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gcrypt.go
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gcrypt.go
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package gcrypt
import (
"crypto/aes"
"crypto/cipher"
"crypto/md5"
"crypto/rand"
"crypto/sha1"
"crypto/sha256"
"crypto/sha512"
"encoding/hex"
"errors"
"io"
"log"
"os"
)
// FUNCTIONS ---------------------------------
func CreateHash(value string, algo string) string {
var sum_bytes []byte
switch algo {
case "sha1":
hasher := sha1.New()
io.WriteString(hasher, value)
sum_bytes = hasher.Sum(nil)
case "sha256":
hasher := sha256.New()
io.WriteString(hasher, value)
sum_bytes = hasher.Sum(nil)
case "sha512":
hasher := sha512.New()
io.WriteString(hasher, value)
sum_bytes = hasher.Sum(nil)
case "md5":
hasher := md5.New()
io.WriteString(hasher, value)
sum_bytes = hasher.Sum(nil)
default:
log.Fatalln("Valid algo was not passed in to function: CreateHash. \nalgo options: sha1, sha256, sha512, md5")
}
return hex.EncodeToString(sum_bytes)
}
func CreateFileHash(algo string, pathToFile string) string {
f, err := os.Open(pathToFile)
if err != nil {
log.Fatalf("Error opening file %s\n%s", pathToFile, err)
}
defer f.Close()
var sum_bytes []byte
switch algo {
case "sha1":
hasher := sha1.New()
if _, err := io.Copy(hasher, f); err != nil {
log.Fatalf("Error during io.Copy.\n%s", err)
}
sum_bytes = hasher.Sum(nil)
case "sha256":
hasher := sha256.New()
if _, err := io.Copy(hasher, f); err != nil {
log.Fatalf("Error during io.Copy.\n%s", err)
}
sum_bytes = hasher.Sum(nil)
case "sha512":
hasher := sha512.New()
if _, err := io.Copy(hasher, f); err != nil {
log.Fatalf("Error during io.Copy.\n%s", err)
}
sum_bytes = hasher.Sum(nil)
case "md5":
hasher := md5.New()
if _, err := io.Copy(hasher, f); err != nil {
log.Fatalf("Error during io.Copy.\n%s", err)
}
sum_bytes = hasher.Sum(nil)
default:
log.Fatalln("Valid algo was not passed in to function: CreateFileHash.\nalgo options: sha1, sha256, sha512, md5.")
}
return hex.EncodeToString(sum_bytes)
}
// AES128/256, GCM
func Encrypt(plaintext_bytes []byte, passphrase string, algo string) ([]byte, error) {
// AES 128 or 256 determined by key size, 16 bytes for AES128 and 32 bytes for AES256
// key derived by hashing passphrase to appropriate length
key, _ := hex.DecodeString(CreateHash(passphrase, "sha256")) // returns []byte, error
switch algo {
case "aes128":
// grab first 16 bytes for AES128 key
key = key[:16]
case "aes256":
// k, all good, key is already 32 bytes
default:
return nil, errors.New("Encrypt: Invalid algo, must be aes128 or aes256.")
}
block, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
gcm, err := cipher.NewGCM(block)
if err != nil {
return nil, err
}
nonce := make([]byte, gcm.NonceSize())
_, err = io.ReadFull(rand.Reader, nonce)
if err != nil {
return nil, err
}
return gcm.Seal(nonce, nonce, plaintext_bytes, nil), nil
}
func Decrypt(ciphertext_bytes []byte, passphrase string, algo string) ([]byte, error) {
key, _ := hex.DecodeString(CreateHash(passphrase, "sha256")) // returns []byte, error
switch algo {
case "aes128":
// grab first 16 bytes for AES128 key
key = key[:16]
case "aes256":
// k, all good, key is already 32 bytes
default:
return nil, errors.New("Encrypt: Invalid algo, must be aes128 or aes256.")
}
block, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
gcm, err := cipher.NewGCM(block)
if err != nil {
return nil, err
}
if len(ciphertext_bytes) < gcm.NonceSize() {
return nil, errors.New("Malformed ciphertext")
}
return gcm.Open(nil, ciphertext_bytes[:gcm.NonceSize()], ciphertext_bytes[gcm.NonceSize():], nil)
}