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authordrebs <drebs@leap.se>2014-08-04 11:40:37 -0300
committerdrebs <drebs@leap.se>2014-08-08 11:49:03 -0300
commit9f455ab44d8f229840a5c6a75e0e7b6a88b04f57 (patch)
treea04556f1407508c539903616230dd8a62ebfa934 /client/src
parentbb4ef28014b7846df8982f0008635f4d05b5a0b8 (diff)
Store decrypted storage secret in memory.
Diffstat (limited to 'client/src')
-rw-r--r--client/src/leap/soledad/client/secrets.py182
1 files changed, 105 insertions, 77 deletions
diff --git a/client/src/leap/soledad/client/secrets.py b/client/src/leap/soledad/client/secrets.py
index 3c6fc569..621e2d99 100644
--- a/client/src/leap/soledad/client/secrets.py
+++ b/client/src/leap/soledad/client/secrets.py
@@ -252,13 +252,9 @@ class SoledadSecrets(object):
try:
self._load_secrets() # try to load from disk
except IOError as e:
- logger.warning('IOError: %s' % str(e))
- try:
- self.storage_secret
- return True
- except Exception as e:
- logger.warning("Couldn't load storage secret: %s" % str(e))
- return False
+ logger.warning('IOError while loading secrets from disk: %s' % str(e))
+ return False
+ return self.storage_secret is not None
def _load_secrets(self):
"""
@@ -371,15 +367,21 @@ class SoledadSecrets(object):
# create salt and key for calculating MAC
salt = os.urandom(self.SALT_LENGTH)
key = scrypt.hash(self._passphrase_as_string(), salt, buflen=32)
+ # encrypt secrets
+ encrypted_secrets = {}
+ for secret_id in self._secrets:
+ encrypted_secrets[secret_id] = self._encrypt_storage_secret(
+ self._secrets[secret_id])
+ # create the recovery document
data = {
- self.STORAGE_SECRETS_KEY: self._secrets,
+ self.STORAGE_SECRETS_KEY: encrypted_secrets,
self.KDF_KEY: self.KDF_SCRYPT,
self.KDF_SALT_KEY: binascii.b2a_base64(salt),
self.KDF_LENGTH_KEY: len(key),
MAC_METHOD_KEY: MacMethods.HMAC,
MAC_KEY: hmac.new(
key,
- json.dumps(self._secrets),
+ json.dumps(encrypted_secrets),
sha256).hexdigest(),
}
return data
@@ -425,10 +427,11 @@ class SoledadSecrets(object):
'contents.')
# include secrets in the secret pool.
secrets = 0
- for secret_id, secret_data in data[self.STORAGE_SECRETS_KEY].items():
+ for secret_id, encrypted_secret in data[self.STORAGE_SECRETS_KEY].items():
if secret_id not in self._secrets:
secrets += 1
- self._secrets[secret_id] = secret_data
+ self._secrets[secret_id] = \
+ self._decrypt_storage_secret(encrypted_secret)
return secrets, mac
def _get_secrets_from_shared_db(self):
@@ -480,30 +483,92 @@ class SoledadSecrets(object):
# Management of secret for symmetric encryption.
#
- @property
- def storage_secret(self):
+ def _decrypt_storage_secret(self, encrypted_secret_dict):
"""
- Return the storage secret.
+ Decrypt the storage secret.
Storage secret is encrypted before being stored. This method decrypts
- and returns the stored secret.
+ and returns the decrypted storage secret.
- :return: The storage secret.
+ :param encrypted_secret_dict: The encrypted storage secret.
+ :type encrypted_secret_dict: dict
+
+ :return: The decrypted storage secret.
:rtype: str
"""
# calculate the encryption key
+ if encrypted_secret_dict[self.KDF_KEY] != self.KDF_SCRYPT:
+ raise Exception("Unknown KDF in stored secret.")
key = scrypt.hash(
self._passphrase_as_string(),
# the salt is stored base64 encoded
binascii.a2b_base64(
- self._secrets[self._secret_id][self.KDF_SALT_KEY]),
+ encrypted_secret_dict[self.KDF_SALT_KEY]),
buflen=32, # we need a key with 256 bits (32 bytes).
