#232 fix decrypt not forwarding sign key

enzevalos_iphone/SMIME.swift

@@ -711,12 +711,13 @@ PkfA6mR7rtcyIbHi34tfkCv/qolV3QivMHov0IJpRyNO
         
         let verifyCryptoObj = verify(data: outputData, email: fromAddr, isMailNew: isMailNew)
         
+        let signKey = verifyCryptoObj.signKey
         let sigState = verifyCryptoObj.signatureState
         let addresses = verifyCryptoObj.signedAdrs
         let plainText = verifyCryptoObj.plaintext
         let decryptedData = plainText!.data(using: .utf8)!
         
-        return CryptoObject(chiphertext: data, plaintext: plainText, decryptedData: decryptedData, sigState: sigState, encState: encState, signKey: fp, encType: CryptoScheme.SMIME, signedAdrs: sigState == SignatureState.ValidSignature ? addresses : [])
+        return CryptoObject(chiphertext: data, plaintext: plainText, decryptedData: decryptedData, sigState: sigState, encState: encState, signKey: signKey, encType: CryptoScheme.SMIME, signedAdrs: sigState == SignatureState.ValidSignature ? addresses : [])
     }
     
     func sign(plainData: Data, myEmail: String, detached: Bool = true) throws -> CryptoObject {
@@ -811,7 +812,13 @@ PkfA6mR7rtcyIbHi34tfkCv/qolV3QivMHov0IJpRyNO
             return pem
         }))
         
-        return CryptoObject(chiphertext: data, plaintext: verStr!, decryptedData: nil, sigState: sigState, encState: EncryptionState.NoEncryption, signKey: nil, encType: .SMIME, signedAdrs: signedAddresses)
+        let signKeyFps = certsFPArr!.map( { (arg) -> String in
+            let (fp, _) = arg
+            return fp
+        })
+    
+        // TODO: set signKey to the entire array after CryptoObject has been modified to use multiple keys
+        return CryptoObject(chiphertext: data, plaintext: verStr!, decryptedData: nil, sigState: sigState, encState: EncryptionState.NoEncryption, signKey: signKeyFps[0], encType: .SMIME, signedAdrs: signedAddresses)
     }
     
     func encrypt(plainData: Data, ids: [String], ownId: String, encryptForMyId: Bool = true) throws -> CryptoObject {