libgocryptfs/cryptfs/openssl_aead.go
Jakob Unterwurzacher 58d1e24b7c Add OpenSSL support for file content encryption/decryption
This brings streaming read performance from 30MB/s to 81MB/s
(similar improvement for writes)
2015-09-06 10:42:34 +02:00

94 lines
2.1 KiB
Go

package cryptfs
// Implements cipher.AEAD with OpenSSL backend
import (
"bytes"
"github.com/spacemonkeygo/openssl"
)
type opensslGCM struct {
key [16]byte
}
func (be opensslGCM) Overhead() int {
return AUTH_TAG_LEN
}
func (be opensslGCM) NonceSize() int {
return NONCE_LEN
}
// Seal encrypts and authenticates plaintext, authenticates the
// additional data and appends the result to dst, returning the updated
// slice. The nonce must be NonceSize() bytes long and unique for all
// time, for a given key.
//
// The plaintext and dst may alias exactly or not at all.
func (be opensslGCM) Seal(dst, nonce, plaintext, data []byte) []byte {
cipherBuf := bytes.NewBuffer(dst)
ectx, err := openssl.NewGCMEncryptionCipherCtx(128, nil, be.key[:], nonce[:])
if err != nil {
panic(err)
}
part, err := ectx.EncryptUpdate(plaintext)
if err != nil {
panic(err)
}
cipherBuf.Write(part)
part, err = ectx.EncryptFinal()
if err != nil {
panic(err)
}
cipherBuf.Write(part)
part, err = ectx.GetTag()
if err != nil {
panic(err)
}
cipherBuf.Write(part)
return cipherBuf.Bytes()
}
// Open decrypts and authenticates ciphertext, authenticates the
// additional data and, if successful, appends the resulting plaintext
// to dst, returning the updated slice. The nonce must be NonceSize()
// bytes long and both it and the additional data must match the
// value passed to Seal.
//
// The ciphertext and dst may alias exactly or not at all.
func (be opensslGCM) Open(dst, nonce, ciphertext, data []byte) ([]byte, error) {
if len(data) > 0 {
panic("Extra data is not supported")
}
l := len(ciphertext)
tag := ciphertext[l-AUTH_TAG_LEN:l]
ciphertext = ciphertext[0:l-AUTH_TAG_LEN]
plainBuf := bytes.NewBuffer(dst)
dctx, err := openssl.NewGCMDecryptionCipherCtx(128, nil, be.key[:], nonce[:])
if err != nil {
return nil, err
}
part, err := dctx.DecryptUpdate(ciphertext)
if err != nil {
return nil, err
}
plainBuf.Write(part)
err = dctx.SetTag(tag)
if err != nil {
return nil, err
}
part, err = dctx.DecryptFinal()
if err != nil {
return nil, err
}
plainBuf.Write(part)
return plainBuf.Bytes(), nil
}