From 786ed012b3510135c60769e6d5e91d6f3fef2725 Mon Sep 17 00:00:00 2001 From: Zooko O'Whielacronx Date: Sat, 4 Jul 2009 19:48:15 -0700 Subject: [PATCH] directories: make the IV for the writecaps in directory entries be computed from the secure hash of the writecap itself This makes encoding of directory entries deterministic, and it is also a tad faster on Macbook Pro than getting a random IV with os.urandom(16). --- src/allmydata/dirnode.py | 2 +- src/allmydata/util/hashutil.py | 4 ++++ 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/src/allmydata/dirnode.py b/src/allmydata/dirnode.py index 302f8df5..851ec4bf 100644 --- a/src/allmydata/dirnode.py +++ b/src/allmydata/dirnode.py @@ -195,7 +195,7 @@ class NewDirectoryNode: def _encrypt_rwcap(self, rwcap): assert isinstance(rwcap, str) - IV = os.urandom(16) + IV = hashutil.mutable_rwcap_iv_hash(self._node.get_writekey()) key = hashutil.mutable_rwcap_key_hash(IV, self._node.get_writekey()) cryptor = AES(key) crypttext = cryptor.process(rwcap) diff --git a/src/allmydata/util/hashutil.py b/src/allmydata/util/hashutil.py index d5b260ad..8987d2dc 100644 --- a/src/allmydata/util/hashutil.py +++ b/src/allmydata/util/hashutil.py @@ -82,6 +82,7 @@ MUTABLE_STORAGEINDEX_TAG = "allmydata_mutable_readkey_to_storage_index_v1" # dirnodes DIRNODE_CHILD_WRITECAP_TAG = "allmydata_mutable_writekey_and_salt_to_dirnode_child_capkey_v1" +DIRNODE_CHILD_IV_TAG = "allmydata_mutable_writekey_to_iv_v1" def storage_index_hash(key): # storage index is truncated to 128 bits (16 bytes). We're only hashing a @@ -122,6 +123,7 @@ def plaintext_segment_hasher(): return tagged_hasher(PLAINTEXT_SEGMENT_TAG) KEYLEN = 16 +IVLEN = 16 def convergence_hash(k, n, segsize, data, convergence): h = convergence_hasher(k, n, segsize, convergence) @@ -170,6 +172,8 @@ def hmac(tag, data): def mutable_rwcap_key_hash(iv, writekey): return tagged_pair_hash(DIRNODE_CHILD_WRITECAP_TAG, iv, writekey, KEYLEN) +def mutable_rwcap_iv_hash(writekey): + return tagged_hash(DIRNODE_CHILD_IV_TAG, writekey, IVLEN) def ssk_writekey_hash(privkey): return tagged_hash(MUTABLE_WRITEKEY_TAG, privkey, KEYLEN) -- 2.45.2