Add vault item

vault/item.go

@@ -0,0 +1,162 @@
+package vault
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/hmac"
+	"crypto/sha512"
+	"crypto/subtle"
+	"encoding/base64"
+	"strings"
+
+	"github.com/dropbox/godropbox/errors"
+	"github.com/pritunl/pritunl-vault/errortypes"
+	"github.com/pritunl/pritunl-vault/utils"
+)
+
+func (i *Item) encrypt(v *Vault) (err error) {
+	block, err := aes.NewCipher(v.aesKey)
+	if err != nil {
+		err = &errortypes.ParseError{
+			errors.Wrap(err, "vault: Failed to parse encryption key"),
+		}
+		return
+	}
+
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		err = &errortypes.ParseError{
+			errors.Wrap(err, "vault: Failed to parse encryption block"),
+		}
+		return
+	}
+
+	nonce, err := utils.RandBytes(12)
+	if err != nil {
+		return
+	}
+
+	ciphertext := gcm.Seal(nil, nonce, []byte(i.Value), nil)
+
+	i.Value = "$SEAV1$&" + base64.StdEncoding.EncodeToString(nonce) + "&" +
+		base64.StdEncoding.EncodeToString(ciphertext)
+
+	hashFunc := hmac.New(sha512.New, v.hmacKey)
+	hashFunc.Write([]byte(i.Collection + "&" + i.Id + "&" +
+		i.Key + "&" + i.Value))
+	hashData := hashFunc.Sum(nil)
+
+	i.Signature = base64.StdEncoding.EncodeToString(hashData)
+
+	return
+}
+
+func (i *Item) decrypt(v *Vault) (err error) {
+	hashFunc := hmac.New(sha512.New, v.hmacKey)
+	hashFunc.Write([]byte(i.Collection + "&" + i.Id + "&" +
+		i.Key + "&" + i.Value))
+	hashData := hashFunc.Sum(nil)
+
+	authorization := base64.StdEncoding.EncodeToString(hashData)
+
+	if subtle.ConstantTimeCompare(
+		[]byte(i.Signature),
+		[]byte(authorization),
+	) != 1 {
+		err = &errortypes.ParseError{
+			errors.Wrap(err, "vault: Invalid item signature"),
+		}
+		return
+	}
+
+	ciphertexts := strings.SplitN(i.Value, "&", 3)
+	if len(ciphertexts) != 3 {
+		err = &errortypes.ParseError{
+			errors.Wrap(err, "vault: Invalid encrypted value"),
+		}
+		return
+	}
+
+	if ciphertexts[0] != "$SEAV1$" {
+		err = &errortypes.ParseError{
+			errors.Wrap(err, "vault: Unknown encryption"),
+		}
+		return
+	}
+
+	nonce, err := base64.StdEncoding.DecodeString(ciphertexts[1])
+	if err != nil {
+		err = &errortypes.ParseError{
+			errors.Wrap(err, "vault: Failed to parse nonce"),
+		}
+		return
+	}
+
+	ciphertext, err := base64.StdEncoding.DecodeString(ciphertexts[2])
+	if err != nil {
+		err = &errortypes.ParseError{
+			errors.Wrap(err, "vault: Failed to parse ciphertext"),
+		}
+		return
+	}
+
+	block, err := aes.NewCipher(v.aesKey)
+	if err != nil {
+		err = &errortypes.ParseError{
+			errors.Wrap(err, "vault: Failed to parse encryption key"),
+		}
+		return
+	}
+
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		err = &errortypes.ParseError{
+			errors.Wrap(err, "vault: Failed to parse encryption block"),
+		}
+		return
+	}
+
+	plaintext, err := gcm.Open(nil, nonce, ciphertext, nil)
+	if err != nil {
+		err = &errortypes.ParseError{
+			errors.Wrap(err, "vault: Failed to decrypt value"),
+		}
+		return
+	}
+
+	i.Value = string(plaintext)
+
+	return
+}
+
+func (i *Item) sign(v *Vault) (err error) {
+	hashFunc := hmac.New(sha512.New, v.hmacKey)
+	hashFunc.Write([]byte(i.Collection + "&" + i.Id + "&" +
+		i.Key + "&" + i.Value))
+	hashData := hashFunc.Sum(nil)
+
+	i.Signature = base64.StdEncoding.EncodeToString(hashData)
+
+	return
+}
+
+func (i *Item) verify(v *Vault) (err error) {
+	hashFunc := hmac.New(sha512.New, v.hmacKey)
+	hashFunc.Write([]byte(i.Collection + "&" + i.Id + "&" +
+		i.Key + "&" + i.Value))
+	hashData := hashFunc.Sum(nil)
+
+	authorization := base64.StdEncoding.EncodeToString(hashData)
+
+	if subtle.ConstantTimeCompare(
+		[]byte(i.Signature),
+		[]byte(authorization),
+	) != 1 {
+		err = &errortypes.ParseError{
+			errors.Wrap(err, "vault: Invalid item signature"),
+		}
+		return
+	}
+
+	return
+}