def cpabe_decrypt(group, mpk, deckey, ctxt):
"""Decrypts a ciphertext using the Bethencourt2007cae CP-ABE Scheme.
The plaintext will be returned iff the policy used to generate the
cipher-text can be satisfied by the set of attributes within the
decryption key.
@param group The `PairingGroup` used within the underlying crypto.
@param mpk The Master Public Key of type `mk_t`.
@param deckey The decryption key of type `sk_t`.
@param ctxt The `bytearray` resulting from io.open or io.IOBytes
containing the ciphertext.
@return The `bytearray` containing the plaintext.
@throws PebelDecryptionException If deckey cannot satisfy the
policy within the ciphertext.
"""
cpabe = CPabe_BSW07(group)
ptxt = io.BytesIO()
iv = ctxt.read(AES.block_size)
session_key_size = struct.unpack('<Q', ctxt.read(struct.calcsize('Q')))[0]
session_key_ctxt = bytesToObject(ctxt.read(session_key_size), group)
session_key = cpabe.decrypt(mpk,deckey, session_key_ctxt)
if session_key:
symcipher = AES.new(sha(session_key)[0:32], AES.MODE_CFB, iv)
for b in read_data(bin_data=ctxt, chunksize=AES.block_size):
ptxt.write(symcipher.decrypt(b))
ptxt.flush()
return ptxt.getvalue()
else:
raise PebelDecryptionException("Unable to decrypt given cipher-text.")
def cpabe_encrypt(group, mpk, ptxt, policy):
"""Encrypts a plain-text using the Bethencourt2007cae CP-ABE Scheme.
@param group The `PairingGroup` used within the underlying crypto.
@param mpk The Master Public Key of type `pk_t`.
@param ptxt The `bytearray` resulting from io.open or io.IOBytes
containing the plaintext.
@param policy The `str` policy used to encrypt the plaintext.
@return The encrypted data returned as a `bytearray`.
"""
cpabe = CPabe_BSW07(group)
session_key = group.random(GT)
session_key_ctxt = cpabe.encrypt(mpk, session_key, policy)
ctxt = io.BytesIO()
iv = Random.new().read(AES.block_size)
symcipher = AES.new(sha(session_key)[0:32], AES.MODE_CFB, iv)
ctxt.write(bytes(iv))
session_key_ctxt_b = objectToBytes(session_key_ctxt, group)
ctxt.write(struct.pack('<Q', len(session_key_ctxt_b)))
ctxt.write(session_key_ctxt_b)
for b in read_data(bin_data=ptxt, chunksize=AES.block_size):
ctxt.write(symcipher.encrypt(b))
ctxt.flush()
return ctxt.getvalue()
def cpabe_encrypt(group, mpk, ptxt, policy):
"""Encrypts a plain-text using the Bethencourt2007cae CP-ABE Scheme.
@param group The `PairingGroup` used within the underlying crypto.
@param mpk The Master Public Key of type `pk_t`.
@param ptxt The `bytearray` resulting from io.open or io.IOBytes
containing the plaintext.
@param policy The `str` policy used to encrypt the plaintext.
@return The encrypted data returned as a `bytearray`.
"""
cpabe = CPabe_BSW07(group)
session_key = group.random(GT)
session_key_ctxt = cpabe.encrypt(mpk, session_key, policy)
ctxt = io.BytesIO()
iv = Random.new().read(AES.block_size)
symcipher = AES.new(sha(session_key)[0:32], AES.MODE_CFB, iv)
ctxt.write(bytes(iv))
session_key_ctxt_b = objectToBytes(session_key_ctxt, group)
ctxt.write(struct.pack('<Q', len(session_key_ctxt_b)))
ctxt.write(session_key_ctxt_b)
for b in read_data(bin_data=ptxt, chunksize=AES.block_size):
ctxt.write(symcipher.encrypt(b))
ctxt.flush()
return ctxt.getvalue()
def kpabe_encrypt(group, mpk, ptxt, attributes):
"""Encrypts a plaintext using the Lewmko2008rws KP-ABE Scheme.
