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PR #214 - Merge branch 'crypto_cleanup' of https://github.com/thomaswaldmann/attic into merge
This commit is contained in:
Thomas Waldmann
commit
0d2cd28c19
3 changed files with 74 additions and 22 deletions
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@ -8,7 +8,7 @@ from libc.stdlib cimport malloc, free
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API_VERSION = 2
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cdef extern from "openssl/rand.h":
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int RAND_bytes(unsigned char *buf,int num)
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int RAND_bytes(unsigned char *buf, int num)
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cdef extern from "openssl/evp.h":
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@ -26,10 +26,16 @@ cdef extern from "openssl/evp.h":
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void EVP_CIPHER_CTX_init(EVP_CIPHER_CTX *a)
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void EVP_CIPHER_CTX_cleanup(EVP_CIPHER_CTX *a)
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int EVP_EncryptInit_ex(EVP_CIPHER_CTX *ctx,const EVP_CIPHER *cipher, ENGINE *impl,
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int EVP_EncryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *cipher, ENGINE *impl,
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const unsigned char *key, const unsigned char *iv)
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int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
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int *outl, const unsigned char *in_, int inl)
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int EVP_DecryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *cipher, ENGINE *impl,
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const unsigned char *key, const unsigned char *iv)
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int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl,
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const unsigned char *in_, int inl)
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int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl,
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const unsigned char *in_, int inl)
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int EVP_EncryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl)
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int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl)
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int PKCS5_PBKDF2_HMAC(const char *password, int passwordlen,
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const unsigned char *salt, int saltlen, int iter,
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@ -47,7 +53,8 @@ long_to_bytes = lambda x: _long.pack(x)
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def num_aes_blocks(length):
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"""Return the number of AES blocks required to encrypt/decrypt *length* bytes of data
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"""Return the number of AES blocks required to encrypt/decrypt *length* bytes of data.
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Note: this is only correct for modes without padding, like AES-CTR.
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"""
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return (length + 15) // 16
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@ -85,11 +92,19 @@ cdef class AES:
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"""A thin wrapper around the OpenSSL EVP cipher API
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"""
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cdef EVP_CIPHER_CTX ctx
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cdef int is_encrypt
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def __cinit__(self, key, iv=None):
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def __cinit__(self, is_encrypt, key, iv=None):
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EVP_CIPHER_CTX_init(&self.ctx)
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if not EVP_EncryptInit_ex(&self.ctx, EVP_aes_256_ctr(), NULL, NULL, NULL):
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raise Exception('EVP_EncryptInit_ex failed')
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self.is_encrypt = is_encrypt
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# Set cipher type and mode
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cipher_mode = EVP_aes_256_ctr()
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if self.is_encrypt:
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if not EVP_EncryptInit_ex(&self.ctx, cipher_mode, NULL, NULL, NULL):
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raise Exception('EVP_EncryptInit_ex failed')
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else: # decrypt
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if not EVP_DecryptInit_ex(&self.ctx, cipher_mode, NULL, NULL, NULL):
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raise Exception('EVP_DecryptInit_ex failed')
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self.reset(key, iv)
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def __dealloc__(self):
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@ -102,8 +117,13 @@ cdef class AES:
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key2 = key
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if iv:
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iv2 = iv
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if not EVP_EncryptInit_ex(&self.ctx, NULL, NULL, key2, iv2):
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raise Exception('EVP_EncryptInit_ex failed')
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# Initialise key and IV
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if self.is_encrypt:
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if not EVP_EncryptInit_ex(&self.ctx, NULL, NULL, key2, iv2):
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raise Exception('EVP_EncryptInit_ex failed')
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else: # decrypt
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if not EVP_DecryptInit_ex(&self.ctx, NULL, NULL, key2, iv2):
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raise Exception('EVP_DecryptInit_ex failed')
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@property
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def iv(self):
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@ -111,15 +131,43 @@ cdef class AES:
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def encrypt(self, data):
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cdef int inl = len(data)
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cdef int outl
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cdef unsigned char *out = <unsigned char *>malloc(inl)
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cdef int ctl = 0
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cdef int outl = 0
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# note: modes that use padding, need up to one extra AES block (16b)
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cdef unsigned char *out = <unsigned char *>malloc(inl+16)
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if not out:
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raise MemoryError
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try:
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if not EVP_EncryptUpdate(&self.ctx, out, &outl, data, inl):
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raise Exception('EVP_EncryptUpdate failed')
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return out[:inl]
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ctl = outl
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if not EVP_EncryptFinal_ex(&self.ctx, out+ctl, &outl):
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raise Exception('EVP_EncryptFinal failed')
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ctl += outl
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return out[:ctl]
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finally:
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free(out)
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decrypt = encrypt
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def decrypt(self, data):
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cdef int inl = len(data)
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cdef int ptl = 0
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cdef int outl = 0
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# note: modes that use padding, need up to one extra AES block (16b).
