def test_stress(self):
"""
Stress test BitStream by writings lots of numbers of different bit
sizes and reading them back.
"""
# num_writes = 10000
num_writes = 1000
min_bit_length = 1
max_bit_length = 8192
# Generate the numbers
nums = []
total_bit_length = 0
for i in range(0, num_writes):
bit_length = random.randint(min_bit_length, max_bit_length)
total_bit_length += bit_length
val = random.randint(0, 2**bit_length - 1)
nums.append({"bit_length" : bit_length, "value" : val})
# Write them to a BitStream object
bitstream = BitStream()
for num in nums:
bitstream.put_num(num["value"], num["bit_length"])
# Check the BitStream length and current position
self.assertEquals(bitstream.get_length(),total_bit_length)
self.assertEquals(bitstream.get_current_pos(),total_bit_length)
# Read all numbers back
bitstream.seek(0)
for num in nums:
self.assertEquals(bitstream.get_num(num["bit_length"]),num["value"])
def test_hex_basic(self):
"""
This method tests put_hex's and get_hex's basic functionality.
"""
bitstream = BitStream()
# Generate a random string of hex digits, ie: ('0'-'9'|'a'-'f'|'A'-'F')*
valid_hex_digits = "0123456789abcdefABCDEF"
num_digits = 50
digits = ""
for i in range(0, num_digits):
digits += random.choice(valid_hex_digits)
# Put those digits in the BitStream...
bitstream.put_hex(digits)
# ...and get them back
bitstream.seek(0)
read_digits = bitstream.get_hex(len(digits) *
4) # 1 hex digit == 4 bits
# Check that the hexadecimal digits were recovered correctly
# Note that case information may be lost. Comparison must be case
# insensitive (ie. 'a9Bc' and 'A9bC' are equal)
self.assertEqual(read_digits.lower(), digits.lower())
def test_put_bitstream_copy_self(self):
"""
Test using the put_bitstream_copy method with the same BitStream object
as origin and destination.
"""
bitstream = BitStream()
# Generate a random string of bits, ie: ('0' | '1')*
num_bits = 50
bits = ""
for i in range(0, num_bits):
bits += random.choice(
('0', '1')) # inefficient, but ok for a test.
# Put those bits in the BitStream...
bitstream.put_bit_dump_string(bits)
# ... copy the bitstream into itself at any point:
bitstream.seek(random.randint(0, 50))
bitstream.put_bitstream_copy(bitstream)
# Check that the bitstream was unchanged by the previous operation:
# (overwriting data with the same data is the same as doing nothing,
# except that the current position is changed to the end of the stream)
self.assertEquals(bitstream.get_length(), num_bits)
self.assertEquals(bitstream.get_current_pos(), num_bits)
bitstream.seek(0)
read_bits = bitstream.get_bit_dump_string(bitstream.get_length())
self.assertEqual(read_bits, bits)
def test_stress(self):
"""
Stress test BitStream by writings lots of numbers of different bit
sizes and reading them back.
"""
# num_writes = 10000
num_writes = 1000
min_bit_length = 1
max_bit_length = 8192
# Generate the numbers
nums = []
total_bit_length = 0
for i in range(0, num_writes):
bit_length = random.randint(min_bit_length, max_bit_length)
total_bit_length += bit_length
val = random.randint(0, 2**bit_length - 1)
nums.append({"bit_length": bit_length, "value": val})
# Write them to a BitStream object
bitstream = BitStream()
for num in nums:
bitstream.put_num(num["value"], num["bit_length"])
# Check the BitStream length and current position
self.assertEquals(bitstream.get_length(), total_bit_length)
self.assertEquals(bitstream.get_current_pos(), total_bit_length)
# Read all numbers back
bitstream.seek(0)
for num in nums:
self.assertEquals(bitstream.get_num(num["bit_length"]),
num["value"])
def test_string_ascii(self):
"""
Test basic put_string and get_string behavior, using ASCII strings.
"""
bitstream = BitStream()
string1 = "Test string " # 12 chars/bytes
string2 = "using only ASCII characters (0-126):\n\t" # 38 chars/bytes
string3 = "Hello World!" # 12 chars/bytes
# Store our message in 3 writes
bitstream.put_string(string1)
bitstream.put_string(string2)
bitstream.put_string(string3)
# Sanity check:
self.assertEquals(bitstream.get_length(), (12 + 38 + 12) * 8)
self.assertEquals(bitstream.get_current_pos(), (12 + 38 + 12) * 8)
# Retrieve our message in 2 reads
bitstream.seek(0)
self.assertEquals(
bitstream.get_string(29 * 8), # read 29 bytes
"Test string using only ASCII ")
self.assertEquals(
bitstream.get_string(33 * 8), # read 33 bytes
"characters (0-126):\n\tHello World!")
def test_put_bitstream_copy_self(self):
"""
Test using the put_bitstream_copy method with the same BitStream object
as origin and destination.
"""
bitstream = BitStream()
# Generate a random string of bits, ie: ('0' | '1')*
num_bits = 50
bits = ""
for i in range(0,num_bits):
bits += random.choice(('0','1')) # inefficient, but ok for a test.
# Put those bits in the BitStream...
bitstream.put_bit_dump_string(bits)
# ... copy the bitstream into itself at any point:
bitstream.seek(random.randint(0,50))
bitstream.put_bitstream_copy(bitstream)
# Check that the bitstream was unchanged by the previous operation:
# (overwriting data with the same data is the same as doing nothing,
# except that the current position is changed to the end of the stream)
self.assertEquals(bitstream.get_length(),num_bits)
self.assertEquals(bitstream.get_current_pos(),num_bits)
bitstream.seek(0)
read_bits = bitstream.get_bit_dump_string(bitstream.get_length())
self.assertEqual(read_bits, bits)
def test_get_hex_invalid_length(self):
"""
Test that trying to read a number of bits that is not a multiple of 4
as hex data raises an exception.
"""
bitstream = BitStream()
bitstream.put_hex("DfF7CE69fF5478A") # 15 digits, 60 bits
bitstream.seek(0)
self.assertRaises(ValueError,
bitstream.get_hex, 47) # read 11.75 hex digits?
def test_get_base64_invalid_length(self):
"""
Test that trying to read a number of bits that is not a multiple of 8
as base64 data raises an exception.
"""
bitstream = BitStream()
bitstream.put_base64("Zm9vYmE=") # 40 bits
bitstream.seek(0)
self.assertRaises(ValueError,
bitstream.get_base64, 26) # read 3.25 bytes?
def test_string_character_zero(self):
"""
Test that we are handling character zero ('\\0') correctly.
"""
bitstream = BitStream()
bitstream.put_string("Evil \0String.") # 13 chars/bytes
self.assertEquals(bitstream.get_length(),13*8)
bitstream.seek(0)
self.assertEquals(bitstream.get_string(bitstream.get_length()),
"Evil \0String.")
def test_get_hex_invalid_length(self):
"""
Test that trying to read a number of bits that is not a multiple of 4
as hex data raises an exception.
"""
bitstream = BitStream()
bitstream.put_hex("DfF7CE69fF5478A") # 15 digits, 60 bits
bitstream.seek(0)
self.assertRaises(ValueError, bitstream.get_hex,
47) # read 11.75 hex digits?
def test_get_base64_invalid_length(self):
"""
Test that trying to read a number of bits that is not a multiple of 8
as base64 data raises an exception.
