Encryption 如何使用NuSMV见证中间人攻击（李约瑟-施罗德协议）？_Encryption_Model Checking_Nusmv

Encryption 如何使用NuSMV见证中间人攻击（李约瑟-施罗德协议）？

encryption

Encryption 如何使用NuSMV见证中间人攻击（李约瑟-施罗德协议）？,encryption,model-checking,nusmv,Encryption,Model Checking,Nusmv,我有以下简化的公钥Needham Schroeder协议： A→ B:{Na，A}Kb B→ 答：{Na，Nb}Ka A→ B:{Nb}Kb 其中，Na，Nb是A，B和Ka，Kb分别是A，B的公钥由参与方公钥加密的消息只能由参与方解密在步骤（1），A通过向B发送nonce及其标识（由B的公钥加密）来启动协议。使用其私钥，B破译消息并获取A的身份在步骤（2），B将A及其当前值（由A的公钥加密）发送回A。使用其私钥，A对消息进行解码，并检查其当前值是否返回在步骤（3），A将B的当前值（由B的

我有以下简化的公钥Needham Schroeder协议：

A→ B:{Na，A}Kb

B→ 答：{Na，Nb}Ka

A→ B:{Nb}Kb

其中，

Na

，

Nb

是

，

和

Ka

，

Kb

分别是

，

的公钥

由参与方公钥加密的消息只能由参与方解密

在步骤（1），

通过向

发送nonce及其标识（由

的公钥加密）来启动协议。使用其私钥，

破译消息并获取

的身份

在步骤（2），

将

及其当前值（由

的公钥加密）发送回

。使用其私钥，

对消息进行解码，并检查其当前值是否返回

在步骤（3），

将

的当前值（由

的公钥加密）返回到

以下是对上述简化协议的中间主攻击：

（1A）
```
A→ E:{Na，A}Ke
```
（
```
A
```
想和
```
E
```
谈谈）
（1B）
```
E→ B:{Na，A}Kb
```
（
```
E
```
想说服
```
B
```
它是
```
A
```
）
（2B）
```
B→ E:{Na，Nb}Ka
```
（
```
B
```
返回由
```
Ka
```
加密的nonce）
（2A）
```
E→ A:{Na，Nb}Ka
```
（
```
E
```
将加密消息转发给
```
A
```
）
（3A）
```
A→ E:{Nb}Ke
```
（
```
A
```
确认它正在与
```
E
```
通话）
（3B）
```
E→ B:{Nb}Kb
```
（
```
E
```
返回
```
B
```
的nonce-back）

我希望当发现攻击时，会提出一个修复方案来防止攻击（

将其标识和nonce一起发送回

）：

A→ B:{Na，A}Kb

B→ A:{Na，Nb，B}Ka

（

将其标识和nonce一起发送回

）

A→ B:{Nb}Kb

问题是:

如何编写LTL公式和NuSMV模块

eve

来模拟攻击者并见证中间人攻击

如何防止攻击

艾丽斯的过程（A）：

bob的过程（B）：

主要流程：

非常感谢

（注意：使用其他工具（如或）对您心目中的系统进行建模和验证要简单得多。）

爱丽丝和鲍勃。

在这里，我们对以诚实、透明的方式行事的

用户类型进行建模，并且在您的用例中可以实例化为Alice
或Bob

作为简化，我硬编码了这样一个事实：如果用户
是Alice
，那么它将通过尝试联系其他实体来启动协议
输入的my\u nonce
、my\u id
和my\u key
定义了用户的身份，而other\u key
和other\u id
表示我们想要联系的另一用户的公开信息。_1
中的、_2
中的和_k
中的输入与代码示例中的输入相同，而_3
中的保留用于交换协议的修补版本中使用的第三个值
用户可以处于以下五种状态之一：

IDLE
：初始状态，Alice
将启动协议，而Bob
等待一些请求
WAIT\u RESPONSE
：当Alice
等待响应她的请求时
等待确认
：当鲍勃
等待确认他的响应时
OK
：当Alice
和Bob
握手成功时
错误
：当握手出现错误时（例如意外输入）

