mini block chain

blockchain/miniblockchain/private.pem

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+-----BEGIN EC PRIVATE KEY-----
+MGwCAQAwEAYHKoZIzj0CAQYFK4EEAAEEVTBTAgEBBBUAFlsrE0ZTspNiuuw/2+Ma
+tEHxhvKgBwYFK4EEAAGhLgMsAAQA/SXr0Ja+KrisdxU9Vw5UWEGyy0AHIrEwzQDR
+Oy6tS3j8y9EhROOt85o=
+-----END EC PRIVATE KEY-----

blockchain/miniblockchain/private1.pem

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+-----BEGIN EC PRIVATE KEY-----
+MGwCAQAwEAYHKoZIzj0CAQYFK4EEAAEEVTBTAgEBBBUBQ8KtHoB8i9szZLYy/5O7
+tqCUN2egBwYFK4EEAAGhLgMsAAQFsrxkbMiCua/AdIkE0Xmj8jwANLAFJWw+SKuH
+kZRZNwJDqDOMl03bW58=
+-----END EC PRIVATE KEY-----

blockchain/miniblockchain/private2.pem

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+-----BEGIN EC PRIVATE KEY-----
+MGwCAQAwEAYHKoZIzj0CAQYFK4EEAAEEVTBTAgEBBBUBISXkhMMqVH4ljZy3FLsy
+7IKyRP+gBwYFK4EEAAGhLgMsAAQDNOCGxozj0Fl8ys5bW5kPps3zanICJbdYdWbo
+rW6p1PH0zpjBF9wDqUg=
+-----END EC PRIVATE KEY-----

blockchain/miniblockchain/private3.pem

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+-----BEGIN EC PRIVATE KEY-----
+MGwCAQAwEAYHKoZIzj0CAQYFK4EEAAEEVTBTAgEBBBUCDZu6TlUXdrq6nHsaiMlh
+jT55XBmgBwYFK4EEAAGhLgMsAAQGmyw1g3+0Q6fjf7tacNliQOnzf4UFZZ7SFEVI
+ZSqMAFWsWUwmS0maRss=
+-----END EC PRIVATE KEY-----

blockchain/miniblockchain/public.pem

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+-----BEGIN EC PUBLIC KEY-----
+MEAwEAYHKoZIzj0CAQYFK4EEAAEDLAAEAP0l69CWviq4rHcVPVcOVFhBsstAByKx
+MM0A0TsurUt4/MvRIUTjrfOa
+-----END EC PUBLIC KEY-----

blockchain/miniblockchain/public1.pem

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+-----BEGIN EC PUBLIC KEY-----
+MEAwEAYHKoZIzj0CAQYFK4EEAAEDLAAEBbK8ZGzIgrmvwHSJBNF5o/I8ADSwBSVs
+Pkirh5GUWTcCQ6gzjJdN21uf
+-----END EC PUBLIC KEY-----

blockchain/miniblockchain/public2.pem

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+-----BEGIN EC PUBLIC KEY-----
+MEAwEAYHKoZIzj0CAQYFK4EEAAEDLAAEAzTghsaM49BZfMrOW1uZD6bN82pyAiW3
+WHVm6K1uqdTx9M6YwRfcA6lI
+-----END EC PUBLIC KEY-----

blockchain/miniblockchain/public3.pem

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+-----BEGIN EC PUBLIC KEY-----
+MEAwEAYHKoZIzj0CAQYFK4EEAAEDLAAEBpssNYN/tEOn43+7WnDZYkDp83+FBWWe
+0hRFSGUqjABVrFlMJktJmkbL
+-----END EC PUBLIC KEY-----