)
+ if encrypted_secret_dict[self.KDF_LENGTH_KEY] != len(key):
+ raise Exception("Wrong length of decryption key.")
+ if encrypted_secret_dict[self.CIPHER_KEY] != self.CIPHER_AES256:
+ raise Exception("Unknown cipher in stored secret.")
# recover the initial value and ciphertext
- iv, ciphertext = self._secrets[self._secret_id][self.SECRET_KEY].split(
+ iv, ciphertext = encrypted_secret_dict[self.SECRET_KEY].split(
self.IV_SEPARATOR, 1)
ciphertext = binascii.a2b_base64(ciphertext)
- return self._crypto.decrypt_sym(ciphertext, key, iv=iv)
+ decrypted_secret = self._crypto.decrypt_sym(ciphertext, key, iv=iv)
+ if encrypted_secret_dict[self.LENGTH_KEY] != len(decrypted_secret):
+ raise Exception("Wrong length of decrypted secret.")
+ return decrypted_secret
+
+ def _encrypt_storage_secret(self, decrypted_secret):
+ """
+ Encrypt the storage secret.
+
+ An encrypted secret has the following structure:
+
+ {
+ '<secret_id>': {
+ 'kdf': 'scrypt',
+ 'kdf_salt': '<b64 repr of salt>'
+ 'kdf_length': <key length>
+ 'cipher': 'aes256',
+ 'length': <secret length>,
+ 'secret': '<encrypted b64 repr of storage_secret>',
+ }
+ }
+
+ :param decrypted_secret: The decrypted storage secret.
+ :type decrypted_secret: str
+
+ :return: The encrypted storage secret.
+ :rtype: dict
+ """
+ # generate random salt
+ salt = os.urandom(self.SALT_LENGTH)
+ # get a 256-bit key
+ key = scrypt.hash(self._passphrase_as_string(), salt, buflen=32)
+ iv, ciphertext = self._crypto.encrypt_sym(decrypted_secret, key)
+ encrypted_secret_dict = {
+ # leap.soledad.crypto submodule uses AES256 for symmetric
+ # encryption.
+ self.KDF_KEY: self.KDF_SCRYPT,
+ self.KDF_SALT_KEY: binascii.b2a_base64(salt),
+ self.KDF_LENGTH_KEY: len(key),
+ self.CIPHER_KEY: self.CIPHER_AES256,
+ self.LENGTH_KEY: len(decrypted_secret),
+ self.SECRET_KEY: '%s%s%s' % (
+ str(iv), self.IV_SEPARATOR, binascii.b2a_base64(ciphertext)),
+ }
+ return encrypted_secret_dict
+
+ @property
+ def storage_secret(self):
+ """
+ Return the storage secret.
+
+ :return: The decrypted storage secret.
+ :rtype: str
+ """
+ return self._secrets.get(self._secret_id)
def set_secret_id(self, secret_id):
"""
@@ -526,19 +591,6 @@ class SoledadSecrets(object):
* SOLEDAD_CREATING_KEYS
* SOLEDAD_DONE_CREATING_KEYS
- A secret has the following structure:
-
- {
- '<secret_id>': {
- 'kdf': 'scrypt',
- 'kdf_salt': '<b64 repr of salt>'
- 'kdf_length': <key length>
- 'cipher': 'aes256',
- 'length': <secret length>,
- 'secret': '<encrypted b64 repr of storage_secret>',
- }
- }
-
:return: The id of the generated secret.
