diff options
Diffstat (limited to 'cryptfs/cryptfs_content.go')
| -rw-r--r-- | cryptfs/cryptfs_content.go | 20 |
1 files changed, 13 insertions, 7 deletions
diff --git a/cryptfs/cryptfs_content.go b/cryptfs/cryptfs_content.go index 7a1859a..03253d3 100644 --- a/cryptfs/cryptfs_content.go +++ b/cryptfs/cryptfs_content.go @@ -30,14 +30,14 @@ type CryptFile struct { } // DecryptBlocks - Decrypt a number of blocks -func (be *CryptFS) DecryptBlocks(ciphertext []byte, firstBlockNo uint64) ([]byte, error) { +func (be *CryptFS) DecryptBlocks(ciphertext []byte, firstBlockNo uint64, fileId []byte) ([]byte, error) { cBuf := bytes.NewBuffer(ciphertext) var err error var pBuf bytes.Buffer for cBuf.Len() > 0 { cBlock := cBuf.Next(int(be.cipherBS)) var pBlock []byte - pBlock, err = be.DecryptBlock(cBlock, firstBlockNo) + pBlock, err = be.DecryptBlock(cBlock, firstBlockNo, fileId) if err != nil { break } @@ -51,7 +51,7 @@ func (be *CryptFS) DecryptBlocks(ciphertext []byte, firstBlockNo uint64) ([]byte // // Corner case: A full-sized block of all-zero ciphertext bytes is translated // to an all-zero plaintext block, i.e. file hole passtrough. -func (be *CryptFS) DecryptBlock(ciphertext []byte, blockNo uint64) ([]byte, error) { +func (be *CryptFS) DecryptBlock(ciphertext []byte, blockNo uint64, fileId []byte) ([]byte, error) { // Empty block? if len(ciphertext) == 0 { @@ -77,6 +77,7 @@ func (be *CryptFS) DecryptBlock(ciphertext []byte, blockNo uint64) ([]byte, erro // Decrypt var plaintext []byte aData := make([]byte, 8) + aData = append(aData, fileId...) binary.BigEndian.PutUint64(aData, blockNo) plaintext, err := be.gcm.Open(plaintext, nonce, ciphertext, aData) @@ -89,8 +90,8 @@ func (be *CryptFS) DecryptBlock(ciphertext []byte, blockNo uint64) ([]byte, erro return plaintext, nil } -// encryptBlock - Encrypt and add MAC using GCM -func (be *CryptFS) EncryptBlock(plaintext []byte, blockNo uint64) []byte { +// encryptBlock - Encrypt and add IV and MAC +func (be *CryptFS) EncryptBlock(plaintext []byte, blockNo uint64, fileId []byte) []byte { // Empty block? if len(plaintext) == 0 { @@ -103,6 +104,7 @@ func (be *CryptFS) EncryptBlock(plaintext []byte, blockNo uint64) []byte { // Encrypt plaintext and append to nonce aData := make([]byte, 8) binary.BigEndian.PutUint64(aData, blockNo) + aData = append(aData, fileId...) ciphertext := be.gcm.Seal(nonce, nonce, plaintext, aData) return ciphertext @@ -118,6 +120,7 @@ func (be *CryptFS) SplitRange(offset uint64, length uint64) []intraBlock { for length > 0 { b.BlockNo = offset / be.plainBS b.Skip = offset % be.plainBS + // Minimum of remaining data and remaining space in the block b.Length = be.minu64(length, be.plainBS-b.Skip) parts = append(parts, b) offset += b.Length @@ -134,6 +137,9 @@ func (be *CryptFS) PlainSize(size uint64) uint64 { return 0 } + // Account for header + size -= HEADER_LEN + overhead := be.cipherBS - be.plainBS nBlocks := (size + be.cipherBS - 1) / be.cipherBS if nBlocks*overhead > size { @@ -171,7 +177,7 @@ func (be *CryptFS) CiphertextRange(offset uint64, length uint64) (alignedOffset firstBlockNo := offset / be.plainBS lastBlockNo := (offset + length - 1) / be.plainBS - alignedOffset = firstBlockNo * be.cipherBS + alignedOffset = HEADER_LEN + firstBlockNo * be.cipherBS alignedLength = (lastBlockNo - firstBlockNo + 1) * be.cipherBS skipBytes = int(skip) @@ -232,5 +238,5 @@ func (be *CryptFS) BlockNoPlainOff(plainOffset uint64) uint64 { // Get the block number at ciphter-text offset func (be *CryptFS) BlockNoCipherOff(cipherOffset uint64) uint64 { - return cipherOffset / be.cipherBS + return (cipherOffset - HEADER_LEN) / be.cipherBS } |