remove checksum functionality, always offer to confirm master password

README.md

@@ -71,12 +71,4 @@ narvi stores its saved configuration in `~/.narvi/config` as JSON.  This file wi
 * `clipboard-time`      (integer) The number of seconds that narvi will keep the generated password on the clipboard.  Default is 8.
 * `default-hashscheme`  (string)  The default hash scheme for new salts.  Default is `scrypt-18-8-1-512`.
 * `default-wordscheme`  (string)  The default word scheme for new salts.  Default is `base64-16-!@-aA1`.
-* `store-checksum`      (boolean) If `true`, store a checksum for new salts.  Default is `false`.  See [Derived Key Checksums](#derived-key-checksums) below.
 
-## Derived Key Checksums
-
-_Storing checksums is disabled by default because the author is not sure that storing them does not compromise the master password or the security of your accounts._
-
-narvi can use a checksum to detect, in most cases, when you've mistyped your master password.  It works like this:
-
-If `store-checksum` is `true`, then when defining a new salt, narvi will prompt you twice for the master password.  If the two entries match, then narvi will derive the key material and compute a byte-wise checksum over all of the raw key material (usually 512 bytes).  narvi will store the 1-byte checksum along with the salt definition.  The next time you use the salt, narvi will re-compute the checksum and compare with what was previously stored.  If the checksums do not match, then you've mistyped your master password.

src/narvi/__main__.py

@@ -150,18 +150,9 @@ def cmd_hash(args, pwh, completer):
 		completer.clear_values()
 	else:
 		saltid = args.saltid
+	#
 	if saltid in pwh.user_salts:
 		salt = pwh.user_salts[saltid]
-		while True:
-			master = getpass.getpass(
-				'Master password for ' + saltid + ': ')
-			password, checksum = pwh.generate_password(
-				salt, master)
-			if (salt['checksum'] is None or
-				checksum == salt['checksum']):
-				break
-			else:
-				print 'ERROR: Checksum does not match.'
 	else:
 		print 'INFO:', saltid, 'not found.'
 		salt = {}
@@ -176,33 +167,20 @@ def cmd_hash(args, pwh, completer):
 		if prompt('Save?', 'y') in ['y', 'Y']:
 			saveit = True
 			salt['description'] = prompt('Description', '')
-			while True:
-				master = getpass.getpass(
-					'Master password for ' + saltid + ': ')
-				if pwh.user_settings['store-checksum']:
-					master2 = getpass.getpass('Again: ')
-					if master == master2:
-						break
-					else:
-						print 'ERROR: Passwords do not match.'
-				else:
-					salt['checksum'] = None
-					break
-		else:
-			saveit = False
-			master = getpass.getpass(
-				'Master password for ' + saltid + ': ')
-		if saveit:
-			pwh.save_config()
-		password, checksum = pwh.generate_password(
-			salt, master)
-		if saveit:
-			if pwh.user_settings['store-checksum']:
-				salt['checksum'] = checksum
-			else:
-				salt['checksum'] = None
 			pwh.user_salts[saltid] = salt
 			pwh.save_config()
+	#
+	while True:
+		master = getpass.getpass(
+			'Master password for ' + saltid + ': ')
+		master2 = getpass.getpass('Again (blank if you\'re sure): ')
+		if not master2 or master == master2:
+			break
+		else:
+			print 'ERROR: Passwords do not match.'
+	#
+	password = pwh.generate_password(salt, master)
+	#
 	clipboardtime = pwh.user_settings['clipboard-time']
 	with TemporaryClipboard(password):
 		sys.stdout.write('.' * clipboardtime)

