access to symmetric ciphers from libcrypto
"""
-from ctypes import create_string_buffer,c_char_p,c_void_p,c_int,c_long,byref,POINTER
-from ctypescrypto import libcrypto
+from ctypes import create_string_buffer, c_char_p, c_void_p, c_int
+from ctypes import byref, POINTER
+from ctypescrypto import libcrypto, pyver, bintype
from ctypescrypto.exception import LibCryptoError
from ctypescrypto.oid import Oid
CIPHER_ALGORITHMS = ("DES", "DES-EDE3", "BF", "AES-128", "AES-192", "AES-256")
-CIPHER_MODES = ("STREAM","ECB","CBC", "CFB", "OFB", "CTR","GCM")
+CIPHER_MODES = ("STREAM", "ECB", "CBC", "CFB", "OFB", "CTR", "GCM")
#
-__all__ = ['CipherError','new','Cipher','CipherType']
+__all__ = ['CipherError', 'new', 'Cipher', 'CipherType']
class CipherError(LibCryptoError):
+ """
+ Exception raise when OpenSSL function returns error
+ """
pass
-def new(algname,key,encrypt=True,iv=None):
+def new(algname, key, encrypt=True, iv=None):
"""
- Returns new cipher object ready to encrypt-decrypt data
+ Returns new cipher object ready to encrypt-decrypt data
- @param algname - string algorithm name like in opemssl command
- line
- @param key - binary string representing ciher key
- @param encrypt - if True (default) cipher would be initialized
+ @param algname - string algorithm name like in opemssl command
+ line
+ @param key - binary string representing ciher key
+ @param encrypt - if True (default) cipher would be initialized
for encryption, otherwise - for decrypton
- @param iv - initialization vector
+ @param iv - initialization vector
"""
- ct=CipherType(algname)
- return Cipher(ct,key,iv,encrypt)
+ ciph_type = CipherType(algname)
+ return Cipher(ciph_type, key, iv, encrypt)
-class CipherType:
+class CipherType(object):
"""
- Describes cihper algorihm. Can be used to produce cipher
- instance and to get various information about cihper
+ Describes cihper algorihm. Can be used to produce cipher
+ instance and to get various information about cihper
"""
def __init__(self, cipher_name):
"""
- Constructs cipher algortihm using textual name as in openssl
- command line
+ Constructs cipher algortihm using textual name as in openssl
+ command line
"""
+ if pyver > 2:
+ cipher_name = cipher_name.encode('utf-8')
self.cipher = libcrypto.EVP_get_cipherbyname(cipher_name)
if self.cipher is None:
raise CipherError("Unknown cipher: %s" % cipher_name)
def __del__(self):
+ """
+ It is constant object with do-nothing del
+ """
pass
+
def block_size(self):
"""
- Returns block size of the cipher
+ Returns block size of the cipher
"""
return libcrypto.EVP_CIPHER_block_size(self.cipher)
+
def key_length(self):
"""
- Returns key length of the cipher
+ Returns key length of the cipher
"""
return libcrypto.EVP_CIPHER_key_length(self.cipher)
+
def iv_length(self):
"""
- Returns initialization vector length of the cipher
+ Returns initialization vector length of the cipher
"""
return libcrypto.EVP_CIPHER_iv_length(self.cipher)
+
def flags(self):
"""
- Return cipher flags. Low three bits of the flags encode
- cipher mode (see mode). Higher bits is combinatuon of
- EVP_CIPH* constants defined in the <openssl/evp.h>
+ Return cipher flags. Low three bits of the flags encode
+ cipher mode (see mode). Higher bits is combinatuon of
+ EVP_CIPH* constants defined in the <openssl/evp.h>
"""
return libcrypto.EVP_CIPHER_flags(self.cipher)
+
def mode(self):
"""
- Returns cipher mode as string constant like CBC, OFB etc.
+ Returns cipher mode as string constant like CBC, OFB etc.
"""
return CIPHER_MODES[self.flags() & 0x7]
+
def algo(self):
"""
- Return cipher's algorithm name, derived from OID
+ Return cipher's algorithm name, derived from OID
"""
- return self.oid().shortname()
+ return self.oid().shortname()
+
def oid(self):
"""
- Returns ASN.1 object identifier of the cipher as
- ctypescrypto.oid.Oid object
+ Returns ASN.1 object identifier of the cipher as
+ ctypescrypto.oid.Oid object
"""
return Oid(libcrypto.EVP_CIPHER_nid(self.cipher))
-class Cipher:
+class Cipher(object):
"""
- Performs actual encrypton decryption
- Note that object keeps some internal state.
- To obtain full ciphertext (or plaintext during decihpering)
- user should concatenate results of all calls of update with
- result of finish
+ Performs actual encrypton decryption
+ Note that object keeps some internal state.
