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ccakem.py
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from Crypto.Random import get_random_bytes
from cpake import generate_kyber_keys, encrypt, decrypt
from params import KYBER_512SK_BYTES, KYBER_768SK_BYTES, KYBER_1024SK_BYTES, KYBER_SYM_BYTES, KYBER_SS_BYTES, \
KYBER_INDCPA_SECRETKEY_BYTES_K512, KYBER_INDCPA_PUBLICKEYBYTES_K512, \
KYBER_INDCPA_SECRETKEY_BYTES_K768, KYBER_INDCPA_PUBLICKEYBYTES_K768, \
KYBER_INDCPA_SECRETKEY_BYTES_K1024, KYBER_INDCPA_PUBLICKEYBYTES_K1024
from Crypto.Hash import SHA3_256, SHA3_512, SHAKE256
from util import cast_to_byte
def kem_keygen512():
"""
generate kyber keys for security level 512
:return: tuple of (private_key, public key), each a byte array
"""
params_k = 2
sk_, pk = generate_kyber_keys(params_k)
md = SHA3_256.new()
md.update(bytearray([x & 0xFF for x in pk]))
H_pk = md.digest()
H_pk = [ cast_to_byte(x) for x in H_pk ]
pkh = [0 for x in range(0, len(H_pk))]
for i in range(0, len(H_pk)):
pkh[i] = H_pk[i]
z = get_random_bytes(KYBER_SYM_BYTES)
z = [ cast_to_byte(x) for x in z]
sk = sk_[:] + pk[:] + H_pk[:] + z[:]
return (sk, pk)
def kem_keygen768():
"""
generate kyber keys for security level 768
:return: tuple of (private_key, public key), each a byte array
"""
params_k = 3
sk_, pk = generate_kyber_keys(params_k)
md = SHA3_256.new()
md.update(bytearray([x & 0xFF for x in pk]))
H_pk = md.digest()
H_pk = [ cast_to_byte(x) for x in H_pk ]
pkh = [0 for x in range(0, len(H_pk))]
for i in range(0, len(H_pk)):
pkh[i] = H_pk[i]
z = get_random_bytes(KYBER_SYM_BYTES)
z = [ cast_to_byte(x) for x in z]
sk = sk_[:] + pk[:] + H_pk[:] + z[:]
return (sk, pk)
def kem_keygen1024():
"""
generate kyber keys for security level 1024
:return: tuple of (private_key, public key), each a byte array
"""
params_k = 4
sk_, pk = generate_kyber_keys(params_k)
md = SHA3_256.new()
md.update(bytearray([x & 0xFF for x in pk]))
H_pk = md.digest()
H_pk = [ cast_to_byte(x) for x in H_pk ]
pkh = [0 for x in range(0, len(H_pk))]
for i in range(0, len(H_pk)):
pkh[i] = H_pk[i]
z = get_random_bytes(KYBER_SYM_BYTES)
z = [ cast_to_byte(x) for x in z]
sk = sk_[:] + pk[:] + H_pk[:] + z[:]
return (sk, pk)
def kem_encaps512(pubkey, seed=None):
"""
:param seed:
:param pubkey:
:return: (cipher, shared_secret)
"""
if(seed != None and (len(seed) != KYBER_SYM_BYTES)):
raise ValueError("KEM encaps: Seed has incorrect length!")
if(seed == None):
seed = get_random_bytes(KYBER_SYM_BYTES)
seed = bytearray([x & 0xFF for x in seed])
params_k = 2
md = SHA3_256.new()
md.update(bytearray(seed))
Hm = md.digest()
Hm = [ cast_to_byte(x) for x in Hm ]
md = SHA3_256.new()
md.update(bytearray([x & 0xFF for x in pubkey]))
Hpk = md.digest()
Hpk = [ cast_to_byte(x) for x in Hpk ]
m = Hm + Hpk
md512 = SHA3_512.new()
md512.update(bytearray([x & 0xFF for x in m]))
kr = md512.digest()
kr = [ cast_to_byte(x) for x in kr]
K = kr[0:KYBER_SYM_BYTES]
r = [ kr[i + KYBER_SYM_BYTES] for i in range(0, len(kr) - KYBER_SYM_BYTES)]
c = encrypt(Hm, pubkey, r, params_k)
md = SHA3_256.new()
md.update(bytearray([x & 0xFF for x in c]))
Hc = md.digest()
Hc = [ cast_to_byte(x) for x in Hc ]
KHc = K + Hc
xof = SHAKE256.new()
xof.update(bytearray([ x & 0xFF for x in KHc]))
shared_secret = xof.read(KYBER_SYM_BYTES)
shared_secret = [ cast_to_byte(x) for x in shared_secret]
return shared_secret, c
def kem_encaps768(pubkey, seed=None):
"""
:param seed:
:param pubkey:
:return: (cipher, shared_secret)
"""
if(seed != None and (len(seed) != KYBER_SYM_BYTES)):
raise ValueError("KEM encaps: Seed has incorrect length!")
