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authorJakob Unterwurzacher2017-08-11 18:42:30 +0200
committerJakob Unterwurzacher2017-08-11 19:02:26 +0200
commit0c520845f3623eff28f0277a52e3ccffd928f5c2 (patch)
tree82a3e0f8c55ae980d29e33b230954638229089c9 /internal/cryptocore
parentf59479736bed49411bda3368f419d6605f1faa78 (diff)
main: purge masterkey from memory as soon as possible
Remove the "Masterkey" field from fusefrontend.Args because it should not be stored longer than neccessary. Instead pass the masterkey as a separate argument to the filesystem initializers. Then overwrite it with zeros immediately so we don't have to wait for garbage collection. Note that the crypto implementation still stores at least a masterkey-derived value, so this change makes it harder, but not impossible, to extract the encryption keys from memory. Suggested at https://github.com/rfjakob/gocryptfs/issues/137
Diffstat (limited to 'internal/cryptocore')
-rw-r--r--internal/cryptocore/cryptocore.go10
1 files changed, 8 insertions, 2 deletions
diff --git a/internal/cryptocore/cryptocore.go b/internal/cryptocore/cryptocore.go
index 1ad928d..aafe12b 100644
--- a/internal/cryptocore/cryptocore.go
+++ b/internal/cryptocore/cryptocore.go
@@ -72,7 +72,7 @@ func New(key []byte, aeadType AEADTypeEnum, IVBitLen int, useHKDF bool, forceDec
emeCipher = eme.New(emeBlockCipher)
}
- // Initilize an AEAD cipher for file content encryption.
+ // Initialize an AEAD cipher for file content encryption.
var aeadCipher cipher.AEAD
if aeadType == BackendOpenSSL || aeadType == BackendGoGCM {
gcmKey := key
@@ -84,7 +84,13 @@ func New(key []byte, aeadType AEADTypeEnum, IVBitLen int, useHKDF bool, forceDec
if IVLen != 16 {
log.Panic("stupidgcm only supports 128-bit IVs")
}
- aeadCipher = stupidgcm.New(gcmKey, forceDecode)
+ // stupidgcm does not create a private copy of the key, so things
+ // break when initFuseFrontend() overwrites it with zeros. Create
+ // a copy here. This is unneccessary when useHKDF == true, but
+ // does no harm.
+ var stupidgcmKey []byte
+ stupidgcmKey = append(stupidgcmKey, gcmKey...)
+ aeadCipher = stupidgcm.New(stupidgcmKey, forceDecode)
case BackendGoGCM:
goGcmBlockCipher, err := aes.NewCipher(gcmKey)
if err != nil {