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// The MIT License
//
// Copyright (c) 2019 Proton Technologies AG
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package srp
import (
"bytes"
"crypto/md5"
"crypto/sha512"
"encoding/base64"
"encoding/hex"
"errors"
"strings"
"github.com/ProtonMail/bcrypt"
)
//based64DotSlash Bcrypt uses an adapted base64 alphabet (using . instead of +, starting with ./ and with no padding).
var based64DotSlash = base64.NewEncoding("./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789").WithPadding(base64.NoPadding)
// bcryptHash bcrypt hash function with prefix start strings
//
// Parameters:
// - password []byte: the thing we need to keep secret and to a hash. mostly the passwords
// - encodedSalt string: a salt must encoded with based64DotSlash. the salt size before encoded is 128 bits for our workflow
// Returns:
// - hashed []byte: a hashed password
// - err error: throw error
// Usage:
//
func bcryptHash(password []byte, encodedSalt string) (hashed []byte, err error) {
return bcrypt.HashBytes(password, []byte("$2y$10$"+encodedSalt))
}
// expandHash extends the byte data for SRP flow
func expandHash(data []byte) []byte {
part0 := sha512.Sum512(append(data, 0))
part1 := sha512.Sum512(append(data, 1))
part2 := sha512.Sum512(append(data, 2))
part3 := sha512.Sum512(append(data, 3))
return bytes.Join([][]byte{
part0[:],
part1[:],
part2[:],
part3[:],
}, []byte{})
}
// MailboxPassword get mailbox password hash
//
// Parameters:
// - password []byte: a mailbox password
// - salt []byte: a salt is random 128 bits data
// Returns:
// - hashed []byte: a hashed password
// - err error: throw error
func MailboxPassword(password []byte, salt []byte) (hashed []byte, err error) {
encodedSalt := based64DotSlash.EncodeToString(salt)
hashed, err = bcryptHash(password, encodedSalt)
return
}
// HashPassword returns the hash of password argument. Based on version number
// following arguments are used in addition to password:
// * 0, 1, 2: userName and modulus
// * 3, 4: salt and modulus
func HashPassword(authVersion int, password []byte, userName string, salt, modulus []byte) ([]byte, error) {
switch authVersion {
case 4, 3:
return hashPasswordVersion3(password, salt, modulus)
case 2:
return hashPasswordVersion2(password, userName, modulus)
case 1:
return hashPasswordVersion1(password, userName, modulus)
case 0:
return hashPasswordVersion0(password, userName, modulus)
default:
return nil, errors.New("pmapi: unsupported auth version")
}
}
// cleanUserName returns the input string in lower-case without characters `_`,
// `.` and `-`.
func cleanUserName(userName string) string {
userName = strings.Replace(userName, "-", "", -1)
userName = strings.Replace(userName, ".", "", -1)
userName = strings.Replace(userName, "_", "", -1)
return strings.ToLower(userName)
}
func hashPasswordVersion3(password []byte, salt, modulus []byte) (res []byte, err error) {
encodedSalt := based64DotSlash.EncodeToString(append(salt, []byte("proton")...))
crypted, err := bcryptHash(password, encodedSalt)
if err != nil {
return
}
return expandHash(append(crypted, modulus...)), nil
}
func hashPasswordVersion2(password []byte, userName string, modulus []byte) (res []byte, err error) {
return hashPasswordVersion1(password, cleanUserName(userName), modulus)
}
func hashPasswordVersion1(password []byte, userName string, modulus []byte) (res []byte, err error) {
prehashed := md5.Sum([]byte(strings.ToLower(userName)))
encodedSalt := hex.EncodeToString(prehashed[:])
crypted, err := bcryptHash(password, encodedSalt)
if err != nil {
return
}
return expandHash(append(crypted, modulus...)), nil
}
func hashPasswordVersion0(password []byte, userName string, modulus []byte) (res []byte, err error) {
b64Hash := make([]byte, 88) // 64 bytes in base64
userAndPass := append([]byte(strings.ToLower(userName)), password...)
defer clear(userAndPass)
prehashed := sha512.Sum512(userAndPass)
defer clear(prehashed[:])
base64.StdEncoding.Encode(b64Hash, prehashed[:])
defer clear(b64Hash)
return hashPasswordVersion1(b64Hash, userName, modulus)
}
func clear(w []byte) {
for k := range w {
w[k] = 0x00
}
}
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