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senc.go
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/
senc.go
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package senc
import (
"bytes"
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"io"
)
const KeyLength = 32 // aes256
func readIV(r io.Reader) ([]byte, error) {
iv := make([]byte, aes.BlockSize)
_, err := io.ReadFull(r, iv)
return iv, err
}
func RandomKey() ([]byte, error) {
k := make([]byte, KeyLength)
_, err := io.ReadFull(rand.Reader, k)
return k, err
}
func Encrypt(key []byte, plaintext io.Reader) (ciphertext io.Reader, err error) {
bc, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
iv, err := readIV(rand.Reader) // generate random IV
if err != nil {
return nil, err
}
ivr := bytes.NewReader(iv)
stream := cipher.NewCTR(bc, iv)
sr := &cipher.StreamReader{S: stream, R: plaintext}
// The IV needs to be unique, but not secure. Therefore it's common to
// include it at the beginning of the ciphertext.
return io.MultiReader(ivr, sr), nil
}
func Decrypt(key []byte, ciphertext io.Reader) (plaintext io.Reader, err error) {
bc, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
// The IV needs to be unique, but not secure. Therefore it's common to
// include it at the beginning of the ciphertext.
iv, err := readIV(ciphertext)
if err != nil {
return nil, err
}
stream := cipher.NewCTR(bc, iv)
sr := &cipher.StreamReader{S: stream, R: ciphertext}
return sr, nil
}