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//
// Copyright (c) 2017 anygone contributors (see AUTHORS file)
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice, this
// list of conditions and the following disclaimer.
//
// * Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
//
// * Neither the name of anygone nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
package satp
import (
"errors"
"strings"
)
type KDRole int
type KeyUsage int
type Label uint32
const (
RoleLeft KDRole = iota
RoleRight
UsageEncryptKey KeyUsage = iota
UsageEncryptSalt
UsageAuthKey
LabelLeftEncrypt = 0x356A192B
LabelRightEncrypt = 0xDA4B9237
LabelLeftEncryptSalt = 0x77DE68DA
LabelRightEncryptSalt = 0x1B645389
LabelLeftAuthKey = 0xAC3478D6
LabelRightAuthKey = 0xC1DFD96E
)
func (r KDRole) String() string {
switch r {
case RoleLeft:
return "left"
case RoleRight:
return "right"
}
return "unknown"
}
func (r *KDRole) FromString(str string) (err error) {
switch strings.ToLower(str) {
case "server":
fallthrough
case "alice":
fallthrough
case "left":
*r = RoleLeft
case "client":
fallthrough
case "bob":
fallthrough
case "right":
*r = RoleRight
default:
return errors.New("invalid role: '" + str + "'")
}
return
}
func (r KDRole) MarshalText() (data []byte, err error) {
data = []byte(r.String())
return
}
func (r *KDRole) UnmarshalText(data []byte) (err error) {
return r.FromString(string(data))
}
type KeyDerivation interface {
Generate(dir Direction, usage KeyUsage, sequenceNumber uint32, out []byte) error
}
func getKDLabel(role KDRole, dir Direction, usage KeyUsage) uint32 {
switch usage {
case UsageEncryptKey:
if (role == RoleLeft && dir == Outbound) || (role == RoleRight && dir == Inbound) {
return LabelLeftEncrypt
}
return LabelRightEncrypt
case UsageEncryptSalt:
if (role == RoleLeft && dir == Outbound) || (role == RoleRight && dir == Inbound) {
return LabelLeftEncryptSalt
}
return LabelRightEncryptSalt
case UsageAuthKey:
if (role == RoleLeft && dir == Outbound) || (role == RoleRight && dir == Inbound) {
return LabelLeftAuthKey
}
return LabelRightAuthKey
}
panic("Key-derivation: invalid role, direction and/or usage")
}
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