block and blockchain concepts

block/block.go

@@ -0,0 +1,27 @@
+package block
+
+import (
+	"bytes"
+	"crypto/sha256"
+)
+
+type Block struct {
+	Data []byte //	this block's data
+	Hash []byte //	this block's hash
+	Link []byte //	the hash of the last block in the chain. this is the key part that links the blocks together
+}
+
+func (b *Block) DeriveHash() []byte {
+	blockInfo := bytes.Join([][]byte{b.Data, b.Link}, []byte{})
+	hash := sha256.Sum256(blockInfo)
+	return hash[:]
+}
+
+func New(data []byte, link []byte) *Block {
+	block := &Block{
+		Data: data,
+		Link: link,
+	}
+	block.Hash = block.DeriveHash()
+	return block
+}

chain/chain.go

@@ -0,0 +1,23 @@
+package chain
+
+import (
+	"github.com/alanvivona/blockchaingo/block"
+)
+
+type Chain struct {
+	Blocks []*block.Block
+}
+
+func (c *Chain) AddBlock(data []byte) {
+	lastBlock := c.Blocks[len(c.Blocks)-1]
+	newBlock := block.New(data, lastBlock.Hash)
+	c.Blocks = append(c.Blocks, newBlock)
+}
+
+func New() *Chain {
+	return &Chain{
+		Blocks: []*block.Block{
+			block.New([]byte("Genesis Block"), []byte{}),
+		},
+	}
+}

go.mod

@@ -0,0 +1,8 @@
+module github.com/alanvivona/blockchaingo
+
+go 1.14
+
+require (
+	github.com/gizak/termui/v3 v3.1.0
+	github.com/sirupsen/logrus v1.6.0
+)

go.sum

@@ -0,0 +1,17 @@
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/gizak/termui v3.1.0+incompatible h1:N3CFm+j087lanTxPpHOmQs0uS3s5I9TxoAFy6DqPqv8=
+github.com/gizak/termui/v3 v3.1.0 h1:ZZmVDgwHl7gR7elfKf1xc4IudXZ5qqfDh4wExk4Iajc=
+github.com/gizak/termui/v3 v3.1.0/go.mod h1:bXQEBkJpzxUAKf0+xq9MSWAvWZlE7c+aidmyFlkYTrY=
+github.com/konsorten/go-windows-terminal-sequences v1.0.3/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
+github.com/mattn/go-runewidth v0.0.2 h1:UnlwIPBGaTZfPQ6T1IGzPI0EkYAQmT9fAEJ/poFC63o=
+github.com/mattn/go-runewidth v0.0.2/go.mod h1:LwmH8dsx7+W8Uxz3IHJYH5QSwggIsqBzpuz5H//U1FU=
+github.com/mitchellh/go-wordwrap v0.0.0-20150314170334-ad45545899c7 h1:DpOJ2HYzCv8LZP15IdmG+YdwD2luVPHITV96TkirNBM=
+github.com/mitchellh/go-wordwrap v0.0.0-20150314170334-ad45545899c7/go.mod h1:ZXFpozHsX6DPmq2I0TCekCxypsnAUbP2oI0UX1GXzOo=
+github.com/nsf/termbox-go v0.0.0-20190121233118-02980233997d h1:x3S6kxmy49zXVVyhcnrFqxvNVCBPb2KZ9hV2RBdS840=
+github.com/nsf/termbox-go v0.0.0-20190121233118-02980233997d/go.mod h1:IuKpRQcYE1Tfu+oAQqaLisqDeXgjyyltCfsaoYN18NQ=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/sirupsen/logrus v1.6.0 h1:UBcNElsrwanuuMsnGSlYmtmgbb23qDR5dG+6X6Oo89I=
+github.com/sirupsen/logrus v1.6.0/go.mod h1:7uNnSEd1DgxDLC74fIahvMZmmYsHGZGEOFrfsX/uA88=
+github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
+golang.org/x/sys v0.0.0-20190422165155-953cdadca894 h1:Cz4ceDQGXuKRnVBDTS23GTn/pU5OE2C0WrNTOYK1Uuc=
+golang.org/x/sys v0.0.0-20190422165155-953cdadca894/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=

main.go

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/alanvivona/blockchaingo/chain"
+	"github.com/alanvivona/blockchaingo/ui"
+)
+
+func main() {
+
+	// create a new blockchain and add the 1st block "Genesis"
+	blockchain := chain.New()
+
+	// add 9 more blocks to the chain
+	for i := 2; i < 11; i++ {
+		message := fmt.Sprintf("Block number %d!", i)
+		blockchain.AddBlock([]byte(message))
+	}
+
+	// print the whole blockchain
+	for _, block := range blockchain.Blocks {
+		ui.PrintBlock(block)
+	}
+
+}

ui/ui.go

@@ -0,0 +1,21 @@
+package ui
+
+import (
+	"encoding/hex"
+
+	"github.com/alanvivona/blockchaingo/block"
+	"github.com/sirupsen/logrus"
+)
+
+func HashBytesToString(hash []byte) string {
+	encoded := make([]byte, hex.EncodedLen(len(hash)))
+	hex.Encode(encoded, hash)
+	return string(encoded)
+}
+
+func PrintBlock(b *block.Block) {
+	logrus.WithFields(logrus.Fields{
+		"hash": HashBytesToString(b.Hash),
+		"link": HashBytesToString(b.Link),
+	}).Info(string(b.Data))
+}