1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
|
// chachapoly.cpp - written and placed in the public domain by Jeffrey Walton
// RFC 8439, Section 2.8, AEAD Construction, http://tools.ietf.org/html/rfc8439
#include "pch.h"
#include "chachapoly.h"
#include "algparam.h"
#include "misc.h"
NAMESPACE_BEGIN(CryptoPP)
void ChaCha20Poly1305_Base::RekeyCipherAndMac(const byte *userKey, size_t keylength, const NameValuePairs ¶ms)
{
// Derive MAC key
AlgorithmParameters block0 = MakeParameters("InitialBlock", (word64)0, true);
AccessSymmetricCipher().SetKey(userKey, keylength, CombinedNameValuePairs(params, block0));
// Only the head 256-bits are used to key the MAC
SecByteBlock derived(NULLPTR, 32);
AccessSymmetricCipher().ProcessString(derived, derived.size());
// Set the Poly1305 key
AccessMAC().SetKey(derived, derived.size(), params);
// Key Cipher for bulk encryption
AlgorithmParameters block1 = MakeParameters("InitialBlock", (word64)1, true);
AccessSymmetricCipher().SetKey(userKey, keylength, CombinedNameValuePairs(params, block1));
}
void ChaCha20Poly1305_Base::SetKeyWithoutResync(const byte *userKey, size_t userKeyLength, const NameValuePairs ¶ms)
{
CRYPTOPP_ASSERT(userKey && userKeyLength == 32);
m_userKey.Assign(userKey, userKeyLength);
RekeyCipherAndMac(userKey, userKeyLength, params);
}
void ChaCha20Poly1305_Base::Resync(const byte *iv, size_t len)
{
CRYPTOPP_ASSERT(iv && len == 12);
RekeyCipherAndMac(m_userKey, m_userKey.SizeInBytes(),
MakeParameters(Name::IV(), ConstByteArrayParameter(iv,len)));
}
size_t ChaCha20Poly1305_Base::AuthenticateBlocks(const byte *data, size_t len)
{
AccessMAC().Update(data, len);
return 0;
}
void ChaCha20Poly1305_Base::AuthenticateLastHeaderBlock()
{
const byte zero[16] = {0};
size_t pad = 16 - (m_totalHeaderLength % 16);
AccessMAC().Update(zero, pad);
}
void ChaCha20Poly1305_Base::AuthenticateLastConfidentialBlock()
{
const byte zero[16] = {0};
size_t pad = 16 - (m_totalMessageLength % 16);
AccessMAC().Update(zero, pad);
}
void ChaCha20Poly1305_Base::AuthenticateLastFooterBlock(byte *mac, size_t macSize)
{
CRYPTOPP_ALIGN_DATA(8) byte length[2*sizeof(word64)];
PutWord(true, LITTLE_ENDIAN_ORDER, length+0, m_totalHeaderLength);
PutWord(true, LITTLE_ENDIAN_ORDER, length+8, m_totalMessageLength);
AccessMAC().Update(length, sizeof(length));
AccessMAC().TruncatedFinal(mac, macSize);
}
void ChaCha20Poly1305_Base::EncryptAndAuthenticate(byte *ciphertext, byte *mac, size_t macSize, const byte *iv, int ivLength, const byte *aad, size_t aadLength, const byte *message, size_t messageLength)
{
Resynchronize(iv, ivLength);
Update(aad, aadLength);
ProcessString(ciphertext, message, messageLength);
TruncatedFinal(mac, macSize);
}
bool ChaCha20Poly1305_Base::DecryptAndVerify(byte *message, const byte *mac, size_t macLength, const byte *iv, int ivLength, const byte *aad, size_t aadLength, const byte *ciphertext, size_t ciphertextLength)
{
Resynchronize(iv, ivLength);
Update(aad, aadLength);
ProcessString(message, ciphertext, ciphertextLength);
return TruncatedVerify(mac, macLength);
}
NAMESPACE_END
|
