From 71eec95c5b5a156ff0e9b5c05cc755c2740df434 Mon Sep 17 00:00:00 2001
From: Jakub Matys <jakub.matys@satoshilabs.com>
Date: Mon, 26 Mar 2018 11:41:32 +0200
Subject: [PATCH] ZCash uses decoded address as AddrID

---
 bchain/coins/btc/bitcoinparser.go |  2 ++
 bchain/coins/zec/address.go       | 41 +++++++++++++++++++++++++++++++
 bchain/coins/zec/zcashparser.go   | 12 +++++++--
 3 files changed, 53 insertions(+), 2 deletions(-)
 create mode 100644 bchain/coins/zec/address.go

diff --git a/bchain/coins/btc/bitcoinparser.go b/bchain/coins/btc/bitcoinparser.go
index 45f6b17a..6918c980 100644
--- a/bchain/coins/btc/bitcoinparser.go
+++ b/bchain/coins/btc/bitcoinparser.go
@@ -33,10 +33,12 @@ func GetChainParams(chain string) *chaincfg.Params {
 	return &chaincfg.MainNetParams
 }
 
+// GetAddrIDFromAddress returns internal address representation of given transaction output
 func (p *BitcoinBlockParser) GetAddrIDFromVout(output *bchain.Vout) ([]byte, error) {
 	return hex.DecodeString(output.ScriptPubKey.Hex)
 }
 
+// GetAddrIDFromAddress returns internal address representation of given address
 func (p *BitcoinBlockParser) GetAddrIDFromAddress(address string) ([]byte, error) {
 	return p.AddressToOutputScript(address)
 }
diff --git a/bchain/coins/zec/address.go b/bchain/coins/zec/address.go
new file mode 100644
index 00000000..be69c4a3
--- /dev/null
+++ b/bchain/coins/zec/address.go
@@ -0,0 +1,41 @@
+package zec
+
+import (
+	"crypto/sha256"
+	"errors"
+	"github.com/btcsuite/btcutil/base58"
+)
+
+var (
+	// ErrChecksumMismatch describes an error where decoding failed due
+	// to a bad checksum.
+	ErrChecksumMismatch = errors.New("checksum mismatch")
+
+	// ErrInvalidFormat describes an error where decoding failed due to invalid version
+	ErrInvalidFormat = errors.New("invalid format: version and/or checksum bytes missing")
+)
+
+// checksum: first four bytes of sha256^2
+func checksum(input []byte) (cksum [4]byte) {
+	h := sha256.Sum256(input)
+	h2 := sha256.Sum256(h[:])
+	copy(cksum[:], h2[:4])
+	return
+}
+
+// CheckDecode decodes a string that was encoded with CheckEncode and verifies the checksum.
+func CheckDecode(input string) (result []byte, version []byte, err error) {
+	decoded := base58.Decode(input)
+	if len(decoded) < 5 {
+		return nil, nil, ErrInvalidFormat
+	}
+	version = append(version, decoded[0:2]...)
+	var cksum [4]byte
+	copy(cksum[:], decoded[len(decoded)-4:])
+	if checksum(decoded[:len(decoded)-4]) != cksum {
+		return nil, nil, ErrChecksumMismatch
+	}
+	payload := decoded[2 : len(decoded)-4]
+	result = append(result, payload...)
+	return
+}
diff --git a/bchain/coins/zec/zcashparser.go b/bchain/coins/zec/zcashparser.go
index 758f9e48..66a80a69 100644
--- a/bchain/coins/zec/zcashparser.go
+++ b/bchain/coins/zec/zcashparser.go
@@ -10,15 +10,19 @@ import (
 
 type ZCashBlockParser struct{}
 
+// GetAddrIDFromAddress returns internal address representation of given transaction output
 func (p *ZCashBlockParser) GetAddrIDFromVout(output *bchain.Vout) ([]byte, error) {
 	if len(output.ScriptPubKey.Addresses) != 1 {
 		return nil, nil
 	}
-	return []byte(output.ScriptPubKey.Addresses[0]), nil
+	hash, _, err := CheckDecode(output.ScriptPubKey.Addresses[0])
+	return hash, err
 }
 
+// GetAddrIDFromAddress returns internal address representation of given address
 func (p *ZCashBlockParser) GetAddrIDFromAddress(address string) ([]byte, error) {
-	return []byte(address), nil
+	hash, _, err := CheckDecode(address)
+	return hash, err
 }
 
 // PackTx packs transaction to byte array
@@ -74,3 +78,7 @@ func (p *ZCashBlockParser) ParseBlock(b []byte) (*bchain.Block, error) {
 func (p *ZCashBlockParser) ParseTx(b []byte) (*bchain.Tx, error) {
 	return nil, errors.New("ParseTx: not implemented")
 }
+
+func (p *ZCashBlockParser) IsUTXOChain() bool {
+	return true
+}