Fix not writing chunk hashes to file; Make payment hash fixed size

Author: pyropy

example/main.go

@@ -109,7 +109,7 @@ func decrypt(inPath, outPath, preimage string, chunkSize int64) error {
 			}
 
 			root := fmt.Sprintf("%x", proof.MerkleProof.Root)
-			log.Println("Generated proof", "proof root", root)
+			log.Println("Generated proof", "root", root)
 		}
 
 		return err

pkg/decrypt.go

@@ -9,9 +9,9 @@ import (
 
 // Decrypt tries to decrypt file with given preimage and returns io.Reader of decrypted file.
 //
-// In case of an error, decrypt returns chunk index alongisde the error.
+// In case of an error, decrypt returns chunk index alongside the error.
 //
-// If chunk index is not -1, then error ocurred while decrypting the chunk
+// If chunk index is not -1, then error occurred while decrypting the chunk
 // hence proof for given chunk should be generated.
 func Decrypt(preimage []byte, file io.ReadSeeker, chunkSize int64) (io.Reader, int, error) {
 	var out bytes.Buffer
@@ -65,9 +65,8 @@ func Decrypt(preimage []byte, file io.ReadSeeker, chunkSize int64) (io.Reader, i
 		h := sha256.New()
 		h.Write(decryptedChunk)
 		hash := h.Sum(nil)
-
 		if !bytes.Equal(expectedHash, hash) {
-			return nil, int(i), fmt.Errorf("failed to decrypt file")
+			return nil, int(i), fmt.Errorf("failed to decrypt chunk %d. expected %x got %x", i, expectedHash, hash)
 		}
 
 		out.Write(decryptedChunk)
@@ -77,5 +76,5 @@ func Decrypt(preimage []byte, file io.ReadSeeker, chunkSize int64) (io.Reader, i
 		i++
 	}
 
-	return nil, 0, nil
+	return io.Reader(&out), 0, nil
 }

pkg/encrypt.go

@@ -2,6 +2,7 @@ package bitstream
 
 import (
 	"bytes"
+	"crypto/sha256"
 	"fmt"
 	"io"
 
@@ -32,7 +33,9 @@ func Encrypt(pk *btcec.PrivateKey, paymentHash, preimage []byte, inFile io.ReadS
 		return fmt.Errorf("failed to write schnorr sig: %w", err)
 	}
 
-	_, err = outFile.Write(paymentHash)
+	var paymentHashFixed [32]byte
+	copy(paymentHashFixed[:], paymentHash)
+	_, err = outFile.Write(paymentHashFixed[:])
 	if err != nil {
 		return fmt.Errorf("failed to write payment hash: %w", err)
 	}
@@ -68,7 +71,13 @@ func EncryptFile(preimage []byte, file io.ReadSeeker, chunkSize int64) (Encrypte
 			return nil, nil, err
 		}
 
+		h := sha256.New()
+		h.Write(chunk)
+		hash := h.Sum(nil)
+
 		encryptedChunk := ChunkCipher(i, preimage, chunk)
+
+		b.Write(hash)
 		b.Write(encryptedChunk)
 
 		encNode := NewNode(encryptedChunk)