Ephemeral / External Key

[Yuri-SVB]

Protocol for encryption of secret information on the protocol:

1. Upon instantiating new profile [profile is the set of all seeds, passwords, salts, keys or any other cryptographic object that, combined make the protocol possible], app true-randomly generates 32 digits hexadecimal* sequence (which means it's 128 bits of entropy) henceforward EKA. Subdivide sequence into 8 chunks of 4 digits each or something like that for less painful UX;
2. Alice is instructed to write it [EKA] down physically and keep the physical backup securely (maybe give tips about storing backup on the physical wallet, etc.);
3. Alice is prompted to type back EKA without having it being displayed in the screen (so to make sure that physical copy is readable / effective);
4. App inputs (so generated and backed up) EKA to Argon2** for 256 bits output. That output is used for (AES) encrypt sensitive information on the profile. Namely, PA0 and TKBA bits, and when SA3 is finally calculated possible, TKBA correct options and KA;
5. App initiates derivation SA0->SA1->SA2->SA3 according to Alice's parameters;
6. Alice proceeds to follow instructions of Memorization Assistant --- One of the cards of the MA deck says "Do you remember where is / are the physical copy / copies of EKA?";
7. When (finally) Memorization Assistant determines that the entire profile has been safely memorized, App deletes the encrypted database and instructs Alice to (forensically) destroy physical copy of EKA (eg.: burn paper) - This provides forensically secure deletion of everything that was encrypted by EKA;
   *Hexadecimal format means key is anti-mnemonic, meaning Alice can plausibly claim not to have memorized it;
   *Additionally, it is 'painful' to transcribe, hence increasing the mental incentive to memorize what Alice actually should memorize;
   **Look up Argon2 literature (like NIST) to properly choose standard Argon2 parameters here - create an issue for it;
   SA0->SA1->SA2->SA3
   .........
   Formosa + Memorization Assistant + Optimization / backup