用户可以执行以下操作之一：

发送请求
：{Na，IA}Kb
SEND_RESPONSE
：{Na，Nb}Ka
发送确认信息
：{Nb}Kb

作为一种简化，与您自己的模型类似，我使输出值在几个转换期间保持不变，而不是立即将它们放回NONE
。这样，在重置输入值之前，我不必添加额外的变量来跟踪输入值
MODULE user(patched, my_nonce, my_id, my_key, other_key, other_id, in_1, in_2, in_3, in_k)
VAR
    state  : { IDLE, WAIT_RESPONSE, WAIT_CONFIRMATION, OK, ERROR };
    action : { NONE, SEND_REQUEST, SEND_RESPONSE, SEND_CONFIRMATION };
    out_1  : { NONE, NA, NB, NE, IA, IB, IE };
    out_2  : { NONE, NA, NB, NE, IA, IB, IE };
    out_3  : { NONE, NA, NB, NE, IA, IB, IE };
    out_k  : { NONE, KA, KB, KE };

INIT
    state = IDLE & action = NONE & out_1 = NONE
    & out_2 = NONE & out_3 = NONE & out_k = NONE;

-- protocol actions defining outputs
TRANS
    next(action) = SEND_REQUEST -> (
        next(out_1) = my_nonce & next(out_2) = my_id &
        next(out_3) = NONE     & next(out_k) = other_key
    );

TRANS
    ((next(action) = SEND_RESPONSE) & patched) -> (
        next(out_1) = in_1     & next(out_2) = my_nonce &
        next(out_3) = my_id    & next(out_k) = other_key
    );

TRANS
    ((next(action) = SEND_RESPONSE) & !patched) -> (
        next(out_1) = in_1     & next(out_2) = my_nonce &
        next(out_3) = NONE     & next(out_k) = other_key
    );

TRANS
    next(action) = SEND_CONFIRMATION -> (
        next(out_1) = in_2     & next(out_2) = NONE &
        next(out_3) = NONE     & next(out_k) = other_key
    );

-- outputs stabilization: easier modeling
TRANS
    next(action) = NONE -> (
        next(out_1) = out_1    & next(out_2) = out_2 &
        next(out_3) = out_3    & next(out_k) = out_k
    );

-- protocol life-cycle
TRANS
case
    -- protocol: end-positions
    (action = NONE &
     state = ERROR)
                        : next(action) = NONE &
                          next(state) = ERROR;
    (action = NONE &
     state = OK)
                        : next(action) = NONE &
                          next(state) = OK;

    -- protocol: send request
    (action = NONE &
     state = IDLE &
     my_id = IA)
                        : next(action) = SEND_REQUEST &
                          next(state) = WAIT_RESPONSE;

    -- protocol: handle request
    (action = NONE &
     state = IDLE &
     in_k = my_key)
                        : next(action) = SEND_RESPONSE &
                          next(state) = WAIT_CONFIRMATION;

    -- protocol: handle response
    -- without patch
    (action = NONE &
     state = WAIT_RESPONSE &
     in_k = my_key &
     in_1 = my_nonce &
     !patched)
                        : next(action) = SEND_CONFIRMATION &
                          next(state) = OK;
    -- with patch
    (action = NONE &
     state = WAIT_RESPONSE &
     in_k = my_key &
     in_1 = my_nonce &
     in_3 = other_id &
     patched)
                        : next(action) = SEND_CONFIRMATION &
                          next(state) = OK;

    -- protocol: handle confirmation
    (action = NONE &
     state = WAIT_CONFIRMATION &
     in_k = my_key &
     in_1 = my_nonce)
                        : next(action) = NONE &
                          next(state) = OK;

    -- protocol: no change state while performing action
    (action != NONE)
                        : next(action) = NONE &
                          next(state) = state;

    -- protocol: no state change if no valid input
    (action = NONE &
     in_k != my_key)
                        : next(action) = NONE &
                          next(state) = state;

    -- sink error condition for malformed inputs
    TRUE
                        : next(action) = NONE &
                          next(state) = ERROR;
esac;

我们添加了一个非常简单的main
模块和一个简单的CTL
属性，以检查Alice
和Bob
是否以预期的方式工作，并能够在正常情况下完成握手：
MODULE main
VAR
    a1 : process user(FALSE, NA, IA, KA, KB, IB, b1.out_1, b1.out_2, b1.out_3, b1.out_k);
    b1 : process user(FALSE, NB, IB, KB, KA, IA, a1.out_1, a1.out_2, a1.out_3, a1.out_k);

FAIRNESS running;


CTLSPEC ! EF (a1.state = OK & b1.state = OK);