"""
bitstream = BitStream()
bitstream.put_base64("Zm9vYmE=") # 40 bits
bitstream.seek(0)
self.assertRaises(ValueError, bitstream.get_base64,
26) # read 3.25 bytes?
def test_string_character_zero(self):
"""
Test that we are handling character zero ('\\0') correctly.
"""
bitstream = BitStream()
bitstream.put_string("Evil \0String.") # 13 chars/bytes
self.assertEquals(bitstream.get_length(), 13 * 8)
bitstream.seek(0)
self.assertEquals(bitstream.get_string(bitstream.get_length()),
"Evil \0String.")
def test_base64_basic(self):
"""
This method tests put_base64's and get_base64's basic functionality.
"""
bitstream = BitStream()
# We use the Base64 Test Vectors defined in RFC4648.
# http://www.ietf.org/rfc/rfc4648.txt
test_vectors = [("",""),
("f","Zg=="),
("fo","Zm8="),
("foo","Zm9v"),
("foob","Zm9vYg=="),
("fooba","Zm9vYmE="),
("foobar","Zm9vYmFy")]
# STEP 1:
# For each test vector, we write its value to the bitstream as a string
# then read it as base64 data.
for (str_val, base64_val) in test_vectors:
vector_bit_length = len(str_val)*8
bitstream.put_string(str_val)
bitstream.seek(0)
self.assertEquals(bitstream.get_base64(vector_bit_length),
base64_val)
bitstream.seek(0)
# NOTE that we are overwriting multiple times our bitstream, this is
# also a feature of BitStream we are testing in this test case.
# STEP 2:
# For each test vector, we write its value to the bitstream as base64
# data, then read it as string *and* base64 data.
for (str_val, base64_val) in test_vectors:
vector_bit_length = len(str_val)*8
bitstream.put_base64(base64_val)
bitstream.seek(0)
self.assertEquals(bitstream.get_string(vector_bit_length),
str_val)
bitstream.seek(0)
self.assertEquals(bitstream.get_base64(vector_bit_length),
base64_val)
bitstream.seek(0)
# STEP 3:
# For each test vector, we write its value to a NEW bitstream as base64
# data, and make sure the length of the stream is the expected one.
for (str_val, base64_val) in test_vectors:
vector_bit_length = len(str_val)*8
new_bs = BitStream()
new_bs.put_base64(base64_val)
self.assertEquals(new_bs.get_length(), vector_bit_length)
self.assertEquals(new_bs.get_current_pos(), vector_bit_length)
def test_string_unicode(self):
"""
Test basic put_string and get_string support for python unicode objects.
"""
bitstream = BitStream()
unicode_string = u"ÄäÜüßЯБГДЖЙŁĄŻĘĆŃŚŹてすとｱｲｳｴｵｶｷｸｹｺｻｼｽｾｿﾀﾁﾂﾃ"
bitstream.put_string(unicode_string)
bitstream.seek(0)
# Note: the string is read back as a "normal" UTF-8 string, unicode
# type information is not stored in the bitstream.
self.assertEquals(bitstream.get_string(bitstream.get_length()),
"ÄäÜüßЯБГДЖЙŁĄŻĘĆŃŚŹてすとｱｲｳｴｵｶｷｸｹｺｻｼｽｾｿﾀﾁﾂﾃ")
def test_string_unicode(self):
"""
Test basic put_string and get_string support for python unicode objects.
"""
bitstream = BitStream()
unicode_string = u"ÄäÜüßЯБГДЖЙŁĄŻĘĆŃŚŹてすとｱｲｳｴｵｶｷｸｹｺｻｼｽｾｿﾀﾁﾂﾃ"
bitstream.put_string(unicode_string)
bitstream.seek(0)
# Note: the string is read back as a "normal" UTF-8 string, unicode
# type information is not stored in the bitstream.
self.assertEquals(bitstream.get_string(bitstream.get_length()),
"ÄäÜüßЯБГДЖЙŁĄŻĘĆŃŚŹてすとｱｲｳｴｵｶｷｸｹｺｻｼｽｾｿﾀﾁﾂﾃ")
def test_get_bit_dump_string_zero_bits(self):
"""
Test that reading zero bits from the stream as a bit dump string
results in getting the empty string: \"\".
"""
bitstream = BitStream()
self.assertEquals(bitstream.get_bit_dump_string(0), "")
# Store some bits in the stream.
bitstream.put_bit_dump_string("0001110101") # 10 bits
bitstream.seek(0)
self.assertEquals(bitstream.get_bit_dump_string(0), "")
def test_get_string_zero_bits(self):
"""
Test that reading zero bits from the stream as a string results in
getting the empty string: \"\".
"""
bitstream = BitStream()
self.assertEquals(bitstream.get_string(0), "")
# Store a string in the stream.
bitstream.put_string("Hello World!")
bitstream.seek(0)
self.assertEquals(bitstream.get_string(0), "")
def test_get_hex_zero_bits(self):
"""
Test that reading zero bits from the stream as hex data results in
getting the empty string: \"\".
"""
bitstream = BitStream()
self.assertEquals(bitstream.get_hex(0), "")
# Store some hex data in the stream.
bitstream.put_hex("DfF7CE69fF5478A") # 15 digits, 60 bits
bitstream.seek(0)
self.assertEquals(bitstream.get_hex(0), "")
def test_get_hex_zero_bits(self):
"""
Test that reading zero bits from the stream as hex data results in
getting the empty string: \"\".
"""
bitstream = BitStream()
self.assertEquals(bitstream.get_hex(0), "")
# Store some hex data in the stream.
bitstream.put_hex("DfF7CE69fF5478A") # 15 digits, 60 bits
bitstream.seek(0)
self.assertEquals(bitstream.get_hex(0), "")
def test_get_string_zero_bits(self):
"""
Test that reading zero bits from the stream as a string results in
getting the empty string: \"\".
"""
bitstream = BitStream()
self.assertEquals(bitstream.get_string(0), "")
# Store a string in the stream.
bitstream.put_string("Hello World!")
bitstream.seek(0)
self.assertEquals(bitstream.get_string(0), "")
def test_get_base64_zero_bits(self):
"""
Test that reading zero bits from the stream as base64 data results in
getting the empty string: \"\".
"""
bitstream = BitStream()
self.assertEquals(bitstream.get_base64(0), "")
# Store some base64 data in the stream.
bitstream.put_base64("Zm9vYmE=") # 40 bits
bitstream.seek(0)
self.assertEquals(bitstream.get_base64(0), "")
def test_get_bit_dump_string_zero_bits(self):
"""
Test that reading zero bits from the stream as a bit dump string
results in getting the empty string: \"\".
"""
bitstream = BitStream()
self.assertEquals(bitstream.get_bit_dump_string(0), "")
# Store some bits in the stream.
bitstream.put_bit_dump_string("0001110101") # 10 bits
bitstream.seek(0)
self.assertEquals(bitstream.get_bit_dump_string(0), "")
def test_get_base64_zero_bits(self):
"""
Test that reading zero bits from the stream as base64 data results in
getting the empty string: \"\".
"""
bitstream = BitStream()
self.assertEquals(bitstream.get_base64(0), "")
# Store some base64 data in the stream.
bitstream.put_base64("Zm9vYmE=") # 40 bits
bitstream.seek(0)
self.assertEquals(bitstream.get_base64(0), "")
def test_get_string_non_bytable_size(self):
"""
Test that calling get_string with a bit_length that is not a multiple
of 8 raises an exception.
