1# blockchainIDsystem
 2A blockchain based anonymous distributed login system
 3
 4### Main concept
 5The objective is to guarantee a decentralized login system, but making sure that registered users are real ones and there are no bots generating large amounts of accounts. Only the verified (by email or phone) users can generate an anonymous ID (the Public-Key blind signed).
 6
 7## How it works?
 8
 9
10#### Network infrastructure
11
12![network](https://raw.githubusercontent.com/arnaucode/blockchainIDsystem/master/documentation/blockchainIDsystem-network.png "network")
13
14There are different types of nodes:
15- peers
16    - the peers of the p2p network that runs the blockchain
17- serverCA
18    - Is a REST server that has been certified (is the Certified Authority) to validate the peers that will be able to participate of the blockchain.
19    - Have the webapp (frontend) to validate peers through a GUI interface
20- server-ID-signer
21    - The server where the user creates a non anonymous account
22    - Also is the server that blind signs the Anonymous ID of the users
23    - Have the webapp (frontend) to interact through a GUI interface
24
25#### Step by step process
261. Once all the nodes of the network are running, a new user can connect to the server-ID-signer.
27- The user registers a non anonymous user (using email, phone, password, etc), and performs the login with that user
28- The user, locally, generates a RSA key pair (private key & public key)
29- The user blinds his Public-Key with the server-ID-signer Public-Key
30- The user's Public-Key blinded, is sent to the server-ID-signer
31- The server-ID-signer Blind Signs the Public-Key blinded from the user, and returns it to the user
32- The user unblinds the Public-Key signed by the server-ID-signer, and now has the Public-Key Blind Signed by the server-ID-signer
33- The user sends the Public-Key blind signed to the p2p network
34- The peers verify that the Public-Key Blind Signed is correctly signed by the server-ID-signer, if it is, they add the Public-Key to the Blockchain, inside a new block
35- Then, when the user wants to login into a platform, just needs to put his Public-Key
36- The platform goes to the Blockchain, to check if this Public-Key is registered in the blockchain
37- The platform sends a message encrypted with the user Public-Key, and the user returns the message decrypted with the Private-Key, to verify that is the owner of that Public-Key
38
39
40##### RSA encryption system
41https://en.wikipedia.org/wiki/RSA_cryptosystem
42- Public parameters: (e, n)
43- Private parameters: (d, p, q, phi, sigma)
44- Public-Key = (e, n)
45- Private-Key = (d, n)
46- Encryption:
47![rsa](https://wikimedia.org/api/rest_v1/media/math/render/svg/fbfc70524a1ad983e6f3aac51226b9ca92fefb10 "rsa")
48- Decryption:
49![rsa](https://wikimedia.org/api/rest_v1/media/math/render/svg/10227461ee5f4784484f082d744ba5b8c468668c "rsa")
50
51
52##### Blind signature process
53https://en.wikipedia.org/wiki/Blind_signature
54- m is the message (in our case, is the Public-Key of the user to be blinded)
55![rsa](https://wikimedia.org/api/rest_v1/media/math/render/svg/a59b57fa153c8b327605672caadb0ecf59e5795a "rsa")
56
57- server-ID-signer blind signs m'
58![rsa](https://wikimedia.org/api/rest_v1/media/math/render/svg/e726b003ff1649f9254032cffae42d80577da787 "rsa")
59
60- user can unblind m, to get m signed
61![rsa](https://wikimedia.org/api/rest_v1/media/math/render/svg/e96fad0e1d46ec4c55986d1c8fc84e8c44259ecc "rsa")
62
63- This works because RSA keys satisfy this equation
64![rsa](https://wikimedia.org/api/rest_v1/media/math/render/svg/d6bd21fb4e25c311df07b50c313a248d978c3212 "rsa") and this ![rsa](https://wikimedia.org/api/rest_v1/media/math/render/svg/c13170a26e031125b417f22644fb64384c04eea7 "rsa")