[macOS] Beta Test: Perfect Privacy VPN Software

Discussion in 'Announcements' started by PP Stephan, Sep 11, 2017.

  1. P

    Pete Member

    GCM and CBC modes internally work quite differently; they both involve a block cipher and an exclusive-or, but they use them in different ways.

    In CBC mode, you encrypt a block of data by taking the current plaintext block and exclusive-oring that wth the previous ciphertext block (or IV), and then sending the result of that through the block cipher; the output of the block cipher is the ciphertext block.
    CBC has an IV and thus needs randomness every time a message is encrypted, changing a part of the message requires re-encrypting everything after the change, transmission errors in one ciphertext block completely destroy the plaintext and change the decryption of the next block, decryption can be parallelized / encryption can't, the plaintext is malleable to a certain degree

    GCM mode provides both privacy (encryption) and integrity. To provide encryption, GCM maintains a counter; for each block of data, it sends the current value of the counter through the block cipher. Then, it takes the output of the block cipher, and exclusive or's that with the plaintext to form the ciphertext.
    GCM is a very fast but arguably complex combination of CTR mode and GHASH, a MAC over the Galois field with 2^128 elements.

    CBC provides confidentiality, but it does not protect against accidental modification or malicious tampering. In contrario GCM offers the integral and authentic transfer of data.

    IMHO CGM is different but better than CBC.
  2. s

    skorp New Member

    @PP Simon Thanks for the replies!

    I'm using High Sierra, but with the updates today, it still doesn't work.

    How/where do you want me to send these log file?
  3. P

    Pete Member

    Did anyone notice that you have PP activated on both devices Apple Handoff isn't working?
  4. r

    rc10 New Member

    Yes, I have noticed that problem. I didn’t report it because I rarely use handoff.