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takyon writes:

The Intercept's Micah Lee wrote a guide explaining how to encrypt a hard drive but was criticized for recommending Microsoft's BitLocker disk encryption utility for Windows users. Microsoft has responded to some of the criticisms by providing more details about how BitLocker works:

The company told me which random number generator BitLocker uses to generate encryption keys, alleviating concerns about a government backdoor in that subsystem; it explained why it removed the Elephant diffuser, citing worries over performance and compatibility that will appease some, but certainly not all, concerned parties; and it said that the government-compromised algorithm it bundles with Windows to generate encryption keys is, by default, not used at all.

Significant questions remain about BitLocker, to be sure, and because the source code for it is not available, those questions will likely remain unanswered. As prominent cryptographer Bruce Schneier has written, "In the cryptography world, we consider open source necessary for good security; we have for decades." Despite all of this, BitLocker still might be the best option for Windows users who want to encrypt their disks.

Microsoft cryptographer Niels Ferguson gave a presentation in 2007 suggesting that Dual_EC_DRBG might have a backdoor. These suspicions were confirmed by the Snowden documents. Microsoft says that the default pseudorandom number generator for Windows is CTR_DRBG, and that BitLocker uses it when it generates a new key.

BitLocker uses an encoding engine, AES-CBC, and originally used the "Elephant diffuser" to protect encrypted files from being modified to become malicious by an attacker with physical access. Microsoft removed the Elephant diffuser because it hurt performance and is not compliant with Federal Information Processing Standards. Linux systems using LUKS disk encryption are vulnerable to the same kind of attack.

Microsoft says that it does not build backdoors into its products, but that it doesn't consider building methods to bypass their security in order to comply with legitimate legal requests "backdoors." It also shares its source code with governments so that they can check for backdoors... or for vulnerabilities which they could use as backdoors. A Microsoft spokesperson would not answer whether Microsoft could comply with a lawful request to unlock a BitLocker-encrypted disk.

TrueCrypt and its VeraCrypt and CipherShed forks do not play well with post-Windows 8 UEFI and GPT partition tables. Bruce Schneier recommends the proprietary BestCrypt full-disk encryption for Windows users. How does he reconcile this recommendation with what he wrote in 1999? "I do recommend BestCrypt because I have met people at the company and I have a good feeling about them. Of course I don't know for sure; this business is all about trust. But right now, given what I know, I trust them."