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crypto: simplify api for new crypto
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@ThomasWaldmann
ThomasWaldmann committed Mar 17, 2022
1 parent a14062b commit bcd8c8b
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Showing 2 changed files with 21 additions and 25 deletions.
28 changes: 13 additions & 15 deletions src/borg/crypto/low_level.pyx
View file
Original file line number Diff line number Diff line change
Expand Up @@ -428,7 +428,7 @@ cdef class _AEAD_BASE:

cdef CIPHER cipher
cdef EVP_CIPHER_CTX *ctx
cdef unsigned char *enc_key
cdef unsigned char *key
cdef int cipher_blk_len
cdef int iv_len
cdef int aad_offset
Expand All @@ -442,30 +442,28 @@ cdef class _AEAD_BASE:
"""check whether library requirements for this ciphersuite are satisfied"""
raise NotImplemented # override / implement in child class

def __init__(self, mac_key, enc_key, iv=None, header_len=1, aad_offset=0):
def __init__(self, key, iv=None, header_len=1, aad_offset=0):
"""
init AEAD crypto
:param mac_key: must be None
:param enc_key: 256bit encrypt-then-mac key
:param key: 256bit encrypt-then-mac key
:param iv: 96bit initialisation vector / nonce
:param header_len: length of header *without* IV
:param header_len: expected length of header *without* IV
:param aad_offset: where in the header the authenticated data starts
"""
assert mac_key is None
assert isinstance(enc_key, bytes) and len(enc_key) == 32
assert isinstance(key, bytes) and len(key) == 32
self.iv_len = sizeof(self.iv)
self.header_len_expected = header_len + self.iv_len
assert aad_offset <= header_len
self.aad_offset = aad_offset
self.mac_len = 16
self.enc_key = enc_key
self.key = key
if iv is not None:
self.set_iv(iv)
else:
self.blocks = -1 # make sure set_iv is called before encrypt

def __cinit__(self, mac_key, enc_key, iv=None, header_len=1, aad_offset=0):
def __cinit__(self, key, iv=None, header_len=1, aad_offset=0):
self.ctx = EVP_CIPHER_CTX_new()

def __dealloc__(self):
Expand Down Expand Up @@ -511,7 +509,7 @@ cdef class _AEAD_BASE:
raise CryptoError('EVP_EncryptInit_ex failed')
if not EVP_CIPHER_CTX_ctrl(self.ctx, EVP_CTRL_AEAD_SET_IVLEN, self.iv_len, NULL):
raise CryptoError('EVP_CIPHER_CTX_ctrl SET IVLEN failed')
rc = EVP_EncryptInit_ex(self.ctx, NULL, NULL, self.enc_key, self.iv)
rc = EVP_EncryptInit_ex(self.ctx, NULL, NULL, self.key, self.iv)
if not rc:
raise CryptoError('EVP_EncryptInit_ex failed')
rc = EVP_EncryptUpdate(self.ctx, NULL, &olen, <const unsigned char*> hdata.buf+aoffset, alen)
Expand Down Expand Up @@ -561,7 +559,7 @@ cdef class _AEAD_BASE:
self.set_iv(iv)
if not EVP_CIPHER_CTX_ctrl(self.ctx, EVP_CTRL_AEAD_SET_IVLEN, self.iv_len, NULL):
raise CryptoError('EVP_CIPHER_CTX_ctrl SET IVLEN failed')
if not EVP_DecryptInit_ex(self.ctx, NULL, NULL, self.enc_key, iv):
if not EVP_DecryptInit_ex(self.ctx, NULL, NULL, self.key, iv):
raise CryptoError('EVP_DecryptInit_ex failed')
if not EVP_CIPHER_CTX_ctrl(self.ctx, EVP_CTRL_AEAD_SET_TAG, self.mac_len, <unsigned char *> idata.buf + hlen):
raise CryptoError('EVP_CIPHER_CTX_ctrl SET TAG failed')
Expand Down Expand Up @@ -637,10 +635,10 @@ cdef class AES256_OCB(_AES_BASE):
if is_libressl:
raise ValueError('AES OCB is not implemented by LibreSSL (yet?).')

def __init__(self, mac_key, enc_key, iv=None, header_len=1, aad_offset=0):
def __init__(self, key, iv=None, header_len=1, aad_offset=0):
self.requirements_check()
self.cipher = EVP_aes_256_ocb
super().__init__(mac_key, enc_key, iv=iv, header_len=header_len, aad_offset=aad_offset)
super().__init__(key, iv=iv, header_len=header_len, aad_offset=aad_offset)


cdef class CHACHA20_POLY1305(_CHACHA_BASE):
Expand All @@ -649,10 +647,10 @@ cdef class CHACHA20_POLY1305(_CHACHA_BASE):
if is_libressl:
raise ValueError('CHACHA20-POLY1305 is not implemented by LibreSSL (yet?).')

