contentenc

package
v1.4.5 Latest Latest
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 Go to latest Published: Apr 5, 2021 License: AGPL-3.0 Imports: 10 Imported by: 0

Documentation

Overview

Package contentenc encrypts and decrypts file blocks.

Index

Constants

View Source 
const (
	//value from FUSE doc
	MAX_KERNEL_WRITE = 128 * 1024

	// DefaultBS is the default plaintext block size
	DefaultBS = 4096
	// DefaultIVBits is the default length of IV, in bits.
	// We always use 128-bit IVs for file content, but the
	// master key in the config file is encrypted with a 96-bit IV for
	// gocryptfs v1.2 and earlier. v1.3 switched to 128 bit.
	DefaultIVBits = 128

	// RandomNonce chooses a random nonce.
	RandomNonce NonceMode = iota
	// ReverseDeterministicNonce chooses a deterministic nonce, suitable for
	// use in reverse mode.
	ReverseDeterministicNonce NonceMode = iota
	// ExternalNonce derives a nonce from external sources.
	ExternalNonce NonceMode = iota
)
View Source 
const (
	// CurrentVersion is the current On-Disk-Format version
	CurrentVersion = 2

	// HeaderLen is the total header length
	HeaderLen = headerVersionLen + headerIDLen
)

Variables

This section is empty.

Functions

func JointPlaintextRange 

func JointPlaintextRange(blocks []IntraBlock) (offset uint64, length uint64)

JointPlaintextRange is the plaintext range corresponding to the sum of all "blocks" (complete blocks)

func MinUint64 

func MinUint64(x uint64, y uint64) uint64

MinUint64 returns the minimum of two uint64 values.

Types

type ContentEnc 

type ContentEnc struct {

	// Ciphertext request data pool. Always returns byte slices of size
	// fuse.MAX_KERNEL_WRITE + encryption overhead.
	// Used by Read() to temporarily store the ciphertext as it is read from
	// disk.
	CReqPool bPool
	// Plaintext request data pool. Slice have size fuse.MAX_KERNEL_WRITE.
	PReqPool bPool
	// contains filtered or unexported fields
}

ContentEnc is used to encipher and decipher file content.

func New 

func New(cc *cryptocore.CryptoCore, plainBS uint64, forceDecode bool) *ContentEnc

New returns an initialized ContentEnc instance.

func (*ContentEnc) BlockNoToCipherOff 

func (be *ContentEnc) BlockNoToCipherOff(blockNo uint64) uint64

BlockNoToCipherOff gets the ciphertext offset of block "blockNo"

func (*ContentEnc) BlockNoToPlainOff 

func (be *ContentEnc) BlockNoToPlainOff(blockNo uint64) uint64

BlockNoToPlainOff gets the plaintext offset of block "blockNo"

func (*ContentEnc) BlockOverhead 

func (be *ContentEnc) BlockOverhead() uint64

BlockOverhead returns the per-block overhead.

func (*ContentEnc) CipherBS 

func (be *ContentEnc) CipherBS() uint64

CipherBS returns the ciphertext block size

func (*ContentEnc) CipherOffToBlockNo 

func (be *ContentEnc) CipherOffToBlockNo(cipherOffset uint64) uint64

CipherOffToBlockNo converts the ciphertext offset to the plaintext block number.

func (*ContentEnc) CipherSizeToPlainSize 

func (be *ContentEnc) CipherSizeToPlainSize(cipherSize uint64) uint64

CipherSizeToPlainSize calculates the plaintext size from a ciphertext size

func (*ContentEnc) DecryptBlock 

func (be *ContentEnc) DecryptBlock(ciphertext []byte, blockNo uint64, fileID []byte) ([]byte, error)

DecryptBlock - Verify and decrypt GCM block

Corner case: A full-sized block of all-zero ciphertext bytes is translated to an all-zero plaintext block, i.e. file hole passthrough.

func (*ContentEnc) DecryptBlocks 

func (be *ContentEnc) DecryptBlocks(ciphertext []byte, firstBlockNo uint64, fileID []byte) ([]byte, error)

DecryptBlocks decrypts a number of blocks

func (*ContentEnc) EncryptBlock 

func (be *ContentEnc) EncryptBlock(plaintext []byte, blockNo uint64, fileID []byte) []byte

EncryptBlock - Encrypt plaintext using a random nonce. blockNo and fileID are used as associated data. The output is nonce + ciphertext + tag.

