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wolfcrypt-py
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Add support for multiple associated data blocks

pull/74/head
Martijn de Milliano 2025-11-12 13:54:39 +01:00
parent 56e7814c6e
commit 523b36bf97
3 changed files with 78 additions and 25 deletions
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5
scripts/build_ffi.py
View File

@ -651,7 +651,10 @@ def build_ffi(local_wolfssl, features):
if features["AES"] and features["AES_SIV"]:
cdef += """
typedef struct { ...; } AesSivAssoc;
typedef struct AesSivAssoc_s {
const byte* assoc;
word32 assocSz;
} AesSivAssoc;
int wc_AesSivEncrypt(const byte* key, word32 keySz, const byte* assoc,
word32 assocSz, const byte* nonce, word32 nonceSz,
const byte* in, word32 inSz, byte* siv, byte* out);

30
tests/test_ciphers.py
View File

@ -61,7 +61,7 @@ from wolfcrypt.ciphers import (
@pytest.fixture
def vectors():
TestVector = namedtuple("TestVector", """key iv plaintext ciphertext
TestVector = namedtuple("TestVector", """key iv plaintext ciphertext
ciphertext_ctr raw_key
pkcs8_key pem""")
TestVector.__new__.__defaults__ = (None,) * len(TestVector._fields)
@ -778,20 +778,15 @@ TEST_VECTOR_CIPHERTEXT_RFC5297 = bytes.fromhex(
@pytest.mark.skipif(not _lib.AES_SIV_ENABLED, reason="AES-SIV not enabled")
@pytest.mark.skip(reason=("Associated data in test vector consists of "
"multiple blocks which is unsupported"))
def test_aessiv_encrypt_kat_rfc5297():
"""
Known-answer test using test vectors from RFC-5297.
"""
aessiv = AesSiv(TEST_VECTOR_KEY_RFC5297)
# This is probably not the correct way of handling the associated data.
# The function wc_AesSivEncrypt_ex supports this but it is currently not
# exposed.
associated_data = (
TEST_VECTOR_ASSOCIATED_DATA_1_RFC5297
+ TEST_VECTOR_ASSOCIATED_DATA_2_RFC5297
)
associated_data = [
TEST_VECTOR_ASSOCIATED_DATA_1_RFC5297,
TEST_VECTOR_ASSOCIATED_DATA_2_RFC5297,
]
siv, ciphertext = aessiv.encrypt(
associated_data,
TEST_VECTOR_NONCE_RFC5297,
@ -802,19 +797,14 @@ def test_aessiv_encrypt_kat_rfc5297():
@pytest.mark.skipif(not _lib.AES_SIV_ENABLED, reason="AES-SIV not enabled")
@pytest.mark.skip(reason=("Associated data in test vector consists "
"of multiple blocks which is unsupported"))
def test_aessiv_decrypt_kat_rfc5297():
"""
Known-answer test using test vectors from RFC-5297.
"""
aessiv = AesSiv(TEST_VECTOR_KEY_RFC5297)
# This is probably not the correct way of handling the associated data.
# The function wc_AesSivEncrypt_ex supports this but it is currently not
# exposed.
associated_data = (
TEST_VECTOR_ASSOCIATED_DATA_1_RFC5297
+ TEST_VECTOR_ASSOCIATED_DATA_2_RFC5297
TEST_VECTOR_ASSOCIATED_DATA_1_RFC5297,
TEST_VECTOR_ASSOCIATED_DATA_2_RFC5297,
)
plaintext = aessiv.decrypt(
associated_data,
@ -850,6 +840,9 @@ TEST_VECTOR_CIPHERTEXT_OPENSSL = bytes.fromhex(
def test_aessiv_encrypt_kat_openssl():
"""
Known-answer test using test vectors from OpenSSL.
This also tests calling AesSiv with a single associated data block, not
provided as a list of blocks.
"""
aessiv = AesSiv(TEST_VECTOR_KEY_OPENSSL)
siv, ciphertext = aessiv.encrypt(
@ -865,6 +858,9 @@ def test_aessiv_encrypt_kat_openssl():
def test_aessiv_decrypt_kat_openssl():
"""
Known-answer test using test vectors from OpenSSL.
This also tests calling AesSiv with a single associated data block, not
provided as a list of blocks.
"""
aessiv = AesSiv(TEST_VECTOR_KEY_OPENSSL)
plaintext = aessiv.decrypt(

