Re: [tlaplus] Parser Error

Hi Stephan,

may I know which variable you are referring to?

thank you!

Regards,

Sara

---------------

Dr. Sara Zain

Postdoctoral Research Associate

Technische Universität Dresden,

Dept. of Computer Science,

Systems Engineering Group.

Office: APB 3077

Phone: +49 351 463-42358

Website: https://tu-dresden.de/ing/informatik/sya/se/die-professur/beschaeftigte/sara_zain?set_language=en

Do you have any specific reason to exclude that variable from the subscript?

I also notice that that variable is not constrained by the initial condition and that the typing invariant asserts

Len(Current_Msg) = 2

whereas action Handshake requires it to be of length 1??

Stephan

On 8 May 2023, at 16:52, Sara Zain <sara.zain@xxxxxxxxxxxxx> wrote:

<Screenshot from 2023-05-08 16-48-43.png>
Hi all,

I am getting this TLC error for the following code. Any idea please?

Thank you.

Regards,

Sara

_________________________________________________________

EXTENDS
\*Crypto,
Integers, FiniteSets, TLC, Sequences

CONSTANTS
Client, Server, Msg,
SK_c, SK_s, \* private keys
N, \* nonce
Certificate, \* certificate
Sig \* signature

VARIABLES
State, \* current state
Current_Msg, \* current message
Current_State \* current state of the secure channel

Init ==
/\ State = "Init"
/\ Current_State = << SK_c, SK_s, N, Certificate, Sig >>

Handshake ==
/\ State = "Handshake"
/\ Current_Msg = << "Hello" >>
/\ Current_State[6] = <<Certificate, Sig>> \* send certificate and signature
/\ State' = "Finished"
/\ UNCHANGED << Current_State, Current_Msg >>

DataTransfer ==
/\ State = "Finished"
/\ Current_Msg = << "Data", "Secret message" >>
(*/\ S[6] = Encrypt(S[2], S[5], M[2], S[6])*) \* encrypt message with server's key
/\ State' = "Closed"
/\ UNCHANGED << Current_State, Current_Msg >>

Next == Handshake \/ DataTransfer

InitStates == << Init >>
NextStates == Next

SecureChannelInvariant ==
/\ Current_State[1] # Current_State[2] \* private keys are different
/\ Current_State[3] # N \* nonce is different each time
/\ Len(Current_State[4]) > 0 \* certificate is not empty
/\ Len(Current_State[5]) > 0 \* signature is not empty
/\ Len(Current_State[6]) > 0 \* IV is not empty

TypeOK ==
/\ State \in {"Init", "Handshake", "Finished", "Closed"}
/\ Len(Current_Msg) = 2
/\ Current_Msg[1] \in {"Hello", "Data"}

SecureChannel ==
/\ State = "Handshake" => Len(Current_State) = 6
/\ State = "Finished" => Len(Current_State) = 7
/\ State = "Closed" => Len(Current_State) = 7
/\ SecureChannelInvariant

NextStep == Next /\ TypeOK
Spec == Init /\ [][NextStep]_<<State, Current_State>>

On Monday, May 1, 2023 at 8:38:27 PM UTC+2 hwa...@gmail.com wrote:

Parser really needs to show line numbers :/

H

On Friday, April 28, 2023 at 4:59:12 AM UTC-5 Stephan Merz wrote:

Typo “Intergers”

Stephan

On 28 Apr 2023, at 11:31, Sara Zain <sara...@xxxxxxxxxxxxx> wrote:

Hi! I just downloaded the TLA toolbox. However, I am getting this error "Parser error" notification. Can anyone help me, please? Also, I don't see a TLA module and directory path compare to what I see in the video tutorial.
<Screenshot from 2023-04-28 11-31-09.png>

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