def new(nbits, prefix="", suffix="", initial_value=1, overflow=0, little_endian=False, allow_wraparound=False, disable_shortcut=False):
# TODO: Document this
# Sanity-check the message size
(nbytes, remainder) = divmod(nbits, 8)
if remainder != 0:
# In the future, we might support arbitrary bit lengths, but for now we don't.
raise ValueError("nbits must be a multiple of 8; got %d" % (nbits,))
if nbytes < 1:
raise ValueError("nbits too small")
elif nbytes > 0xffff:
raise ValueError("nbits too large")
initval = _encode(initial_value, nbytes, little_endian)
if little_endian:
if sys.platform == "cli":
return _counter._newLE(str(prefix, "raw_unicode_escape"), str(suffix, "raw_unicode_escape"),
initval, allow_wraparound=allow_wraparound, disable_shortcut=disable_shortcut)
else:
return _counter._newLE(str(prefix), str(suffix), initval, allow_wraparound=allow_wraparound, disable_shortcut=disable_shortcut)
else:
if sys.platform == "cli":
return _counter._newBE(str(prefix, "raw_unicode_escape"), str(suffix, "raw_unicode_escape"),
initval, allow_wraparound=allow_wraparound, disable_shortcut=disable_shortcut)
else:
return _counter._newBE(str(prefix), str(suffix), initval, allow_wraparound=allow_wraparound, disable_shortcut=disable_shortcut)
def new(nbits,
prefix="",
suffix="",
initial_value=1,
overflow=0,
little_endian=False,
allow_wraparound=False,
disable_shortcut=False):
# TODO: Document this
# Sanity-check the message size
(nbytes, remainder) = divmod(nbits, 8)
if remainder != 0:
# In the future, we might support arbitrary bit lengths, but for now we don't.
raise ValueError("nbits must be a multiple of 8; got %d" % (nbits, ))
if nbytes < 1:
raise ValueError("nbits too small")
elif nbytes > 0xffff:
raise ValueError("nbits too large")
initval = _encode(initial_value, nbytes, little_endian)
if little_endian:
return _counter._newLE(str(prefix),
str(suffix),
initval,
allow_wraparound=allow_wraparound,
disable_shortcut=disable_shortcut)
else:
return _counter._newBE(str(prefix),
str(suffix),
initval,
allow_wraparound=allow_wraparound,
disable_shortcut=disable_shortcut)
def new(nbits, prefix=b(""), suffix=b(""), initial_value=1, overflow=0, little_endian=False, allow_wraparound=False, disable_shortcut=_deprecated):
"""Create a stateful counter block function suitable for CTR encryption modes.
Each call to the function returns the next counter block.
Each counter block is made up by three parts::
prefix || counter value || postfix
The counter value is incremented by 1 at each call.
:Parameters:
nbits : integer
Length of the desired counter, in bits. It must be a multiple of 8.
prefix : byte string
The constant prefix of the counter block. By default, no prefix is
used.
suffix : byte string
The constant postfix of the counter block. By default, no suffix is
used.
initial_value : integer
The initial value of the counter. Default value is 1.
overflow : integer
This value is currently ignored.
little_endian : boolean
If *True*, the counter number will be encoded in little endian format.
If *False* (default), in big endian format.
allow_wraparound : boolean
If *True*, the counter will automatically restart from zero after
reaching the maximum value (``2**nbits-1``).
If *False* (default), the object will raise an *OverflowError*.
disable_shortcut : deprecated
This option is a no-op for backward compatibility. It will be removed
in a future version. Don't use it.
:Returns:
The counter block function.
"""
# Sanity-check the message size
(nbytes, remainder) = divmod(nbits, 8)
if remainder != 0:
# In the future, we might support arbitrary bit lengths, but for now we don't.
raise ValueError("nbits must be a multiple of 8; got %d" % (nbits,))
if nbytes < 1:
raise ValueError("nbits too small")
elif nbytes > 0xffff:
raise ValueError("nbits too large")
initval = _encode(initial_value, nbytes, little_endian)
if disable_shortcut is not _deprecated: # exact object comparison
warnings.warn("disable_shortcut has no effect and is deprecated", DisableShortcut_DeprecationWarning)
if little_endian:
return _counter._newLE(bstr(prefix), bstr(suffix), initval, allow_wraparound=allow_wraparound)
else:
return _counter._newBE(bstr(prefix), bstr(suffix), initval, allow_wraparound=allow_wraparound)
def new(nbits, prefix=b(""), suffix=b(""), initial_value=1, overflow=0, little_endian=False, allow_wraparound=False, disable_shortcut=_deprecated):
"""Create a stateful counter block function suitable for CTR encryption modes.
Each call to the function returns the next counter block.
Each counter block is made up by three parts::
prefix || counter value || postfix
The counter value is incremented by 1 at each call.
