Cryptography Termination of the certificates business of Startcom

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• Termination of the certificates business of Startcom
• Is this level a cipher?
• ECDH in reverse... does this have another name?
• Encrypt messages in iOS app

Termination of the certificates business of Startcom Posted: 20 Nov 2017 11:37 AM PST submitted by /u/johnmountain [link] [comments]

Is this level a cipher? Posted: 21 Nov 2017 02:01 AM PST Are these random text and numbers ciphers? Hint:Take 1 from each half in the source hint. Source Hint:kibc5sak https://i.imgur.com/Y9UFfdm.png Level in text form: phqghumeaylnlfdxfircvscxggbwkfnqduxwfnfozvsrtkjprepggxrpnrvystmwcysyycqpevikeffmznimkkasvwsrenzkycxfxtlsgypsfadpooefxzbc This level is all about sorcery. Watch me whip! The one with an important shift and John Doe. 208, 181, 387, 361, 199, 359, 163, 113, 397, 112, 219, 313, 253, 93, 42, 218, 379, 313 Thank you! submitted by /u/edgycorner [link] [comments]

ECDH in reverse... does this have another name? Posted: 20 Nov 2017 08:25 AM PST Typically ECDH is used for key exchange where Alice has a keypair (a, A = Ga) and Bob has a keypair (b, B = Gb), G is the generator point of the group or order n. The shared secret is S = Ba = Ab = G(ab). That's all nice, but suppose Bob already has an EC point Q which he wants to pass as a key (and he knows q such that Q= Gq). Bob generally can't pick b with Ab = Q as that implies Bob can calculate the discrete logarithm... so if the shared secret is Q, Bob can calculate: R = A*q Bob passes R to Alice. Alice then calculates: Q = R*d where d is the modular inverse of a (in n-1) , i.e. ad = 1 mod (n-1), which is generally easy to calculate. As I understand things, this construction is similar to the Pohlig-Hellman Cipher (which is defined on exponentiation in a finite field Zn, i.e. encryption is c = m ^ a, decryption m=c ^ d). This seems like an obvious alternative to conventional ECDH but I haven't found any exploration of this model... is there another name for this that I should be looking for? submitted by /u/jadeblaquiere [link] [comments]

Encrypt messages in iOS app Posted: 20 Nov 2017 11:21 AM PST I'm planning to create an iOS app for decrypt and encrypt a certain message. Inside the app you can choose the algorithm, a passphrase or sth similar (F.e. in Caesar-Cipher you need to enter the shift size) and click on encrypt / decrypt. The app should contain some simple and well known ciphers and some more strong based on public / private key. With this project I wanna to learn sth about iOS programming and about encryption methods. Can you make some suggestions what encryption methods are a "must have" for this kind of app? submitted by /u/marvpaul [link] [comments]

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