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I have read about this encryption feature for OS X but want to know how secure it is compared to PGP.

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    Welcome to security.se, Can you rewrite your question? for now it is not specific and mixes diffrent technologies that have nothing to do with each other, – LvB Oct 27 '15 at 13:55
  • Hi. I have created an encrypted space on the disk where I 'drop' files and which I eject when away from the laptop. Though I am on track to read how it works, especially what to do with the original file that can only be copied to the mounted disk, I want to find out if files encrypted there are as safe as they are if they were encrypted with GPG. – user87589 Oct 28 '15 at 13:36
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Here is the official documentation for enterprise about Apple's full disk encryption solution FileVault 2.

FileVault 2

FileVault 2 uses the user's login password as the encryption pass phrase. It uses the AES-XTS mode of AES with 128 bit blocks and a 256 bit key to encrypt the disk.

The problem there is that the user's password used to encrypt the key are generally pretty weak unless the policy which required long and complex password is enforces.

XTS mode is susceptible to data manipulation and tampering. It is also susceptible to traffic analysis, replay and randomisation attacks on sectors and 16-byte blocks. As a given sector is rewritten, attackers can collect fine-grained (16 byte) ciphertexts, which can be used for analysis or replay attacks (at a 16 byte granularity). It would be possible to define sector-wide block ciphers, unfortunately with degraded performance.

VeraCrypt

When you are speaking about "PGP-Disk Encryption", I guess your are speaking about TrueCrypt aka VeraCrypt (forked now). VeraCrypt uses the XTS mode of operation for AES which presents the same vulnerabilities as above. It supports also other combinations of cascaded algorithms such as are available: AES-Twofish, AES-Twofish-Serpent, Serpent-AES, Serpent-Twofish-AES and Twofish-Serpent. This cascading combination of different symmetrical encryption algorithm presents a better security since if one of them is affected by an attack you'll still have the break the other layer.

  • I am sure going to research about these options. Thanks for the answer. For now I am looking into Disk Utility and GnuPG (books and manuals). – user87589 Oct 28 '15 at 13:40

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