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---  MIKROLOCK MANUAL - Version 1.1  ------------- UTF-8 FILE --- June 2016 ---
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OSI Certified Open Source Software

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MikroLock combines modern cryptography and ease of use. It is based on the open
miniLock file format (https://minilock.io/).


CONTENT:
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1. Overview
2. How does it work?
3. Features
4. Compatibility with the miniLock browser extension
5. Applied crypto functions
6. Platforms
7. Contact


1.  Overview
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MikroLock is a fast native implementation of the minilock file format.
Despite its name (and in contrast to the original implementation), it can also 
handle BIG files.

The main goal of development is to provide an easy exchange of encrypted data
using mail or cloud services. MikroLock is based on modern public key encryption
without configuration or learning efforts. The miniLock file format may also be
applied using the Chrome extension, this might help if corporate rules do not
allow an installation of MikroLock.

The key element of encryption is the Lock-ID, which can be calculated on 
any computer, based on a mail address and a passphrase.
This Lock-ID is a short public key to be published on websites, mail
signatures, twitter etc. to enable anyone to encrypt data for this ID. 
Only the receiver who applies the correct mail and passphrase to derive the 
same ID can decrypt the content.

A Lock-ID looks like this: jrcY8VJWKihbiLsDnaMaNSoL2fZSTiRmEeJcKGBYxnb83

Since Lock-IDs are very comfortable to handle, there is no need for a
cumbersome key exchange process like using keyservers or manually copying key
files to hosts.

A sender can define a list of Lock-IDs to let multiple recipients decrypt 
the file. There is no need to generate a new file for each receiver.
A minilock file does not contain any visible information about its recipients.

Read more about the cryptographic details: https://minilock.io.


2. How does it work?
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A wants to encrypt a file for B. B enters his mail address and passphrase into
MikroLock to obtain his Lock-ID. He sends this ID to A.
A encrypts the file and adds B's Lock-ID as recipient ID. A now sends the
encrypted file to B, who is able to decrypt it using his passphrase/mail
combination.
It is important to keep the passphrase secret - only the Lock-IDs (=public
keys) are being exchanged.


3.  Features
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USAGE: mikrolock [OPTION]...
mikrolock reads and writes encrypted miniLock files (https://minilock.io/)

Available options:

  -E, --encrypt <file>  Encrypt the given file (see -r)
  -D, --decrypt <file>  Decrypt the given miniLock file
  -o, --output <file>   Override the target file name (assumes -D or -E)
  -k, --kdf <name>      Key derivation function to use (name: "scrypt" or "argon2")
                        scrypt is the default, argon2 is experimental
  -m, --mail <string>   Mail address (salt for key derivation)
  -r, --rcpt <string>   Recipient's Lock-ID (may be repeated, assumes -E)

  -h, --help            Print this help screen
  -l, --list <file>     Recipient list text file (contains one Lock-ID per line)
                        ID descriptions may be added using these delimiters: space or one of [,;/|-]
  -p, --pinentry        Use pinentry program to ask for the passphrase
  -q, --quiet           Do not print progress information
  -R, --random-name     Generate random output filename; write to current working directory (assumes -E)
  -v, --version         Print version information
  -x, --exclude-me      Exlude own Lock-ID from recipient list (assumes -E)

If neither -E nor -D is given, mikrolock exits after showing your Lock-ID.


Examples:
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ENCRYPTION

mikrolock --encrypt secret.data --mail sendersalt@holygrail.com --rcpt EX9k9VmGzjg7mUBFN9mzc7nkcvhmD6fGZTq3nefEajjxX

Please enter your secret passphrase:
Unlocking...
Your Lock-ID: aUwncs2D48MqB8VFta7RRJ5bjL9PfsmtWF3zYVb3zFLLW
Encrypting file secret.data...
Progress 100%
Calculating file hash...
Progress 100%
Destination file: secret.data.minilock

The encrypted file is secret.data.minilock
This file can be decrypted by the receiver EX9k9VmGzjg7mUBFN9mzc7nkcvhmD6fGZTq3nefEajjxX


DECRYPTION

mikrolock --decrypt secret.data.minilock --mail receiver@test.org
Please enter your secret passphrase:
Unlocking...
Your Lock-ID: EX9k9VmGzjg7mUBFN9mzc7nkcvhmD6fGZTq3nefEajjxX
Decrypting file secret.data.minilock...
Calculating file hash...
Progress 100%
Writing to file secret.data...
Progress 100%
Destination file: secret.data


4. Compatibility with the miniLock browser extension
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The miniLock file format was established by the miniLock Chrome browser
extension. While the produced files are interchangeable with each program, the
accepted input to obtain a Lock-ID differs:

 * miniLock only supports Lock-IDs generated by scrypt
 
 * miniLock accepts only valid mail addresses as salt; MikroLock accepts any
   value

 * miniLock applies a passphrase entropy check; MikroLock may accept passphrases
   with lower entropy

If you are going to use MikroLock and miniLock in parallel, choose scrypt as kdf, 
and check whether salt and passphrase are being accepted in both applications.


5. Applied crypto functions
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A Lock-ID is defined as:

secret_key :=      scrypt (blake2(passphrase), mail, 131072, 1) 
               OR argon2i (blake2(passphrase), generichash(mail), 
                           OPSLIMIT_SENSITIVE, MEMLIMIT_SENSITIVE)
          
public_key := crypto_scalarmult_base (secret_key) 

Lock-ID := base58 ( public_key + blake2(public_key) )

The user may choose scrypt or Argon2 to calculate the secret_key.
Scrypt parameters were taken from miniLock, whereas Argon2 parameters are 
recommended for handling sensitive data.

The JSON header of a miniLock file contains the sender's Lock-ID,
the recipient's IDs, file hash and the random key of the encrypted input file.
This information is encrypted separately with each given recipient ID as public
key using crypto_box_easy
(key exchange: Curve25519; encryption: XSalsa20 stream cipher; authentication:
Poly1305 MAC).

The input file is encrypted using crypto_secretbox_easy
(encryption: XSalsa20 stream cipher; authentication: Poly1305 MAC).

Read more about the cryptographic details and the file format:
https://minilock.io.

https://doc.libsodium.org/password_hashing/index.html
https://blake2.net
https://en.wikipedia.org/wiki/Base58
https://download.libsodium.org/libsodium/content/password_hashing/scrypt.html
https://download.libsodium.org/libsodium/content/password_hashing/the_argon2i_function.html
https://doc.libsodium.org/advanced/scalar_multiplication.html
https://doc.libsodium.org/public-key_cryptography/authenticated_encryption.html


6.  Platforms
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MikroLock is currently available for Linux and Windows.


7.  Contact
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Andre Simon
andre.simon1@gmx.de
http://www.andre-simon.de/
http://wiki.andre-simon.de/