输出如下所示：
NuSMV > reset; read_model -i ns01.smv ; go ; check_property             
...
-- specification !(EF (a1.state = OK & b1.state = OK))  is false
-- as demonstrated by the following execution sequence
Trace Description: CTL Counterexample 
Trace Type: Counterexample 
  -> State: 1.1 <-
    a1.state = IDLE
    a1.action = NONE
    a1.out_1 = NONE
    a1.out_2 = NONE
    a1.out_3 = NONE
    a1.out_k = NONE
    b1.state = IDLE
    b1.action = NONE
    b1.out_1 = NONE
    b1.out_2 = NONE
    b1.out_3 = NONE
    b1.out_k = NONE
  -> Input: 1.2 <-
    _process_selector_ = main
    running = TRUE
    b1.running = FALSE
    a1.running = FALSE
  -> State: 1.2 <-
    a1.state = WAIT_RESPONSE
    a1.action = SEND_REQUEST
    a1.out_1 = NA
    a1.out_2 = IA
    a1.out_k = KB
  -> Input: 1.3 <-
  -> State: 1.3 <-
    a1.action = NONE
    b1.state = WAIT_CONFIRMATION
    b1.action = SEND_RESPONSE
    b1.out_1 = NA
    b1.out_2 = NB
    b1.out_k = KA
  -> Input: 1.4 <-
  -> State: 1.4 <-
    a1.state = OK
    a1.action = SEND_CONFIRMATION
    a1.out_1 = NB
    a1.out_2 = NONE
    b1.action = NONE
  -> Input: 1.5 <-
  -> State: 1.5 <-
    a1.action = NONE
    b1.state = OK

同样，我们添加了一个非常简单的main
模块和一个简单的CTL
属性来检查Eve
是否能够成功攻击Alice
和Bob
。。最后，Alice
认为是在和Eve
（实际上）说话，Bob
认为是在和Alice
说话，而实际上是在和Eve
说话
MODULE main
VAR
    a2 : process user(FALSE, NA, IA, KA, KE, IE, e2.aout_1, e2.aout_2, e2.aout_3, e2.aout_k);
    b2 : process user(FALSE, NB, IB, KB, KA, IA, e2.bout_1, e2.bout_2, e2.bout_3, e2.bout_k);
    e2 : process attacker(NE, IE, KE, KA, KB,
                          a2.out_1, a2.out_2, a2.out_3, a2.out_k,
                          b2.out_1, b2.out_2, b2.out_3, b2.out_k);

FAIRNESS running;


CTLSPEC ! EF (a2.state = OK & b2.state = OK & e2.state = OK);

结果如下：
NuSMV > reset; read_model -i ns02.smv ; go ; check_property
...
-- specification !(EF ((a2.state = OK & b2.state = OK) & e2.state = OK))  is false
-- as demonstrated by the following execution sequence
Trace Description: CTL Counterexample 
Trace Type: Counterexample 
  -> State: 1.1 <-
    a2.state = IDLE
    a2.action = NONE
    a2.out_1 = NONE
    a2.out_2 = NONE
    a2.out_3 = NONE
    a2.out_k = NONE
    b2.state = IDLE
    b2.action = NONE
    b2.out_1 = NONE
    b2.out_2 = NONE
    b2.out_3 = NONE
    b2.out_k = NONE
    e2.state = IDLE
    e2.action = NONE
    e2.aout_1 = NONE
    e2.aout_2 = NONE
    e2.aout_3 = NONE
    e2.aout_k = NONE
    e2.bout_1 = NONE
    e2.bout_2 = NONE
    e2.bout_3 = NONE
    e2.bout_k = NONE
  -> Input: 1.2 <-
    _process_selector_ = main
    running = TRUE
    e2.running = FALSE
    b2.running = FALSE
    a2.running = FALSE
  -> State: 1.2 <-
    a2.state = WAIT_RESPONSE
    a2.action = SEND_REQUEST
    a2.out_1 = NA
    a2.out_2 = IA
    a2.out_k = KE
  -> Input: 1.3 <-
  -> State: 1.3 <-
    a2.action = NONE
    e2.state = WAIT_RESPONSE
    e2.action = SEND_REQUEST
    e2.bout_1 = NA
    e2.bout_2 = IA
    e2.bout_k = KB
  -> Input: 1.4 <-
  -> State: 1.4 <-
    b2.state = WAIT_CONFIRMATION
    b2.action = SEND_RESPONSE
    b2.out_1 = NA
    b2.out_2 = NB
    b2.out_k = KA
    e2.action = NONE
  -> Input: 1.5 <-
  -> State: 1.5 <-
    b2.action = NONE
    e2.state = WAIT_CONFIRMATION
    e2.action = SEND_RESPONSE
    e2.aout_1 = NA
    e2.aout_2 = NB
    e2.aout_k = KA
    e2.bout_1 = NONE
    e2.bout_2 = NONE
    e2.bout_k = NONE
  -> Input: 1.6 <-
  -> State: 1.6 <-
    a2.state = OK
    a2.action = SEND_CONFIRMATION
    a2.out_1 = NB
    a2.out_2 = NONE
    e2.action = NONE
  -> Input: 1.7 <-
  -> State: 1.7 <-
    a2.action = NONE
    e2.state = OK
    e2.action = SEND_CONFIRMATION
    e2.aout_1 = NONE
    e2.aout_2 = NONE
    e2.aout_k = NONE
    e2.bout_1 = NB
    e2.bout_k = KB
  -> Input: 1.8 <-
  -> State: 1.8 <-
    b2.state = OK
    e2.action = NONE

NuSMV > reset; read_model -i ns03.smv ; go ; check_property             
...
-- specification !(EF ((a3.state = OK & b3.state = OK) & e3.state = OK))  is true
-- specification !(EF (a3.state = ERROR & b3.state = ERROR))  is false
-- as demonstrated by the following execution sequence
Trace Description: CTL Counterexample 
Trace Type: Counterexample 
  -> State: 1.1 <-
    a3.state = IDLE
    a3.action = NONE
    a3.out_1 = NONE
    a3.out_2 = NONE
    a3.out_3 = NONE
    a3.out_k = NONE
    b3.state = IDLE
    b3.action = NONE
    b3.out_1 = NONE
    b3.out_2 = NONE
    b3.out_3 = NONE
    b3.out_k = NONE
    e3.state = IDLE
    e3.action = NONE
    e3.aout_1 = NONE
    e3.aout_2 = NONE
    e3.aout_3 = NONE
    e3.aout_k = NONE
    e3.bout_1 = NONE
    e3.bout_2 = NONE
    e3.bout_3 = NONE
    e3.bout_k = NONE
  -> Input: 1.2 <-
    _process_selector_ = main
    running = TRUE
    e3.running = FALSE
    b3.running = FALSE
    a3.running = FALSE
  -> State: 1.2 <-
    a3.state = WAIT_RESPONSE
    a3.action = SEND_REQUEST
    a3.out_1 = NA
    a3.out_2 = IA
    a3.out_k = KE
  -> Input: 1.3 <-
  -> State: 1.3 <-
    a3.action = NONE
    e3.state = WAIT_RESPONSE
    e3.action = SEND_REQUEST
    e3.bout_1 = NA
    e3.bout_2 = IA
    e3.bout_k = KB
  -> Input: 1.4 <-
  -> State: 1.4 <-
    b3.state = WAIT_CONFIRMATION
    b3.action = SEND_RESPONSE
    b3.out_1 = NA
    b3.out_2 = NB
    b3.out_3 = IB
    b3.out_k = KA
    e3.action = NONE
  -> Input: 1.5 <-
  -> State: 1.5 <-
    b3.action = NONE
    e3.state = WAIT_CONFIRMATION
    e3.action = SEND_RESPONSE
    e3.aout_1 = NA
    e3.aout_2 = NB
    e3.aout_3 = IB
    e3.aout_k = KA
    e3.bout_1 = NONE
    e3.bout_2 = NONE
    e3.bout_k = NONE
  -> Input: 1.6 <-
  -> State: 1.6 <-
    a3.state = ERROR
    e3.action = NONE
  -> Input: 1.7 <-
  -> State: 1.7 <-
    e3.state = OK
    e3.action = SEND_CONFIRMATION
    e3.aout_1 = NONE
    e3.aout_2 = NONE
    e3.aout_3 = NONE
    e3.aout_k = NONE
    e3.bout_1 = NA
    e3.bout_k = KB
  -> Input: 1.8 <-
  -> State: 1.8 <-a
    b3.state = ERROR
    e3.action = NONE

