Wallet login

.gitignore

@@ -1 +1,2 @@
+.idea/
 *~

text/0068-feat-login-into-portable-account-with-metamask.md

@@ -0,0 +1,116 @@
+- FIP: 68
+- title: Login into Portable account with metamask 
+- author: Sabyasachi Patra, @asabya
+- status: draft
+- created: 2023-03-01
+
+# Summary
+Addressing web3 login workflow to portable account where users can retrieve their wallet in a decentralized manner from browser with metamask.
+
+# Context, motivation and guide level explanation
+
+The solution worked out here allows to log in to the user account from any browser into the same account described in [FIP-59](https://github.com/fairDataSociety/FIPs/blob/master/text/0059-portable-account.md) created with
+[fdp-create-account](https://github.com/fairDataSociety/fdp-create-account) project.
+
+# Reference-level explanation
+
+For the login to work with metamask, user should already have a portable account created with [fdp-create-account](https://github.com/fairDataSociety/fdp-create-account).
+
+As we know while creating a portable account users can provide a 12 word mnemonic phrase for the portable wallet or a 12 word mnemonic will be generated for them.
+
+This solution starts with importing the portable wallet into metamask. After that it is a two-step process
+
+## Step 1: 
+```go
+ConnectPortableAccountWithWallet(userName, passPhrase, addressHex, signature string) error
+```
+
+This function will get the portable wallet (wallet seed) and re-upload an alternate socTopic described later
+
+## Step 2: 
+```go
+LoginWithWallet(addressHex, signature string) (*user.Info, error) 
+```
+
+This function will get the encrypted portable wallet (wallet seed) and username from the alternate socTopic and decrypt it with the signature provided by the user.
+
+
+## Uploading portable wallet (wallet seed) to Ethereum Swarm to an alternate socTopic
+
+In FIP-59 we have discussed, about the socTopic which is a topic in the swarm where the portable account is stored. In this solution we will be using an alternate socTopic, but with the same logic, to store the wallet seed.
+```
+socTopic = H(fdpLoginVersion + portableWalletAddress + signature)
+```
+
+Where `portableWalletAddress` and the `signature` will be provided by the user. As we have already imported the portable wallet into metamask, we can get the `portableWalletAddress` from there. The `signature` will be generated by signing the `portableWalletAddress` with metamask with the portable wallet.
+
+## Wallet seed encryption
+In FIP-59 we have discussed, about the encryption of wallet seed and storing it in a chunk. 
+
+- We will first generate FIP-59 socTopic with username and password provided by the user.
+- Then download the wallet seed chunk from FIP-59 socTopic and decrypt it with the password provided by the user.
+
+We have the seed now. We will store the username with the seed for identifying the user while logging in with metamask.
+
+### Creating the chunk
+
+The content of the chunk will look something lite this
+
+```
+SEED + USERNAME_SIZE + USERNAME + RANDOM_DATA
+```
+
+We store the username length in 8 bytes, then the username and then the random data.
+
+The `SEED + USERNAME_SIZE + USERNAME` will be padded with random data with byte length `CHUNK_SIZE - SEED_SIZE - IV_LENGTH - USERNAME_LENGTH - USERNAME_SIZE`.
+
+*** `USERNAME_SIZE` is 8 bytes, `USERNAME_LENGTH` is the length of the username provided by the user.
+
+The resulted data will be encrypted with AES, where the encryption key is the SHA256 hash of the signature.
+
+```go
+func (*Info) PadSeedName(seed []byte, username string, passphrase string) ([]byte, error) {
+    usernameLength := len(username)
+    endIndexBytes := make([]byte, nameSize)
+    binary.LittleEndian.PutUint64(endIndexBytes, uint64(usernameLength))
+    paddingLength := utils.MaxChunkLength - aes.BlockSize - seedSize - nameSize - usernameLength
+    randomBytes, err := utils.GetRandBytes(paddingLength)
+    if err != nil { 
+        return nil, err
+    }
+    chunkData := make([]byte, 0, utils.MaxChunkLength)
+    chunkData = append(chunkData, seed...)
+    chunkData = append(chunkData, endIndexBytes...)
+    chunkData = append(chunkData, []byte(username)...)
+    chunkData = append(chunkData, randomBytes...)
+    encryptedBytes, err := utils.EncryptBytes([]byte(passphrase), chunkData)
+    if err != nil {
+        return nil, fmt.Errorf("seed padding failed: %w", err)
+    }
+    return encryptedBytes, nil
+}
+```
+
+### Getting seed back from the chunk
+
+We decrypt the chunk with the same signature and then get the seed and username from the decrypted data.
+
+```go
+func (*Info) RemovePadFromSeedName(paddedSeed []byte, passphrase string) ([]byte, string, error) {
+	decryptedBytes, err := utils.DecryptBytes([]byte(passphrase), paddedSeed)
+	if err != nil {
+		return nil, "", fmt.Errorf("seed decryption failed: %w", err)
+	}
+	usernameLength := int(binary.LittleEndian.Uint64(decryptedBytes[seedSize : seedSize+nameSize]))
+	return decryptedBytes[:seedSize], string(decryptedBytes[seedSize+nameSize : seedSize+nameSize+usernameLength]), nil
+}
+```
+
+Implementation can be found [here](https://github.com/fairDataSociety/fairOS-dfs/blob/feat/podSubscription.0/pkg/account/account.go) 
+
+# Prior art
+[FIP-59](https://github.com/fairDataSociety/FIPs/blob/master/text/0059-portable-account.md)
+
+## Copyright
+
+Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).