:Parameters:
nbits : integer
Length of the desired counter, in bits. It must be a multiple of 8.
prefix : byte string
The constant prefix of the counter block. By default, no prefix is
used.
suffix : byte string
The constant postfix of the counter block. By default, no suffix is
used.
initial_value : integer
The initial value of the counter. Default value is 1.
overflow : integer
This value is currently ignored.
little_endian : boolean
If *True*, the counter number will be encoded in little endian format.
If *False* (default), in big endian format.
allow_wraparound : boolean
If *True*, the counter will automatically restart from zero after
reaching the maximum value (``2**nbits-1``).
If *False* (default), the object will raise an *OverflowError*.
disable_shortcut : deprecated
This option is a no-op for backward compatibility. It will be removed
in a future version. Don't use it.
:Returns:
The counter block function.
"""
# Sanity-check the message size
(nbytes, remainder) = divmod(nbits, 8)
if remainder != 0:
# In the future, we might support arbitrary bit lengths, but for now we don't.
raise ValueError("nbits must be a multiple of 8; got %d" % (nbits,))
if nbytes < 1:
raise ValueError("nbits too small")
elif nbytes > 0xffff:
raise ValueError("nbits too large")
initval = _encode(initial_value, nbytes, little_endian)
if disable_shortcut is not _deprecated: # exact object comparison
warnings.warn("disable_shortcut has no effect and is deprecated", DisableShortcut_DeprecationWarning)
if little_endian:
return _counter._newLE(bstr(prefix), bstr(suffix), initval, allow_wraparound=allow_wraparound)
else:
return _counter._newBE(bstr(prefix), bstr(suffix), initval, allow_wraparound=allow_wraparound)
def new(nbits, prefix=b(""), suffix=b(""), initial_value=1, overflow=0, little_endian=False, allow_wraparound=False,
disable_shortcut=False):
"""Create a stateful counter block function suitable for CTR encryption modes.
Each call to the function returns the next counter block.
Each counter block is made up by three parts::
prefix || counter value || postfix
The counter value is incremented by one at each call.
:Parameters:
nbits : integer
Length of the desired counter, in bits. It must be a multiple of 8.
prefix : byte string
The constant prefix of the counter block. By default, no prefix is
used.
suffix : byte string
The constant postfix of the counter block. By default, no suffix is
used.
initial_value : integer
The initial value of the counter. Default value is 1.
little_endian : boolean
If True, the counter number will be encoded in little endian format.
If False (default), in big endian format.
allow_wraparound : boolean
If True, the function will raise an *OverflowError* exception as soon
as the counter wraps around. If False (default), the counter will
simply restart from zero.
disable_shortcut : boolean
If True, do not make ciphers from `Crypto.Cipher` bypass the Python
layer when invoking the counter block function.
If False (default), bypass the Python layer.
:Returns:
The counter block function.
"""
# Sanity-check the message size
(nbytes, remainder) = divmod(nbits, 8)
if remainder != 0:
# In the future, we might support arbitrary bit lengths, but for now we don't.
raise ValueError("nbits must be a multiple of 8; got %d" % (nbits,))
if nbytes < 1:
raise ValueError("nbits too small")
elif nbytes > 0xffff:
raise ValueError("nbits too large")
initval = _encode(initial_value, nbytes, little_endian)
if little_endian:
return _counter._newLE(bstr(prefix), bstr(suffix), initval, allow_wraparound=allow_wraparound,
disable_shortcut=disable_shortcut)
else:
return _counter._newBE(bstr(prefix), bstr(suffix), initval, allow_wraparound=allow_wraparound,
disable_shortcut=disable_shortcut)
def aes_ctr(data, key, ivector, encrypt=True):
"""AES CTR Mode"""
output = ''
ctr = _counter._newBE('', '', ivector, allow_wraparound=False)
cipher = AES.new(key.decode('hex'), mode=AES.MODE_CTR, counter=ctr)
if encrypt:
output += cipher.encrypt(pad(data))
else:
output += cipher.decrypt(pad(data))
return output
def new(nbits, prefix = b(''), suffix = b(''), initial_value = 1, overflow = 0, little_endian = False, allow_wraparound = False, disable_shortcut = False):
nbytes, remainder = divmod(nbits, 8)
if remainder != 0:
raise ValueError('nbits must be a multiple of 8; got %d' % (nbits,))
if nbytes < 1:
raise ValueError('nbits too small')
elif nbytes > 65535:
raise ValueError('nbits too large')
initval = _encode(initial_value, nbytes, little_endian)
if little_endian:
return _counter._newLE(bstr(prefix), bstr(suffix), initval, allow_wraparound=allow_wraparound, disable_shortcut=disable_shortcut)
else:
return _counter._newBE(bstr(prefix), bstr(suffix), initval, allow_wraparound=allow_wraparound, disable_shortcut=disable_shortcut)
def aes_sng(key, ivector):
ctr = counter._newBE(b'', b'', ivector, allow_wraparound=False)
return AES.new(key, mode=AES.MODE_CTR, counter=ctr)
