libgocryptfs/cryptfs/cryptfs.go

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package cryptfs
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// CryptFS is the crypto backend of GoCryptFS
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import (
"fmt"
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"crypto/cipher"
"crypto/aes"
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)
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const (
KEY_LEN = 16
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NONCE_LEN = 12
AUTH_TAG_LEN = 16
DEFAULT_PLAINBS = 4096
)
type CryptFS struct {
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blockCipher cipher.Block
gcm cipher.AEAD
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plainBS uint64
cipherBS uint64
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}
func NewCryptFS(key []byte, useOpenssl bool) *CryptFS {
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if len(key) != KEY_LEN {
panic(fmt.Sprintf("Unsupported key length %d", len(key)))
}
b, err := aes.NewCipher(key)
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if err != nil {
panic(err)
}
var gcm cipher.AEAD
if useOpenssl {
var k16 [16]byte
copy(k16[:], key)
gcm = opensslGCM{k16}
} else {
gcm, err = cipher.NewGCM(b)
if err != nil {
panic(err)
}
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}
return &CryptFS{
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blockCipher: b,
gcm: gcm,
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plainBS: DEFAULT_PLAINBS,
cipherBS: DEFAULT_PLAINBS + NONCE_LEN + AUTH_TAG_LEN,
}
}
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func (be *CryptFS) PlainBS() uint64 {
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return be.plainBS
}