blockchain/miniblockchain/src/BlockChainStarter.java

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+import core.Block;
+import core.Transaction;
+import core.Wallet;
+import org.bouncycastle.jce.provider.BouncyCastleProvider;
+import util.EC;
+import util.Utils;
+
+import java.security.PrivateKey;
+import java.security.PublicKey;
+import java.security.Security;
+import java.util.ArrayList;
+
+public class BlockChainStarter {
+
+    public static void main(String[] args) throws Exception {
+
+        Security.addProvider(new BouncyCastleProvider());
+        EC ec = new EC();
+
+        ec.generate("private1.pem", "public1.pem");
+        ec.generate("private2.pem", "public2.pem");
+        ec.generate("private3.pem", "public3.pem");
+
+        Wallet wallet1 = new Wallet();
+        wallet1.setFromFile("private1.pem", "public1.pem");
+        Wallet wallet2 = new Wallet();
+        wallet2.setFromFile("private2.pem", "public2.pem");
+        Wallet wallet3 = new Wallet();
+        wallet3.setFromFile("private3.pem", "public3.pem");
+
+        Block block1 = new Block(1, null, 0, new ArrayList());
+        block1.mine();
+        block1.showInformation();
+
+        Block block2 = new Block(2, block1.getBlockHash(), 0, new ArrayList());
+
+        // 지갑1에서 지갑2로 코인을 전송했다는 의미를 가진 트랜잭션을 생성
+        Transaction transaction1 = new Transaction(wallet1, wallet2.getPublicKey(), 1.5, Utils.getDate());
+        block2.addTransaction(transaction1);
+
+        Thread.sleep(1000);
+
+        // 지갑2에서 지갑3으로 코인을 전송했다는 의미를 가진 트랜잭션을 생성
+        Transaction transaction2 = new Transaction(wallet2, wallet3.getPublicKey(), 3.7, Utils.getDate());
+        block2.addTransaction(transaction2);
+
+        block2.mine();
+        block2.showInformation();
+
+        Block block3 = new Block(3, block2.getBlockHash(), 0, new ArrayList());
+
+        Thread.sleep(1000);
+
+        // 지갑1에서 지갑3으로 코인을 전송했다는 의미를 가진 트랜잭션을 생성
+        Transaction transaction3 = new Transaction(wallet1, wallet3.getPublicKey(), 2.3, Utils.getDate());
+        block3.addTransaction(transaction3);
+
+        Thread.sleep(1000);
+
+        // 지갑2에서 지감3으로 코인을 전송했다는 의미를 가진 트랜잭션을 생성
+        Transaction transaction4 = new Transaction(wallet2, wallet3.getPublicKey(), 1.4, Utils.getDate());
+        block3.addTransaction(transaction4);
+
+        block3.mine();
+        block3.showInformation();
+    }
+}