if(seed == None):
seed = get_random_bytes(KYBER_SYM_BYTES)
seed = bytearray([x & 0xFF for x in seed])
params_k = 3
md = SHA3_256.new()
md.update(bytearray(seed))
Hm = md.digest()
Hm = [ cast_to_byte(x) for x in Hm ]
md = SHA3_256.new()
md.update(bytearray([x & 0xFF for x in pubkey]))
Hpk = md.digest()
Hpk = [ cast_to_byte(x) for x in Hpk ]
m = Hm + Hpk
md512 = SHA3_512.new()
md512.update(bytearray([x & 0xFF for x in m]))
kr = md512.digest()
kr = [ cast_to_byte(x) for x in kr]
K = kr[0:KYBER_SYM_BYTES]
r = [ kr[i + KYBER_SYM_BYTES] for i in range(0, len(kr) - KYBER_SYM_BYTES)]
c = encrypt(Hm, pubkey, r, params_k)
md = SHA3_256.new()
md.update(bytearray([x & 0xFF for x in c]))
Hc = md.digest()
Hc = [ cast_to_byte(x) for x in Hc ]
KHc = K + Hc
xof = SHAKE256.new()
xof.update(bytearray([ x & 0xFF for x in KHc]))
shared_secret = xof.read(KYBER_SYM_BYTES)
shared_secret = [ cast_to_byte(x) for x in shared_secret]
return shared_secret, c
def kem_encaps1024(pubkey, seed=None):
"""
:param seed:
:param pubkey:
:return: (cipher, shared_secret)
"""
if(seed != None and (len(seed) != KYBER_SYM_BYTES)):
raise ValueError("KEM encaps: Seed has incorrect length!")
if(seed == None):
seed = get_random_bytes(KYBER_SYM_BYTES)
seed = bytearray([x & 0xFF for x in seed])
params_k = 4
md = SHA3_256.new()
md.update(bytearray(seed))
Hm = md.digest()
Hm = [ cast_to_byte(x) for x in Hm ]
md = SHA3_256.new()
md.update(bytearray([x & 0xFF for x in pubkey]))
Hpk = md.digest()
Hpk = [ cast_to_byte(x) for x in Hpk ]
m = Hm + Hpk
md512 = SHA3_512.new()
md512.update(bytearray([x & 0xFF for x in m]))
kr = md512.digest()
kr = [ cast_to_byte(x) for x in kr]
K = kr[0:KYBER_SYM_BYTES]
r = [ kr[i + KYBER_SYM_BYTES] for i in range(0, len(kr) - KYBER_SYM_BYTES)]
c = encrypt(Hm, pubkey, r, params_k)
md = SHA3_256.new()
md.update(bytearray([x & 0xFF for x in c]))
Hc = md.digest()
Hc = [ cast_to_byte(x) for x in Hc ]
KHc = K + Hc
xof = SHAKE256.new()
xof.update(bytearray([ x & 0xFF for x in KHc]))
shared_secret = xof.read(KYBER_SYM_BYTES)
shared_secret = [ cast_to_byte(x) for x in shared_secret]
return shared_secret, c
def kem_decaps512(private_key, ciphertext):
"""
:param private_key:
:param ciphertext:
:return: (shared_secret, variant)
"""
params_k = 2
sk = private_key[0: KYBER_INDCPA_SECRETKEY_BYTES_K512]
pk = private_key[KYBER_INDCPA_SECRETKEY_BYTES_K512:KYBER_INDCPA_SECRETKEY_BYTES_K512+KYBER_INDCPA_PUBLICKEYBYTES_K512]
z = private_key[KYBER_512SK_BYTES - KYBER_SYM_BYTES:]
h = private_key[KYBER_512SK_BYTES - 2 * KYBER_SYM_BYTES:KYBER_512SK_BYTES - KYBER_SYM_BYTES]
m_ = decrypt(ciphertext, sk, params_k)
md512 = SHA3_512.new()
md512.update(bytearray([ x & 0xFF for x in (m_[:] + h[:])]))
K_r_ = md512.digest()
K_r_ = [ cast_to_byte(x) for x in K_r_ ]
r_ = K_r_[-KYBER_SYM_BYTES:]
cmp = encrypt(m_, pk, r_, params_k)
md = SHA3_256.new()
md.update(bytearray([x & 0xff for x in ciphertext]))
Hc = md.digest()
Hc = [ cast_to_byte(x) for x in Hc ]
k = K_r_[0:KYBER_SYM_BYTES]
if(cmp == ciphertext):
temp_buf = k + Hc
else:
temp_buf = z[:] + Hc
xof = SHAKE256.new()
xof.update(bytearray([ x & 0xFF for x in temp_buf]))
sharedSecretFixedLength = xof.read(KYBER_SS_BYTES)
