X-Git-Url: http://wagner.pp.ru/gitweb/?a=blobdiff_plain;f=ctypescrypto%2Fcipher.py;fp=ctypescrypto%2Fcipher.py;h=73a14ce1de988e1c993991b3afb77ad4a729cf32;hb=1ff9b1899959673512927b6afa317855908b7073;hp=0000000000000000000000000000000000000000;hpb=7b229d0dba6fc42eddf3c359c3d9510330a1eeaf;p=oss%2Fctypescrypto.git

diff --git a/ctypescrypto/cipher.py b/ctypescrypto/cipher.py
new file mode 100644
index 0000000..73a14ce
--- /dev/null
+++ b/ctypescrypto/cipher.py
@@ -0,0 +1,102 @@
+from ctypes import *
+
+CIPHER_ALGORITHMS = ("DES", "DES-EDE3", "BF", "AES-128", "AES-192", "AES-256")
+CIPHER_MODES = ("CBC", "CFB", "OFB", "ECB")
+
+class CipherError(Exception):
+    pass
+
+class CipherType:
+
+    def __init__(self, libcrypto, cipher_algo, cipher_mode):
+        self.libcrypto = libcrypto
+        self.cipher_algo = cipher_algo
+        self.cipher_mode = cipher_mode
+        cipher_name = "-".join([self.cipher_algo, self.cipher_mode])
+        self.cipher = self.libcrypto.EVP_get_cipherbyname(cipher_name)
+        if self.cipher == 0:
+            raise CipherError, "Unknown cipher: %s" % cipher_name
+
+    def __del__(self):
+        pass
+
+    def algo(self):
+        return self.cipher_algo
+
+    def mode(self):
+        return self.cipher_mode
+
+class Cipher:
+
+    def __init__(self, libcrypto, cipher_type, key, iv, encrypt=True):
+        self.libcrypto = libcrypto
+        self._clean_ctx()
+        key_ptr = c_char_p(key)
+        iv_ptr = c_char_p(iv)
+        self.ctx = self.libcrypto.EVP_CIPHER_CTX_new(cipher_type.cipher, None, key_ptr, iv_ptr)
+        if self.ctx == 0:
+            raise CipherError, "Unable to create cipher context"
+        self.encrypt = encrypt
+        if encrypt: 
+            enc = 1
+        else: 
+            enc = 0
+        result = self.libcrypto.EVP_CipherInit_ex(self.ctx, cipher_type.cipher, None, key_ptr, iv_ptr, c_int(enc))
+        self.cipher_type = cipher_type
+        if result == 0:
+            self._clean_ctx()
+            raise CipherError, "Unable to initialize cipher"
+
+    def __del__(self):
+        self._clean_ctx()
+
+    def enable_padding(self, padding=True):
+        if padding:
+            padding_flag = 1
+        else:
+            padding_flag = 0
+        self.libcrypto.EVP_CIPHER_CTX_set_padding(self.ctx, padding_flag)
+
+    def update(self, data):
+        if self.cipher_finalized :
+            raise CipherError, "No updates allowed"
+        if type(data) != type(""):
+            raise TypeError, "A string is expected"
+        if len(data) <= 0:
+            return ""
+        self.data = self.data + data
+    
+    def finish(self, data=None):
+        if data is not None:
+            self.update(data)
+        return self._finish()
+        
+    def _finish(self):
+        if self.cipher_finalized :
+            raise CipherError, "Cipher operation is already completed"
+        self.cipher_out = create_string_buffer(len(self.data) + 32)
+        result = self.libcrypto.EVP_CipherUpdate(self.ctx, byref(self.cipher_out), byref(self.cipher_out_len), c_char_p(self.data), len(self.data))
+        if result == 0:
+            self._clean_ctx()
+            raise CipherError, "Unable to update cipher"
+        self.cipher_finalized = True
+        update_data = self.cipher_out.raw[:self.cipher_out_len.value]
+        result = self.libcrypto.EVP_CipherFinal_ex(self.ctx, byref(self.cipher_out), byref(self.cipher_out_len))
+        if result == 0:
+            self._clean_ctx()
+            raise CipherError, "Unable to finalize cipher"
+        final_data = self.cipher_out.raw[:self.cipher_out_len.value]
+        return update_data + final_data
+        
+    def _clean_ctx(self):
+        try:
+            if self.ctx is not None:
+                self.libcrypto.EVP_CIPHER_CTX_cleanup(self.ctx)
+                self.libcrypto.EVP_CIPHER_CTX_free(self.ctx)
+                del(self.ctx)
+        except AttributeError:
+            pass
+        self.cipher_out = None
+        self.cipher_out_len = c_long(0)
+        self.data = ""
+        self.cipher_finalized = False
\ No newline at end of file