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Jun
5
awarded  Critic
Jun
4
revised How do we know a cryptographic primitive won't fail suddenly?
Copy-editing
Jun
4
suggested approved edit on How do we know a cryptographic primitive won't fail suddenly?
Jun
4
comment What makes SHA-2 and SHA-3 have security levels half their output hash length?
@yyyyyyy Sounds to me like the beginnings of a decent answer.
Jun
4
comment What makes SHA-2 and SHA-3 have security levels half their output hash length?
@user3491648 Well, that makes some modicum of sense, I suppose. But birthday attacks do have some fairly specific requirements (specifically that the attacker is able to control both inputs) which aren't really generally applicable, right? So how does that justify boiling down the entire "security level" of the hash function to half the hash length? Now, don't get me wrong; I recognize that birthday attacks are valid in some situations (and I should have thought of that) but they aren't always useful.
Jun
4
asked What makes SHA-2 and SHA-3 have security levels half their output hash length?
Jun
4
awarded  Organizer
Jun
4
revised How do we know a cryptographic primitive won't fail suddenly?
Better title, some copy-editing
Jun
4
suggested approved edit on How do we know a cryptographic primitive won't fail suddenly?
Apr
18
revised Why does applying 56-bit DES twice only give 57 bits of security?
Better title, improved formatting
Apr
18
comment Why is triple-DES using three different keys vulnerable to a meet-in-the-middle-attack?
Let me just see if I understand this correctly. The absolute security of a two-key 3DES EDE (or said differently, three-key EDE where K1 == K3) scheme is very near identical to that of a three-independent-keys 3DES EDE scheme; the three-key scheme is only considered "worse" because we'd expect the three-key scheme to, in an ideal world, provide three times the algorithm's key length worth of security, not twice the algorithm's key length, so in the three-independent-keys scheme we aren't getting our full 168 bits worth?
Apr
18
suggested approved edit on Why does applying 56-bit DES twice only give 57 bits of security?
Mar
31
awarded  Citizen Patrol
Oct
5
awarded  Editor
Oct
5
revised How is XOR used for encryption?
Copy editing
Oct
5
suggested approved edit on How is XOR used for encryption?
Aug
1
awarded  Commentator
Dec
17
awarded  Scholar
Dec
17
accepted What is the GnuPG process for going from a passphrase to a symmetric key?
Dec
16
comment What is the GnuPG process for going from a passphrase to a symmetric key?
So if I understand you and the RFC correctly, the user-provided passphrase is basically concatenated as many times as necessary to achieve the string length defined in RFC 4880 § 3.7.1.3, hashed according to the selected S2K algorithm, and then as stated in 3.7.1.1 the selected encryption algorithm's key length number of bits is taken out of the resultant hash value. That data is then used as the key to encrypt the ESK packet (5.3, holding a random session key which is used to encrypt the payload), stated in 3.7.2.2. Would you say that this interpretation agrees with yours?