+ To obtain full ciphertext (or plaintext during decihpering)
+ user should concatenate results of all calls of update with
+ result of finish
"""
- def __init__(self, cipher_type, key, iv, encrypt=True):
+ def __init__(self, cipher_type, key, iv, encrypt=True):
"""
- Initializing cipher instance.
+ Initializing cipher instance.
- @param cipher_type - CipherType object
- @param key = binary string representing the key
- @param iv - binary string representing initializtion vector
- @param encrypt - if True(default) we ere encrypting.
- Otherwise decrypting
+ @param cipher_type - CipherType object
+ @param key = binary string representing the key
+ @param iv - binary string representing initializtion vector
+ @param encrypt - if True(default) we ere encrypting.
+ Otherwise decrypting
"""
self._clean_ctx()
if self.ctx == 0:
raise CipherError("Unable to create cipher context")
self.encrypt = encrypt
- enc=1 if encrypt else 0
+ enc = 1 if encrypt else 0
if not iv is None and len(iv) != cipher_type.iv_length():
raise ValueError("Invalid IV length for this algorithm")
-
+
if len(key) != cipher_type.key_length():
if (cipher_type.flags() & 8) != 0:
# Variable key length cipher.
- result = libcrypto.EVP_CipherInit_ex(self.ctx, cipher_type.cipher, None, None, None, c_int(enc))
- result = libcrypto.EVP_CIPHER_CTX_set_key_length(self.ctx,len(key))
+ result = libcrypto.EVP_CipherInit_ex(self.ctx,
+ cipher_type.cipher,
+ None, None, None,
+ c_int(enc))
+ result = libcrypto.EVP_CIPHER_CTX_set_key_length(self.ctx,
+ len(key))
if result == 0:
self._clean_ctx()
raise CipherError("Unable to set key length")
- result = libcrypto.EVP_CipherInit_ex(self.ctx, None, None, key_ptr, iv_ptr, c_int(enc))
+ result = libcrypto.EVP_CipherInit_ex(self.ctx, None, None,
+ key_ptr, iv_ptr,
+ c_int(enc))
else:
raise ValueError("Invalid key length for this algorithm")
else:
- result = libcrypto.EVP_CipherInit_ex(self.ctx, cipher_type.cipher, None, key_ptr, iv_ptr, c_int(enc))
+ result = libcrypto.EVP_CipherInit_ex(self.ctx, cipher_type.cipher,
+ None, key_ptr, iv_ptr,
+ c_int(enc))
if result == 0:
self._clean_ctx()
raise CipherError("Unable to initialize cipher")
self.cipher_finalized = False
def __del__(self):
+ """
+ We define _clean_ctx() to do all the cleanup
+ """
self._clean_ctx()
def padding(self, padding=True):
"""
- Sets padding mode of the cipher
+ Sets padding mode of the cipher
"""
- padding_flag=1 if padding else 0
+ padding_flag = 1 if padding else 0
libcrypto.EVP_CIPHER_CTX_set_padding(self.ctx, padding_flag)
def update(self, data):
"""
- Performs actual encrypton/decrypion
+ Performs actual encrypton/decrypion
- @param data - part of the plain text/ciphertext to process
- @returns - part of ciphercext/plain text
+ @param data - part of the plain text/ciphertext to process
+ @returns - part of ciphercext/plain text
- Passd chunk of text doeesn't need to contain full ciher
- blocks. If neccessery, part of passed data would be kept
- internally until next data would be received or finish
- called
+ Passed chunk of text doesn't need to contain full ciher
+ blocks. If neccessery, part of passed data would be kept
+ internally until next data would be received or finish
+ called
"""
- if self.cipher_finalized :
+ if self.cipher_finalized:
raise CipherError("No updates allowed")
- if not isinstance(data,str):
- raise TypeError("A string is expected")
+ if not isinstance(data, bintype):
+ raise TypeError("A byte string is expected")
if len(data) == 0:
return ""
- outbuf=create_string_buffer(self.block_size+len(data))
- outlen=c_int(0)
- ret=libcrypto.EVP_CipherUpdate(self.ctx,outbuf,byref(outlen),
- data,len(data))
- if ret <=0:
+ outbuf = create_string_buffer(self.block_size+len(data))
+ outlen = c_int(0)
+ ret = libcrypto.EVP_CipherUpdate(self.ctx, outbuf, byref(outlen),
+ data, len(data))
+ if ret <= 0:
self._clean_ctx()
- self.cipher_finalized=True
- del self.ctx
+ self.cipher_finalized = True
raise CipherError("problem processing data")
- return outbuf.raw[:outlen.value]
-
+ return outbuf.raw[:int(outlen.value)]
+
def finish(self):
"""
- Finalizes processing. If some data are kept in the internal
- state, they would be processed and returned.
+ Finalizes processing. If some data are kept in the internal
+ state, they would be processed and returned.
