update README

Signed-off-by: Jeronimo Irazabal <[email protected]>

Author: jeroiraz

README.md

@@ -95,12 +95,11 @@ immudb!](https://img.shields.io/twitter/url/http/shields.io.svg?style=social&lab
 4.  [Migration from older releases](#migration-from-older-releases) - Easily migrate your existent database to latest release
 5.  [News](#news) - The latest news about immudb
 6.  [Tech specs](#tech-specs) - Technical details of the system in a nutshell
-7.  [How immudb works](#how-immudb-works) - A high-level diagram of how immudb works
-8.  [Real world examples](#real-world-examples) - Read about how others use immudb
-9.  [Multiple databases](#multiple-databases) - Multiple databases
-10.  [Documentation](#documentation) - Read the documentation
-11.  [Community](#community) - Discuss immudb with others and get support
-12.  [License](#license) - Check immudb's licencing
+7.  [Real world examples](#real-world-examples) - Read about how others use immudb
+8.  [Multiple databases](#multiple-databases) - Multiple databases
+9.  [Documentation](#documentation) - Read the documentation
+10.  [Community](#community) - Discuss immudb with others and get support
+11.  [License](#license) - Check immudb's licencing
 
 ## Quickstart
 
@@ -480,50 +479,6 @@ docker build -t myown/immuadmin:latest -f Dockerfile.immuadmin .
 docker build -t myown/immuclient:latest -f Dockerfile.immuclient .
 ```
 
-## Migration from older releases
-
-As for release 0.8 of immudb, which includes multi-key insertions, key-value data needs to be univocally referenced by a monotonic increasing index i.e. internally referred as `ts`. Values are prefixed with the uniquely assigned `ts` value for the entry. Thus, databases created before release 0.8 needs to be migrated.
-Under tools folder you will find a simple migration tool which will format data according to the new structure.
-
-### Building migration tool binary
-
-Building migration tool binary is as simple as:
-
-```
-go build tools/migration/migration_v0.8.go
-```
-
-### How to use migration tool
-
-```
-./migration_v0.8 --help
-```
-
-```
-Usage of ./migration_v0.8:
-  -sourceDataDir string
-    	immudb data directory to migrate e.g. ./data_v0.7 (default "data_v0.7")
-  -targetDataDir string
-    	immudb data directory where migrated immudb databases will be stored e.g. ./data_v0.8 (default "data_v0.8")
-```
-
-### Migrating existent databases
-
-The migration tool builds new databases by doing a full scan of existent ones. While it's a read-only process for existent databases, doing a backup is always a safe recommendation.
-
-```
-./migration_v0.8 -sourceDataDir ./data_v0.7 -targetDataDir ./data_v0.8
-
-2 databases will be migrated
-
-Started migration of data_v0.7/defaultdb to ./data_v0.8/defaultdb.................................................................................COMPLETED!
-
-Started migration of data_v0.7/systemdb to ./data_v0.8/systemdb........COMPLETED!
-
-All databases have been successfully migrated!
-```
-
-
 ## News
 `August 21th, 2020` - **Updated and New SDKs!**
 
@@ -536,7 +491,6 @@ SDKs for Java, Golang, .net, Python and Node are fully compatible with latest im
 5. Node.js [immudb-node](https://github.com/codenotary/immudb-node)
 
 
-
 ## Tech specs
 
 | Topic                   | Description                                                   |
@@ -557,98 +511,6 @@ SDKs for Java, Golang, .net, Python and Node are fully compatible with latest im
 | High Write throughput   | Yes                                                           |
 | Optimized for SSD       | Yes                                                           |
 
-## How immudb works
-
-Download [immudb short research paper](https://codenotary.io/technologies/immudb/) to have a conceptual understanding of the technical foundations of immudb.
-
-#### adding data
-
-When adding data the merkle tree changes as well as shown in the diagram
-
-![the merkle tree changes with every new data](img/immudb-adding-data-diagram.png)
-
-#### checking data consistency
-
-The following diagram explains how data is inserted, verified and consistency checked.
-
-![How immudb data consistency works](img/immudb-consistency-diagram.png)
-
-
-#### Structured value
-
-The messages structure allows callers to use key value pairs as embedded payload. Thus, it will soon be possible to decouple and extend
-the value structure. The value, currently a stream of bytes, can be augmented with some client provided metadata.
-This also permits use of an on-demand serialization/deserialization strategy.
-
-The payload includes a timestamp and a value at the moment. In the near future cryptographic signatures will be added as well, but it's
-possible to decouple and extend. The entire payload contribute to hash generation and is inserted in
-the merkle tree.
-
-All the complexity is hidden by the SDK.
-
-#### Root signature
-
-Providing `immudb` with a signing key enables the cryptographic root signature.
-In this way an auditor for instance or a third party client could verify the authenticity of the returned root hash / index pair after calling `currentRoot` gRPC method.
-Here the gRPC message definitions:
-```proto
-message Root {
-	RootIndex payload = 1;
-	Signature signature = 2;
-}
-
-message RootIndex {
-	uint64 index = 1;
-	bytes root = 2;
-}
-
-message Signature {
-	bytes signature = 1;
-	bytes publicKey = 2;
-}
-```
-It's possible to use the environment `IMMUDB_SIGNING_KEY` or `--signingKey` immudb flag.
-
-To generate a valid key it's possible to use `openssl` tool:
-```.bash
-openssl ecparam -name prime256v1 -genkey -noout -out my.key
-```
-Immuclient and [immugw](https://github.com/codenotary/immugw) are shipped with auditor capabilities.
-To obtain the advantages of using the signed root in combination with the auditor it's possible to launch:
-* immuclient with auditor capabilities:
-```bash
-immuclient audit-mode --audit-username {immudb-username} --audit-password {immudb-pw} --audit-signature validate
-```
-* with [immugw](https://github.com/codenotary/immugw) with auditor capabilities:
-```bash
-./immugw --audit --audit-username {immudb-username} --audit-password {immudb-pw} --audit-signature validate
-```
-
-#### Item References
-
-Enables the insertion of a special entry which references to another item
-
-#### Value timestamp
-
-The server should not set the timestamp, to avoid relying on a non-verifiable “single source of truth”.
-Thus, the clients must provide it. The client driver implementation can automatically do that for the user.
-
-#### Primary Index
-
-Index enables queries and search based on the data key
-
-#### Secondary Index
-
-Index enables queries and search based on the data value
-
-#### Cryptographic signatures
-
-A signature (PKI) provided by the client can be became part of the insertion process
-
-#### Authentication (transport)
-
-Integrated mTLS offers the best approach for machine-to-machine authentication, also providing communications security (entryption) over the transport channel
-
 ## Real world examples
 
 We already learned about the following use cases from users: