Definition Instantiate (entropy nonce pers_string: string) : DRBG_functions.DRBG_working_state :=
HMAC256_DRBG_instantiate_algorithm (hexstring_to_Zlist entropy) 
                                   (hexstring_to_Zlist nonce) 
                                   (hexstring_to_Zlist pers_string)
                                   0 (*sec_strength -- ignored by HMAC256_DRBG_instantiate_algorithm*).Definition reseedInterval:Z := 100000.Definition Generate (WS: DRBG_functions.DRBG_working_state) (addInput:list Z): DRBG_functions.DRBG_generate_algorithm_result :=
           HMAC256_DRBG_generate_algorithm reseedInterval
                                           WS
                                           128 (*number of bytes: 1024bits*)
                                           addInput.Definition CheckWS (WS:DRBG_functions.DRBG_working_state) 
  (V K: string) (rc:Z):=
  match WS with (value, key, reseedcounter) =>
   listZ_eq (hexstring_to_Zlist V) value &&
   listZ_eq (hexstring_to_Zlist K) key && 
   zeq reseedcounter rc = true
  end.(*no personalization string, no additional input*)
Definition Check_A (entropy nonce Value0 Key0 Value1 Key1 Bits Value2 Key2: string) :=
  let ws0 := Instantiate entropy nonce ""
  in match Generate ws0 nil with 
       DRBG_functions.generate_algorithm_success Bits1 ws1 =>
         match Generate ws1 nil with
             DRBG_functions.generate_algorithm_success Bits2 ws2 =>
             CheckWS ws0 Value0 Key0 1 /\ CheckWS ws1 Value1 Key1 2 /\  
             CheckWS ws2 Value2 Key2 3 /\ Bits2 = hexstring_to_Zlist Bits
         | err => False
         end
    | err => False
    end.(*no personalization string, but additional input*)
Definition Check_B (entropy nonce Value0 Key0 addInput1 Value1 Key1 addInput2 Bits Value2 Key2: string) :=
  let ws0 := Instantiate entropy nonce ""
  in match Generate ws0 (hexstring_to_Zlist addInput1) with 
       DRBG_functions.generate_algorithm_success Bits1 ws1 =>
         match Generate ws1 (hexstring_to_Zlist addInput2) with
             DRBG_functions.generate_algorithm_success Bits2 ws2 =>
             CheckWS ws0 Value0 Key0 1 /\ CheckWS ws1 Value1 Key1 2 /\  
             CheckWS ws2 Value2 Key2 3 /\ Bits2 = hexstring_to_Zlist Bits
         | err => False
         end
    | err => False
    end.(*personalization string, no additional input*)
Definition Check_C (entropy nonce pers Value0 Key0 Value1 Key1 Bits Value2 Key2: string) :=
  let ws0 := Instantiate entropy nonce pers
  in match Generate ws0 nil with 
       DRBG_functions.generate_algorithm_success Bits1 ws1 =>
         match Generate ws1 nil with
             DRBG_functions.generate_algorithm_success Bits2 ws2 =>
             CheckWS ws0 Value0 Key0 1 /\ CheckWS ws1 Value1 Key1 2 /\  
             CheckWS ws2 Value2 Key2 3 /\ Bits2 = hexstring_to_Zlist Bits
         | err => False
         end
    | err => False
    end.(*personalization string, additional input*)
Definition Check_D (entropy nonce pers Value0 Key0 addInput1 Value1 Key1 addInput2 Bits Value2 Key2: string) :=
  let ws0 := Instantiate entropy nonce pers
  in match Generate ws0 (hexstring_to_Zlist addInput1) with 
       DRBG_functions.generate_algorithm_success Bits1 ws1 =>
         match Generate ws1 (hexstring_to_Zlist addInput2) with
             DRBG_functions.generate_algorithm_success Bits2 ws2 =>
             CheckWS ws0 Value0 Key0 1 /\ CheckWS ws1 Value1 Key1 2 /\  
             CheckWS ws2 Value2 Key2 3 /\ Bits2 = hexstring_to_Zlist Bits
         | err => False
         end
    | err => False
    end.(*Relevant Section of HMAC_DRBG.txt: lines 8424 -- 8685
[SHA-256]
[PredictionResistance = False]
[EntropyInputLen = 256]
[NonceLen = 128]
[PersonalizationStringLen = 0]
[AdditionalInputLen = 0]
[ReturnedBitsLen = 1024]*)

Definition Inst0: DRBG_functions.DRBG_working_state :=
  Instantiate "ca851911349384bffe89de1cbdc46e6831e44d34a4fb935ee285dd14b71a7488" 
              "659ba96c601dc69fc902940805ec0ca8" "".Definition Gen0_1: DRBG_functions.DRBG_generate_algorithm_result := Generate Inst0 nil.

Lemma Intantiate0: CheckWS Inst0 "e75855f93b971ac468d200992e211960202d53cf08852ef86772d6490bfb53f9" "302a4aba78412ab36940f4be7b940a0c728542b8b81d95b801a57b3797f9dd6e" 1.