blockchain/miniblockchain/src/core/Block.java

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+package core;
+
+import util.Utils;
+
+import java.math.BigInteger;
+import java.security.Signature;
+import java.util.ArrayList;
+
+public class Block {
+    private static final String ALGORITHM = "SHA1withECDSA";
+
+    private int blockID;
+    private String previousBlockHash;
+    private int nonce;
+    private ArrayList<Transaction> transactionList;
+
+    public int getBlockID() {
+        return blockID;
+    }
+    public void setBlockID(int blockID) {
+        this.blockID = blockID;
+    }
+    public String getPreviousBlockHash() {
+        return previousBlockHash;
+    }
+    public void setPreviousBlockHash(String previousBlockHash) {
+        this.previousBlockHash = previousBlockHash;
+    }
+    public int getNonce() {
+        return nonce;
+    }
+    public void setNonce(int nonce) {
+        this.nonce = nonce;
+    }
+    public String getTransaction() {
+        String transactionInformations = "";
+
+        for(int i=0;i<transactionList.size();i++) {
+            transactionInformations += transactionList.get(i).getInformation();
+        }
+
+        return transactionInformations;
+    }
+
+    public Block(int blockID, String previousBlockHash, int nonce, ArrayList<Transaction> transactionList) {
+        this.blockID = blockID;
+        this.previousBlockHash = previousBlockHash;
+        this.nonce = nonce;
+        this.transactionList = transactionList;
+    }
+
+    // 특정한 트랜잭션이 정상적인지 검증
+    public boolean verifyTransaction(Transaction transaction) throws Exception {
+        Signature signature;
+        signature = Signature.getInstance(ALGORITHM);
+        byte[] baText = transaction.getData().getBytes("UTF-8");
+        signature.initVerify(transaction.getSender());;
+        signature.update(baText);
+        return signature.verify(new BigInteger(transaction.getSignature(), 16).toByteArray());
+    }
+
+    // 정상적인 트랜잭션만 블록에 추가
+    public void addTransaction(Transaction transaction) throws Exception {
+        if(verifyTransaction(transaction)) {
+            System.out.println("정상적인 트랜잭션을 발견했습니다.");
+            transactionList.add(transaction);
+        } else {
+            System.out.println("트랜잭션이 바르게 인증되지 않았습니다.");
+        }
+    }
+
+    public String getBlockHash() {
+        return Utils.getHash(nonce + getTransaction() + previousBlockHash);
+    }
+
+    public void showInformation() {
+        System.out.println("---------------------------");
+        System.out.println("블록 번호: " + getBlockID());
+        System.out.println("이전 해시: " + getPreviousBlockHash());
+        System.out.println("채굴 변수 값: " + getNonce());
+        System.out.println("블록 데이터: ");
+        for(int i=0;i<transactionList.size();i++) System.out.println(transactionList.get(i).getInformation());
+        System.out.println("블록 해시: " + getBlockHash());
+        System.out.println("---------------------------");
+    }
+
+    public void mine() {
+        while(true) {
+            if(getBlockHash().substring(0, 4).equals("0000")) {
+                System.out.println(blockID + "번째 블록의 채굴에 성공했습니다.");
+                break;
+            }
+            nonce++;
+        }
+    }
+}

blockchain/miniblockchain/src/core/Transaction.java

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+package core;
+
+import util.Utils;
+
+import java.security.PublicKey;
+import java.sql.Timestamp;
+
+public class Transaction {
+    String signature;
+    PublicKey sender;
+    PublicKey receiver;
+    double amount;
+    Timestamp timestamp;
+
+    public String getSignature() {
+        return signature;
+    }
+    public void setSignature(String signature) {
+        this.signature = signature;
+    }
+    public PublicKey getSender() {
+        return sender;
+    }
+    public void setSender(PublicKey sender) {
+        this.sender = sender;
+    }
+    public PublicKey getReceiver() {
+        return receiver;
+    }
+    public void setReceiver(PublicKey receiver) {
+        this.receiver = receiver;
+    }
+    public double getAmount() {
+        return amount;
+    }
+    public void setAmount(double amount) {
+        this.amount = amount;
+    }
+    public Timestamp getTimestamp() {
+        return timestamp;
+    }
+    public void setTimestamp(Timestamp timestamp) {
+        this.timestamp = timestamp;
+    }
+
+    // 어떠한 지갑 주소로 얼마만큼의 가상화폐를 보냈는지에 대한 정보를 기준으로 초기화
+    public Transaction(Wallet wallet, PublicKey receiver, double amount, String timestamp) throws Exception {
+        this.sender = wallet.getPublicKey();
+        this.receiver = receiver;
+        this.amount = amount;
+        this.timestamp = java.sql.Timestamp.valueOf(timestamp);
+        this.signature = wallet.sign(getData());
+    }
+
+    // 서명 값을 포함한 트랜잭션 정보를 반환
+    public String getInformation() {
+        return "<" + signature + ">\n" +
+                new Utils().getHash(sender.toString()) + " -> " +
+                new Utils().getHash(receiver.toString()) + " : " +
+                amount + "개 (" + timestamp + ")";
+    }
+
+    // 서명 값을 제외한 단순 트랜잭션 정보를 반환
+    public String getData() {
+        return new Utils().getHash(sender.toString()) + " -> " +
+                new Utils().getHash(receiver.toString()) + " : " +
+                amount + "개 (" + timestamp + ")";
+    }
+}