That is, we cannot read partial bytes as string data.
"""
bitstream = BitStream()
bitstream.put_string("Hello World!")
bitstream.seek(0)
self.assertRaises(ValueError, bitstream.get_string, 18)
# Current position should not have been changed
self.assertEquals(bitstream.get_current_pos(), 0)
def test_get_string_non_bytable_size(self):
"""
Test that calling get_string with a bit_length that is not a multiple
of 8 raises an exception.
That is, we cannot read partial bytes as string data.
"""
bitstream = BitStream()
bitstream.put_string("Hello World!")
bitstream.seek(0)
self.assertRaises(ValueError, bitstream.get_string, 18)
# Current position should not have been changed
self.assertEquals(bitstream.get_current_pos(),0)
def test_get_num_zero_bits(self):
"""
Test that reading zero bits from the stream as a number results in
getting the number 0.
"""
bitstream = BitStream()
self.assertEquals(bitstream.get_num(0), 0)
# Store a 64-bit integer in the stream.
num = int('00000000000000110101011001010011'
'00101100001000101000100110101111', 2)
bitstream.put_num(num, 64)
bitstream.seek(0)
self.assertEquals(bitstream.get_num(0), 0)
def test_base64_basic(self):
"""
This method tests put_base64's and get_base64's basic functionality.
"""
bitstream = BitStream()
# We use the Base64 Test Vectors defined in RFC4648.
# http://www.ietf.org/rfc/rfc4648.txt
test_vectors = [("", ""), ("f", "Zg=="), ("fo", "Zm8="),
("foo", "Zm9v"), ("foob", "Zm9vYg=="),
("fooba", "Zm9vYmE="), ("foobar", "Zm9vYmFy")]
# STEP 1:
# For each test vector, we write its value to the bitstream as a string
# then read it as base64 data.
for (str_val, base64_val) in test_vectors:
vector_bit_length = len(str_val) * 8
bitstream.put_string(str_val)
bitstream.seek(0)
self.assertEquals(bitstream.get_base64(vector_bit_length),
base64_val)
bitstream.seek(0)
# NOTE that we are overwriting multiple times our bitstream, this is
# also a feature of BitStream we are testing in this test case.
# STEP 2:
# For each test vector, we write its value to the bitstream as base64
# data, then read it as string *and* base64 data.
for (str_val, base64_val) in test_vectors:
vector_bit_length = len(str_val) * 8
bitstream.put_base64(base64_val)
bitstream.seek(0)
self.assertEquals(bitstream.get_string(vector_bit_length), str_val)
bitstream.seek(0)
self.assertEquals(bitstream.get_base64(vector_bit_length),
base64_val)
bitstream.seek(0)
# STEP 3:
# For each test vector, we write its value to a NEW bitstream as base64
# data, and make sure the length of the stream is the expected one.
for (str_val, base64_val) in test_vectors:
vector_bit_length = len(str_val) * 8
new_bs = BitStream()
new_bs.put_base64(base64_val)
self.assertEquals(new_bs.get_length(), vector_bit_length)
self.assertEquals(new_bs.get_current_pos(), vector_bit_length)
def test_get_num_zero_bits(self):
"""
Test that reading zero bits from the stream as a number results in
getting the number 0.
"""
bitstream = BitStream()
self.assertEquals(bitstream.get_num(0), 0)
# Store a 64-bit integer in the stream.
num = int(
'00000000000000110101011001010011'
'00101100001000101000100110101111', 2)
bitstream.put_num(num, 64)
bitstream.seek(0)
self.assertEquals(bitstream.get_num(0), 0)
def test_get_string_utf8_read_partial_characters(self):
"""
Test that it is possible to read "partial" utf-8 characters from the
bitstream and that concatenation restores the full character/glyph.
"""
bitstream = BitStream()
string = "てすとｱｲｳｴｵｶｷｸｹｺｻｼｽｾｿﾀﾁﾂﾃ" # 22 chars, 66 bytes
bitstream.put_string(string)
bitstream.seek(0)
# First read 32 bytes
readString = bitstream.get_string(32 * 8)
self.assertEquals(readString, "てすとｱｲｳｴｵｶｷ\xef\xbd")
# Now read the rest
readString += bitstream.get_string(34 * 8)
self.assertEquals(readString, "てすとｱｲｳｴｵｶｷｸｹｺｻｼｽｾｿﾀﾁﾂﾃ")
def test_get_string_utf8_read_partial_characters(self):
"""
Test that it is possible to read "partial" utf-8 characters from the
bitstream and that concatenation restores the full character/glyph.
"""
bitstream = BitStream()
string = "てすとｱｲｳｴｵｶｷｸｹｺｻｼｽｾｿﾀﾁﾂﾃ" # 22 chars, 66 bytes
bitstream.put_string(string)
bitstream.seek(0)
# First read 32 bytes
readString = bitstream.get_string(32*8)
self.assertEquals(readString,"てすとｱｲｳｴｵｶｷ\xef\xbd")
# Now read the rest
readString += bitstream.get_string(34*8)
self.assertEquals(readString,"てすとｱｲｳｴｵｶｷｸｹｺｻｼｽｾｿﾀﾁﾂﾃ")
def test_get_byte_beyond_eos(self):
"""
Test that trying to read beyond the end of the stream raises an
exception when calling get_byte(...).
"""
bitstream = BitStream()
self.assertRaises(NotEnoughBitsInStreamError, bitstream.get_byte)
# Current position should not have been changed
self.assertEquals(bitstream.get_current_pos(),0)
bitstream.put_byte(14)
bitstream.seek(1)
# Read a single bit beyond EOS
self.assertRaises(NotEnoughBitsInStreamError, bitstream.get_byte)
# Current position should not have been changed
self.assertEquals(bitstream.get_current_pos(),1)
def test_get_byte_beyond_eos(self):
"""
Test that trying to read beyond the end of the stream raises an
exception when calling get_byte(...).
"""
bitstream = BitStream()
self.assertRaises(NotEnoughBitsInStreamError, bitstream.get_byte)
# Current position should not have been changed
self.assertEquals(bitstream.get_current_pos(), 0)
bitstream.put_byte(14)
bitstream.seek(1)
# Read a single bit beyond EOS
self.assertRaises(NotEnoughBitsInStreamError, bitstream.get_byte)
# Current position should not have been changed
self.assertEquals(bitstream.get_current_pos(), 1)
def test_get_base64_beyond_eos(self):
"""
Test that trying to read beyond the end of the stream raises an
exception when calling get_base64(...).
"""
bitstream = BitStream()
self.assertRaises(NotEnoughBitsInStreamError, bitstream.get_base64, 8)
# Current position should not have been changed
self.assertEquals(bitstream.get_current_pos(), 0)
bitstream.put_base64("Zm9vYmE=") # 40 bits
bitstream.seek(0)
# Read beyond EOS
self.assertRaises(NotEnoughBitsInStreamError, bitstream.get_base64, 48)
# Current position should not have been changed
self.assertEquals(bitstream.get_current_pos(), 0)
def test_get_hex_beyond_eos(self):
"""
Test that trying to read beyond the end of the stream raises an
exception when calling get_hex(...).
"""
bitstream = BitStream()
self.assertRaises(NotEnoughBitsInStreamError, bitstream.get_hex, 1)
# Current position should not have been changed
self.assertEquals(bitstream.get_current_pos(), 0)
bitstream.put_hex("DfF7CE69fF5478A") # 15 digits, 60 bits
bitstream.seek(0)
# Read beyond EOS
self.assertRaises(NotEnoughBitsInStreamError, bitstream.get_hex, 61)
# Current position should not have been changed
self.assertEquals(bitstream.get_current_pos(), 0)
def test_get_string_beyond_eos(self):
"""
Test that trying to read beyond the end of the stream raises an
exception when calling get_string(...).
"""
bitstream = BitStream()
self.assertRaises(NotEnoughBitsInStreamError, bitstream.get_string, 1)
# Current position should not have been changed
self.assertEquals(bitstream.get_current_pos(), 0)
bitstream.put_string("Hello World!") # 12 chars/bytes
bitstream.seek(0)
# Read beyond EOS
self.assertRaises(NotEnoughBitsInStreamError, bitstream.get_string,
13 * 8)
# Current position should not have been changed
self.assertEquals(bitstream.get_current_pos(), 0)
def test_get_string_beyond_eos(self):
"""
Test that trying to read beyond the end of the stream raises an
exception when calling get_string(...).
"""
bitstream = BitStream()
self.assertRaises(NotEnoughBitsInStreamError, bitstream.get_string, 1)
# Current position should not have been changed
self.assertEquals(bitstream.get_current_pos(),0)
bitstream.put_string("Hello World!") # 12 chars/bytes
bitstream.seek(0)
# Read beyond EOS
self.assertRaises(NotEnoughBitsInStreamError, bitstream.get_string,
13*8)
# Current position should not have been changed
self.assertEquals(bitstream.get_current_pos(),0)
def test_get_hex_beyond_eos(self):
"""
Test that trying to read beyond the end of the stream raises an
exception when calling get_hex(...).
"""
bitstream = BitStream()
self.assertRaises(NotEnoughBitsInStreamError,
bitstream.get_hex, 1)
# Current position should not have been changed
self.assertEquals(bitstream.get_current_pos(),0)
bitstream.put_hex("DfF7CE69fF5478A") # 15 digits, 60 bits
bitstream.seek(0)
# Read beyond EOS
self.assertRaises(NotEnoughBitsInStreamError,
bitstream.get_hex, 61)
# Current position should not have been changed
self.assertEquals(bitstream.get_current_pos(),0)
def test_get_base64_beyond_eos(self):
"""
Test that trying to read beyond the end of the stream raises an
exception when calling get_base64(...).
"""
bitstream = BitStream()
self.assertRaises(NotEnoughBitsInStreamError,
bitstream.get_base64, 8)
# Current position should not have been changed
self.assertEquals(bitstream.get_current_pos(),0)
bitstream.put_base64("Zm9vYmE=") # 40 bits
bitstream.seek(0)
# Read beyond EOS
self.assertRaises(NotEnoughBitsInStreamError,
bitstream.get_base64, 48)
# Current position should not have been changed
self.assertEquals(bitstream.get_current_pos(),0)
def test_num_write_part(self):
"""
Test that we can write a large number piece by piece and read it as
whole number.
"""
bitstream = BitStream()
# Store a 64-bit integer in the stream.
num = int('00000000000000110101011001010011'
'00101100001000101000100110101111', 2)
# ... in 8-bit, 16-bit and 32-bit increments
bitstream.put_num(int('00000000',2), 8)
bitstream.put_num(int('0000001101010110',2), 16)
bitstream.put_num(int('01010011001011000010001010001001',2), 32)
bitstream.put_num(int('10101111',2), 8)
# Get it as a single 64-bit number
bitstream.seek(0)
self.assertEqual(bitstream.get_num(64),num)
def test_num_write_part(self):
"""
Test that we can write a large number piece by piece and read it as
whole number.
"""
bitstream = BitStream()
# Store a 64-bit integer in the stream.
num = int(
'00000000000000110101011001010011'
'00101100001000101000100110101111', 2)
# ... in 8-bit, 16-bit and 32-bit increments
bitstream.put_num(int('00000000', 2), 8)
bitstream.put_num(int('0000001101010110', 2), 16)
bitstream.put_num(int('01010011001011000010001010001001', 2), 32)
bitstream.put_num(int('10101111', 2), 8)
# Get it as a single 64-bit number
bitstream.seek(0)
self.assertEqual(bitstream.get_num(64), num)
def test_byte_basic(self):
"""
Test basic put_byte and get_byte behavior.
"""
bitstream = BitStream()
# Put a couple of bytes in the stream:
bytes = [ 12, # 00001100
222, # 11011110
145, # 10010001
42, # 00101010
0, # 00000000
255] # 11111111
for byte in bytes:
bitstream.put_byte(byte)
# Sanity check:
self.assertEquals(bitstream.get_length(),len(bytes)*8)
self.assertEquals(bitstream.get_current_pos(),len(bytes)*8)
# Read the bytes back from the stream
bitstream.seek(0)
for byte in bytes:
self.assertEquals(bitstream.get_byte(), byte)
# Read some bits from the stream, interpreting them as bytes, but
# without restricting ourselves to 8-bit aligned bytes
# e.g. read the "byte" defined by bits #4 to #12
bitstream.seek(4)
self.assertEquals(bitstream.get_byte(), 205) # 11001101
bitstream.seek(19)
self.assertEquals(bitstream.get_byte(), 137) # 10001001
def test_get_num_beyond_eos(self):
"""
Test than trying to read beyond the end of the stream raises an
exception when calling get_num(...).
"""
bitstream = BitStream()
# Store a 64-bit integer in the stream.
num = int('00000000000000110101011001010011'
'00101100001000101000100110101111', 2)
bitstream.put_num(num, 64)
# Check that trying to read 65 bits from the beginning of the stream
# raises NotEnoughBitsInStreamError
bitstream.seek(0)
self.assertRaises(NotEnoughBitsInStreamError, bitstream.get_num, 65)
# An invalid read call should not move the position indicator.
self.assertEquals(bitstream.get_current_pos(), 0)
# Check that trying to read 33 bits from the middle of the stream
# (pos = 32) raises NotEnoughBitsInStreamError
bitstream.seek(32)
self.assertRaises(NotEnoughBitsInStreamError, bitstream.get_num, 33)
# An invalid read call should not move the position indicator.
self.assertEquals(bitstream.get_current_pos(), 32)
# Check that trying to read a single bit while at the end of the stream
# raises NotEnoughBitsInStreamError
bitstream.seek(64)
self.assertRaises(NotEnoughBitsInStreamError, bitstream.get_num, 1)
# An invalid read call should not move the position indicator.
self.assertEquals(bitstream.get_current_pos(), 64)
def test_get_num_beyond_eos(self):
"""
Test than trying to read beyond the end of the stream raises an
exception when calling get_num(...).
"""
bitstream = BitStream()
# Store a 64-bit integer in the stream.
num = int(
'00000000000000110101011001010011'
'00101100001000101000100110101111', 2)
bitstream.put_num(num, 64)
# Check that trying to read 65 bits from the beginning of the stream
# raises NotEnoughBitsInStreamError
bitstream.seek(0)
self.assertRaises(NotEnoughBitsInStreamError, bitstream.get_num, 65)
# An invalid read call should not move the position indicator.
self.assertEquals(bitstream.get_current_pos(), 0)
# Check that trying to read 33 bits from the middle of the stream
# (pos = 32) raises NotEnoughBitsInStreamError
bitstream.seek(32)
self.assertRaises(NotEnoughBitsInStreamError, bitstream.get_num, 33)
# An invalid read call should not move the position indicator.
self.assertEquals(bitstream.get_current_pos(), 32)
# Check that trying to read a single bit while at the end of the stream
# raises NotEnoughBitsInStreamError
bitstream.seek(64)
self.assertRaises(NotEnoughBitsInStreamError, bitstream.get_num, 1)
# An invalid read call should not move the position indicator.
self.assertEquals(bitstream.get_current_pos(), 64)
def test_string_utf8(self):
"""
Test basic put_string and get_string support for UTF-8 strings.
"""
bitstream = BitStream()
string1 = "ÄäÜüß" # 5 chars, 10 bytes
string2 = "ЯБГДЖЙŁĄŻĘĆŃŚŹ" # 14 chars, 28 bytes
string3 = "てすとｱｲｳｴｵｶｷｸｹｺｻｼｽｾｿﾀﾁﾂﾃ" # 22 chars, 66 bytes
# Store our message in 3 writes
bitstream.put_string(string1)
bitstream.put_string(string2)
bitstream.put_string(string3)
# Sanity check:
self.assertEquals(bitstream.get_length(),(10+28+66)*8)
self.assertEquals(bitstream.get_current_pos(),(10+28+66)*8)
# Retrieve the whole message
bitstream.seek(0)
self.assertEquals(bitstream.get_string(bitstream.get_length()),
"ÄäÜüßЯБГДЖЙŁĄŻĘĆŃŚŹてすとｱｲｳｴｵｶｷｸｹｺｻｼｽｾｿﾀﾁﾂﾃ")
def test_bit_dump_string_basic(self):
"""
This method tests put_bit_dump_string's and get_bit_dump_string's
basic functionality.
"""
bitstream = BitStream()
# Generate a random string of bits, ie: ('0' | '1')*
num_bits = 50
bits = ""
for i in range(0,num_bits):
bits += random.choice(('0','1')) # inefficient, but ok for a test.
# Put those bits in the BitStream...
bitstream.put_bit_dump_string(bits)
# ...and get them back
bitstream.seek(0)
read_bits = bitstream.get_bit_dump_string(len(bits))
# Check that the bits were recovered correctly
self.assertEqual(read_bits, bits)
def test_string_utf8(self):
"""
Test basic put_string and get_string support for UTF-8 strings.
"""
bitstream = BitStream()
string1 = "ÄäÜüß" # 5 chars, 10 bytes
string2 = "ЯБГДЖЙŁĄŻĘĆŃŚŹ" # 14 chars, 28 bytes
string3 = "てすとｱｲｳｴｵｶｷｸｹｺｻｼｽｾｿﾀﾁﾂﾃ" # 22 chars, 66 bytes
# Store our message in 3 writes
bitstream.put_string(string1)
bitstream.put_string(string2)
bitstream.put_string(string3)
# Sanity check:
self.assertEquals(bitstream.get_length(), (10 + 28 + 66) * 8)
self.assertEquals(bitstream.get_current_pos(), (10 + 28 + 66) * 8)
# Retrieve the whole message
bitstream.seek(0)
self.assertEquals(bitstream.get_string(bitstream.get_length()),
"ÄäÜüßЯБГДЖЙŁĄŻĘĆŃŚŹてすとｱｲｳｴｵｶｷｸｹｺｻｼｽｾｿﾀﾁﾂﾃ")
def test_num_basic(self):
"""
Test basic put_num and get_num behavior
"""
bitstream = BitStream()
# Some parameters
num_sizes = [4, 8, 16, 32, 64, 128, 256, 2839]
num_writes = 10
nums = []
# Add num_writes integers of each size to nums:
for i in range(0, len(num_sizes)):
max_val = 2**num_sizes[i] - 1
nums.append([])
for j in range(0, num_writes):
# append a random number between 0 and max_val, inclusive
nums[i].append(random.randint(0, max_val))
# Write all values in nums to the stream
for i in range(0, len(num_sizes)):
for j in range(0, num_writes):
bitstream.put_num(nums[i][j], num_sizes[i])
# Go back to start of the stream
bitstream.seek(0)
# Sanity check:
expected_length = 0
for num_size in num_sizes:
expected_length += num_size * num_writes
self.assertEqual(bitstream.get_length(), expected_length)
# Read them back and compare
for i in range(0, len(num_sizes)):
for j in range(0, num_writes):
n = bitstream.get_num(num_sizes[i])
self.assertEqual(n, nums[i][j])
def test_bit_dump_string_basic(self):
"""
This method tests put_bit_dump_string's and get_bit_dump_string's
basic functionality.
"""
bitstream = BitStream()
# Generate a random string of bits, ie: ('0' | '1')*
num_bits = 50
bits = ""
for i in range(0, num_bits):
bits += random.choice(
('0', '1')) # inefficient, but ok for a test.
# Put those bits in the BitStream...
bitstream.put_bit_dump_string(bits)
# ...and get them back
bitstream.seek(0)
read_bits = bitstream.get_bit_dump_string(len(bits))
# Check that the bits were recovered correctly
self.assertEqual(read_bits, bits)
def test_num_basic(self):
"""
Test basic put_num and get_num behavior
"""
bitstream = BitStream()
# Some parameters
num_sizes = [4,8,16,32,64,128,256,2839]
num_writes = 10
nums = []
# Add num_writes integers of each size to nums:
for i in range(0,len(num_sizes)):
max_val = 2**num_sizes[i] - 1
nums.append([])
for j in range(0,num_writes):
# append a random number between 0 and max_val, inclusive
nums[i].append(random.randint(0, max_val))
# Write all values in nums to the stream
for i in range(0,len(num_sizes)):
for j in range(0,num_writes):
bitstream.put_num(nums[i][j], num_sizes[i])
# Go back to start of the stream
bitstream.seek(0)
# Sanity check:
expected_length = 0
for num_size in num_sizes: expected_length += num_size * num_writes
self.assertEqual(bitstream.get_length(), expected_length)
# Read them back and compare
for i in range(0,len(num_sizes)):
for j in range(0,num_writes):
n = bitstream.get_num(num_sizes[i])
self.assertEqual(n, nums[i][j])
def test_string_ascii(self):
"""
Test basic put_string and get_string behavior, using ASCII strings.
"""
bitstream = BitStream()
string1 = "Test string " # 12 chars/bytes
string2 = "using only ASCII characters (0-126):\n\t" # 38 chars/bytes
string3 = "Hello World!" # 12 chars/bytes
# Store our message in 3 writes
bitstream.put_string(string1)
bitstream.put_string(string2)
bitstream.put_string(string3)
# Sanity check:
self.assertEquals(bitstream.get_length(),(12+38+12)*8)
self.assertEquals(bitstream.get_current_pos(),(12+38+12)*8)
# Retrieve our message in 2 reads
bitstream.seek(0)
self.assertEquals(bitstream.get_string(29*8), # read 29 bytes
"Test string using only ASCII ")
self.assertEquals(bitstream.get_string(33*8), # read 33 bytes
"characters (0-126):\n\tHello World!")
def test_hex_basic(self):
"""
This method tests put_hex's and get_hex's basic functionality.
