Env. prop.: Org.BouncyCastle.Asn1.AllowUnsafeInteger

- set to "true" to weaken ASN.1 INTEGER checks
- see https://github.com/bcgit/bc-csharp/issues/156

2 files changed, 18 insertions, 13 deletions

diff --git a/crypto/src/asn1/DerEnumerated.cs b/crypto/src/asn1/DerEnumerated.cs
index db27065bb..6690feceb 100644
--- a/crypto/src/asn1/DerEnumerated.cs
+++ b/crypto/src/asn1/DerEnumerated.cs
@@ -62,19 +62,18 @@ namespace Org.BouncyCastle.Asn1
         }
 
         public DerEnumerated(
-            byte[]   bytes)
+            byte[] bytes)
         {
             if (bytes.Length > 1)
             {
-                if (bytes[0] == 0 && (bytes[1] & 0x80) == 0)
+                if ((bytes[0] == 0 && (bytes[1] & 0x80) == 0)
+                    || (bytes[0] == (byte)0xff && (bytes[1] & 0x80) != 0))
                 {
-                    throw new ArgumentException("malformed enumerated");
-                }
-                if (bytes[0] == (byte)0xff && (bytes[1] & 0x80) != 0)
-                {
-                    throw new ArgumentException("malformed enumerated");
+                    if (!DerInteger.AllowUnsafe())
+                        throw new ArgumentException("malformed enumerated");
                 }
             }
+
             this.bytes = Arrays.Clone(bytes);
         }
 
diff --git a/crypto/src/asn1/DerInteger.cs b/crypto/src/asn1/DerInteger.cs
index 5b240d281..ae14d2a9f 100644
--- a/crypto/src/asn1/DerInteger.cs
+++ b/crypto/src/asn1/DerInteger.cs
@@ -8,6 +8,14 @@ namespace Org.BouncyCastle.Asn1
     public class DerInteger
         : Asn1Object
     {
+        public const string AllowUnsafeProperty = "Org.BouncyCastle.Asn1.AllowUnsafeInteger";
+
+        internal static bool AllowUnsafe()
+        {
+            string allowUnsafeValue = Platform.GetEnvironmentVariable(AllowUnsafeProperty);
+            return allowUnsafeValue != null && Platform.EqualsIgnoreCase("true", allowUnsafeValue);
+        }
+
         private readonly byte[] bytes;
 
         /**
@@ -72,13 +80,11 @@ namespace Org.BouncyCastle.Asn1
         {
             if (bytes.Length > 1)
             {
-                if (bytes[0] == 0 && (bytes[1] & 0x80) == 0)
-                {
-                    throw new ArgumentException("malformed integer");
-                }
-                if (bytes[0] == (byte)0xff && (bytes[1] & 0x80) != 0)
+                if ((bytes[0] == 0 && (bytes[1] & 0x80) == 0)
+                    || (bytes[0] == (byte)0xff && (bytes[1] & 0x80) != 0))
                 {
-                    throw new ArgumentException("malformed integer");
+                    if (!AllowUnsafe())
+                        throw new ArgumentException("malformed integer");
                 }
             }
             this.bytes = Arrays.Clone(bytes);