X-Git-Url: http://wagner.pp.ru/gitweb/?a=blobdiff_plain;ds=sidebyside;f=ctypescrypto%2Fdigest.py;h=26b46bd7337e5bbd467a8252ec29514775a5edd9;hb=0032b97ea6d4348c0f11ee160c824ebe2e181696;hp=4e33d92bb3e147b28a05fd22dd18ef315078dff2;hpb=22338425226b926b97b2e821e4d7d2ea9b2f1b88;p=oss%2Fctypescrypto.git

diff --git a/ctypescrypto/digest.py b/ctypescrypto/digest.py
index 4e33d92..26b46bd 100644
--- a/ctypescrypto/digest.py
+++ b/ctypescrypto/digest.py
@@ -1,5 +1,6 @@
 """
-	Implmenets interface to OpenSSL EVP_Digest* functions.
+	Implements interface to OpenSSL EVP_Digest* functions.
+
 	Interface  made as close to hashlib as possible.
 
 	This module is really an excess effort. Hashlib allows access to
@@ -18,6 +19,7 @@ from ctypescrypto.exception import LibCryptoError
 from ctypescrypto.oid import Oid
 DIGEST_ALGORITHMS = ("MD5", "SHA1", "SHA224", "SHA256", "SHA384", "SHA512")
 
+__all__ = ['DigestError','Digest','DigestType','new']
 
 class DigestError(LibCryptoError):
 	pass
@@ -44,7 +46,7 @@ class DigestType:
 		self.digest_name = digest_name
 		self.digest = libcrypto.EVP_get_digestbyname(self.digest_name)
 		if self.digest is None:
-			raise DigestError, "Unknown digest: %s" % self.digest_name
+			raise DigestError("Unknown digest: %s" % self.digest_name)
 
 	def __del__(self):
 		pass
@@ -68,11 +70,11 @@ class Digest:
 		self._clean_ctx()
 		self.ctx = libcrypto.EVP_MD_CTX_create()
 		if self.ctx == 0:
-			raise DigestError, "Unable to create digest context"
+			raise DigestError("Unable to create digest context")
 		result = libcrypto.EVP_DigestInit_ex(self.ctx, digest_type.digest, None)
 		if result == 0:
 			self._clean_ctx()
-			raise DigestError, "Unable to initialize digest"
+			raise DigestError("Unable to initialize digest")
 		self.digest_type = digest_type
 		self.digest_size = self.digest_type.digest_size()
 		self.block_size = self.digest_type.block_size()
@@ -80,15 +82,23 @@ class Digest:
 	def __del__(self):
 		self._clean_ctx()
 
-	def update(self, data):
+	def update(self, data, length=None):
 		"""
-			Hashes given byte string as data
+			Hashes given byte string 
+
+			@param data - string to hash
+			@param length - if not specifed, entire string is hashed,
+					otherwise only first length bytes
 		"""
 		if self.digest_finalized:
-			raise DigestError, "No updates allowed"
+			raise DigestError("No updates allowed")
 		if type(data) != type(""):
-			raise TypeError, "A string is expected"
-		result = libcrypto.EVP_DigestUpdate(self.ctx, c_char_p(data), len(data))
+			raise TypeError("A string is expected")
+		if length is None:
+			length=len(data)
+		elif length> len(data):
+			raise ValueError("Specified length is greater than length of data")
+		result = libcrypto.EVP_DigestUpdate(self.ctx, c_char_p(data), length)
 		if result != 1:
 			raise DigestError, "Unable to update digest"
 		
@@ -105,7 +115,7 @@ class Digest:
 		length = c_long(0)
 		result = libcrypto.EVP_DigestFinal_ex(self.ctx, self.digest_out, byref(length))
 		if result != 1 :
-			raise DigestError, "Unable to finalize digest"
+			raise DigestError("Unable to finalize digest")
 		self.digest_finalized = True
 		return self.digest_out.raw[:self.digest_size]
 	def copy(self):