-from ctypes import create_string_buffer,c_char_p,c_void_p,c_int,c_long,byref\r
-from ctypescrypto import libcrypto\r
-from ctypescryto.exception import LibCrytoError\r
-\r
-CIPHER_ALGORITHMS = ("DES", "DES-EDE3", "BF", "AES-128", "AES-192", "AES-256")\r
-CIPHER_MODES = ("STREAM","ECB","CBC", "CFB", "OFB", "CTR","GCM")\r
-\r
-#\r
-\r
-class CipherError(LibCryptoError):\r
- pass\r
-\r
-def new(algname,key,encrypt=True,iv=None):\r
- ct=CipherType(algname)\r
- return Cipher(ct,key,iv,encrypt)\r
-\r
-class CipherType:\r
-\r
- def __init__(self, cipher_name):\r
- self.cipher = libcrypto.EVP_get_cipherbyname(cipher_name)\r
- if self.cipher is None:\r
- raise CipherError, "Unknown cipher: %s" % cipher_name\r
-\r
- def __del__(self):\r
- pass\r
- def block_size(self):\r
- return libcrypto.EVP_CIHPER_block_size(self.cipher)\r
- def key_length(self):\r
- return libcrypto.EVP_CIPHER_key_length(self.cipher)\r
- def iv_length(self):\r
- return libcrypto.EVP_CIPHER_iv_length(self.cipher)\r
- def flags(self):\r
- return libcrypto.EVP_CIPHER_flags(self.cipher)\r
- def mode(self):\r
- return CIPHER_MODES[self.flags & 0x7]\r
- def algo(self):\r
- return self.oid().short_name() \r
- def mode(self):\r
- return self.cipher_mode\r
- def oid(self):\r
- return Oid(libcrypto.EVP_CIPHER_nid(self.cipher))\r
-\r
-class Cipher:\r
-\r
- def __init__(self, cipher_type, key, iv, encrypt=True):\r
- self._clean_ctx()\r
- key_ptr = c_char_p(key)\r
- iv_ptr = c_char_p(iv)\r
- self.ctx = libcrypto.EVP_CIPHER_CTX_new(cipher_type.cipher, None, key_ptr, iv_ptr)\r
- if self.ctx == 0:\r
- raise CipherError, "Unable to create cipher context"\r
- self.encrypt = encrypt\r
- if encrypt: \r
- enc = 1\r
- else: \r
- enc = 0\r
- result = libcrypto.EVP_CipherInit_ex(self.ctx, cipher_type.cipher, None, key_ptr, iv_ptr, c_int(enc))\r
- self.cipher_type = cipher_type\r
- self.block_size = self.cipher_type.block_size()\r
- if result == 0:\r
- self._clean_ctx()\r
- raise CipherError, "Unable to initialize cipher"\r
-\r
- def __del__(self):\r
- self._clean_ctx()\r
-\r
- def enable_padding(self, padding=True):\r
- if padding:\r
- padding_flag = 1\r
- else:\r
- padding_flag = 0\r
- libcrypto.EVP_CIPHER_CTX_set_padding(self.ctx, padding_flag)\r
-\r
- def update(self, data):\r
- if self.cipher_finalized :\r
- raise CipherError, "No updates allowed"\r
- if type(data) != type(""):\r
- raise TypeError, "A string is expected"\r
- if len(data) <= 0:\r
- return ""\r
- outbuf=string_buffer_create(self.blocsize+len(data))\r
- outlen=c_int(0)\r
- ret=libcrypto.EVP_CipherUpdate(self.ctx,outbuf,byref(outlen),\r
- data,len(data))\r
- if ret <=0:\r
- self._clean_ctx()\r
- self.cipher_finalized=True\r
- del self.ctx\r
- raise CipherError("problem processing data")\r
- return outbuf.raw[:outlen]\r
- \r
- def finish(self):\r
- if self.cipher_finalized :\r
- raise CipherError, "Cipher operation is already completed"\r
- outbuf=create_string_buffer(self.block_size)\r
- self.cipher_finalized = True\r
- result = self.libcrypto.EVP_CipherFinal_ex(self.ctx,outbuf , byref(outlen))\r
- if result == 0:\r
- self._clean_ctx()\r
- raise CipherError, "Unable to finalize cipher"\r
- if outlen>0:\r
- return outbuf.raw[:outlen]\r
- else\r
- return ""\r
- \r
- def _clean_ctx(self):\r
- try:\r
- if self.ctx is not None:\r
- self.libcrypto.EVP_CIPHER_CTX_cleanup(self.ctx)\r
- self.libcrypto.EVP_CIPHER_CTX_free(self.ctx)\r
- del(self.ctx)\r
- except AttributeError:\r
