preservation of digest AlgIds in existing CMSSignedData github #1585

Author: dghgit

pkix/src/main/java/org/bouncycastle/cms/CMSSignedData.java

@@ -21,6 +21,7 @@
 import org.bouncycastle.asn1.ASN1Sequence;
 import org.bouncycastle.asn1.ASN1Set;
 import org.bouncycastle.asn1.BERSequence;
+import org.bouncycastle.asn1.DERNull;
 import org.bouncycastle.asn1.DLSet;
 import org.bouncycastle.asn1.cms.ContentInfo;
 import org.bouncycastle.asn1.cms.SignedData;
@@ -617,8 +618,17 @@ public static CMSSignedData replaceSigners(CMSSignedData signedData, SignerInfor
             vec.add(signer.toASN1Structure());
         }
 
-        ASN1Set digestSet = CMSUtils.convertToDlSet(digestAlgs);
+        // keep ourselves compatible with what was there before - issue with
+        // NULL appearing and disappearing in AlgorithmIdentifier parameters.
+        Set<AlgorithmIdentifier> oldDigestAlgs = signedData.getDigestAlgorithmIDs();
+        AlgorithmIdentifier[] oldDigestAlgIds = (AlgorithmIdentifier[])oldDigestAlgs.toArray(new AlgorithmIdentifier[oldDigestAlgs.size()]);
+        AlgorithmIdentifier[] newDigestAlgIds = (AlgorithmIdentifier[])digestAlgs.toArray(new AlgorithmIdentifier[digestAlgs.size()]);
+
+        compareAndReplaceAlgIds(oldDigestAlgIds, newDigestAlgIds);
+
+        ASN1Set digestSet = new DLSet(newDigestAlgIds);
         ASN1Set signerSet = new DLSet(vec);
+
         ASN1Sequence sD = (ASN1Sequence)signedData.signedData.toASN1Primitive();
 
         //
@@ -645,6 +655,27 @@ public static CMSSignedData replaceSigners(CMSSignedData signedData, SignerInfor
         return cms;
     }
 
+    private static void compareAndReplaceAlgIds(AlgorithmIdentifier[] oldDigestAlgIds, AlgorithmIdentifier[] newDigestAlgIds)
+    {
+        for (int i = 0; i != newDigestAlgIds.length; i++)
+        {
+            AlgorithmIdentifier newId = newDigestAlgIds[i];
+
+            for (int j = 0; j != oldDigestAlgIds.length; j++)
+            {
+                AlgorithmIdentifier oldId = oldDigestAlgIds[j];
+                if (newId.getAlgorithm().equals(oldId.getAlgorithm()))
+                {
+                    if (newId.getParameters() == null || DERNull.INSTANCE.equals(newId.getParameters()))
+                    {
+                        newDigestAlgIds[i] = oldId;
+                        break;
+                    }
+                }
+            }
+        }
+    }
+
     /**
      * Replace the certificate and CRL information associated with this
      * CMSSignedData object with the new one passed in.