fully specify retention behavior (#44)

* fully specify retention behavior

* update codeowners

* update go version

* remove test

.github/workflows/ci.yml

@@ -23,7 +23,7 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@v3
         with:
-          go-version: 1.21.3
+          go-version: 1.21.4
 
       - name: Install Mage
         run: go install github.com/magefile/mage
@@ -41,7 +41,7 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@v3
         with:
-          go-version: 1.21.3
+          go-version: 1.21.4
 
       - name: Install Mage
         run: go install github.com/magefile/mage

CODEOWNERS

@@ -9,7 +9,7 @@
 # The format is described: https://github.blog/2017-07-06-introducing-code-owners/
 
 # These owners will be the default owners for everything in the repo.
-*       @decentralgabe csuwildcat
+*       @decentralgabe @csuwildcat
 
 
 # -----------------------------------------------

impl/build/Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.21.3-alpine
+FROM golang:1.21.4-alpine
 
 # Create directory for our app inside the container
 WORKDIR /app

impl/internal/did/client.go

@@ -60,6 +60,26 @@ func (c *GatewayClient) GetDIDDocument(id string) (*did.Document, []TypeIndex, e
 	return d.FromDNSPacket(msg)
 }
 
+func (c *GatewayClient) GetMessage(id string) (*dns.Msg, error) {
+	resp, err := http.Get(c.gatewayURL + "/" + id)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to get did document")
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return nil, errors.Errorf("failed to get did document, status code: %d", resp.StatusCode)
+	}
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to read response body")
+	}
+	msg := new(dns.Msg)
+	if err = msg.Unpack(body[72:]); err != nil {
+		return nil, util.LoggingErrorMsg(err, "failed to unpack records")
+	}
+	return msg, nil
+}
+
 // PutDocument puts a bep44.Put message to a did:dht Gateway
 func (c *GatewayClient) PutDocument(id string, put bep44.Put) error {
 	d := DHT(id)

impl/internal/did/pow.go

@@ -0,0 +1,42 @@
+package did
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"math/big"
+	"strings"
+)
+
+// computeSHA256Hash computes the SHA-256 hash of a string and returns it as a hexadecimal string.
+func computeSHA256Hash(text string) string {
+	hash := sha256.Sum256([]byte(text))
+	return hex.EncodeToString(hash[:])
+}
+
+// has26LeadingZeros checks if the binary representation of the hash has 26 leading zeros.
+func hasLeadingZeros(hash string, difficulty int) bool {
+	// Convert hex hash to big.Int to handle binary conversion
+	hashInt := new(big.Int)
+	hashInt.SetString(hash, 16)
+
+	// Convert to binary string
+	binaryHash := fmt.Sprintf("%0256b", hashInt)
+
+	target := strings.Repeat("0", difficulty)
+
+	// Check if the first 26 characters are all zeros
+	return strings.HasPrefix(binaryHash, target)
+}
+
+// computeRetentionProof generates the Retention Proof Hash and checks if it meets the criteria.
+func computeRetentionProof(didIdentifier, bitcoinBlockHash string, difficulty, nonce int) (string, bool) {
+	// Concatenating the DID identifier with the retention value
+	retentionValue := didIdentifier + (bitcoinBlockHash + fmt.Sprintf("%d", nonce))
+
+	// Computing the SHA-256 hash
+	hash := computeSHA256Hash(retentionValue)
+
+	// Checking for the required number of leading zeros according to the difficulty
+	return hash, hasLeadingZeros(hash, difficulty)
+}

impl/internal/did/pow_test.go

@@ -0,0 +1,29 @@
+package did
+
+import (
+	"fmt"
+	"math"
+	"testing"
+	"time"
+)
+
+func TestPOW(t *testing.T) {
+	// Example usage of computeRetentionProof
+	didIdentifier := "did:dht:test"
+	bitcoinBlockHash := "000000000000000000022be0c55caae4152d023dd57e8d63dc1a55c1f6de46e7"
+
+	// 26 leading zeros
+	difficulty := 26
+
+	timer := time.Now()
+	for nonce := 0; nonce < math.MaxInt; nonce++ {
+		hash, isValid := computeRetentionProof(didIdentifier, bitcoinBlockHash, difficulty, nonce)
+		if isValid {
+			fmt.Printf("Hash: %s\n", hash)
+			fmt.Printf("Valid Retention Proof: %v\n", isValid)
+			fmt.Printf("Nonce: %d\n", nonce)
+			break
+		}
+	}
+	fmt.Printf("Time taken: %s\n", time.Since(timer))
+}