hardcoresushi/libgocryptfs
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stupidgcm: create private copy of the key

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Relieves the caller from worrying about whether they
can overwrite the key.
This commit is contained in:
Jakob Unterwurzacher 2018-02-18 12:33:48 +01:00
parent 18f6c6106c
commit 72ddbae1e6
2 changed files with 5 additions and 9 deletions
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8
internal/cryptocore/cryptocore.go
View File

@ -86,13 +86,7 @@ func New(key []byte, aeadType AEADTypeEnum, IVBitLen int, useHKDF bool, forceDec
if IVLen != 16 { if IVLen != 16 {
log.Panic("stupidgcm only supports 128-bit IVs") log.Panic("stupidgcm only supports 128-bit IVs")
} }
// stupidgcm does not create a private copy of the key, so things aeadCipher = stupidgcm.New(gcmKey, forceDecode)
// break when initFuseFrontend() overwrites it with zeros. Create
// a copy here. This is unnecessary when useHKDF == true, but
// does no harm.
var stupidgcmKey []byte
stupidgcmKey = append(stupidgcmKey, gcmKey...)
aeadCipher = stupidgcm.New(stupidgcmKey, forceDecode)
case BackendGoGCM: case BackendGoGCM:
goGcmBlockCipher, err := aes.NewCipher(gcmKey) goGcmBlockCipher, err := aes.NewCipher(gcmKey)
if err != nil { if err != nil {

6
internal/stupidgcm/stupidgcm.go
View File

@ -33,10 +33,12 @@ type StupidGCM struct {
var _ cipher.AEAD = &StupidGCM{} var _ cipher.AEAD = &StupidGCM{}
// New returns a new cipher.AEAD implementation.. // New returns a new cipher.AEAD implementation..
func New(key []byte, forceDecode bool) cipher.AEAD { func New(keyIn []byte, forceDecode bool) cipher.AEAD {
if len(key) != keyLen { if len(keyIn) != keyLen {
log.Panicf("Only %d-byte keys are supported", keyLen) log.Panicf("Only %d-byte keys are supported", keyLen)
} }
// Create a private copy of the key
key := append([]byte{}, keyIn...)
return &StupidGCM{key: key, forceDecode: forceDecode} return &StupidGCM{key: key, forceDecode: forceDecode}
} }