Proxy Re-Encryption Demo in Python

This is the demo of Proxy Re-Encryption(PRE) which demonstrates how it can be used properly combining with symmetric encryption to achieve extremely high security of user data privacy.

In this case, stream cipher CHACHA20 and Block Cipher AES is used to make sure the proxy(server) cannot get user's private key and the plain data stored on it.

Usage

pip3 install -r requirements.txt
python3 demo.py

Demo/Sample output

A    ---------------------Request key pair---------------------->   CA

A    <-----------------A key pair, global param------------------   CA

B    ---------------------Request key pair---------------------->   CA

B    <-----------------B key pair, global param------------------   CA

---------------A want to restore something on the Proxy---------------

Plain msg sent from A:             b'This is a demo'

Seed from A:                       b'\x04+\xa4\xbe\xb9N\x95m(` 1H\x19\
                                   xbf\xe6\n\xe89!\xc8I\xc3q\xd8]C:P\x
                                   da\xdeo\t\xd3\x9eR>\x1d\x19\xc4\xe3
                                   _@D\xdd\\\x8b\x0c'

CHACHA20 msg sent from A:          b'\x87\xe7))\x0bN^i\xb2\x03\xa1\x93
                                   \x97\x96'

PRE encrpyted seed from A:         b'\x93\xda\x00"\x01\x02\xf0\xe8\x9e
                                   \xa6FZ\xbd\xb9KN\x87:\xd5\xdb\x99\x
                                   01\xe3\xadG\xc0\xfc|P&\xe5e\xa7\xbf
                                   }^E1\xda\x00"\x01\x02\x1044\x0c\x18
                                   \x11\xb0#\xa8\xc5=\x9e\xa2\xd8\x9c\
                                   xb4\x8c\xc6\x98p\x93\x91\xfcdW,\xcd
                                   \xce\x8b\xe3j\x1d\xda\x00"\x01\x02\
                                   xf1i\xc4\xa7\x94\xddJA\xb3\xe2B\xd6
                                   \xeeG\xa6\xf8?\x1c\x9e\x05(Q\ra\xae
                                   A\xeco\x1cV\x9f\xb4'

A    -------------(CHACHA20 msg,PRE encrypted seed)------------->PROXY

AES encrypted data on Proxy:       b'\xcd\xef\xb8\xc0h\xbclGC\x85\xbem
                                   O\xd1'

---------------The data is safely restored on the Proxy---------------

------------Of course A can download and see it at anytime------------

A    -------------------Request CHACHA 20 msg------------------->PROXY

A    <--(PRE_enc_seed, PRE_enc_aes_key), Request plain aes_key---PROXY

Plain AES key re-decrypted by A:   b'\x1a\xa4B\xd1\x94\x94\xdd\x15|,q\
                                   xe6\x8f4\x8bk2M\x9c\x0c%\n\xbc}\xe2
                                   \x04\xa2\xe5\xa5\xdf\xd6\xec\xe8\xe
                                   3T\x18\xd5\xd1\xbc\x18\xad\xc2\xcc\
                                   x1b\xda\xbc\x03\xf3'

a    -----------------------plain aes_key----------------------->Proxy

CHACHA20 msg decrypted by Proxy:   b'\x87\xe7))\x0bN^i\xb2\x03\xa1\x93
                                   \x97\x96'

A    <-----------------------CHACHA 20 msg-----------------------Proxy

Seed PRE decrypted by A:           b'\x04+\xa4\xbe\xb9N\x95m(` 1H\x19\
                                   xbf\xe6\n\xe89!\xc8I\xc3q\xd8]C:P\x
                                   da\xdeo\t\xd3\x9eR>\x1d\x19\xc4\xe3
                                   _@D\xdd\\\x8b\x0c'

Plain msg received from A:         b'This is a demo'

