Class: BTC::TransactionSignatureChecker

Inherits:
Object
  • Object
show all
Includes:
SignatureChecker
Defined in:
lib/btcruby/script/transaction_signature_checker.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(version: 0, transaction: nil, input_index: nil, amount: 0) ⇒ TransactionSignatureChecker

Returns a new instance of TransactionSignatureChecker.



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# File 'lib/btcruby/script/transaction_signature_checker.rb', line 10

def initialize(version: 0, transaction: nil, input_index: nil, amount: 0)
  @version     = version
  @transaction = transaction
  @input_index = input_index
  @amount      = amount
end

Instance Attribute Details

#amount ⇒ Object

Returns the value of attribute amount.



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# File 'lib/btcruby/script/transaction_signature_checker.rb', line 8

def amount
  @amount
end

#input_index ⇒ Object

Returns the value of attribute input_index.



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# File 'lib/btcruby/script/transaction_signature_checker.rb', line 7

def input_index
  @input_index
end

#transaction ⇒ Object

Returns the value of attribute transaction.



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# File 'lib/btcruby/script/transaction_signature_checker.rb', line 6

def transaction
  @transaction
end

#version ⇒ Object

Returns the value of attribute version.



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# File 'lib/btcruby/script/transaction_signature_checker.rb', line 5

def version
  @version
end

Instance Method Details

#check_lock_time(lock_time) ⇒ Object 



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# File 'lib/btcruby/script/transaction_signature_checker.rb', line 41

def check_lock_time(lock_time)
  # There are two times of nLockTime: lock-by-blockheight
  # and lock-by-blocktime, distinguished by whether
  # nLockTime < LOCKTIME_THRESHOLD.
  #
  # We want to compare apples to apples, so fail the script
  # if the type of nLockTime being tested is not the same as
  # the nLockTime in the transaction.
  if !(
       (@transaction.lock_time <  LOCKTIME_THRESHOLD && lock_time <  LOCKTIME_THRESHOLD) ||
       (@transaction.lock_time >= LOCKTIME_THRESHOLD && lock_time >= LOCKTIME_THRESHOLD)
   )
    return false
  end

  # Now that we know we're comparing apples-to-apples, the
  # comparison is a simple numeric one.
  if lock_time > @transaction.lock_time
    return false
  end

  # Finally the nLockTime feature can be disabled and thus
  # CHECKLOCKTIMEVERIFY bypassed if every txin has been
  # finalized by setting nSequence to maxint. The
  # transaction would be allowed into the blockchain, making
  # the opcode ineffective.
  #
  # Testing if this vin is not final is sufficient to
  # prevent this condition. Alternatively we could test all
  # inputs, but testing just this input minimizes the data
  # required to prove correct CHECKLOCKTIMEVERIFY execution.
  if @transaction.inputs[@input_index].final?
    return false
  end

  return true
end

#check_signature(script_signature: nil, public_key: nil, script: nil) ⇒ Object 



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# File 'lib/btcruby/script/transaction_signature_checker.rb', line 17

def check_signature(script_signature:nil, public_key:nil, script:nil)
  # Signature must be long enough to contain a sighash byte.
  return false if script_signature.size < 1
  
  hashtype = script_signature[-1].bytes.first

  # Extract raw ECDSA signature by stripping off the last hashtype byte
  ecdsa_sig = script_signature[0..-2]
  
  key = BTC::Key.new(public_key: public_key)
  hash = @transaction.signature_hash(
    input_index:   @input_index, 
    output_script: script, 
    hash_type:     hashtype, 
    version:       version, 
    amount:        amount
  )
  result = key.verify_ecdsa_signature(ecdsa_sig, hash)
  return result
rescue BTC::FormatError => e # public key is invalid
  Diagnostics.current.add_message(e.message)
  return false
end