From fa32935e7724213820e8d819471274cc451b9b7c Mon Sep 17 00:00:00 2001
From: Richard G Brown <richard@r3cev.com>
Date: Sat, 21 Nov 2015 16:55:50 +0000
Subject: [PATCH] legalContractRef changed String to SecureHash (of contract
 contents)

---
 src/contracts/Cash.kt                  | 11 ++++++++++-
 src/contracts/CommercialPaper.kt       |  3 ++-
 src/contracts/DummyContract.kt         |  3 ++-
 src/contracts/JavaCommercialPaper.java |  5 +++--
 src/core/Structures.kt                 |  8 +++++---
 5 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/src/contracts/Cash.kt b/src/contracts/Cash.kt
index 8b46c60fc9..bd23aa6176 100644
--- a/src/contracts/Cash.kt
+++ b/src/contracts/Cash.kt
@@ -29,7 +29,16 @@ class InsufficientBalanceException(val amountMissing: Amount) : Exception()
  * vaults can ignore the issuer/depositRefs and just examine the amount fields.
  */
 object Cash : Contract {
-    override val legalContractReference: String = "https://www.big-book-of-banking-law.gov/cash-claims.html"
+    /**
+     * TODO:
+     * 1) hash should be of the contents, not the URI
+     * 2) allow the content to be specified at time of instance creation?
+     *  Motivation: it's the difference between a state object referencing a programRef, which references a
+     *  legalContractReference and a state object which directly references both.  The latter allows the legal wording
+     *  to evolve without requiring code changes. But creates a risk that users create objects governed by a program
+     *  that is inconsistent with the legal contract
+     */
+    override val legalContractReference: SecureHash = SecureHash.sha256("https://www.big-book-of-banking-law.gov/cash-claims.html");
 
     /** A state representing a cash claim against some institution */
     data class State(
diff --git a/src/contracts/CommercialPaper.kt b/src/contracts/CommercialPaper.kt
index 18273ea20b..197d32c64f 100644
--- a/src/contracts/CommercialPaper.kt
+++ b/src/contracts/CommercialPaper.kt
@@ -23,7 +23,8 @@ val CP_PROGRAM_ID = SecureHash.sha256("replace-me-later-with-bytecode-hash")
 
 // TODO: Generalise the notion of an owned instrument into a superclass/supercontract. Consider composition vs inheritance.
 object CommercialPaper : Contract {
-    override val legalContractReference: String = "https://en.wikipedia.org/wiki/Commercial_paper"
+    // TODO: should reference the content of the legal agreement, not its URI
+    override val legalContractReference: SecureHash = SecureHash.sha256("https://en.wikipedia.org/wiki/Commercial_paper")
 
     data class State(
         val issuance: InstitutionReference,
diff --git a/src/contracts/DummyContract.kt b/src/contracts/DummyContract.kt
index e7f117c3c0..c1a6b2ae41 100644
--- a/src/contracts/DummyContract.kt
+++ b/src/contracts/DummyContract.kt
@@ -18,5 +18,6 @@ object DummyContract : Contract {
         // Always accepts.
     }
 
-    override val legalContractReference: String = "/dev/null"
+    // The "empty contract"
+    override val legalContractReference: SecureHash = SecureHash.sha256("")
 }
\ No newline at end of file
diff --git a/src/contracts/JavaCommercialPaper.java b/src/contracts/JavaCommercialPaper.java
index 0c81b06a9a..00611ae19a 100644
--- a/src/contracts/JavaCommercialPaper.java
+++ b/src/contracts/JavaCommercialPaper.java
@@ -118,7 +118,8 @@ public class JavaCommercialPaper implements Contract {
 
     @NotNull
     @Override
-    public String getLegalContractReference() {
-        return "https://en.wikipedia.org/wiki/Commercial_paper";
+    public SecureHash getLegalContractReference() {
+        // TODO: Should return hash of the contract's contents, not its URI
+        return SecureHash.Companion.sha256("https://en.wikipedia.org/wiki/Commercial_paper");
     }
 }
diff --git a/src/core/Structures.kt b/src/core/Structures.kt
index 859486382d..f95173aa3a 100644
--- a/src/core/Structures.kt
+++ b/src/core/Structures.kt
@@ -69,7 +69,9 @@ interface Contract {
      */
     fun verify(tx: TransactionForVerification)
 
-    // TODO: This should probably be a hash of a document, rather than a URL to it.
-    /** Unparsed reference to the natural language contract that this code is supposed to express (usually a URL). */
-    val legalContractReference: String
+    /**
+     * Unparsed reference to the natural language contract that this code is supposed to express (usually a hash of
+     * the contract's contents).
+     */
+    val legalContractReference: SecureHash
 }
\ No newline at end of file