:rtype: str
"""
@@ -548,22 +600,7 @@ class SoledadSecrets(object):
self.LOCAL_STORAGE_SECRET_LENGTH
+ self.REMOTE_STORAGE_SECRET_LENGTH)
secret_id = sha256(secret).hexdigest()
- # generate random salt
- salt = os.urandom(self.SALT_LENGTH)
- # get a 256-bit key
- key = scrypt.hash(self._passphrase_as_string(), salt, buflen=32)
- iv, ciphertext = self._crypto.encrypt_sym(secret, key)
- self._secrets[secret_id] = {
- # leap.soledad.crypto submodule uses AES256 for symmetric
- # encryption.
- self.KDF_KEY: self.KDF_SCRYPT,
- self.KDF_SALT_KEY: binascii.b2a_base64(salt),
- self.KDF_LENGTH_KEY: len(key),
- self.CIPHER_KEY: self.CIPHER_AES256,
- self.LENGTH_KEY: len(secret),
- self.SECRET_KEY: '%s%s%s' % (
- str(iv), self.IV_SEPARATOR, binascii.b2a_base64(ciphertext)),
- }
+ self._secrets[secret_id] = secret
self._store_secrets()
signal(SOLEDAD_DONE_CREATING_KEYS, self._uuid)
return secret_id
@@ -596,24 +633,6 @@ class SoledadSecrets(object):
# ensure there's a secret for which the passphrase will be changed.
if not self._has_secret():
raise NoStorageSecret()
- secret = self.storage_secret
- # generate random salt
- new_salt = os.urandom(self.SALT_LENGTH)
- # get a 256-bit key
- key = scrypt.hash(new_passphrase.encode('utf-8'), new_salt, buflen=32)
- iv, ciphertext = self._crypto.encrypt_sym(secret, key)
- # XXX update all secrets in the dict
- self._secrets[self._secret_id] = {
- # leap.soledad.crypto submodule uses AES256 for symmetric
- # encryption.
- self.KDF_KEY: self.KDF_SCRYPT, # TODO: remove hard coded kdf
- self.KDF_SALT_KEY: binascii.b2a_base64(new_salt),
- self.KDF_LENGTH_KEY: len(key),
- self.CIPHER_KEY: self.CIPHER_AES256,
- self.LENGTH_KEY: len(secret),
- self.SECRET_KEY: '%s%s%s' % (
- str(iv), self.IV_SEPARATOR, binascii.b2a_base64(ciphertext)),
- }
self._passphrase = new_passphrase
self._store_secrets()
self._put_secrets_in_shared_db()
@@ -655,27 +674,36 @@ class SoledadSecrets(object):
# TODO: implement.
pass
- def get_remote_secret(self):
+ def _get_remote_storage_secret(self):
"""
Return the secret for remote storage.
"""
# TODO: implement
pass
- def get_local_storage_key(self):
+
+ def _get_local_storage_secret(self):
"""
- Return the local storage key derived from the local storage secret.
+ Return the local storage secret.
+ """
+ pwd_start = self.REMOTE_STORAGE_SECRET_LENGTH + self.SALT_LENGTH
+ pwd_end = self.REMOTE_STORAGE_SECRET_LENGTH + self.LOCAL_STORAGE_SECRET_LENGTH
+ return self.storage_secret[pwd_start:pwd_end]
+
+ def _get_local_storage_salt(self):
+ """
+ Return the local storage salt.
"""
- # salt indexes
salt_start = self.REMOTE_STORAGE_SECRET_LENGTH
salt_end = salt_start + self.SALT_LENGTH
- # password indexes
- pwd_start = salt_end
- pwd_end = salt_start + self.LOCAL_STORAGE_SECRET_LENGTH
- # calculate the key for local encryption
- secret = self.storage_secret
+ return self.storage_secret[salt_start:salt_end]
+
+ def get_local_storage_key(self):
+ """
+ Return the local storage key derived from the local storage secret.
+ """
return scrypt.hash(
- secret[pwd_start:pwd_end], # the password
- secret[salt_start:salt_end], # the salt
+ self._get_local_storage_secret(), # the password
+ self._get_local_storage_salt(), # the salt
buflen=32, # we need a key with 256 bits (32 bytes)
)