"""
bitstream = BitStream()
# Generate a random string of hex digits, ie: ('0'-'9'|'a'-'f'|'A'-'F')*
valid_hex_digits = "0123456789abcdefABCDEF"
num_digits = 50
digits = ""
for i in range(0,num_digits):
digits += random.choice(valid_hex_digits)
# Put those digits in the BitStream...
bitstream.put_hex(digits)
# ...and get them back
bitstream.seek(0)
read_digits = bitstream.get_hex(len(digits)*4) # 1 hex digit == 4 bits
# Check that the hexadecimal digits were recovered correctly
# Note that case information may be lost. Comparison must be case
# insensitive (ie. 'a9Bc' and 'A9bC' are equal)
self.assertEqual(read_digits.lower(), digits.lower())
def test_multiformat_write_multiformat_read(self):
"""
This test writes numeric, byte and string data to a stream and then
reads the whole stream as binary, hex and base64 data, ensuring that
the output is the expected one in each case.
"""
# Write a number, 2 bytes and a string
bitstream = BitStream()
bitstream.put_num(10438341575639894917, 64)
bitstream.put_byte(230)
bitstream.put_byte(191)
bitstream.put_string("ÄäÜüßTestЯБГДЖЙŁĄŻStringĘĆŃŚŹてす" \
"とｱｲｳｴｵｶｷｸ4234ｹｺｻｼｽｾｿﾀﾁﾂﾃ")
# Read in binary, hex and base64 formats
expected_bits = \
"1001000011011100011100000101101110111100001101010000101110000101" \
"1110011010111111110000111000010011000011101001001100001110011100" \
"1100001110111100110000111001111101010100011001010111001101110100" \
"1101000010101111110100001001000111010000100100111101000010010100" \
"1101000010010110110100001001100111000101100000011100010010000100" \
"1100010110111011010100110111010001110010011010010110111001100111" \
"1100010010011000110001001000011011000101100000111100010110011010" \
"1100010110111001111000111000000110100110111000111000000110011001" \
"1110001110000001101010001110111110111101101100011110111110111101" \
"1011001011101111101111011011001111101111101111011011010011101111" \
"1011110110110101111011111011110110110110111011111011110110110111" \
"1110111110111101101110000011010000110010001100110011010011101111" \
"1011110110111001111011111011110110111010111011111011110110111011" \
"1110111110111101101111001110111110111101101111011110111110111101" \
"1011111011101111101111011011111111101111101111101000000011101111" \
"1011111010000001111011111011111010000010111011111011111010000011"
expected_hex = \
"90dc705bbc350b85e6bfc384c3a4c39cc3bcc39f54657374d0afd091d093d094" \
"d096d099c581c484c5bb537472696e67c498c486c583c59ac5b9e381a6e38199" \
"e381a8efbdb1efbdb2efbdb3efbdb4efbdb5efbdb6efbdb7efbdb834323334ef" \
"bdb9efbdbaefbdbbefbdbcefbdbdefbdbeefbdbfefbe80efbe81efbe82efbe83"
expected_base64 = \
"kNxwW7w1C4Xmv8OEw6TDnMO8w59UZXN00K/QkdCT0JTQltCZxYHEhMW7U3RyaW5n" \
"xJjEhsWDxZrFueOBpuOBmeOBqO+9se+9su+9s++9tO+9te+9tu+9t++9uDQyMzTv" \
"vbnvvbrvvbvvvbzvvb3vvb7vvb/vvoDvvoHvvoLvvoM="
bitstream.seek(0)
self.assertEquals( \
bitstream.get_bit_dump_string(bitstream.get_length()),
expected_bits)
bitstream.seek(0)
self.assertEquals(
bitstream.get_hex(bitstream.get_length()).lower(), expected_hex)
bitstream.seek(0)
self.assertEquals(bitstream.get_base64(bitstream.get_length()),
expected_base64)
def test_multiformat_write_multiformat_read(self):
"""
This test writes numeric, byte and string data to a stream and then
reads the whole stream as binary, hex and base64 data, ensuring that
the output is the expected one in each case.
"""
# Write a number, 2 bytes and a string
bitstream = BitStream()
bitstream.put_num(10438341575639894917, 64)
bitstream.put_byte(230)
bitstream.put_byte(191)
bitstream.put_string("ÄäÜüßTestЯБГДЖЙŁĄŻStringĘĆŃŚŹてす" \
"とｱｲｳｴｵｶｷｸ4234ｹｺｻｼｽｾｿﾀﾁﾂﾃ")
# Read in binary, hex and base64 formats
expected_bits = \
"1001000011011100011100000101101110111100001101010000101110000101" \
"1110011010111111110000111000010011000011101001001100001110011100" \
"1100001110111100110000111001111101010100011001010111001101110100" \
"1101000010101111110100001001000111010000100100111101000010010100" \
"1101000010010110110100001001100111000101100000011100010010000100" \
"1100010110111011010100110111010001110010011010010110111001100111" \
"1100010010011000110001001000011011000101100000111100010110011010" \
"1100010110111001111000111000000110100110111000111000000110011001" \
"1110001110000001101010001110111110111101101100011110111110111101" \
"1011001011101111101111011011001111101111101111011011010011101111" \
"1011110110110101111011111011110110110110111011111011110110110111" \
"1110111110111101101110000011010000110010001100110011010011101111" \
"1011110110111001111011111011110110111010111011111011110110111011" \
"1110111110111101101111001110111110111101101111011110111110111101" \
"1011111011101111101111011011111111101111101111101000000011101111" \
"1011111010000001111011111011111010000010111011111011111010000011"
expected_hex = \
"90dc705bbc350b85e6bfc384c3a4c39cc3bcc39f54657374d0afd091d093d094" \
"d096d099c581c484c5bb537472696e67c498c486c583c59ac5b9e381a6e38199" \
"e381a8efbdb1efbdb2efbdb3efbdb4efbdb5efbdb6efbdb7efbdb834323334ef" \
"bdb9efbdbaefbdbbefbdbcefbdbdefbdbeefbdbfefbe80efbe81efbe82efbe83"
expected_base64 = \
"kNxwW7w1C4Xmv8OEw6TDnMO8w59UZXN00K/QkdCT0JTQltCZxYHEhMW7U3RyaW5n" \
"xJjEhsWDxZrFueOBpuOBmeOBqO+9se+9su+9s++9tO+9te+9tu+9t++9uDQyMzTv" \
"vbnvvbrvvbvvvbzvvb3vvb7vvb/vvoDvvoHvvoLvvoM="
bitstream.seek(0)
self.assertEquals( \
bitstream.get_bit_dump_string(bitstream.get_length()),
expected_bits)
bitstream.seek(0)
self.assertEquals(bitstream.get_hex(bitstream.get_length()).lower(),
expected_hex)
bitstream.seek(0)
self.assertEquals(bitstream.get_base64(bitstream.get_length()),
expected_base64)
def test_num_read_part(self):
"""
Test that we can read only some bits of a large number and interpret
them as a shorter number with the expected value.