# could also return buf for debugging...
return [cast_to_byte(x) for x in sharedSecretFixedLength ]
def kem_decaps768(private_key, ciphertext):
"""
:param private_key:
:param ciphertext:
:return: (shared_secret, variant)
"""
params_k = 3
sk = private_key[0: KYBER_INDCPA_SECRETKEY_BYTES_K768]
pk = private_key[KYBER_INDCPA_SECRETKEY_BYTES_K768:KYBER_INDCPA_SECRETKEY_BYTES_K768+KYBER_INDCPA_PUBLICKEYBYTES_K768]
z = private_key[KYBER_768SK_BYTES - KYBER_SYM_BYTES:]
h = private_key[KYBER_768SK_BYTES - 2 * KYBER_SYM_BYTES:KYBER_768SK_BYTES - KYBER_SYM_BYTES]
m_ = decrypt(ciphertext, sk, params_k)
md512 = SHA3_512.new()
md512.update(bytearray([ x & 0xFF for x in (m_[:] + h[:])]))
K_r_ = md512.digest()
K_r_ = [ cast_to_byte(x) for x in K_r_ ]
r_ = K_r_[-KYBER_SYM_BYTES:]
cmp = encrypt(m_, pk, r_, params_k)
md = SHA3_256.new()
md.update(bytearray([x & 0xff for x in ciphertext]))
Hc = md.digest()
Hc = [ cast_to_byte(x) for x in Hc ]
k = K_r_[0:KYBER_SYM_BYTES]
if(cmp == ciphertext):
temp_buf = k + Hc
else:
temp_buf = z[:] + Hc
xof = SHAKE256.new()
xof.update(bytearray([ x & 0xFF for x in temp_buf]))
sharedSecretFixedLength = xof.read(KYBER_SS_BYTES)
# could also return buf for debugging...
return [cast_to_byte(x) for x in sharedSecretFixedLength ]
def kem_decaps1024(private_key, ciphertext):
"""
:param private_key:
:param ciphertext:
:return: (shared_secret, variant)
"""
params_k = 4
sk = private_key[0: KYBER_INDCPA_SECRETKEY_BYTES_K1024]
pk = private_key[KYBER_INDCPA_SECRETKEY_BYTES_K1024:KYBER_INDCPA_SECRETKEY_BYTES_K1024+KYBER_INDCPA_PUBLICKEYBYTES_K1024]
z = private_key[KYBER_1024SK_BYTES - KYBER_SYM_BYTES:]
h = private_key[KYBER_1024SK_BYTES - 2 * KYBER_SYM_BYTES:KYBER_1024SK_BYTES - KYBER_SYM_BYTES]
m_ = decrypt(ciphertext, sk, params_k)
md512 = SHA3_512.new()
md512.update(bytearray([ x & 0xFF for x in (m_[:] + h[:])]))
K_r_ = md512.digest()
K_r_ = [ cast_to_byte(x) for x in K_r_ ]
r_ = K_r_[-KYBER_SYM_BYTES:]
cmp = encrypt(m_, pk, r_, params_k)
md = SHA3_256.new()
md.update(bytearray([x & 0xff for x in ciphertext]))
Hc = md.digest()
Hc = [ cast_to_byte(x) for x in Hc ]
k = K_r_[0:KYBER_SYM_BYTES]
if(cmp == ciphertext):
temp_buf = k + Hc
else:
temp_buf = z[:] + Hc
xof = SHAKE256.new()
xof.update(bytearray([ x & 0xFF for x in temp_buf]))
sharedSecretFixedLength = xof.read(KYBER_SS_BYTES)
# could also return buf for debugging...
return [cast_to_byte(x) for x in sharedSecretFixedLength ]