docs: add checksum and integrity hash func instrument

README.md

@@ -5,8 +5,9 @@ Support common libs for different repos of greenfield
 
 ### 1. Erasure encode/decode algorithm 
 
-(1) erasure package support RSEncoder which contain basic Encode and Decode reedSolomon APIs 
-```
+- erasure package support RSEncoder which contain basic Encode and Decode ReedSolomon APIs 
+
+```go
 // first step, create a new rs encoder, the blockSize indicate the data size to be encoded
 func NewRSEncoder(dataShards, parityShards int, blockSize int64) (r RSEncoder, err error) {
 // encode data and return the encoded shard number
@@ -16,8 +17,10 @@ func (r *RSEncoder) DecodeDataShards(content [][]byte) error
 // decode the input data and reconstruct the data shards and parity Shards
 func (r *RSEncoder) DecodeShards(data [][]byte) error
 ```
-(2) redundancy package support methods to encode/decode segments data using RSEncoder 
-```
+
+- redundancy package support methods to encode/decode segments data using RSEncoder 
+
+```go
 // encode one segment 
 func EncodeRawSegment(content []byte, dataShards, parityShards int) ([][]byte, error) 
 
@@ -30,7 +33,7 @@ func DecodeRawSegment(pieceData [][]byte, segmentSize int64, dataShards, parityS
 hash package support methods to compute hash roots of greenfield objects , the computed methods is based on 
 redundancy strategy of greenfield
 
-```
+```go
 // compute hash roots fromm io reader, the parameters should fetch from chain besides reader
 func ComputeIntegrityHash(reader io.Reader, segmentSize int64, dataShards, parityShards int) ([]string, int64, error)
 
@@ -40,3 +43,26 @@ func ComputerHashFromFile(filePath string, segmentSize int64, dataShards, parity
 
 
 ### 3. Generate checksum and integrity hash
+common library supports generating checksum and integrity hash. `GenerateChecksum` uses sha256 algorithm to compute hash. `GenerateIntegrityHash` is used to compute all checksum to get a integrity hash.
+
+Function as follows:
+
+```go
+// GenerateChecksum generates the checksum of one piece data
+func GenerateIntegrityHash(checksumList [][]byte) []byte
+
+// GenerateIntegrityHash generates integrity hash of all piece data checksum
+func GenerateIntegrityHash(checksumList [][]byte) []byte
+
+// ChallengePieceHash challenge integrity hash and checksum list
+// integrityHash represents the integrity hash of one piece list, this piece list may be ec piece data list or
+// segment piece data list; if piece data list is ec, this list is all ec1 piece data; if piece list is segment, all
+// piece data is all segments of an object
+// checksumList is composed of  one piece list's individual checksum
+// index represents which piece is used to challenge
+// pieceData represents piece physical data that user want to challenge
+func ChallengePieceHash(integrityHash []byte, checksumList [][]byte, index int, pieceData []byte) error
+
+// VerifyIntegrityHash verify integrity hash if right
+func VerifyIntegrityHash(integrityHash []byte, checksumList [][]byte) error
+```