried to decrypt it with my password, the nasty surprise followed. The password was not accepted.
The reason for this is that I used a password of more than 100 digits and Microsoft does not consider it necessary to inform the user during the initial encryption that Bitlocker will only use the first 100 digits for encryption.
Maximum 100 characters for the Bitlocker password – but nobody tells you…
Once more, this is a prime example of Microsoft’s commitments on the user experience for their customers.
You play it safe, use a 256-digit password for Bitlocker encryption, Bitlocker encrypts the hard disk and afterwards you can’t decrypt the medium.
The reason for this is that Bitlocker doesn’t give you an error message that you have exceeded the maximum length of the password when you paste the password using copy and paste. It only inserts the first 100 digits of the clipboard and then encrypts the external device. For usability reasons this is a complete failure, but fortunately it can be fixed. Just use the first 100 digits of the previously used password, then the medium can be decrypted again.
If that doesn’t work either: Use recovery key
In my tests, decryption with the first one hundred digits used did not work in one in five tests. For whatever reason. Maybe Bitlocker does not accept all the special characters I use without telling the user.
In this case you can alternatively decrypt the external medium with the recovery key (55 characters with hyphens, 48 digits without hyphens). Then you can change the password by right-clicking on the device.