def mimc_encrypt(key, ms):
"""
ms - blocks of plaintext, that is, plaintext -> {m1, m2,...,ml}
Each plaintext is a field element.
ciphertext <- F_MiMC(counter, key) + plaintext
"""
return [mimc_plain(idx, key) + m for (idx, m) in enumerate(ms)]
def mimc_encrypt(pub_key, ms, seed=None):
"""
Encrypts blocks of plaintext data using counter-mode encryption.
args:
pub_key (Point): public key for encryption
ms (list): list of message/plaintext data to encode
seed(int): seed to use for random generation in encryption
output:
ciphertext (list): encoded blocks
a_ (Point) auxilliary point sent to caller for decryption
"""
# Randomly generated variable hold only by the dealer
a = Jubjub.Field.random() if seed is None else seed
# Auxiliary variable needed for decryption
a_ = a * GP
# secret key kept by dealer
k = (a * pub_key).x
# ciphertext sent to user
ciphertext = [mimc_plain(idx, k) + m for (idx, m) in enumerate(ms)]
return (ciphertext, a_)
async def _prog(context):
xs = [context.preproc.get_rand(context) for _ in range(20)]
# Compute F_MiMC_mpc, mm - mimc_mpc
mm = await mimc_mpc_batch(context, xs, key)
mm_open = await context.ShareArray(mm).open()
# open x, then compute F_MiMC_plain, mp - mimc_plain
xs_open = await context.ShareArray(xs).open()
mp = [mimc_plain(x, key) for x in xs_open]
# Compare the MPC evaluation to the plain one
assert mm_open == mp
async def _prog(context):
x = context.preproc.get_zero(context)
field = GF(Subgroup.BLS12_381)
key = field(15)
# Compute F_MiMC_mpc
mm = await mimc_mpc(context, x, key)
mm_open = await mm.open()
# open x, then compute F_MiMC_plain
x_open = await x.open()
mp = mimc_plain(x_open, key)
# Compare the MPC evaluation to the plain one
assert mm_open == mp