blob: db3a149ad795d0508e4f29bb601a890460d443b5 [file] [log] [blame]
Pragya Arya324337e2020-02-20 14:35:08 +05301package crypto
2
3import (
4 "crypto/des"
5 "crypto/hmac"
6 "crypto/sha1"
7 "errors"
8 "hash"
9
10 "gopkg.in/jcmturner/gokrb5.v7/crypto/common"
11 "gopkg.in/jcmturner/gokrb5.v7/crypto/rfc3961"
12 "gopkg.in/jcmturner/gokrb5.v7/iana/chksumtype"
13 "gopkg.in/jcmturner/gokrb5.v7/iana/etypeID"
14)
15
16//RFC: 3961 Section 6.3
17
18/*
19 des3-cbc-hmac-sha1-kd, hmac-sha1-des3-kd
20 ------------------------------------------------
21 protocol key format 24 bytes, parity in low
22 bit of each
23
24 key-generation seed 21 bytes
25 length
26
27 hash function SHA-1
28
29 HMAC output size 160 bits
30
31 message block size 8 bytes
32
33 default string-to-key empty string
34 params
35
36 encryption and triple-DES encrypt and
37 decryption functions decrypt, in outer-CBC
38 mode (cipher block size
39 8 octets)
40
41 key generation functions:
42
43 random-to-key DES3random-to-key (see
44 below)
45
46 string-to-key DES3string-to-key (see
47 below)
48
49 The des3-cbc-hmac-sha1-kd encryption type is assigned the value
50 sixteen (16). The hmac-sha1-des3-kd checksum algorithm is assigned a
51 checksum type number of twelve (12)*/
52
53// Des3CbcSha1Kd implements Kerberos encryption type des3-cbc-hmac-sha1-kd
54type Des3CbcSha1Kd struct {
55}
56
57// GetETypeID returns the EType ID number.
58func (e Des3CbcSha1Kd) GetETypeID() int32 {
59 return etypeID.DES3_CBC_SHA1_KD
60}
61
62// GetHashID returns the checksum type ID number.
63func (e Des3CbcSha1Kd) GetHashID() int32 {
64 return chksumtype.HMAC_SHA1_DES3_KD
65}
66
67// GetKeyByteSize returns the number of bytes for key of this etype.
68func (e Des3CbcSha1Kd) GetKeyByteSize() int {
69 return 24
70}
71
72// GetKeySeedBitLength returns the number of bits for the seed for key generation.
73func (e Des3CbcSha1Kd) GetKeySeedBitLength() int {
74 return 21 * 8
75}
76
77// GetHashFunc returns the hash function for this etype.
78func (e Des3CbcSha1Kd) GetHashFunc() func() hash.Hash {
79 return sha1.New
80}
81
82// GetMessageBlockByteSize returns the block size for the etype's messages.
83func (e Des3CbcSha1Kd) GetMessageBlockByteSize() int {
84 //For traditional CBC mode with padding, it would be the underlying cipher's block size
85 return des.BlockSize
86}
87
88// GetDefaultStringToKeyParams returns the default key derivation parameters in string form.
89func (e Des3CbcSha1Kd) GetDefaultStringToKeyParams() string {
90 var s string
91 return s
92}
93
94// GetConfounderByteSize returns the byte count for confounder to be used during cryptographic operations.
95func (e Des3CbcSha1Kd) GetConfounderByteSize() int {
96 return des.BlockSize
97}
98
99// GetHMACBitLength returns the bit count size of the integrity hash.
100func (e Des3CbcSha1Kd) GetHMACBitLength() int {
101 return e.GetHashFunc()().Size() * 8
102}
103
104// GetCypherBlockBitLength returns the bit count size of the cypher block.
105func (e Des3CbcSha1Kd) GetCypherBlockBitLength() int {
106 return des.BlockSize * 8
107}
108
109// StringToKey returns a key derived from the string provided.
110func (e Des3CbcSha1Kd) StringToKey(secret string, salt string, s2kparams string) ([]byte, error) {
111 if s2kparams != "" {
112 return []byte{}, errors.New("s2kparams must be an empty string")
113 }
114 return rfc3961.DES3StringToKey(secret, salt, e)
115}
116
117// RandomToKey returns a key from the bytes provided.
118func (e Des3CbcSha1Kd) RandomToKey(b []byte) []byte {
119 return rfc3961.DES3RandomToKey(b)
120}
121
122// DeriveRandom generates data needed for key generation.
123func (e Des3CbcSha1Kd) DeriveRandom(protocolKey, usage []byte) ([]byte, error) {
124 r, err := rfc3961.DeriveRandom(protocolKey, usage, e)
125 return r, err
126}
127
128// DeriveKey derives a key from the protocol key based on the usage value.
129func (e Des3CbcSha1Kd) DeriveKey(protocolKey, usage []byte) ([]byte, error) {
130 r, err := e.DeriveRandom(protocolKey, usage)
131 if err != nil {
132 return nil, err
133 }
134 return e.RandomToKey(r), nil
135}
136
137// EncryptData encrypts the data provided.
138func (e Des3CbcSha1Kd) EncryptData(key, data []byte) ([]byte, []byte, error) {
139 return rfc3961.DES3EncryptData(key, data, e)
140}
141
142// EncryptMessage encrypts the message provided and concatenates it with the integrity hash to create an encrypted message.
143func (e Des3CbcSha1Kd) EncryptMessage(key, message []byte, usage uint32) ([]byte, []byte, error) {
144 return rfc3961.DES3EncryptMessage(key, message, usage, e)
145}
146
147// DecryptData decrypts the data provided.
148func (e Des3CbcSha1Kd) DecryptData(key, data []byte) ([]byte, error) {
149 return rfc3961.DES3DecryptData(key, data, e)
150}
151
152// DecryptMessage decrypts the message provided and verifies the integrity of the message.
153func (e Des3CbcSha1Kd) DecryptMessage(key, ciphertext []byte, usage uint32) ([]byte, error) {
154 return rfc3961.DES3DecryptMessage(key, ciphertext, usage, e)
155}
156
157// VerifyIntegrity checks the integrity of the plaintext message.
158func (e Des3CbcSha1Kd) VerifyIntegrity(protocolKey, ct, pt []byte, usage uint32) bool {
159 return rfc3961.VerifyIntegrity(protocolKey, ct, pt, usage, e)
160}
161
162// GetChecksumHash returns a keyed checksum hash of the bytes provided.
163func (e Des3CbcSha1Kd) GetChecksumHash(protocolKey, data []byte, usage uint32) ([]byte, error) {
164 return common.GetHash(data, protocolKey, common.GetUsageKc(usage), e)
165}
166
167// VerifyChecksum compares the checksum of the message bytes is the same as the checksum provided.
168func (e Des3CbcSha1Kd) VerifyChecksum(protocolKey, data, chksum []byte, usage uint32) bool {
169 c, err := e.GetChecksumHash(protocolKey, data, usage)
170 if err != nil {
171 return false
172 }
173 return hmac.Equal(chksum, c)
174}