class SignatureFragmentGenerator(Iterator[TryteString]):
"""
Used to generate signature fragments progressively.
Each instance can generate 1 signature per fragment in the private
key.
"""
def __init__(self, private_key: PrivateKey, hash_: Hash) -> None:
super(SignatureFragmentGenerator, self).__init__()
self._key_chunks = private_key.iter_chunks(FRAGMENT_LENGTH)
self._iteration = -1
self._normalized_hash = normalize(hash_)
self._sponge = Kerl()
def __iter__(self) -> 'SignatureFragmentGenerator':
return self
def __len__(self) -> int:
"""
Returns the number of fragments this generator can create.
Note: This method always returns the same result, no matter how
many iterations have been completed.
"""
return len(self._key_chunks)
def __next__(self) -> TryteString:
"""
Returns the next signature fragment.
"""
key_trytes: TryteString = next(self._key_chunks)
self._iteration += 1
# If the key is long enough, loop back around to the start.
normalized_chunk = (
self._normalized_hash[self._iteration % len(self._normalized_hash)]
)
signature_fragment = key_trytes.as_trits()
# Build the signature, one hash at a time.
for i in range(key_trytes.count_chunks(Hash.LEN)):
hash_start = i * HASH_LENGTH
hash_end = hash_start + HASH_LENGTH
buffer: List[int] = signature_fragment[hash_start:hash_end]
for _ in range(13 - normalized_chunk[i]):
self._sponge.reset()
self._sponge.absorb(buffer)
self._sponge.squeeze(buffer)
signature_fragment[hash_start:hash_end] = buffer
return TryteString.from_trits(signature_fragment)
def _create_sponge(self, index: int) -> Kerl:
"""
Prepares the hash sponge for the generator.
"""
seed = self.seed_as_trits[:]
sponge = Kerl()
sponge.absorb(add_trits(seed, trits_from_int(index)))
# Squeeze all of the trits out of the sponge and re-absorb them.
# Note that the sponge transforms several times per operation,
# so this sequence is not as redundant as it looks at first
# glance.
sponge.squeeze(seed)
sponge.reset()
sponge.absorb(seed)
return sponge
def _create_sponge(self, index):
# type: (int) -> Kerl
"""
Prepares the hash sponge for the generator.
"""
seed = self.seed_as_trits[:]
sponge = Kerl()
sponge.absorb(add_trits(seed, trits_from_int(index)))
# Squeeze all of the trits out of the sponge and re-absorb them.
# Note that the sponge transforms several times per operation, so
# this sequence is not as redundant as it looks at first glance.
sponge.squeeze(seed)
sponge.reset()
sponge.absorb(seed)
return sponge
class SignatureFragmentGenerator(Iterator[TryteString]):
"""
Used to generate signature fragments progressively.
Each instance can generate 1 signature per fragment in the private
key.
"""
def __init__(self, private_key, hash_):
# type: (PrivateKey, Hash) -> None
super(SignatureFragmentGenerator, self).__init__()
self._key_chunks = private_key.iter_chunks(FRAGMENT_LENGTH)
self._iteration = -1
self._normalized_hash = normalize(hash_)
self._sponge = Kerl()
def __iter__(self):
# type: () -> SignatureFragmentGenerator
return self
def __len__(self):
# type: () -> int
"""
Returns the number of fragments this generator can create.
Note: This method always returns the same result, no matter how
many iterations have been completed.
"""
return len(self._key_chunks)
def __next__(self):
# type: () -> TryteString
"""
Returns the next signature fragment.
"""
key_trytes = next(self._key_chunks) # type: TryteString
self._iteration += 1
# If the key is long enough, loop back around to the start.
normalized_chunk =\
self._normalized_hash[self._iteration % len(self._normalized_hash)]
signature_fragment = key_trytes.as_trits()
# Build the signature, one hash at a time.
for i in range(key_trytes.count_chunks(Hash.LEN)):
hash_start = i * HASH_LENGTH
hash_end = hash_start + HASH_LENGTH
buffer = signature_fragment[hash_start:hash_end] # type: MutableSequence[int]
for _ in range(13 - normalized_chunk[i]):
self._sponge.reset()
self._sponge.absorb(buffer)
self._sponge.squeeze(buffer)
signature_fragment[hash_start:hash_end] = buffer
return TryteString.from_trits(signature_fragment)
if PY2:
next = __next__