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Merge pull request #73 from libsv/feature/brc-74
feature: BRC-74 implementation of a BSV Universal Merkle Path format (BUMP)
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,187 @@ | ||
| package bc | ||
|
|
||
| import ( | ||
| "encoding/hex" | ||
| "encoding/json" | ||
| "errors" | ||
| "fmt" | ||
| "sort" | ||
|
|
||
| "github.com/libsv/go-bt/v2" | ||
| ) | ||
|
|
||
| // BUMP data model json format according to BRC-74. | ||
| type BUMP struct { | ||
| BlockHeight uint32 `json:"blockHeight"` | ||
| Path [][]leaf `json:"path"` | ||
| } | ||
|
|
||
| // It should be written such that the internal bytes are kept for calculations. | ||
| // and the JSON is generated from the internal struct to an external format. | ||
| // leaf represents a leaf in the Merkle tree. | ||
| type leaf struct { | ||
| Offset uint64 `json:"offset,omitempty"` | ||
| Hash string `json:"hash,omitempty"` | ||
| Txid *bool `json:"txid,omitempty"` | ||
| Duplicate *bool `json:"duplicate,omitempty"` | ||
| } | ||
|
|
||
| // NewBUMPFromBytes creates a new BUMP from a byte slice. | ||
| func NewBUMPFromBytes(bytes []byte) (*BUMP, error) { | ||
| bump := &BUMP{} | ||
|
|
||
| // first bytes are the block height. | ||
| var skip int | ||
| index, size := bt.NewVarIntFromBytes(bytes[skip:]) | ||
| skip += size | ||
| bump.BlockHeight = uint32(index) | ||
|
|
||
| // Next byte is the tree height. | ||
| treeHeight := uint(bytes[skip]) | ||
| skip++ | ||
|
|
||
| // We expect tree height levels. | ||
| bump.Path = make([][]leaf, treeHeight) | ||
|
|
||
| for lv := uint(0); lv < treeHeight; lv++ { | ||
| // For each level we parse a bunch of nLeaves. | ||
| n, size := bt.NewVarIntFromBytes(bytes[skip:]) | ||
| skip += size | ||
| nLeavesAtThisHeight := uint64(n) | ||
| bump.Path[lv] = make([]leaf, nLeavesAtThisHeight) | ||
| for lf := uint64(0); lf < nLeavesAtThisHeight; lf++ { | ||
| // For each leaf we parse the offset, hash, txid and duplicate. | ||
| offset, size := bt.NewVarIntFromBytes(bytes[skip:]) | ||
| skip += size | ||
| var l leaf | ||
| l.Offset = uint64(offset) | ||
| flags := bytes[skip] | ||
| skip++ | ||
| var dup bool | ||
| var txid bool | ||
| dup = flags&1 > 0 | ||
| txid = flags&2 > 0 | ||
| if dup { | ||
| l.Duplicate = &dup | ||
| } | ||
| if txid { | ||
| l.Txid = &txid | ||
| } | ||
| l.Hash = StringFromBytesReverse(bytes[skip : skip+32]) | ||
| skip += 32 | ||
| bump.Path[lv][lf] = l | ||
| } | ||
| } | ||
|
|
||
| // Sort each of the levels by the offset for consistency. | ||
| for _, level := range bump.Path { | ||
| sort.Slice(level, func(i, j int) bool { | ||
| return level[i].Offset < level[j].Offset | ||
| }) | ||
| } | ||
|
|
||
| return bump, nil | ||
| } | ||
|
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||
| // NewBUMPFromStr creates a BUMP from hex string. | ||
| func NewBUMPFromStr(str string) (*BUMP, error) { | ||
| bytes, err := hex.DecodeString(str) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| return NewBUMPFromBytes(bytes) | ||
| } | ||
|
|
||
| // NewBUMPFromJSON creates a BUMP from a JSON string. | ||
| func NewBUMPFromJSON(jsonStr string) (*BUMP, error) { | ||
| bump := &BUMP{} | ||
| err := json.Unmarshal([]byte(jsonStr), bump) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| return bump, nil | ||
| } | ||
|
|
||
| // Bytes encodes a BUMP as a slice of bytes. BUMP Binary Format according to BRC-74 https://brc.dev/74 | ||
| func (bump *BUMP) Bytes() ([]byte, error) { | ||
| bytes := []byte{} | ||
| bytes = append(bytes, bt.VarInt(bump.BlockHeight).Bytes()...) | ||
| treeHeight := len(bump.Path) | ||
| bytes = append(bytes, byte(treeHeight)) | ||
| for level := 0; level < treeHeight; level++ { | ||
| nLeaves := len(bump.Path[level]) | ||
| bytes = append(bytes, bt.VarInt(nLeaves).Bytes()...) | ||
| for _, leaf := range bump.Path[level] { | ||
| bytes = append(bytes, bt.VarInt(leaf.Offset).Bytes()...) | ||
| flags := byte(0) | ||
| if leaf.Duplicate != nil { | ||
| flags |= 1 | ||
| } | ||
| if leaf.Txid != nil { | ||
| flags |= 2 | ||
| } | ||
| bytes = append(bytes, flags) | ||
| if (flags & 1) == 0 { | ||
| bytes = append(bytes, BytesFromStringReverse(leaf.Hash)...) | ||
| } | ||
| } | ||
| } | ||
| return bytes, nil | ||
| } | ||
|
|
||
| func (bump *BUMP) String() (string, error) { | ||
| bytes, err := bump.Bytes() | ||
| if err != nil { | ||
| return "", err | ||
| } | ||
