1// Copyright (c) 2020, Google Inc.
2//
3// Permission to use, copy, modify, and/or distribute this software for any
4// purpose with or without fee is hereby granted, provided that the above
5// copyright notice and this permission notice appear in all copies.
6//
7// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
8// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
9// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
10// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
11// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
12// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
13// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
14
15package subprocess
16
17import (
18	"encoding/binary"
19	"encoding/hex"
20	"encoding/json"
21	"fmt"
22)
23
24type tlsKDFVectorSet struct {
25	Groups []tlsKDFTestGroup `json:"testGroups"`
26}
27
28type tlsKDFTestGroup struct {
29	ID           uint64       `json:"tgId"`
30	Hash         string       `json:"hashAlg"`
31	TLSVersion   string       `json:"tlsVersion"`
32	KeyBlockBits uint64       `json:"keyBlockLength"`
33	PMSLength    uint64       `json:"preMasterSecretLength"`
34	Tests        []tlsKDFTest `json:"tests"`
35}
36
37type tlsKDFTest struct {
38	ID     uint64 `json:"tcId"`
39	PMSHex string `json:"preMasterSecret"`
40	// ClientHelloRandomHex and ServerHelloRandomHex are used for deriving the
41	// master secret. ClientRandomHex and ServerRandomHex are used for deriving the
42	// key block. Having different values for these is not possible in a TLS
43	// handshake unless you squint at a resumption handshake and somehow rederive
44	// the master secret from the session information during resumption.
45	ClientHelloRandomHex string `json:"clientHelloRandom"`
46	ServerHelloRandomHex string `json:"serverHelloRandom"`
47	ClientRandomHex      string `json:"clientRandom"`
48	ServerRandomHex      string `json:"serverRandom"`
49}
50
51type tlsKDFTestGroupResponse struct {
52	ID    uint64               `json:"tgId"`
53	Tests []tlsKDFTestResponse `json:"tests"`
54}
55
56type tlsKDFTestResponse struct {
57	ID              uint64 `json:"tcId"`
58	MasterSecretHex string `json:"masterSecret"`
59	KeyBlockHex     string `json:"keyBlock"`
60}
61
62type tlsKDF struct{}
63
64func (k *tlsKDF) Process(vectorSet []byte, m Transactable) (interface{}, error) {
65	var parsed tlsKDFVectorSet
66	if err := json.Unmarshal(vectorSet, &parsed); err != nil {
67		return nil, err
68	}
69
70	// See https://usnistgov.github.io/ACVP/draft-celi-acvp-kdf-tls.html
71	var ret []tlsKDFTestGroupResponse
72	for _, group := range parsed.Groups {
73		response := tlsKDFTestGroupResponse{
74			ID: group.ID,
75		}
76
77		var tlsVer string
78		switch group.TLSVersion {
79		case "v1.0/1.1":
80			tlsVer = "1.0"
81		case "v1.2":
82			tlsVer = "1.2"
83		default:
84			return nil, fmt.Errorf("unknown TLS version %q", group.TLSVersion)
85		}
86
87		hashIsTLS10 := false
88		switch group.Hash {
89		case "SHA-1":
90			hashIsTLS10 = true
91		case "SHA2-256", "SHA2-384", "SHA2-512":
92			break
93		default:
94			return nil, fmt.Errorf("unknown hash %q", group.Hash)
95		}
96
97		if (tlsVer == "1.0") != hashIsTLS10 {
98			return nil, fmt.Errorf("hash %q not permitted with TLS version %q", group.Hash, group.TLSVersion)
99		}
100
101		if group.KeyBlockBits%8 != 0 {
102			return nil, fmt.Errorf("requested key-block length (%d bits) is not a whole number of bytes", group.KeyBlockBits)
103		}
104
105		method := "TLSKDF/" + tlsVer + "/" + group.Hash
106
107		for _, test := range group.Tests {
108			pms, err := hex.DecodeString(test.PMSHex)
109			if err != nil {
110				return nil, err
111			}
112
113			clientHelloRandom, err := hex.DecodeString(test.ClientHelloRandomHex)
114			if err != nil {
115				return nil, err
116			}
117
118			serverHelloRandom, err := hex.DecodeString(test.ServerHelloRandomHex)
119			if err != nil {
120				return nil, err
121			}
122
123			clientRandom, err := hex.DecodeString(test.ClientRandomHex)
124			if err != nil {
125				return nil, err
126			}
127
128			serverRandom, err := hex.DecodeString(test.ServerRandomHex)
129			if err != nil {
130				return nil, err
131			}
132
133			const (
134				masterSecretLength = 48
135				masterSecretLabel  = "master secret"
136				keyBlockLabel      = "key expansion"
137			)
138
139			var outLenBytes [4]byte
140			binary.LittleEndian.PutUint32(outLenBytes[:], uint32(masterSecretLength))
141			result, err := m.Transact(method, 1, outLenBytes[:], pms, []byte(masterSecretLabel), clientHelloRandom, serverHelloRandom)
142			if err != nil {
143				return nil, err
144			}
145
146			binary.LittleEndian.PutUint32(outLenBytes[:], uint32(group.KeyBlockBits/8))
147			// TLS 1.0, 1.1, and 1.2 use a different order for the client and server
148			// randoms when computing the key block.
149			result2, err := m.Transact(method, 1, outLenBytes[:], result[0], []byte(keyBlockLabel), serverRandom, clientRandom)
150			if err != nil {
151				return nil, err
152			}
153
154			response.Tests = append(response.Tests, tlsKDFTestResponse{
155				ID:              test.ID,
156				MasterSecretHex: hex.EncodeToString(result[0]),
157				KeyBlockHex:     hex.EncodeToString(result2[0]),
158			})
159		}
160
161		ret = append(ret, response)
162	}
163
164	return ret, nil
165}
166