Fund. C Prog.代写、代做Databases、代做Java/CS程序、代写Python/C/C++代写

日期：2018-10-08 09:56

Fund. C Prog. Assessment task 3: Group 16

Project - Checkpoint 1

UCrypt - USB Crypto tool

(48430-2018-SPRING-CITY)

Matthew Delotavo Changhui He Shihao Li

Wei Ting Tuan Tianqi Zhang

September 21, 2018

Contents

1 Objective 2

2 Scope 2

3 Program Features 3

3.1 InitDB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3.2 Users . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3.3 RSA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3.3.1 Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3.4 Database . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3.4.1 Tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3.4.2 Credentials . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3.4.3 Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3.5 Search . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

4 Structure Chart 5

5 References 5

1

1 Objective

UCrypt is a USB file vault; inspired by KeePass1 and Pass2

. It let’s users define

their own RSA-inspired crypto scheme for their UCrypt database as well as

external files.

2 Scope

1. Autodetect and access USB storage devices with a UCrypt database

2. RSA for encryption and decryption

3. Encrypt data before saving to disk

4. Store decrypted entries in RAM as linked list nodes

5. Search and filter decrypted entries

6. A single UCrypt database can accomodate multiple users

(a) users are asked to authenticate their username and private key to

decrypt their data

i. a test string encrypted with the user’s public key will be decrypted

to verify a user has entered a valid private key

(b) users can add, edit and delete encrypted credentials

(c) users can encrypt files with another user’s public key to send them a

secret message

7. Users can encrypt and decrypt their database and external files using the

default scheme or define their own

8. Provides interactive and non-interactive (via command-line arguments)

modes

1https://keepass.info

2https://www.passwordstore.org

2

3 Program Features

3.1 InitDB

Initialize a UCrypt hidden database on a specified USB storage device.

3.2 Users

Users have the following:

1. username

2. password (private key)

3. public key

4. UCryptDB (database)

3.3 RSA

UCrypt uses a simple implementation of the RSA3

cryptosystem as follows:

1. Use

(me)d ≡ m (mod n)

where e, d and n are tunable parameters (default paramaters will be provided)

2. encrypt message m with a user’s public key e via

c ≡ me

(mod n)

3. decrypt ciphertext c above via

cd ≡ (me)d ≡ m (mod n)

where d is the user’s private key

Users can also define a custom number of passes of the RSA cryptosystem over

their data in addition to tuning the default parameters.

3.3.1 Example

If public key is n = 3233, e = 17 and private key is n = 3233, d = 413, then

encryption function is:

c(m) = m17 mod 3233

and decryption function is:

m(c) = c

413 mod 3233

3https://en.wikipedia.org/wiki/RSA_(cryptosystem)

3

3.4 Database

3.4.1 Tree

.ucryptdb/

.alice.pubkey

.bob.pubkey

.anon.pubkey

users

credentials/

alice.crd

bob.crd

anon.crd

messages/

alice.msg

bob.msg

anon.msg

3.4.2 Credentials

TBD

3.4.3 Messages

TBD

3.5 Search

TBD

4

4 Structure Chart

UCrypt

ucrypt.c

help()

menu()

initdb()

findusb()

openusb()

newfile()

savefile()

encrypt()

loadfile()

decrypt()

editfile()

displaydata()

searchdata()

createuser()

usermod()

showdetails()

editdetails()

deleteuser()

keygen()

createnewcrypto()

resetcrypto()

showuserfiles()

authenticateuser()

isvalidpass()

ucrypt.h

prototypes

RSA definitions

makefile

5 References

https://keepass.info

https://www.passwordstore.org

https://en.wikipedia.org/wiki/RSA_(cryptosystem)