68
wolfcrypt/ciphers.py
View File

@ -293,16 +293,24 @@ if _lib.AES_SIV_ENABLED:
"""
Encrypt plaintext data using the nonce provided. The associated
data is not encrypted but is included in the authentication tag.
Associated data may be provided as single str or bytes, or as a
list of str or bytes in case of multiple blocks.
Returns a tuple of the IV and ciphertext.
"""
associated_data = t2b(associated_data)
# Prepare the associated data blocks. Make sure to hold on to the
# returned references until the C function has been called in order
# to prevent garbage collection of them until the function is done.
associated_data, _refs = (
AesSiv._prepare_associated_data(associated_data))
nonce = t2b(nonce)
plaintext = t2b(plaintext)
siv = _ffi.new("byte[%d]" % AesSiv.block_size)
ciphertext = _ffi.new("byte[%d]" % len(plaintext))
ret = _lib.wc_AesSivEncrypt(self._key, len(self._key), associated_data, len(associated_data),
nonce, len(nonce), plaintext, len(plaintext), siv, ciphertext)
ret = _lib.wc_AesSivEncrypt_ex(self._key, len(self._key),
associated_data, len(associated_data), nonce, len(nonce),
plaintext, len(plaintext), siv, ciphertext)
if ret < 0: # pragma: no cover
raise WolfCryptError("AES-SIV encryption error (%d)" % ret)
return _ffi.buffer(siv)[:], _ffi.buffer(ciphertext)[:]
@ -312,9 +320,16 @@ if _lib.AES_SIV_ENABLED:
Decrypt the ciphertext using the nonce and SIV provided.
The integrity of the associated data is checked.
Associated data may be provided as single str or bytes, or as a
list of str or bytes in case of multiple blocks.
Returns the decrypted plaintext.
"""
associated_data = t2b(associated_data)
# Prepare the associated data blocks. Make sure to hold on to the
# returned references until the C function has been called in order
# to prevent garbage collection of them until the function is done.
associated_data, _refs = (
AesSiv._prepare_associated_data(associated_data))
nonce = t2b(nonce)
siv = t2b(siv)
if len(siv) != AesSiv.block_size:
@ -322,12 +337,51 @@ if _lib.AES_SIV_ENABLED:
(AesSiv.block_size, len(siv)))
ciphertext = t2b(ciphertext)
plaintext = _ffi.new("byte[%d]" % len(ciphertext))
ref = _lib.wc_AesSivDecrypt(self._key, len(self._key), associated_data, len(associated_data),
nonce, len(nonce), ciphertext, len(ciphertext), siv, plaintext)
ref = _lib.wc_AesSivDecrypt_ex(self._key, len(self._key),
associated_data, len(associated_data), nonce, len(nonce),
ciphertext, len(ciphertext), siv, plaintext)
if ref < 0:
raise WolfCryptError("AES-SIV decryption error (%d)" % ref)
return _ffi.buffer(plaintext)[:]
@staticmethod
def _prepare_associated_data(associated_data):
"""
Prepare associated data for sending to C library.
Associated data may be provided as single str or bytes, or as a
list of str or bytes in case of multiple blocks.
The result is a tuple of the list of cffi cdata pointers to
AesSivAssoc structures, as well as the converted associated
data blocks. The caller **must** hold on to these until the
C function has been called, in order to make sure that the memory
is not freed by the FFI garbage collector before the data is read.
"""
if (isinstance(associated_data, str) or isinstance(associated_data, bytes)):
# A single block is provided.
# Make sure we have bytes.
associated_data = t2b(associated_data)
result = _ffi.new("AesSivAssoc[1]")
result[0].assoc = _ffi.from_buffer(associated_data)
result[0].assocSz = len(associated_data)
else:
# It is assumed that a list is provided.
num_blocks = len(associated_data)
if (num_blocks > 126):
raise WolfCryptError("AES-SIV does not support more than 126 blocks "
"of associated data, got: %d" % num_blocks)
# Make sure we have bytes.
associated_data = [t2b(block) for block in associated_data]
result = _ffi.new("AesSivAssoc[]", num_blocks)
for index, block in enumerate(associated_data):
result[index].assoc = _ffi.from_buffer(block)
result[index].assocSz = len(block)
# Return the converted associated data blocks so the caller can
# hold on to them until the function has been called.
return result, associated_data
if _lib.AESGCM_STREAM_ENABLED:
class AesGcmStream(object):
"""