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# This is what the openssl docs say. I am not sure this is correct,
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# but OTOH it will not cause any harm if our buffer is a little bigger.
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cdef unsigned char *out = <unsigned char *>malloc(inl+16)
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if not out:
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raise MemoryError
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try:
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if not EVP_DecryptUpdate(&self.ctx, out, &outl, data, inl):
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raise Exception('EVP_DecryptUpdate failed')
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ptl = outl
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if EVP_DecryptFinal_ex(&self.ctx, out+ptl, &outl) <= 0:
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# this error check is very important for modes with padding or
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# authentication. for them, a failure here means corrupted data.
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# CTR mode does not use padding nor authentication.
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raise Exception('EVP_DecryptFinal failed')
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ptl += outl
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return out[:ptl]
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finally:
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free(out)
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@ -144,8 +144,8 @@ class AESKeyBase(KeyBase):
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self.chunk_seed = self.chunk_seed - 0xffffffff - 1
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def init_ciphers(self, enc_iv=b''):
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self.enc_cipher = AES(self.enc_key, enc_iv)
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self.dec_cipher = AES(self.enc_key)
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self.enc_cipher = AES(is_encrypt=True, key=self.enc_key, iv=enc_iv)
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self.dec_cipher = AES(is_encrypt=False, key=self.enc_key)
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class PassphraseKey(AESKeyBase):
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@ -244,7 +244,7 @@ class KeyfileKey(AESKeyBase):
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assert d[b'version'] == 1
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assert d[b'algorithm'] == b'sha256'
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key = pbkdf2_sha256(passphrase.encode('utf-8'), d[b'salt'], d[b'iterations'], 32)
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data = AES(key).decrypt(d[b'data'])
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data = AES(is_encrypt=False, key=key).decrypt(d[b'data'])
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if HMAC(key, data, sha256).digest() != d[b'hash']:
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return None
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return data
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@ -254,7 +254,7 @@ class KeyfileKey(AESKeyBase):
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iterations = 100000
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key = pbkdf2_sha256(passphrase.encode('utf-8'), salt, iterations, 32)
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hash = HMAC(key, data, sha256).digest()
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cdata = AES(key).encrypt(data)
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cdata = AES(is_encrypt=True, key=key).encrypt(data)
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d = {
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'version': 1,
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'salt': salt,
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@ -30,11 +30,15 @@ class CryptoTestCase(AtticTestCase):
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def test_aes(self):
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key = b'X' * 32
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data = b'foo' * 10
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aes = AES(key)
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# encrypt
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aes = AES(is_encrypt=True, key=key)
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self.assert_equal(bytes_to_long(aes.iv, 8), 0)
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cdata = aes.encrypt(data)
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self.assert_equal(hexlify(cdata), b'c6efb702de12498f34a2c2bbc8149e759996d08bf6dc5c610aefc0c3a466')
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self.assert_equal(bytes_to_long(aes.iv, 8), 2)
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self.assert_not_equal(data, aes.decrypt(cdata))
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aes.reset(iv=b'\0' * 16)
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self.assert_equal(data, aes.decrypt(cdata))
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# decrypt
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aes = AES(is_encrypt=False, key=key)
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self.assert_equal(bytes_to_long(aes.iv, 8), 0)
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pdata = aes.decrypt(cdata)
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self.assert_equal(data, pdata)
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self.assert_equal(bytes_to_long(aes.iv, 8), 2)
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