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// Copyright (c) 2021, Google Inc.
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
package subprocess
import (
"encoding/binary"
"encoding/hex"
"encoding/json"
"fmt"
)
// The following structures reflect the JSON of ACVP hash tests. See
// https://pages.nist.gov/ACVP/draft-celi-acvp-symmetric.html
type xtsTestVectorSet struct {
Groups []xtsTestGroup `json:"testGroups"`
}
type xtsTestGroup struct {
ID uint64 `json:"tgId"`
Type string `json:"testType"`
Direction string `json:"direction"`
KeyLen int `json:"keyLen"`
PayloadLen int `json:"payloadLen"`
Tests []struct {
ID uint64 `json:"tcId"`
KeyHex string `json:"key"`
PlaintextHex string `json:"pt"`
CiphertextHex string `json:"ct"`
SectorNum *uint64 `json:"sequenceNumber"`
TweakHex *string `json:"tweakValue"`
} `json:"tests"`
}
type xtsTestGroupResponse struct {
ID uint64 `json:"tgId"`
Tests []xtsTestResponse `json:"tests"`
}
type xtsTestResponse struct {
ID uint64 `json:"tcId"`
PlaintextHex string `json:"pt,omitempty"`
CiphertextHex string `json:"ct,omitempty"`
}
// xts implements an ACVP algorithm by making requests to the subprocess to
// encrypt/decrypt with AES-XTS.
type xts struct{}
func (h *xts) Process(vectorSet []byte, m Transactable) (interface{}, error) {
var parsed xtsTestVectorSet
if err := json.Unmarshal(vectorSet, &parsed); err != nil {
return nil, err
}
var ret []xtsTestGroupResponse
for _, group := range parsed.Groups {
response := xtsTestGroupResponse{
ID: group.ID,
}
if group.Type != "AFT" {
return nil, fmt.Errorf("unknown XTS test type %q", group.Type)
}
var decrypt bool
switch group.Direction {
case "encrypt":
decrypt = false
case "decrypt":
decrypt = true
default:
return nil, fmt.Errorf("unknown XTS direction %q", group.Direction)
}
funcName := "AES-XTS/" + group.Direction
for _, test := range group.Tests {
if group.KeyLen != len(test.KeyHex)*4/2 {
return nil, fmt.Errorf("test case %d/%d contains hex message of length %d but specifies a key length of %d (remember that XTS keys are twice the length of the underlying key size)", group.ID, test.ID, len(test.KeyHex), group.KeyLen)
}
key, err := hex.DecodeString(test.KeyHex)
if err != nil {
return nil, fmt.Errorf("failed to decode hex in test case %d/%d: %s", group.ID, test.ID, err)
}
var tweak [16]byte
if test.TweakHex != nil {
t, err := hex.DecodeString(*test.TweakHex)
if err != nil {
return nil, fmt.Errorf("failed to decode hex in test case %d/%d: %s", group.ID, test.ID, err)
}
if len(t) != len(tweak) {
return nil, fmt.Errorf("wrong tweak length (%d bytes) in test case %d/%d", len(t), group.ID, test.ID)
}
copy(tweak[:], t)
} else if test.SectorNum != nil {
// Sector numbers (or "sequence numbers", as NIST calls them) are turned
// into tweak values by encoding them in little-endian form. See IEEE
// 1619-2007, section 5.1.
binary.LittleEndian.PutUint64(tweak[:8], *test.SectorNum)
} else {
return nil, fmt.Errorf("neither sector number nor explicit tweak in test case %d/%d", group.ID, test.ID)
}
var msg []byte
if decrypt {
msg, err = hex.DecodeString(test.CiphertextHex)
} else {
msg, err = hex.DecodeString(test.PlaintextHex)
}
if err != nil {
return nil, fmt.Errorf("failed to decode hex in test case %d/%d: %s", group.ID, test.ID, err)
}
result, err := m.Transact(funcName, 1, key, msg, tweak[:])
if err != nil {
return nil, fmt.Errorf("submodule failed on test case %d/%d: %s", group.ID, test.ID, err)
}
testResponse := xtsTestResponse{ID: test.ID}
if decrypt {
testResponse.PlaintextHex = hex.EncodeToString(result[0])
} else {
testResponse.CiphertextHex = hex.EncodeToString(result[0])
}
response.Tests = append(response.Tests, testResponse)
}
ret = append(ret, response)
}
return ret, nil
}