From fddc2c80dea8f7ad03f85203d818fcc0eb4bcfa7 Mon Sep 17 00:00:00 2001
From: lloyd <lloyd@randombit.net>
Date: Wed, 4 Mar 2015 02:08:57 +0000
Subject: When comparing algorithm identifiers consider NULL and empty
 parameters as equivalent. Based on a patch sent to the mailing list by Uri
 Blumenthal.

---
 doc/relnotes/1_11_15.rst |  4 ++++
 src/lib/asn1/alg_id.cpp  | 20 +++++++++++++++++---
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/doc/relnotes/1_11_15.rst b/doc/relnotes/1_11_15.rst
index 4c47785df..a0937deb2 100644
--- a/doc/relnotes/1_11_15.rst
+++ b/doc/relnotes/1_11_15.rst
@@ -3,3 +3,7 @@ Version 1.11.15, Not Yet Released
 
 * A bug in ffi.cpp meant Python could only encrypt. Github issue 53.
 
+* When comparing two ASN.1 algorithm identifiers, consider empty and
+  NULL parameters the same.
+
+* Fix compilation problem on OS X
diff --git a/src/lib/asn1/alg_id.cpp b/src/lib/asn1/alg_id.cpp
index 8e6651d52..7d476a225 100644
--- a/src/lib/asn1/alg_id.cpp
+++ b/src/lib/asn1/alg_id.cpp
@@ -63,13 +63,27 @@ AlgorithmIdentifier::AlgorithmIdentifier(const std::string& alg_id,
 /*
 * Compare two AlgorithmIdentifiers
 */
+namespace {
+
+bool param_null_or_empty(const std::vector<byte>& p)
+   {
+   if(p.size() == 2 && (p[0] == 0x05) && (p[1] == 0x00))
+      return true;
+   return p.empty();
+   }
+
+}
+
 bool operator==(const AlgorithmIdentifier& a1, const AlgorithmIdentifier& a2)
    {
    if(a1.oid != a2.oid)
       return false;
-   if(a1.parameters != a2.parameters)
-      return false;
-   return true;
+
+   if(param_null_or_empty(a1.parameters) &&
+      param_null_or_empty(a2.parameters))
+      return true;
+
+   return (a1.parameters == a2.parameters);
    }
 
 /*
-- 
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