fix: make PKCS#7 parameter optional as per RFC 5280

Author: troyfactor4

lib/pkcs7.js

@@ -837,7 +837,7 @@ function _recipientFromAsn1(obj) {
     serialNumber: forge.util.createBuffer(capture.serial).toHex(),
     encryptedContent: {
       algorithm: asn1.derToOid(capture.encAlgorithm),
-      parameter: capture.encParameter.value,
+      parameter: capture.encParameter ? capture.encParameter.value : null,
       content: capture.encKey
     }
   };

lib/pkcs7asn1.js

@@ -397,7 +397,8 @@ p7v.recipientInfoValidator = {
       name: 'RecipientInfo.keyEncryptionAlgorithm.parameter',
       tagClass: asn1.Class.UNIVERSAL,
       constructed: false,
-      captureAsn1: 'encParameter'
+      captureAsn1: 'encParameter',
+      optional: true
     }]
   }, {
     name: 'RecipientInfo.encryptedKey',