"""
bitstream = BitStream()
# Store a 64-bit integer in the stream.
num = int(
'00000000000000110101011001010011'
'00101100001000101000100110101111', 2)
bitstream.put_num(num, 64)
# Get it as 8-bit numbers
bitstream.seek(0)
self.assertEqual(bitstream.get_num(8), int('00000000', 2))
self.assertEqual(bitstream.get_num(8), int('00000011', 2))
self.assertEqual(bitstream.get_num(8), int('01010110', 2))
self.assertEqual(bitstream.get_num(8), int('01010011', 2))
self.assertEqual(bitstream.get_num(8), int('00101100', 2))
self.assertEqual(bitstream.get_num(8), int('00100010', 2))
self.assertEqual(bitstream.get_num(8), int('10001001', 2))
self.assertEqual(bitstream.get_num(8), int('10101111', 2))
# Get it as 16-bit numbers
bitstream.seek(0)
self.assertEqual(bitstream.get_num(16), int('0000000000000011', 2))
self.assertEqual(bitstream.get_num(16), int('0101011001010011', 2))
self.assertEqual(bitstream.get_num(16), int('0010110000100010', 2))
self.assertEqual(bitstream.get_num(16), int('1000100110101111', 2))
# Get it as 32-bit numbers
bitstream.seek(0)
self.assertEqual(bitstream.get_num(32),
int('00000000000000110101011001010011', 2))
self.assertEqual(bitstream.get_num(32),
int('00101100001000101000100110101111', 2))
def test_num_read_part(self):
"""
Test that we can read only some bits of a large number and interpret
them as a shorter number with the expected value.
"""
bitstream = BitStream()
# Store a 64-bit integer in the stream.
num = int('00000000000000110101011001010011'
'00101100001000101000100110101111', 2)
bitstream.put_num(num, 64)
# Get it as 8-bit numbers
bitstream.seek(0)
self.assertEqual(bitstream.get_num(8),int('00000000',2))
self.assertEqual(bitstream.get_num(8),int('00000011',2))
self.assertEqual(bitstream.get_num(8),int('01010110',2))
self.assertEqual(bitstream.get_num(8),int('01010011',2))
self.assertEqual(bitstream.get_num(8),int('00101100',2))
self.assertEqual(bitstream.get_num(8),int('00100010',2))
self.assertEqual(bitstream.get_num(8),int('10001001',2))
self.assertEqual(bitstream.get_num(8),int('10101111',2))
# Get it as 16-bit numbers
bitstream.seek(0)
self.assertEqual(bitstream.get_num(16),int('0000000000000011',2))
self.assertEqual(bitstream.get_num(16),int('0101011001010011',2))
self.assertEqual(bitstream.get_num(16),int('0010110000100010',2))
self.assertEqual(bitstream.get_num(16),int('1000100110101111',2))
# Get it as 32-bit numbers
bitstream.seek(0)
self.assertEqual(bitstream.get_num(32),
int('00000000000000110101011001010011',2))
self.assertEqual(bitstream.get_num(32),
int('00101100001000101000100110101111',2))
def test_byte_basic(self):
"""
Test basic put_byte and get_byte behavior.
"""
bitstream = BitStream()
# Put a couple of bytes in the stream:
bytes = [
12, # 00001100
222, # 11011110
145, # 10010001
42, # 00101010
0, # 00000000
255
] # 11111111
for byte in bytes:
bitstream.put_byte(byte)
# Sanity check:
self.assertEquals(bitstream.get_length(), len(bytes) * 8)
self.assertEquals(bitstream.get_current_pos(), len(bytes) * 8)
# Read the bytes back from the stream
bitstream.seek(0)
for byte in bytes:
self.assertEquals(bitstream.get_byte(), byte)
# Read some bits from the stream, interpreting them as bytes, but
# without restricting ourselves to 8-bit aligned bytes
# e.g. read the "byte" defined by bits #4 to #12
bitstream.seek(4)
self.assertEquals(bitstream.get_byte(), 205) # 11001101
bitstream.seek(19)
self.assertEquals(bitstream.get_byte(), 137) # 10001001
def test_put_bitstream_copy(self):
"""
Test the basic functionality of the put_bitstream_copy method.
"""
bitstream1 = BitStream()
bitstream1.put_string("This is bitstream1")
bitstream2 = BitStream()
bitstream2.put_string("This is bitstream2")
bitstream3 = BitStream()
# bitstream3 remains empty
bitstream4 = BitStream()
bitstream4.put_string("This is bitstream4")
# copy the full contents of bitstream2 to the end of bitstream1
bitstream2.seek(0)
bitstream1.put_bitstream_copy(bitstream2)
self.assertEquals(bitstream2.get_current_pos(),
bitstream2.get_length())
# check the contents of bitstream1
bitstream1.seek(0)
self.assertEquals(bitstream1.get_string(bitstream1.get_length()),
"This is bitstream1This is bitstream2")
# copy the full contents of bitstream3 (aka. nothing) to the end of
# bitstream4
bitstream3.seek(0)
bitstream4.put_bitstream_copy(bitstream3)
# check the contents of bitstream4
bitstream4.seek(0)
self.assertEquals(bitstream4.get_string(bitstream4.get_length()),
"This is bitstream4")
# copy the contents of bitstream4 from the position 8 onwards
bitstream4.seek(8 * 8)
bitstream1.put_bitstream_copy(bitstream4)
self.assertEquals(bitstream4.get_current_pos(),
bitstream4.get_length())
# check the contents of bitstream1
bitstream1.seek(0)
self.assertEquals(bitstream1.get_string(bitstream1.get_length()),
"This is bitstream1This is bitstream2bitstream4")
def verify(self, original_collection, shuffled_collection):
"""
Verifies that original_collection and shuffled_collection are
equivalent as proven by this ShufflingProof object.
If this method returns true, then we have proof that both collections
contain encryptions of the same collection of plaintexts, save for the
negligible probability (for a correct security parameter configured in
params.py) that the zero-knowledge proof has been faked. Otherwise we
gain no information about the two collections, other than they are not
shown to be equivalent by this particular proof.
ShufflingProof is a zero-knowledge proof: the result of this
verification or the information within the ShufflingProof object for
which two collections pass this verification, provide no information as
to the association of particular ciphertexts in original_collection
with particular ciphertexts of shuffled_collection.
Arguments:
original_collection::CiphertextCollection --
The original collection of ciphertexts.
shuffled_collection::CiphertextCollection --
Another collection for which we wish to know if the current
ShufflingProof object demonstrates equivalence with
original_collection.
Returns:
result::bool -- True if this proof shows both collections to be
equivalent.
False otherwise.