- pass\r
- self.cipher_finalized = True\r
+"""
+access to symmetric ciphers from libcrypto
+
+"""
+from ctypes import create_string_buffer, c_char_p, c_void_p, c_int
+from ctypes import byref, POINTER
+from ctypescrypto import libcrypto
+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")
+
+#
+
+__all__ = ['CipherError', 'new', 'Cipher', 'CipherType']
+
+class CipherError(LibCryptoError):
+ """
+ Exception raise when OpenSSL function returns error
+ """
+ pass
+
+def new(algname, key, encrypt=True, iv=None):
+ """
+ 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
+ for encryption, otherwise - for decrypton
+ @param iv - initialization vector
+ """
+ ciph_type = CipherType(algname)
+ return Cipher(ciph_type, key, iv, encrypt)
+
+class CipherType(object):
+ """
+ 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
+ """
+ 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
+ """
+ return libcrypto.EVP_CIPHER_block_size(self.cipher)
+
+ def key_length(self):
+ """
+ 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
+ """
+ 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 libcrypto.EVP_CIPHER_flags(self.cipher)
+
+ def mode(self):
+ """
+ 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 self.oid().shortname()
+
+ def oid(self):
+ """
+ Returns ASN.1 object identifier of the cipher as
+ ctypescrypto.oid.Oid object
+ """
+ return Oid(libcrypto.EVP_CIPHER_nid(self.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
+ """
+ def __init__(self, cipher_type, key, iv, encrypt=True):
+ """
+ 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
+
+ """
+ self._clean_ctx()
+ # Check key and iv length
+ if key is None:
+ raise ValueError("No key specified")
+
+ key_ptr = c_char_p(key)
+ iv_ptr = c_char_p(iv)
+ self.ctx = libcrypto.EVP_CIPHER_CTX_new()
+ if self.ctx == 0:
+ raise CipherError("Unable to create cipher context")
+ self.encrypt = encrypt
+ 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))
+ 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))
+ 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))
+ if result == 0:
+ self._clean_ctx()
+ raise CipherError("Unable to initialize cipher")
+ self.cipher_type = cipher_type
+ self.block_size = self.cipher_type.block_size()
+ 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
+ """
+ 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
+
+ @param data - part of the plain text/ciphertext to process
+ @returns - part of ciphercext/plain text
+
+ 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:
+ raise CipherError("No updates allowed")
+ if not isinstance(data, str):
+ raise TypeError("A 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:
+ self._clean_ctx()
+ self.cipher_finalized = True
+ raise CipherError("problem processing data")
+ 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.
+ """
+ if self.cipher_finalized:
+ raise CipherError("Cipher operation is already completed")
+ 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))
+ if result == 0:
+ self._clean_ctx()
+ raise CipherError("Unable to finalize cipher")
+ if outlen.value > 0:
+ return outbuf.raw[:int(outlen.value)]
+ else:
+ return ""
+
+ def _clean_ctx(self):
+ """
+ Cleans up cipher ctx and deallocates it
+ """
+ try:
+ if self.ctx is not None:
+ self.__ctxcleanup(self.ctx)
+ libcrypto.EVP_CIPHER_CTX_free(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, )
+
+#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