结果如下：
NuSMV > reset; read_model -i ns02.smv ; go ; check_property
...
-- specification !(EF ((a2.state = OK & b2.state = OK) & e2.state = OK))  is false
-- as demonstrated by the following execution sequence
Trace Description: CTL Counterexample 
Trace Type: Counterexample 
  -> State: 1.1 <-
    a2.state = IDLE
    a2.action = NONE
    a2.out_1 = NONE
    a2.out_2 = NONE
    a2.out_3 = NONE
    a2.out_k = NONE
    b2.state = IDLE
    b2.action = NONE
    b2.out_1 = NONE
    b2.out_2 = NONE
    b2.out_3 = NONE
    b2.out_k = NONE
    e2.state = IDLE
    e2.action = NONE
    e2.aout_1 = NONE
    e2.aout_2 = NONE
    e2.aout_3 = NONE
    e2.aout_k = NONE
    e2.bout_1 = NONE
    e2.bout_2 = NONE
    e2.bout_3 = NONE
    e2.bout_k = NONE
  -> Input: 1.2 <-
    _process_selector_ = main
    running = TRUE
    e2.running = FALSE
    b2.running = FALSE
    a2.running = FALSE
  -> State: 1.2 <-
    a2.state = WAIT_RESPONSE
    a2.action = SEND_REQUEST
    a2.out_1 = NA
    a2.out_2 = IA
    a2.out_k = KE
  -> Input: 1.3 <-
  -> State: 1.3 <-
    a2.action = NONE
    e2.state = WAIT_RESPONSE
    e2.action = SEND_REQUEST
    e2.bout_1 = NA
    e2.bout_2 = IA
    e2.bout_k = KB
  -> Input: 1.4 <-
  -> State: 1.4 <-
    b2.state = WAIT_CONFIRMATION
    b2.action = SEND_RESPONSE
    b2.out_1 = NA
    b2.out_2 = NB
    b2.out_k = KA
    e2.action = NONE
  -> Input: 1.5 <-
  -> State: 1.5 <-
    b2.action = NONE
    e2.state = WAIT_CONFIRMATION
    e2.action = SEND_RESPONSE
    e2.aout_1 = NA
    e2.aout_2 = NB
    e2.aout_k = KA
    e2.bout_1 = NONE
    e2.bout_2 = NONE
    e2.bout_k = NONE
  -> Input: 1.6 <-
  -> State: 1.6 <-
    a2.state = OK
    a2.action = SEND_CONFIRMATION
    a2.out_1 = NB
    a2.out_2 = NONE
    e2.action = NONE
  -> Input: 1.7 <-
  -> State: 1.7 <-
    a2.action = NONE
    e2.state = OK
    e2.action = SEND_CONFIRMATION
    e2.aout_1 = NONE
    e2.aout_2 = NONE
    e2.aout_k = NONE
    e2.bout_1 = NB
    e2.bout_k = KB
  -> Input: 1.8 <-
  -> State: 1.8 <-
    b2.state = OK
    e2.action = NONE