"""
# Get the security parameter P with which the proof was originally
# created. This is reflect in the length of self._collections and
# self._mappings.
assert len(self._collections) == len(self._mappings), \
"The length of the private properties self._collections and " \
"self._mappings of ShufflingProof must always be the same."
security_parameter = len(self._collections)
# Get the security parameter specified in params
minimum_allowed_security_parameter = params.SHUFFLING_PROOF_SECURITY_PARAMETER
# Check that the security parameter is <= 256, since that is the most
# bits of challenge we can currently have. Also check that P is at least 1
if(minimum_allowed_security_parameter < 1 or
minimum_allowed_security_parameter > 256):
raise ValueError("Security parameter for shuffling proof " \
"(params.SHUFFLING_PROOF_SECURITY_PARAMETER) is out of " \
"range. The security parameter must be between 1 and 256, "\
"its current value is %d. If you have set " \
"CUSTOM_SHUFFLING_PROOF_SECURITY_PARAMETER in the file " \
"params.py, please correct this value or set it to None, " \
"in order for the security parameter to be decided based " \
"on the global SECURITY_LEVEL of plonevotecryptolib. It " \
"is recommended that " \
"CUSTOM_SHUFFLING_PROOF_SECURITY_PARAMETER be always set " \
"to None for deployment operation of plonevotecryptolib." \
% security_parameter)
# Check that the security parameter for which the proof was generated
# is correct and meets the security standards declared in params.py
if(security_parameter < minimum_allowed_security_parameter or
security_parameter < 1 or
security_parameter > 256):
raise InvalidShuffilingProofError("The security parameter for " \
"(which the current proof was created is %d. This is " \
"(either an incorrect value (outside of the [1,256] " \
"(range) or not secure enough to meet the standards set " \
"(in the configuration of params.py (< %d). The proof " \
"(is thus invalid." \
% (security_parameter,
minimum_allowed_security_parameter))
# Generate the challenge
challenge = \
self._generate_challenge(original_collection, shuffled_collection)
# Verify that the challenge corresponds to the stored one
if(challenge != self._challenge):
return False
# Get the challenge as a BitStream for easier manipulation
challenge_bits = BitStream()
challenge_bits.put_hex(challenge)
challenge_bits.seek(0) # back to the beginning of the stream
# For each of the first P bits in the stream
for i in range(0, security_parameter):
bit = challenge_bits.get_num(1)
if(bit == 0):
# verify that self._mapping[i] maps original_collection into
# self._collections[i]
if(not self._mappings[i].verify(original_collection,
self._collections[i])):
return False
elif(bit == 1):
# verify that self._mapping[i] self._collections[i] into
# self._collections[i]
if(not self._mappings[i].verify(self._collections[i],
shuffled_collection)):
return False
else:
assert False, "We took a single bit, its value must be either "\
"0 or 1."
# If we made it so far, the proof is correct
# (each mapping is in accordance to the challenge and valid)
return True
def encrypt_bitstream(self, bitstream, pad_to=None, task_monitor=None):
"""
Encrypts the given bitstream into a ciphertext object.
Arguments:
bitstream::BitStream-- A stream of bits to encrypt
(see BitStream utility class).
pad_to::int -- Minimum size (in bytes) of the resulting
ciphertext. Data will be padded before
encryption to match this size.
task_monitor::TaskMonitor -- A task monitor for this task.
Returns:
ciphertext:Ciphertext -- A ciphertext object encapsulating the
encrypted data.
"""
random = StrongRandom()
## PART 1
# First, format the bitstream as per Ciphertext.py Note 001,
# previous to encryption.
# [size (64 bits) | message (size bits) | padding (X bits) ]
##
formated_bitstream = BitStream()
# The first 64 encode the size of the actual data in bits
SIZE_BLOCK_LENGTH = 64
size_in_bits = bitstream.get_length()
if(size_in_bits >= 2**SIZE_BLOCK_LENGTH):
raise ValueError("The size of the bitstream to encrypt is larger " \
"than 16 Exabits. The current format for " \
"PloneVote ciphertext only allows encrypting a " \
"maximum of 16 Exabits of information.")
formated_bitstream.put_num(size_in_bits, SIZE_BLOCK_LENGTH)
# We then copy the contents of the original bitstream
bitstream.seek(0)
formated_bitstream.put_bitstream_copy(bitstream)
# Finally, we append random data until we reach the desired pad_to
# length
unpadded_length = formated_bitstream.get_length()
if(pad_to != None and (pad_to * 8) > unpadded_length):
full_length = pad_to * 8
else:
full_length = unpadded_length
padding_left = full_length - unpadded_length
while(padding_left > 1024):
padding_bits = random.randint(1, 2**1024)
formated_bitstream.put_num(padding_bits,1024)
padding_left -= 1024
if(padding_left > 0):
padding_bits = random.randint(1, 2**padding_left)
formated_bitstream.put_num(padding_bits, padding_left)
padding_left = 0
## PART 2
# We encrypt the formated bitsteam using ElGamal into a Ciphertext
# object.
# See "Handbook of Applied Cryptography" Algorithm 8.18
##
# block_size is the size of each block of bits to encrypt
# since we can only encrypt messages in [0, p - 1]
# we should use (nbits - 1) as the block size, where
# 2**(nbits - 1) < p < 2**nbits
block_size = self.cryptosystem.get_nbits() - 1
prime = self.cryptosystem.get_prime()
generator = self.cryptosystem.get_generator()
# We pull data from the bitstream one block at a time and encrypt it
formated_bitstream.seek(0)
ciphertext = \
Ciphertext(self.cryptosystem.get_nbits(), self.get_fingerprint())
plaintext_bits_left = formated_bitstream.get_length()
# Check if we have a task monitor and register with it
if(task_monitor != None):
# We will do two tick()s per block to encrypt: one for generating
# the gamma component of the ciphertext block and another for the
# delta component (those are the two time intensive steps,
# because of exponentiation).
ticks = math.ceil((1.0 * plaintext_bits_left) / block_size) * 2
encrypt_task_mon = \
task_monitor.new_subtask("Encrypt data", expected_ticks = ticks)
while(plaintext_bits_left > 0):
# get next block (message, m, etc) to encrypt
if(plaintext_bits_left >= block_size):
block = formated_bitstream.get_num(block_size)
plaintext_bits_left -= block_size
else:
block = formated_bitstream.get_num(plaintext_bits_left)
# Encrypt as if the stream was filled with random data past its
# end, this avoids introducing a 0's gap during decryption to
# bitstream
displacement = block_size - plaintext_bits_left
block = block << displacement
padding = random.randint(0, 2**displacement - 1)
assert (padding / 2**displacement == 0), \
"padding should be at most displacement bits long"
block = block | padding
plaintext_bits_left = 0
# Select a random integer k, 1 <= k <= p − 2
k = random.randint(1, prime - 2)
# Compute gamma and delta
gamma = pow(generator, k, prime)
if(task_monitor != None): encrypt_task_mon.tick()
delta = (block * pow(self._key, k, prime)) % prime
if(task_monitor != None): encrypt_task_mon.tick()
# Add this encrypted data portion to the ciphertext object
ciphertext.append(gamma, delta)
# return the ciphertext object
return ciphertext
def test_seek_basic(self):
"""
Use seek to read data at different points in the bitstream.
"""
bitstream = BitStream()
# Store a 64-bit integer in the stream.
num = int(
'00000000000000110101011001010011'
'00101100001000101000100110101111', 2)
bitstream.put_num(num, 64)
# Get the 0th, 3rd, 5th and 6th bytes of the stream
# First in forwards order
bitstream.seek(0)
self.assertEqual(bitstream.get_num(8), int('00000000', 2))
bitstream.seek(3 * 8)
self.assertEqual(bitstream.get_num(8), int('01010011', 2))
bitstream.seek(5 * 8)
self.assertEqual(bitstream.get_num(8), int('00100010', 2))
self.assertEqual(bitstream.get_num(8), int('10001001', 2))
# Then in backwards order
bitstream.seek(6 * 8)
self.assertEqual(bitstream.get_num(8), int('10001001', 2))
bitstream.seek(5 * 8)
self.assertEqual(bitstream.get_num(8), int('00100010', 2))
bitstream.seek(3 * 8)
self.assertEqual(bitstream.get_num(8), int('01010011', 2))
bitstream.seek(0)
self.assertEqual(bitstream.get_num(8), int('00000000', 2))