feat: asset fingerprint

Fixes #297

Author: agaffney

ledger/block.go

@@ -34,18 +34,6 @@ type BlockHeader interface {
 	Cbor() []byte
 }
 
-type Blake2b256 [32]byte
-
-func (b Blake2b256) String() string {
-	return hex.EncodeToString([]byte(b[:]))
-}
-
-type Blake2b224 [28]byte
-
-func (b Blake2b224) String() string {
-	return hex.EncodeToString([]byte(b[:]))
-}
-
 func NewBlockFromCbor(blockType uint, data []byte) (Block, error) {
 	switch blockType {
 	case BLOCK_TYPE_BYRON_EBB:

ledger/common.go

@@ -15,13 +15,64 @@
 package ledger
 
 import (
+	"encoding/hex"
 	"fmt"
 
 	"github.com/blinklabs-io/gouroboros/cbor"
 	"github.com/blinklabs-io/gouroboros/internal/base58"
 	"github.com/blinklabs-io/gouroboros/internal/bech32"
+
+	"golang.org/x/crypto/blake2b"
 )
 
+type Blake2b256 [32]byte
+
+func NewBlake2b256(data []byte) Blake2b256 {
+	b := Blake2b256{}
+	copy(b[:], data)
+	return b
+}
+
+func (b Blake2b256) String() string {
+	return hex.EncodeToString([]byte(b[:]))
+}
+
+func (b Blake2b256) Bytes() []byte {
+	return b[:]
+}
+
+type Blake2b224 [28]byte
+
+func NewBlake2b224(data []byte) Blake2b224 {
+	b := Blake2b224{}
+	copy(b[:], data)
+	return b
+}
+
+func (b Blake2b224) String() string {
+	return hex.EncodeToString([]byte(b[:]))
+}
+
+func (b Blake2b224) Bytes() []byte {
+	return b[:]
+}
+
+type Blake2b160 [20]byte
+
+func NewBlake2b160(data []byte) Blake2b160 {
+	b := Blake2b160{}
+	copy(b[:], data)
+	return b
+}
+
+func (b Blake2b160) String() string {
+	return hex.EncodeToString([]byte(b[:]))
+}
+
+func (b Blake2b160) Bytes() []byte {
+	return b[:]
+}
+
 // MultiAsset represents a collection of policies, assets, and quantities. It's used for
 // TX outputs (uint64) and TX asset minting (int64 to allow for negative values for burning)
 type MultiAsset[T int64 | uint64] struct {
@@ -65,6 +116,40 @@ func (m *MultiAsset[T]) Asset(policyId Blake2b224, assetName []byte) T {
 	return policy[cbor.ByteString(assetName)]
 }
 
+type AssetFingerprint struct {
+	policyId  []byte
+	assetName []byte
+}
+
+func NewAssetFingerprint(policyId []byte, assetName []byte) AssetFingerprint {
+	return AssetFingerprint{
+		policyId:  policyId,
+		assetName: assetName,
+	}
+}
+
+func (a AssetFingerprint) Hash() Blake2b160 {
+	// We can ignore the error return here because our fixed size/key arguments will
+	// never trigger an error
+	tmpHash, _ := blake2b.New(20, nil)
+	tmpHash.Write(a.policyId)
+	tmpHash.Write(a.assetName)
+	return NewBlake2b160(tmpHash.Sum(nil))
+}
+
+func (a AssetFingerprint) String() string {
+	// Convert data to base32 and encode as bech32
+	convData, err := bech32.ConvertBits(a.Hash().Bytes(), 8, 5, true)
+	if err != nil {
+		panic(fmt.Sprintf("unexpected error converting data to base32: %s", err))
+	}
+	encoded, err := bech32.Encode("asset", convData)
+	if err != nil {
+		panic(fmt.Sprintf("unexpected error encoding data as bech32: %s", err))
+	}
+	return encoded
+}
+
 const (
 	addressHeaderTypeMask    = 0xF0
 	addressHeaderNetworkMask = 0x0F

ledger/common_test.go

@@ -0,0 +1,45 @@
+package ledger
+
+import (
+	"encoding/hex"
+	"testing"
+)
+
+func TestAssetFingerprint(t *testing.T) {
+	testDefs := []struct {
+		policyIdHex         string
+		assetNameHex        string
+		expectedFingerprint string
+	}{
+		// NOTE: these test defs were created from a random sampling of recent assets on cexplorer.io
+		{
+			policyIdHex:         "29a8fb8318718bd756124f0c144f56d4b4579dc5edf2dd42d669ac61",
+			assetNameHex:        "6675726e697368613239686e",
+			expectedFingerprint: "asset1jdu2xcrwlqsjqqjger6kj2szddz8dcpvcg4ksz",
+		},
+		{
+			policyIdHex:         "eaf8042c1d8203b1c585822f54ec32c4c1bb4d3914603e2cca20bbd5",
+			assetNameHex:        "426f7764757261436f6e63657074733638",
+			expectedFingerprint: "asset1kp7hdhqc7chmyqvtqrsljfdrdt6jz8mg5culpe",
+		},
+		{
+			policyIdHex:         "cf78aeb9736e8aa94ce8fab44da86b522fa9b1c56336b92a28420525",
+			assetNameHex:        "363438346330393264363164373033656236333233346461",
+			expectedFingerprint: "asset1rx3cnlsvh3udka56wyqyed3u695zd5q2jck2yd",
+		},
+	}
+	for _, test := range testDefs {
+		policyIdBytes, err := hex.DecodeString(test.policyIdHex)
+		if err != nil {
+			t.Fatalf("failed to decode policy ID hex: %s", err)
+		}
+		assetNameBytes, err := hex.DecodeString(test.assetNameHex)
+		if err != nil {
+			t.Fatalf("failed to decode asset name hex: %s", err)
+		}
+		fp := NewAssetFingerprint(policyIdBytes, assetNameBytes)
+		if fp.String() != test.expectedFingerprint {
+			t.Fatalf("asset fingerprint did not match expected value, got: %s, wanted: %s", fp.String(), test.expectedFingerprint)
+		}
+	}
+}