@param group The `PairingGroup` used within the underlying crypto.
@param mpk The master public key of type `mk_t`.
@param ptxt The `bytearray` resulting from io.open or `io.IOBytes`
containing the plaintext.
@param attributes The set of `str` attributes used to encrypt the
plaintext.
@return The encrypted data returned as a `bytearray`.
"""
kpabe = KPabe(group)
session_key = group.random(GT)
session_key_ctxt = kpabe.encrypt(mpk, session_key,
[a.upper() for a in attributes])
ctxt = io.BytesIO()
iv = Random.new().read(AES.block_size)
symcipher = AES.new(sha(session_key)[0:32], AES.MODE_CFB, iv)
ctxt.write(bytes(iv))
session_key_ctxt_b = objectToBytes(session_key_ctxt, group)
ctxt.write(struct.pack('Q', len(session_key_ctxt_b)))
ctxt.write(session_key_ctxt_b)
for b in read_data(bin_data=ptxt, chunksize=AES.block_size):
ctxt.write(symcipher.encrypt(b))
ctxt.flush()
return ctxt.getvalue()
def kpabe_encrypt(group, mpk, ptxt, attributes):
"""Encrypts a plaintext using the Lewmko2008rws KP-ABE Scheme.
@param group The `PairingGroup` used within the underlying crypto.
@param mpk The master public key of type `mk_t`.
@param ptxt The `bytearray` resulting from io.open or `io.IOBytes`
containing the plaintext.
@param attributes The set of `str` attributes used to encrypt the
plaintext.
@return The encrypted data returned as a `bytearray`.
"""
kpabe = KPabe(group)
session_key = group.random(GT)
session_key_ctxt = kpabe.encrypt(mpk,
session_key,
[a.upper() for a in attributes])
ctxt = io.BytesIO()
iv = Random.new().read(AES.block_size)
symcipher = AES.new(sha(session_key)[0:32], AES.MODE_CFB, iv)
ctxt.write(bytes(iv))
session_key_ctxt_b = objectToBytes(session_key_ctxt, group)
ctxt.write(struct.pack('Q' ,len(session_key_ctxt_b)))
ctxt.write(session_key_ctxt_b)
for b in read_data(bin_data=ptxt, chunksize=AES.block_size):
ctxt.write(symcipher.encrypt(b))
ctxt.flush()
return ctxt.getvalue()
def cpabe_decrypt(group, mpk, deckey, ctxt):
"""Decrypts a ciphertext using the Bethencourt2007cae CP-ABE Scheme.
The plaintext will be returned iff the policy used to generate the
cipher-text can be satisfied by the set of attributes within the
decryption key.
@param group The `PairingGroup` used within the underlying crypto.
@param mpk The Master Public Key of type `mk_t`.
@param deckey The decryption key of type `sk_t`.
@param ctxt The `bytearray` resulting from io.open or io.IOBytes
containing the ciphertext.
@return The `bytearray` containing the plaintext.
@throws PebelDecryptionException If deckey cannot satisfy the
policy within the ciphertext.
"""
cpabe = CPabe_BSW07(group)
ptxt = io.BytesIO()
iv = ctxt.read(AES.block_size)
session_key_size = struct.unpack('<Q', ctxt.read(struct.calcsize('Q')))[0]
session_key_ctxt = bytesToObject(ctxt.read(session_key_size), group)
session_key = cpabe.decrypt(mpk,deckey, session_key_ctxt)
if session_key:
symcipher = AES.new(sha(session_key)[0:32], AES.MODE_CFB, iv)
for b in read_data(bin_data=ctxt, chunksize=AES.block_size):
ptxt.write(symcipher.decrypt(b))
ptxt.flush()
return ptxt.getvalue()
else:
raise PebelDecryptionException("Unable to decrypt given cipher-text.")