"""
- if self.cipher_finalized :
+ if self.cipher_finalized:
raise CipherError("Cipher operation is already completed")
- outbuf=create_string_buffer(self.block_size)
+ outbuf = create_string_buffer(self.block_size)
self.cipher_finalized = True
- outlen=c_int(0)
- result = libcrypto.EVP_CipherFinal_ex(self.ctx,outbuf , byref(outlen))
+ outlen = c_int(0)
+ result = libcrypto.EVP_CipherFinal_ex(self.ctx, outbuf, byref(outlen))
if result == 0:
self._clean_ctx()
raise CipherError("Unable to finalize cipher")
- if outlen.value>0:
- return outbuf.raw[:outlen.value]
+ if outlen.value > 0:
+ return outbuf.raw[:int(outlen.value)]
else:
- return ""
-
+ return b""
+
def _clean_ctx(self):
+ """
+ Cleans up cipher ctx and deallocates it
+ """
try:
if self.ctx is not None:
- libcrypto.EVP_CIPHER_CTX_cleanup(self.ctx)
+ self.__ctxcleanup(self.ctx)
libcrypto.EVP_CIPHER_CTX_free(self.ctx)
- del(self.ctx)
+ del self.ctx
except AttributeError:
pass
self.cipher_finalized = True
#
# Used C function block_size
#
-libcrypto.EVP_CIPHER_block_size.argtypes=(c_void_p,)
-libcrypto.EVP_CIPHER_CTX_cleanup.argtypes=(c_void_p,)
-libcrypto.EVP_CIPHER_CTX_free.argtypes=(c_void_p,)
-libcrypto.EVP_CIPHER_CTX_new.restype=c_void_p
-libcrypto.EVP_CIPHER_CTX_set_padding.argtypes=(c_void_p,c_int)
-libcrypto.EVP_CipherFinal_ex.argtypes=(c_void_p,c_char_p,POINTER(c_int))
-libcrypto.EVP_CIPHER_flags.argtypes=(c_void_p,)
-libcrypto.EVP_CipherInit_ex.argtypes=(c_void_p,c_void_p,c_void_p,c_char_p,c_char_p,c_int)
-libcrypto.EVP_CIPHER_iv_length.argtypes=(c_void_p,)
-libcrypto.EVP_CIPHER_key_length.argtypes=(c_void_p,)
-libcrypto.EVP_CIPHER_nid.argtypes=(c_void_p,)
-libcrypto.EVP_CipherUpdate.argtypes=(c_void_p,c_char_p,POINTER(c_int),c_char_p,c_int)
-libcrypto.EVP_get_cipherbyname.restype=c_void_p
-libcrypto.EVP_get_cipherbyname.argtypes=(c_char_p,)
-libcrypto.EVP_CIPHER_CTX_set_key_length.argtypes=(c_void_p,c_int)
+libcrypto.EVP_CIPHER_block_size.argtypes = (c_void_p, )
+
+#Function EVP_CIPHER_CTX_cleanup renamed to EVP_CIPHER_CTX_reset
+# in the OpenSSL 1.1.0
+if hasattr(libcrypto,"EVP_CIPHER_CTX_cleanup"):
+ Cipher.__ctxcleanup = libcrypto.EVP_CIPHER_CTX_cleanup
+else:
+ Cipher.__ctxcleanup = libcrypto.EVP_CIPHER_CTX_reset
+Cipher.__ctxcleanup.argtypes = (c_void_p, )
+libcrypto.EVP_CIPHER_CTX_free.argtypes = (c_void_p, )
+libcrypto.EVP_CIPHER_CTX_new.restype = c_void_p
+libcrypto.EVP_CIPHER_CTX_set_padding.argtypes = (c_void_p, c_int)
+libcrypto.EVP_CipherFinal_ex.argtypes = (c_void_p, c_char_p, POINTER(c_int))
+libcrypto.EVP_CIPHER_flags.argtypes = (c_void_p, )
+libcrypto.EVP_CipherInit_ex.argtypes = (c_void_p, c_void_p, c_void_p, c_char_p,
+ c_char_p, c_int)
+libcrypto.EVP_CIPHER_iv_length.argtypes = (c_void_p, )
+libcrypto.EVP_CIPHER_key_length.argtypes = (c_void_p, )
+libcrypto.EVP_CIPHER_nid.argtypes = (c_void_p, )
+libcrypto.EVP_CipherUpdate.argtypes = (c_void_p, c_char_p, POINTER(c_int),
+ c_char_p, c_int)
+libcrypto.EVP_get_cipherbyname.restype = c_void_p
+libcrypto.EVP_get_cipherbyname.argtypes = (c_char_p, )
+libcrypto.EVP_CIPHER_CTX_set_key_length.argtypes = (c_void_p, c_int)
projects / oss / ctypescrypto.git / blobdiff