/
encrypt.go
100 lines (85 loc) · 2.19 KB
/
encrypt.go
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package libeae
import (
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"fmt"
"os"
"ekyu.moe/eae/lib/aeadstream"
"golang.org/x/crypto/chacha20poly1305"
"golang.org/x/crypto/scrypt"
)
func EncryptFile(outFilename, inFilename string, N, r, p uint8, algo Algorithm, passphrase []byte) error {
var inFile, outFile *os.File
var err error
// open in file
if inFilename == "-" {
inFile = os.Stdin
} else {
inFile, err = os.OpenFile(inFilename, os.O_RDONLY, 0)
if err != nil {
return err
}
defer inFile.Close()
}
// create out file
if outFilename == "-" {
outFile = os.Stdout
} else {
outFile, err = os.OpenFile(outFilename, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
if err != nil {
return err
}
defer outFile.Close()
}
// generate salt
salt := make([]byte, SaltSize)
if _, err := rand.Read(salt); err != nil {
return fmt.Errorf("gen salt: %s", err)
}
// key derivation with scrypt
key, err := scrypt.Key(passphrase, salt, 1<<N, int(r), int(p), KeySize)
if err != nil {
return fmt.Errorf("key derivation: %s", err)
}
// generate nonceSeed
nonceSeed := make([]byte, NonceSize)
if _, err := rand.Read(nonceSeed); err != nil {
return fmt.Errorf("generate nonceSeed: %s", err)
}
// write header
header := make([]byte, 0, 7+SaltSize+NonceSize+4)
header = append(header, magic[:]...)
header = append(header, salt...)
header = append(header, nonceSeed...)
header = append(header, N, r, p, uint8(algo))
if _, err := outFile.Write(header); err != nil {
return fmt.Errorf("write header: %s", err)
}
// create aead cipher
var aead cipher.AEAD
switch algo {
case AES256GCM:
block, err := aes.NewCipher(key)
if err != nil {
return fmt.Errorf("create aead: %s", err)
}
aead, err = cipher.NewGCMWithNonceSize(block, NonceSize)
if err != nil {
return fmt.Errorf("create aead: %s", err)
}
case ChaCha20Poly1305:
aead, err = chacha20poly1305.New(key)
if err != nil {
return fmt.Errorf("create aead: %s", err)
}
default:
panic("shouldn't reach")
}
// on to the core business
s := aeadstream.NewAEADStream(aead)
if _, err := s.StreamEncrypt(outFile, inFile, nonceSeed, ChunkSize); err != nil {
return fmt.Errorf("encrypt: %s", err)
}
return nil
}