def __init__(self, mac_key, enc_key, iv=None, header_len=1, aad_offset=0):
def __init__(self, key, iv=None, header_len=1, aad_offset=0):
self.requirements_check()
self.cipher = EVP_chacha20_poly1305
super().__init__(mac_key, enc_key, iv=iv, header_len=header_len, aad_offset=aad_offset)
super().__init__(key, iv=iv, header_len=header_len, aad_offset=aad_offset)


cdef class AES:
Expand Down
18 changes: 8 additions & 10 deletions src/borg/testsuite/crypto.py
View file
Original file line number Diff line number Diff line change
Expand Up @@ -91,8 +91,7 @@ def test_AES256_CTR_HMAC_SHA256_aad(self):

def test_AE(self):
# used in legacy-like layout (1 type byte, no aad)
mac_key = None
enc_key = b'X' * 32
key = b'X' * 32
iv = 0
data = b'foo' * 10
header = b'\x23'
Expand All @@ -111,7 +110,7 @@ def test_AE(self):
for cs_cls, exp_mac, exp_cdata in tests:
# print(repr(cs_cls))
# encrypt/mac
cs = cs_cls(mac_key, enc_key, iv, header_len=len(header), aad_offset=1)
cs = cs_cls(key, iv, header_len=len(header), aad_offset=1)
hdr_mac_iv_cdata = cs.encrypt(data, header=header)
hdr = hdr_mac_iv_cdata[0:1]
iv = hdr_mac_iv_cdata[1:13]
Expand All @@ -123,20 +122,19 @@ def test_AE(self):
self.assert_equal(hexlify(cdata), exp_cdata)
self.assert_equal(cs.next_iv(), 1)
# auth/decrypt
cs = cs_cls(mac_key, enc_key, header_len=len(header), aad_offset=1)
cs = cs_cls(key, header_len=len(header), aad_offset=1)
pdata = cs.decrypt(hdr_mac_iv_cdata)
self.assert_equal(data, pdata)
self.assert_equal(cs.next_iv(), 1)
# auth-failure due to corruption (corrupted data)
cs = cs_cls(mac_key, enc_key, header_len=len(header), aad_offset=1)
cs = cs_cls(key, header_len=len(header), aad_offset=1)
hdr_mac_iv_cdata_corrupted = hdr_mac_iv_cdata[:29] + b'\0' + hdr_mac_iv_cdata[30:]
self.assert_raises(IntegrityError,
lambda: cs.decrypt(hdr_mac_iv_cdata_corrupted))

def test_AEAD(self):
# test with aad
mac_key = None
enc_key = b'X' * 32
key = b'X' * 32
iv = 0
data = b'foo' * 10
header = b'\x12\x34\x56'
Expand All @@ -155,7 +153,7 @@ def test_AEAD(self):
for cs_cls, exp_mac, exp_cdata in tests:
# print(repr(cs_cls))
# encrypt/mac
cs = cs_cls(mac_key, enc_key, iv, header_len=len(header), aad_offset=1)
cs = cs_cls(key, iv, header_len=len(header), aad_offset=1)
hdr_mac_iv_cdata = cs.encrypt(data, header=header)
hdr = hdr_mac_iv_cdata[0:3]
iv = hdr_mac_iv_cdata[3:15]
Expand All @@ -167,12 +165,12 @@ def test_AEAD(self):
self.assert_equal(hexlify(cdata), exp_cdata)
self.assert_equal(cs.next_iv(), 1)
# auth/decrypt
cs = cs_cls(mac_key, enc_key, header_len=len(header), aad_offset=1)
cs = cs_cls(key, header_len=len(header), aad_offset=1)
pdata = cs.decrypt(hdr_mac_iv_cdata)
self.assert_equal(data, pdata)
self.assert_equal(cs.next_iv(), 1)
# auth-failure due to corruption (corrupted aad)
cs = cs_cls(mac_key, enc_key, header_len=len(header), aad_offset=1)
cs = cs_cls(key, header_len=len(header), aad_offset=1)
hdr_mac_iv_cdata_corrupted = hdr_mac_iv_cdata[:1] + b'\0' + hdr_mac_iv_cdata[2:]
self.assert_raises(IntegrityError,
lambda: cs.decrypt(hdr_mac_iv_cdata_corrupted))
Expand Down

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