NuSMV > reset; read_model -i ns03.smv ; go ; check_property             
...
-- specification !(EF ((a3.state = OK & b3.state = OK) & e3.state = OK))  is true
-- specification !(EF (a3.state = ERROR & b3.state = ERROR))  is false
-- as demonstrated by the following execution sequence
Trace Description: CTL Counterexample 
Trace Type: Counterexample 
  -> State: 1.1 <-
    a3.state = IDLE
    a3.action = NONE
    a3.out_1 = NONE
    a3.out_2 = NONE
    a3.out_3 = NONE
    a3.out_k = NONE
    b3.state = IDLE
    b3.action = NONE
    b3.out_1 = NONE
    b3.out_2 = NONE
    b3.out_3 = NONE
    b3.out_k = NONE
    e3.state = IDLE
    e3.action = NONE
    e3.aout_1 = NONE
    e3.aout_2 = NONE
    e3.aout_3 = NONE
    e3.aout_k = NONE
    e3.bout_1 = NONE
    e3.bout_2 = NONE
    e3.bout_3 = NONE
    e3.bout_k = NONE
  -> Input: 1.2 <-
    _process_selector_ = main
    running = TRUE
    e3.running = FALSE
    b3.running = FALSE
    a3.running = FALSE
  -> State: 1.2 <-
    a3.state = WAIT_RESPONSE
    a3.action = SEND_REQUEST
    a3.out_1 = NA
    a3.out_2 = IA
    a3.out_k = KE
  -> Input: 1.3 <-
  -> State: 1.3 <-
    a3.action = NONE
    e3.state = WAIT_RESPONSE
    e3.action = SEND_REQUEST
    e3.bout_1 = NA
    e3.bout_2 = IA
    e3.bout_k = KB
  -> Input: 1.4 <-
  -> State: 1.4 <-
    b3.state = WAIT_CONFIRMATION
    b3.action = SEND_RESPONSE
    b3.out_1 = NA
    b3.out_2 = NB
    b3.out_3 = IB
    b3.out_k = KA
    e3.action = NONE
  -> Input: 1.5 <-
  -> State: 1.5 <-
    b3.action = NONE
    e3.state = WAIT_CONFIRMATION
    e3.action = SEND_RESPONSE
    e3.aout_1 = NA
    e3.aout_2 = NB
    e3.aout_3 = IB
    e3.aout_k = KA
    e3.bout_1 = NONE
    e3.bout_2 = NONE
    e3.bout_k = NONE
  -> Input: 1.6 <-
  -> State: 1.6 <-
    a3.state = ERROR
    e3.action = NONE
  -> Input: 1.7 <-
  -> State: 1.7 <-
    e3.state = OK
    e3.action = SEND_CONFIRMATION
    e3.aout_1 = NONE
    e3.aout_2 = NONE
    e3.aout_3 = NONE
    e3.aout_k = NONE
    e3.bout_1 = NA
    e3.bout_k = KB
  -> Input: 1.8 <-
  -> State: 1.8 <-a
    b3.state = ERROR
    e3.action = NONE

NuSMV>reset；read_model-i ns03.smv；去；检查属性
...
--规格！（EF（（a3.state=OK&b3.state=OK）和e3.state=OK））为真
--规格！（EF（a3.state=ERROR&b3.state=ERROR））为false
--如下面的执行顺序所示
跟踪描述：CTL反例
跟踪类型：计数器示例
NuSMV > reset; read_model -i ns02.smv ; go ; check_property
...
-- specification !(EF ((a2.state = OK & b2.state = OK) & e2.state = OK))  is false
-- as demonstrated by the following execution sequence
Trace Description: CTL Counterexample 
Trace Type: Counterexample 
  -> State: 1.1 <-
    a2.state = IDLE
    a2.action = NONE
    a2.out_1 = NONE
    a2.out_2 = NONE
    a2.out_3 = NONE
    a2.out_k = NONE
    b2.state = IDLE
    b2.action = NONE
    b2.out_1 = NONE
    b2.out_2 = NONE
    b2.out_3 = NONE
    b2.out_k = NONE
    e2.state = IDLE
    e2.action = NONE
    e2.aout_1 = NONE
    e2.aout_2 = NONE
    e2.aout_3 = NONE
    e2.aout_k = NONE
    e2.bout_1 = NONE
    e2.bout_2 = NONE
    e2.bout_3 = NONE
    e2.bout_k = NONE
  -> Input: 1.2 <-
    _process_selector_ = main
    running = TRUE
    e2.running = FALSE
    b2.running = FALSE
    a2.running = FALSE
  -> State: 1.2 <-
    a2.state = WAIT_RESPONSE
    a2.action = SEND_REQUEST
    a2.out_1 = NA
    a2.out_2 = IA
    a2.out_k = KE
  -> Input: 1.3 <-
  -> State: 1.3 <-
    a2.action = NONE
    e2.state = WAIT_RESPONSE
    e2.action = SEND_REQUEST
    e2.bout_1 = NA
    e2.bout_2 = IA
    e2.bout_k = KB
  -> Input: 1.4 <-
  -> State: 1.4 <-
    b2.state = WAIT_CONFIRMATION
    b2.action = SEND_RESPONSE
    b2.out_1 = NA
    b2.out_2 = NB
    b2.out_k = KA
    e2.action = NONE
  -> Input: 1.5 <-
  -> State: 1.5 <-
    b2.action = NONE
    e2.state = WAIT_CONFIRMATION
    e2.action = SEND_RESPONSE
    e2.aout_1 = NA
    e2.aout_2 = NB
    e2.aout_k = KA
    e2.bout_1 = NONE
    e2.bout_2 = NONE
    e2.bout_k = NONE
  -> Input: 1.6 <-
  -> State: 1.6 <-
    a2.state = OK
    a2.action = SEND_CONFIRMATION
    a2.out_1 = NB
    a2.out_2 = NONE
    e2.action = NONE
  -> Input: 1.7 <-
  -> State: 1.7 <-
    a2.action = NONE
    e2.state = OK
    e2.action = SEND_CONFIRMATION
    e2.aout_1 = NONE
    e2.aout_2 = NONE
    e2.aout_k = NONE
    e2.bout_1 = NB
    e2.bout_k = KB
  -> Input: 1.8 <-
  -> State: 1.8 <-
    b2.state = OK
    e2.action = NONE

