From 49cf707d2ced72698cd44c6f4f3f64072c2fc308 Mon Sep 17 00:00:00 2001
From: Jack Grigg <jack@z.cash>
Date: Wed, 1 Mar 2017 11:20:42 -0800
Subject: [PATCH] Add Base58 encoding of viewing keys

---
 src/base58.cpp        |  8 ++++++++
 src/base58.h          | 11 +++++++++++
 src/chainparams.cpp   |  4 ++++
 src/chainparams.h     |  1 +
 src/zcash/Address.hpp |  1 +
 5 files changed, 25 insertions(+)

diff --git a/src/base58.cpp b/src/base58.cpp
index 2fd2475fe..09977ea35 100644
--- a/src/base58.cpp
+++ b/src/base58.cpp
@@ -365,6 +365,14 @@ template libzcash::PaymentAddress CZCEncoding<libzcash::PaymentAddress,
                                               CChainParams::ZCPAYMENT_ADDRRESS,
                                               libzcash::SerializedPaymentAddressSize>::Get() const;
 
+// Explicit instantiations for libzcash::ViewingKey
+template bool CZCEncoding<libzcash::ViewingKey,
+                          CChainParams::ZCVIEWING_KEY,
+                          libzcash::SerializedViewingKeySize>::Set(const libzcash::ViewingKey& vk);
+template libzcash::ViewingKey CZCEncoding<libzcash::ViewingKey,
+                                          CChainParams::ZCVIEWING_KEY,
+                                          libzcash::SerializedViewingKeySize>::Get() const;
+
 // Explicit instantiations for libzcash::SpendingKey
 template bool CZCEncoding<libzcash::SpendingKey,
                           CChainParams::ZCSPENDING_KEY,
diff --git a/src/base58.h b/src/base58.h
index c239e0e99..c65f89b0c 100644
--- a/src/base58.h
+++ b/src/base58.h
@@ -118,6 +118,17 @@ public:
     CZCPaymentAddress(const libzcash::PaymentAddress& addr) { Set(addr); }
 };
 
+class CZCViewingKey : public CZCEncoding<libzcash::ViewingKey, CChainParams::ZCVIEWING_KEY, libzcash::SerializedViewingKeySize> {
+protected:
+    std::string PrependName(const std::string& s) const { return "viewing key" + s; }
+
+public:
+    CZCViewingKey() {}
+
+    CZCViewingKey(const std::string& strViewingKey) { SetString(strViewingKey.c_str(), 3); }
+    CZCViewingKey(const libzcash::ViewingKey& vk) { Set(vk); }
+};
+
 class CZCSpendingKey : public CZCEncoding<libzcash::SpendingKey, CChainParams::ZCSPENDING_KEY, libzcash::SerializedSpendingKeySize> {
 protected:
     std::string PrependName(const std::string& s) const { return "spending key" + s; }
diff --git a/src/chainparams.cpp b/src/chainparams.cpp
index 034eee6b2..23544f488 100644
--- a/src/chainparams.cpp
+++ b/src/chainparams.cpp
@@ -110,6 +110,8 @@ public:
         base58Prefixes[EXT_SECRET_KEY]     = {0x04,0x88,0xAD,0xE4};
         // guarantees the first 2 characters, when base58 encoded, are "zc"
         base58Prefixes[ZCPAYMENT_ADDRRESS] = {0x16,0x9A};
+        // guarantees the first 4 characters, when base58 encoded, are "ZiVK"
+        base58Prefixes[ZCVIEWING_KEY]      = {0xA8,0xAB,0xD3};
         // guarantees the first 2 characters, when base58 encoded, are "SK"
         base58Prefixes[ZCSPENDING_KEY]     = {0xAB,0x36};
 
@@ -241,6 +243,8 @@ public:
         base58Prefixes[EXT_SECRET_KEY]     = {0x04,0x35,0x83,0x94};
         // guarantees the first 2 characters, when base58 encoded, are "zt"
         base58Prefixes[ZCPAYMENT_ADDRRESS] = {0x16,0xB6};
+        // guarantees the first 4 characters, when base58 encoded, are "ZiVt"
+        base58Prefixes[ZCVIEWING_KEY]      = {0xA8,0xAC,0x0C};
         // guarantees the first 2 characters, when base58 encoded, are "ST"
         base58Prefixes[ZCSPENDING_KEY]     = {0xAC,0x08};
 
diff --git a/src/chainparams.h b/src/chainparams.h
index a1de7b493..0de8d01b5 100644
--- a/src/chainparams.h
+++ b/src/chainparams.h
@@ -44,6 +44,7 @@ public:
 
         ZCPAYMENT_ADDRRESS,
         ZCSPENDING_KEY,
+        ZCVIEWING_KEY,
 
         MAX_BASE58_TYPES
     };
diff --git a/src/zcash/Address.hpp b/src/zcash/Address.hpp
index 4287fee4f..2dbe10a60 100644
--- a/src/zcash/Address.hpp
+++ b/src/zcash/Address.hpp
@@ -8,6 +8,7 @@
 namespace libzcash {
 
 const size_t SerializedPaymentAddressSize = 64;
+const size_t SerializedViewingKeySize = 64;
 const size_t SerializedSpendingKeySize = 32;
 
 class PaymentAddress {