-----------Now A successfully received the own correct data-----------

-----------------------A want to send that to B-----------------------

A    -------------Request Re-encryption Key with B-------------->   CA

Re-encryption Key A->B:            b'\x00\xbe\xe9\xfdi\xaa\xe7\xd3\xf8
                                   \xe8&\r\xc9\x8a^\x1af\xdeY<*I\x8b\x
                                   0b\xbb.\x80\x8bR\xd6\xc4\xf3\xeb'

A    <------------------Re-encryption Key A->B-------------------   CA

A    --------------------Re-encryption A->B--------------------->Proxy

Re-encrypted seed:                 b'\x93\xda\x00"\x01\x02\x1d\xd8-t+\
                                   xce\x05x\xd3\xdc\x0fg_\xaa;\xe3\x08
                                   \xfc\xa7\x10\xbb\xba\xafbeG\xb8\x1f
                                   \xa0\xf7\xea<\xda\x00"\x01\x02\x104
                                   4\x0c\x18\x11\xb0#\xa8\xc5=\x9e\xa2
                                   \xd8\x9c\xb4\x8c\xc6\x98p\x93\x91\x
                                   fcdW,\xcd\xce\x8b\xe3j\x1d\xda\x00"
                                   \x01\x02\xf1i\xc4\xa7\x94\xddJA\xb3
                                   \xe2B\xd6\xeeG\xa6\xf8?\x1c\x9e\x05
                                   (Q\ra\xaeA\xeco\x1cV\x9f\xb4'

Re-encrypted AES key:              b'\x93\xda\x00"\x01\x03}>\xb9)5V\x1
                                   e\xa0\xc5\x8d)\x89\xd0+\xb6\xa4\xc1
                                   \x84w\x82\xadL\xe3@\xdd\x01\xcf\xd0
                                   "\xf8L\x10\xda\x00"\x01\x02\x8e\xaa
                                   \xe8\r\x8d% \xfe%<\x95\xa5~1\xd7\xe
                                   6\xc0\xe7\x03\xfe\x1a>b_\x940\xeei\
                                   xf9X\xa9E\xda\x00"\x01\x03\xdb\x9b\
                                   x93Zt\x87-h\xe23\x08+\xd2\xa7\xa5A`
                                   *\xce\x19\x13\xcb\xae\xd6\xfe\xba\x
                                   c8\xdf\x1c.O\n'

B    <---(re_enc_seed, re_enc_aes_key), Request plain aes_key----Proxy

Plain AES key re-decrypted by B:   b'\x1a\xa4B\xd1\x94\x94\xdd\x15|,q\
                                   xe6\x8f4\x8bk2M\x9c\x0c%\n\xbc}\xe2
                                   \x04\xa2\xe5\xa5\xdf\xd6\xec\xe8\xe
                                   3T\x18\xd5\xd1\xbc\x18\xad\xc2\xcc\
                                   x1b\xda\xbc\x03\xf3'

B    -----------------------plain aes_key----------------------->Proxy

CHACHA20 msg decrypted by Proxy:   b'\x87\xe7))\x0bN^i\xb2\x03\xa1\x93
                                   \x97\x96'

B    <-----------------------CHACHA 20 msg-----------------------Proxy

Seed re-decrypted by B:            b'\x04+\xa4\xbe\xb9N\x95m(` 1H\x19\
                                   xbf\xe6\n\xe89!\xc8I\xc3q\xd8]C:P\x
                                   da\xdeo\t\xd3\x9eR>\x1d\x19\xc4\xe3
                                   _@D\xdd\\\x8b\x0c'

Plain msg received from B:         b'This is a demo'

---------Now B successfully received the correct data from A----------

Advantage

• The client(user) only needs to caculate stream cipher and PRE on keys, which is very fast.
• Using symmetric encryption like CHACHA20 and AES, make the actual data size the same as the plain data, therefore the data stored on proxy(server) will be the same.
• The proxy(server) knows nothing about the secrete key of any users and the actual plain data. What is actually stored is the data which has been encrypted twice (CHACHA20 and AES), along with PRE encryptedseed(CHACHA20 key) and aes_key.
• All the data during the transmission is encrypted as well.