src/pwhash/__init__.py

@@ -65,7 +65,6 @@ def _default_user_config(self):
 				'default-hashscheme': 'scrypt-18-8-1-512',
 				'default-wordscheme': 'base64-16-!@-aA1',
 				'clipboard-time': 8,
-				'store-checksum': False,
 				'lib-version': ''
 				},
 			'salts': {},
@@ -244,181 +243,8 @@ def generate_password(self, sd, masterpassword):
 			raise PWHashError('Word function \'' + wordfid + '\' not available.')
 		# generate derived key
 		derivedkey = hashf(self, hashp, masterpassword, salt)
-		# compute checksum
-		checksum = self.generate_checksum(derivedkey)
 		# convert to word
 		password = wordf(self, wordp, derivedkey)
-		return (password, checksum)
-
-	def generate_checksum(self, buf):
-		cksum = 0
-		for b in buf:
-			cksum = (cksum + ord(b)) & 0xff
-		return cksum
-
-
-# data
-#
-# globals:
-#  DEFAULT_HASHSCHEME
-#  DEFAULT_WORDSCHEME
-#  STORE_CHECKSUM
-#
-# list of SALTs:
-#   SALT
-#   DESCRIPTION
-#   HASHSCHEME
-#   WORDSCHEME
-#   CHECKSUM
-#
-# list of HASHSCHEMEs:
-#   HASHSCHEME
-#   DESCRIPTION
-#   FUNCTION
-#   PARAMS
-#
-# list of WORDSCHEMEs:
-#   WORDSCHEME
-#   DESCRIPTION
-#   FUNCTION
-#   PARAMS
-#
-# list of HASHFUNCTIONS:
-#   HASHFUNCTION
-#   f
-#
-# list of WORDFUNCTIONS:
-#   WORDFUNCTION
-#   f
-#   
-
-# pwhash
-#   prompt for salt, go to hash sub cmd
-#
-# pwhash hash SALT
-#   if SALT is known:
-#     prompt for MASTER
-#     run key derivation function
-#     compute checksum of key
-#     if checksum does not match:
-#       back to password prompt
-#     convert key bytes to password
-#     copy password to clipboard
-#   else SALT is unknown:
-#     prompt for DESCRIPTION
-#     prompt for KDFARGS
-#     prompt for WORDIFIER
-#     prompt for MASTER
-#     prompt for MASTER
-#     if not match: restart
-#     run key derivation function
-#     compute CHECKSUM
-#     store DESCRIPTION, SALT, KDF, CHECKSUM
-#     convert key bytes to password
-#     copy password to clipboard
-#
-# pwhash list [-l]
-#   list known SALTs [with DESCRIPTION]
-#
-# pwhash info SALT
-#   list all info on SALT
-#
-# pwhash forget SALT
-#   remove SALT from cache
-#
-# pwhash lshashschemes [-l]
-#   list KDFs
-#
-# pwhash lswordschemes [-l]
-#   list wordifiers
-#
-# pwhash lsglobal
-# pwhash getglobal
-# pwhash setglobal
-#
-#
-# data storage:
-#   json-encoded
-#   {
-#     'modulepaths': [
-#     ]
-#     'globalsettings' :{
-#       'default-hashscheme': string,
-#     '  default-wordscheme': string,
-#     }
-#     'salts': {
-#        SALT1: {
-#          'value': string,
-#          'description': string,
-#          'hashschemeid': string,
-#          'wordschemeid': string,
-#          'checksum': number
-#        },
-#        SALT2: {
-#          'value': string,
-#          'description': string,
-#          'hashschemeid ': string,
-#          'wordschemeid ': string,
-#          'checksum': number
-#        }
-#      }
-#   }
-#
-#
-# KDFs:
-#
-#  scrypt-16-8-1-512  (relative strength 0)
-#  scrypt-20-8-1-512  (10)
-#
-# wordifiers:
-#
-#  base64-!@-16-aA1
-#  pin-4
-#
-#
-# modules:
-#
-#  mods/scrypt.py
-#  mods/base64.py
-#
-#  each mod has one export:
-#
-#   provides = {
-#     'hashfunctions' = {
-#        KDFNAME: {
-#          'f': function(parameters, password, salt)
-#        }
-#     },
-#     'hashschemes' = {
-#        'scrypt-16-8-1-512': {
-#          'description':  '...',
-#          'hashfunctionid': 'scrypt'
-#          'hashparams': {
-#            'N':     (1 << 16),
-#            'r':     8,
-#            'p':     1,
-#            'dklen': 512
-#          }
-#        }
-#     },
-#     'wordfunctions' = {
-#        NAME: {
-#          'f': function(parameters, buf)
-#        }
-#     }
-#     'wordschemes': {
-#        'base64-16-!@-aA1': {
-#          'description':  '...',
-#          'wordfunctionid': 'base64'
-#          'wordparams':   {
-#            'pwlen':     16
-#            'altchars': '!@'
-#          }
-#        }
-#     }
-#   }
-#
-
-
+		return password