blockchain/miniblockchain/src/core/Wallet.java

@@ -0,0 +1,40 @@
+package core;
+
+import util.EC;
+
+import java.math.BigInteger;
+import java.security.PrivateKey;
+import java.security.PublicKey;
+import java.security.Signature;
+
+public class Wallet {
+    private static final String ALGORIGHM = "SHA1withECDSA";
+
+    private PrivateKey privateKey;
+    private PublicKey publicKey;
+
+    public PrivateKey getPrivateKey() {
+        return privateKey;
+    }
+
+    public PublicKey getPublicKey() {
+        return publicKey;
+    }
+
+    // 특정한 파일로부터 개인키 및 공개키를 불러와 초기화
+    public void setFromFile(String privateKey, String publicKey) throws Exception {
+        this.privateKey = new EC().readPrivateKeyFromPemFile(privateKey);
+        this.publicKey = new EC().readPublicKeyFromPemFile(publicKey);
+    }
+
+    // 특정한 데이터를 개인키로 서명해서 얻은 결과를 문자열로 반환
+    public String sign(String data) throws Exception {
+        Signature signature;
+        signature = Signature.getInstance(ALGORIGHM);
+        signature.initSign(privateKey);
+        byte[] baText = data.getBytes("UTF-8");
+        signature.update(baText);
+        byte[] baSignature = signature.sign();
+        return (new BigInteger(1, baSignature).toString(16)).toUpperCase();
+    }
+}

blockchain/miniblockchain/src/util/EC.java

@@ -0,0 +1,100 @@
+package util;
+
+import org.bouncycastle.util.encoders.Base64;
+
+import java.io.BufferedReader;
+import java.io.FileNotFoundException;
+import java.io.FileReader;
+import java.io.IOException;
+import java.security.*;
+import java.security.spec.ECGenParameterSpec;
+import java.security.spec.InvalidKeySpecException;
+import java.security.spec.PKCS8EncodedKeySpec;
+import java.security.spec.X509EncodedKeySpec;
+
+public class EC {
+
+    // 세부 알고리즘으로 sect163k1을 사용
+    private final String ALGORITHM = "sect163k1";
+
+    public void generate(String privateKeyName, String publicKeyName) throws Exception{
+
+        // 바운시 캐슬의 타원 곡선 표준 알고리즘(ECDSA)을 사용
+        KeyPairGenerator generator = KeyPairGenerator.getInstance("ECDSA", "BC");
+
+        // 타원 곡선의 세부 알고리즘으로 sect163k1을 사용
+        ECGenParameterSpec ecsp;
+        ecsp = new ECGenParameterSpec(ALGORITHM);
+        generator.initialize(ecsp, new SecureRandom());
+
+        // 해당 알고리즘으로 랜덤의 키 한 쌍을 생성
+        KeyPair keyPair = generator.generateKeyPair();
+        System.out.println("타원곡선 암호키 한 쌍을 생성했습니다.");
+
+        // 생성한 키 한쌍에서 개인키와 공개키를 추출
+        PrivateKey priv = keyPair.getPrivate();
+        PublicKey pub = keyPair.getPublic();
+
+        // 개인키와 공개키를 특정한 파일 이름으로 저장
+        writePemFile(priv, "EC PRIVATE KEY", privateKeyName);
+        writePemFile(pub, "EC PUBLIC KEY", publicKeyName);
+    }
+
+    // Pem 클래스를 이용해 생성된 암호키를 파일로 저장
+    private void writePemFile(Key key, String description, String filename)
+            throws FileNotFoundException, IOException{
+        Pem pemFile = new Pem(key, description);
+        pemFile.write(filename);
+        System.out.printf("EC 암호키 %s을(를) %s 파일로 내보냈습니다.%n", description, filename);
+    }
+
+    // 문자열 형태의 인증서에서 개인키를 추출하는 함수
+    public PrivateKey readPrivateKeyFromPemFile(String privateKeyName)
+            throws FileNotFoundException, IOException, NoSuchAlgorithmException, InvalidKeySpecException {
+
+        String data = readString(privateKeyName);
+        System.out.println("EC 개인키를 " + privateKeyName + "로부터 불러왔습니다.");
+        System.out.println(data);
+
+        // 불필요한 설명 구문 제거
+        data = data.replaceAll("-----BEGIN EC PRIVATE KEY-----", "");
+        data = data.replaceAll("-----END EC PRIVATE KEY-----", "");
+
+        // PEM 파일은 Base64로 인코딩 되어있으므로 디코딩
+        byte[] decoded = Base64.decode(data);
+        PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(decoded);
+        KeyFactory factory = KeyFactory.getInstance("ECDSA");
+        return factory.generatePrivate(spec);
+    }
+
+    // 문자열 형태의 인증서에서 공키를 추출하는 함수
+    public PublicKey readPublicKeyFromPemFile(String publicKeyName)
+            throws FileNotFoundException, IOException, NoSuchAlgorithmException, InvalidKeySpecException {
+
+        String data = readString(publicKeyName);
+        System.out.println("EC 개인키를 " + publicKeyName + "로부터 불러왔습니다.");
+        System.out.println(data);
+
+        // 불필요한 설명 구문 제거
+        data = data.replaceAll("-----BEGIN EC PUBLIC KEY-----", "");
+        data = data.replaceAll("-----END EC PUBLIC KEY-----", "");
+
+        // PEM 파일은 Base64로 인코딩 되어있으므로 디코딩
+        byte[] decoded = Base64.decode(data);
+        X509EncodedKeySpec spec = new X509EncodedKeySpec(decoded);
+        KeyFactory factory = KeyFactory.getInstance("ECDSA");
+        return factory.generatePublic(spec);
+    }
+
+    // 특정한 파일에 작성되어 있는 문자열을 읽어옴.
+    private String readString(String filename) throws FileNotFoundException, IOException {
+        StringBuilder pem = new StringBuilder();
+        BufferedReader br = new BufferedReader(new FileReader(filename));
+
+        String line;
+        while((line = br.readLine()) != null) pem.append(line).append("\n");
+
+        br.close();
+        return pem.toString();
+    }
+}