func (*ContentEnc) EncryptBlockNonce 

func (be *ContentEnc) EncryptBlockNonce(plaintext []byte, blockNo uint64, fileID []byte, nonce []byte) []byte

EncryptBlockNonce - Encrypt plaintext using a nonce chosen by the caller. blockNo and fileID are used as associated data. The output is nonce + ciphertext + tag. This function can only be used in SIV mode.

func (*ContentEnc) EncryptBlocks 

func (be *ContentEnc) EncryptBlocks(plaintextBlocks [][]byte, firstBlockNo uint64, fileID []byte) []byte

EncryptBlocks is like EncryptBlock but takes multiple plaintext blocks. Returns a byte slice from CReqPool - so don't forget to return it to the pool.

func (*ContentEnc) ExplodeCipherRange 

func (be *ContentEnc) ExplodeCipherRange(offset uint64, length uint64) []IntraBlock

ExplodeCipherRange splits a ciphertext byte range into (possibly partial) blocks This is used in reverse mode when reading files

func (*ContentEnc) ExplodePlainRange 

func (be *ContentEnc) ExplodePlainRange(offset uint64, length uint64) []IntraBlock

ExplodePlainRange splits a plaintext byte range into (possibly partial) blocks Returns an empty slice if length == 0.

func (*ContentEnc) MergeBlocks 

func (be *ContentEnc) MergeBlocks(oldData []byte, newData []byte, offset int) []byte

MergeBlocks - Merge newData into oldData at offset New block may be bigger than both newData and oldData

func (*ContentEnc) PlainBS 

func (be *ContentEnc) PlainBS() uint64

PlainBS returns the plaintext block size

func (*ContentEnc) PlainOffToBlockNo 

func (be *ContentEnc) PlainOffToBlockNo(plainOffset uint64) uint64

PlainOffToBlockNo converts a plaintext offset to the ciphertext block number.

func (*ContentEnc) PlainSizeToCipherSize 

func (be *ContentEnc) PlainSizeToCipherSize(plainSize uint64) uint64

PlainSizeToCipherSize calculates the ciphertext size from a plaintext size

func (*ContentEnc) Wipe 

func (be *ContentEnc) Wipe()

Wipe tries to wipe secret keys from memory by overwriting them with zeros and/or setting references to nil.

type FileHeader 

type FileHeader struct {
	Version uint16
	ID      []byte
}

FileHeader represents the header stored on each non-empty file.

func ParseHeader 

func ParseHeader(buf []byte) (*FileHeader, error)

ParseHeader - parse "buf" into fileHeader object

func RandomHeader 

func RandomHeader() *FileHeader

RandomHeader - create new fileHeader object with random Id

func (*FileHeader) Pack 

func (h *FileHeader) Pack() []byte

Pack - serialize fileHeader object

type IntraBlock 

type IntraBlock struct {
	// BlockNo is the block number in the file
	BlockNo uint64
	// Skip is an offset into the block payload
	// In forward mode: block plaintext
	// In reverse mode: offset into block ciphertext. Takes the header into
	// account.
	Skip uint64
	// Length of payload data in this block
	// In forward mode: length of the plaintext
	// In reverse mode: length of the ciphertext. Takes header and trailer into
	// account.
	Length uint64
	// contains filtered or unexported fields
}

IntraBlock identifies a part of a file block

func (*IntraBlock) BlockCipherOff 

func (ib *IntraBlock) BlockCipherOff() (offset uint64)

BlockCipherOff returns the ciphertext offset corresponding to BlockNo

func (*IntraBlock) BlockPlainOff 

func (ib *IntraBlock) BlockPlainOff() (offset uint64)

BlockPlainOff returns the plaintext offset corresponding to BlockNo

func (*IntraBlock) CropBlock 

func (ib *IntraBlock) CropBlock(d []byte) []byte

CropBlock - crop a potentially larger plaintext block down to the relevant part

func (*IntraBlock) IsPartial 

func (ib *IntraBlock) IsPartial() bool

IsPartial - is the block partial? This means we have to do read-modify-write.

func (*IntraBlock) JointCiphertextRange 

func (ib *IntraBlock) JointCiphertextRange(blocks []IntraBlock) (offset uint64, length uint64)

JointCiphertextRange is the ciphertext range corresponding to the sum of all "blocks" (complete blocks)

type NonceMode 

type NonceMode int

NonceMode determines how nonces are created.

Source Files

View all Source files

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