| return hex.EncodeToString(bytes), nil | ||
| } | ||
|
|
||
| // CalculateRootGivenTxid calculates the root of the Merkle tree given a txid. | ||
| func (bump *BUMP) CalculateRootGivenTxid(txid string) (string, error) { | ||
| // Find the index of the txid at the lowest level of the Merkle tree | ||
| var index uint64 | ||
| txidFound := false | ||
| for _, l := range bump.Path[0] { | ||
| if l.Hash == txid { | ||
| txidFound = true | ||
| index = l.Offset | ||
| break | ||
| } | ||
| } | ||
| if !txidFound { | ||
| return "", errors.New("The BUMP does not contain the txid: " + txid) | ||
| } | ||
|
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||
| // Calculate the root using the index as a way to determine which direction to concatenate. | ||
| workingHash := BytesFromStringReverse(txid) | ||
| for height, leaves := range bump.Path { | ||
| offset := (index >> height) ^ 1 | ||
| var leafAtThisLevel leaf | ||
| offsetFound := false | ||
| for _, l := range leaves { | ||
| if l.Offset == offset { | ||
| offsetFound = true | ||
| leafAtThisLevel = l | ||
| break | ||
| } | ||
| } | ||
| if !offsetFound { | ||
| return "", fmt.Errorf("We do not have a hash for this index at height: %v", height) | ||
| } | ||
|
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||
| var digest []byte | ||
| if leafAtThisLevel.Duplicate != nil { | ||
| digest = append(workingHash, workingHash...) | ||
| } else { | ||
| leafBytes := BytesFromStringReverse(leafAtThisLevel.Hash) | ||
| if (offset % 2) != 0 { | ||
| digest = append(workingHash, leafBytes...) | ||
| } else { | ||
| digest = append(leafBytes, workingHash...) | ||
| } | ||
| } | ||
| workingHash = Sha256Sha256(digest) | ||
| } | ||
| return StringFromBytesReverse(workingHash), nil | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,39 @@ | ||
| package bc | ||
|
|
||
| import ( | ||
| "testing" | ||
|
|
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| "github.com/stretchr/testify/require" | ||
| ) | ||
|
|
||
| const ( | ||
| jsonExample = `{"blockHeight":814435,"path":[[{"offset":20,"hash":"0dc75b4efeeddb95d8ee98ded75d781fcf95d35f9d88f7f1ce54a77a0c7c50fe"},{"offset":21,"txid":true,"hash":"3ecead27a44d013ad1aae40038acbb1883ac9242406808bb4667c15b4f164eac"}],[{"offset":11,"hash":"5745cf28cd3a31703f611fb80b5a080da55acefa4c6977b21917d1ef95f34fbc"}],[{"offset":4,"hash":"522a096a1a6d3b64a4289ab456134158d8443f2c3b8ed8618bd2b842912d4b57"}],[{"offset":3,"hash":"191c70d2ecb477f90716d602f4e39f2f81f686f8f4230c255d1b534dc85fa051"}],[{"offset":0,"hash":"1f487b8cd3b11472c56617227e7e8509b44054f2a796f33c52c28fd5291578fd"}],[{"offset":1,"hash":"5ecc0ad4f24b5d8c7e6ec5669dc1d45fcb3405d8ce13c0860f66a35ef442f562"}],[{"offset":1,"hash":"31631241c8124bc5a9531c160bfddb6fcff3729f4e652b10d57cfd3618e921b1"}]]}` | ||
|
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| hexExample = `fe636d0c0007021400fe507c0c7aa754cef1f7889d5fd395cf1f785dd7de98eed895dbedfe4e5bc70d1502ac4e164f5bc16746bb0868404292ac8318bbac3800e4aad13a014da427adce3e010b00bc4ff395efd11719b277694cface5aa50d085a0bb81f613f70313acd28cf4557010400574b2d9142b8d28b61d88e3b2c3f44d858411356b49a28a4643b6d1a6a092a5201030051a05fc84d531b5d250c23f4f886f6812f9fe3f402d61607f977b4ecd2701c19010000fd781529d58fc2523cf396a7f25440b409857e7e221766c57214b1d38c7b481f01010062f542f45ea3660f86c013ced80534cb5fd4c19d66c56e7e8c5d4bf2d40acc5e010100b121e91836fd7cd5102b654e9f72f3cf6fdbfd0b161c53a9c54b12c841126331` | ||
| rootExample = `bb6f640cc4ee56bf38eb5a1969ac0c16caa2d3d202b22bf3735d10eec0ca6e00` | ||
| txidExample = `3ecead27a44d013ad1aae40038acbb1883ac9242406808bb4667c15b4f164eac` | ||
| ) | ||
|
|
||
| func TestNewBUMPFromStr(t *testing.T) { | ||
| bump, err := NewBUMPFromStr(hexExample) | ||
| require.NoError(t, err) | ||
| str, err := bump.String() | ||
| require.NoError(t, err) | ||
| require.Equal(t, hexExample, str) | ||
| } | ||
|
|
||
| func TestNewBUMPFromJson(t *testing.T) { | ||
| jBump, err := NewBUMPFromJSON(jsonExample) | ||
| require.NoError(t, err) | ||
| jStr, err := jBump.String() | ||
| require.NoError(t, err) | ||
| require.Equal(t, hexExample, jStr) | ||
| } | ||
|
|
||
| func TestCalculateRootGivenTxid(t *testing.T) { | ||
| bump, err := NewBUMPFromJSON(jsonExample) | ||
| require.NoError(t, err) | ||
| root, err := bump.CalculateRootGivenTxid(txidExample) | ||
| require.NoError(t, err) | ||
| require.Equal(t, rootExample, root) | ||
| } |
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