MODULE main
VAR
    a3 : process user(TRUE, NA, IA, KA, KE, IE, e3.aout_1, e3.aout_2, e3.aout_3, e3.aout_k);
    b3 : process user(TRUE, NB, IB, KB, KA, IA, e3.bout_1, e3.bout_2, e3.bout_3, e3.bout_k);
    e3 : process attacker(NE, IE, KE, KA, KB,
                          a3.out_1, a3.out_2, a3.out_3, a3.out_k,
                          b3.out_1, b3.out_2, b3.out_3, b3.out_k);

FAIRNESS running;


CTLSPEC ! EF (a3.state = OK & b3.state = OK & e3.state = OK);
CTLSPEC ! EF (a3.state = ERROR & b3.state = ERROR);

NuSMV > reset; read_model -i ns03.smv ; go ; check_property             
...
-- specification !(EF ((a3.state = OK & b3.state = OK) & e3.state = OK))  is true
-- specification !(EF (a3.state = ERROR & b3.state = ERROR))  is false
-- as demonstrated by the following execution sequence
Trace Description: CTL Counterexample 
Trace Type: Counterexample 
  -> State: 1.1 <-
    a3.state = IDLE
    a3.action = NONE
    a3.out_1 = NONE
    a3.out_2 = NONE
    a3.out_3 = NONE
    a3.out_k = NONE
    b3.state = IDLE
    b3.action = NONE
    b3.out_1 = NONE
    b3.out_2 = NONE
    b3.out_3 = NONE
    b3.out_k = NONE
    e3.state = IDLE
    e3.action = NONE
    e3.aout_1 = NONE
    e3.aout_2 = NONE
    e3.aout_3 = NONE
    e3.aout_k = NONE
    e3.bout_1 = NONE
    e3.bout_2 = NONE
    e3.bout_3 = NONE
    e3.bout_k = NONE
  -> Input: 1.2 <-
    _process_selector_ = main
    running = TRUE
    e3.running = FALSE
    b3.running = FALSE
    a3.running = FALSE
  -> State: 1.2 <-
    a3.state = WAIT_RESPONSE
    a3.action = SEND_REQUEST
    a3.out_1 = NA
    a3.out_2 = IA
    a3.out_k = KE
  -> Input: 1.3 <-
  -> State: 1.3 <-
    a3.action = NONE
    e3.state = WAIT_RESPONSE
    e3.action = SEND_REQUEST
    e3.bout_1 = NA
    e3.bout_2 = IA
    e3.bout_k = KB
  -> Input: 1.4 <-
  -> State: 1.4 <-
    b3.state = WAIT_CONFIRMATION
    b3.action = SEND_RESPONSE
    b3.out_1 = NA
    b3.out_2 = NB
    b3.out_3 = IB
    b3.out_k = KA
    e3.action = NONE
  -> Input: 1.5 <-
  -> State: 1.5 <-
    b3.action = NONE
    e3.state = WAIT_CONFIRMATION
    e3.action = SEND_RESPONSE
    e3.aout_1 = NA
    e3.aout_2 = NB
    e3.aout_3 = IB
    e3.aout_k = KA
    e3.bout_1 = NONE
    e3.bout_2 = NONE
    e3.bout_k = NONE
  -> Input: 1.6 <-
  -> State: 1.6 <-
    a3.state = ERROR
    e3.action = NONE
  -> Input: 1.7 <-
  -> State: 1.7 <-
    e3.state = OK
    e3.action = SEND_CONFIRMATION
    e3.aout_1 = NONE
    e3.aout_2 = NONE
    e3.aout_3 = NONE
    e3.aout_k = NONE
    e3.bout_1 = NA
    e3.bout_k = KB
  -> Input: 1.8 <-
  -> State: 1.8 <-a
    b3.state = ERROR
    e3.action = NONE