blockchain/miniblockchain/src/util/Pem.java

@@ -0,0 +1,28 @@
+package util;
+
+import org.bouncycastle.util.io.pem.PemObject;
+import org.bouncycastle.util.io.pem.PemWriter;
+
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.OutputStreamWriter;
+import java.security.Key;
+
+public class Pem {
+
+    private final PemObject pemObject;
+
+    public Pem(Key key, String description) {
+        this.pemObject = new PemObject(description, key.getEncoded());
+    }
+
+    public void write(String filename) throws IOException {
+        PemWriter pemWriter = new PemWriter(new OutputStreamWriter(new FileOutputStream(filename)));
+
+        try {
+            pemWriter.writeObject(this.pemObject);
+        } finally {
+            pemWriter.close();
+        }
+    }
+}

blockchain/miniblockchain/src/util/Utils.java

@@ -0,0 +1,32 @@
+package util;
+
+import java.security.MessageDigest;
+import java.text.SimpleDateFormat;
+import java.util.Date;
+
+public class Utils {
+
+    public static String getHash(String input) {
+        StringBuffer result = new StringBuffer();
+
+        try {
+            MessageDigest md = MessageDigest.getInstance("SHA-256");
+            md.update(input.getBytes());
+            byte bytes[] = md.digest();
+            for (byte aByte : bytes) {
+                result.append(Integer.toString((aByte & 0xff) + 0x100, 16).substring(1));
+            }
+        } catch(Exception e) {
+            e.printStackTrace();
+        }
+        return result.toString();
+    }
+
+    public static String getDate() {
+        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss.S");
+        Date time = new Date();
+
+        String nowTime = format.format(time);
+        return nowTime;
+    }
+}