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 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258
|
// default.cpp - written and placed in the public domain by Wei Dai
#include "pch.h"
#include "default.h"
#include "queue.h"
#include <time.h>
#include <memory>
NAMESPACE_BEGIN(CryptoPP)
static const unsigned int MASH_ITERATIONS = 200;
static const unsigned int SALTLENGTH = 8;
static const unsigned int BLOCKSIZE = Default_BlockCipher::Encryption::BLOCKSIZE;
static const unsigned int KEYLENGTH = Default_BlockCipher::Encryption::DEFAULT_KEYLENGTH;
// The purpose of this function Mash() is to take an arbitrary length input
// string and *deterministicly* produce an arbitrary length output string such
// that (1) it looks random, (2) no information about the input is
// deducible from it, and (3) it contains as much entropy as it can hold, or
// the amount of entropy in the input string, whichever is smaller.
static void Mash(const byte *in, size_t inLen, byte *out, size_t outLen, int iterations)
{
if (BytePrecision(outLen) > 2)
throw InvalidArgument("Mash: output legnth too large");
size_t bufSize = RoundUpToMultipleOf(outLen, (size_t)DefaultHashModule::DIGESTSIZE);
byte b[2];
SecByteBlock buf(bufSize);
SecByteBlock outBuf(bufSize);
DefaultHashModule hash;
unsigned int i;
for(i=0; i<outLen; i+=DefaultHashModule::DIGESTSIZE)
{
b[0] = (byte) (i >> 8);
b[1] = (byte) i;
hash.Update(b, 2);
hash.Update(in, inLen);
hash.Final(outBuf+i);
}
while (iterations-- > 1)
{
memcpy(buf, outBuf, bufSize);
for (i=0; i<bufSize; i+=DefaultHashModule::DIGESTSIZE)
{
b[0] = (byte) (i >> 8);
b[1] = (byte) i;
hash.Update(b, 2);
hash.Update(buf, bufSize);
hash.Final(outBuf+i);
}
}
memcpy(out, outBuf, outLen);
}
static void GenerateKeyIV(const byte *passphrase, size_t passphraseLength, const byte *salt, size_t saltLength, byte *key, byte *IV)
{
SecByteBlock temp(passphraseLength+saltLength);
memcpy(temp, passphrase, passphraseLength);
memcpy(temp+passphraseLength, salt, saltLength);
SecByteBlock keyIV(KEYLENGTH+BLOCKSIZE);
Mash(temp, passphraseLength + saltLength, keyIV, KEYLENGTH+BLOCKSIZE, MASH_ITERATIONS);
memcpy(key, keyIV, KEYLENGTH);
memcpy(IV, keyIV+KEYLENGTH, BLOCKSIZE);
}
// ********************************************************
DefaultEncryptor::DefaultEncryptor(const char *passphrase, BufferedTransformation *attachment)
: ProxyFilter(NULL, 0, 0, attachment), m_passphrase((const byte *)passphrase, strlen(passphrase))
{
}
DefaultEncryptor::DefaultEncryptor(const byte *passphrase, size_t passphraseLength, BufferedTransformation *attachment)
: ProxyFilter(NULL, 0, 0, attachment), m_passphrase(passphrase, passphraseLength)
{
}
void DefaultEncryptor::FirstPut(const byte *)
{
// VC60 workaround: __LINE__ expansion bug
CRYPTOPP_COMPILE_ASSERT_INSTANCE(SALTLENGTH <= DefaultHashModule::DIGESTSIZE, 1);
CRYPTOPP_COMPILE_ASSERT_INSTANCE(BLOCKSIZE <= DefaultHashModule::DIGESTSIZE, 2);
SecByteBlock salt(DefaultHashModule::DIGESTSIZE), keyCheck(DefaultHashModule::DIGESTSIZE);
DefaultHashModule hash;
// use hash(passphrase | time | clock) as salt
hash.Update(m_passphrase, m_passphrase.size());
time_t t=time(0);
hash.Update((byte *)&t, sizeof(t));
clock_t c=clock();
hash.Update((byte *)&c, sizeof(c));
hash.Final(salt);
// use hash(passphrase | salt) as key check
hash.Update(m_passphrase, m_passphrase.size());
hash.Update(salt, SALTLENGTH);
hash.Final(keyCheck);
AttachedTransformation()->Put(salt, SALTLENGTH);
// mash passphrase and salt together into key and IV
SecByteBlock key(KEYLENGTH);
SecByteBlock IV(BLOCKSIZE);
GenerateKeyIV(m_passphrase, m_passphrase.size(), salt, SALTLENGTH, key, IV);
m_cipher.SetKeyWithIV(key, key.size(), IV);
SetFilter(new StreamTransformationFilter(m_cipher));
m_filter->Put(keyCheck, BLOCKSIZE);
}
void DefaultEncryptor::LastPut(const byte *inString, size_t length)
{
m_filter->MessageEnd();
}
// ********************************************************
DefaultDecryptor::DefaultDecryptor(const char *p, BufferedTransformation *attachment, bool throwException)
: ProxyFilter(NULL, SALTLENGTH+BLOCKSIZE, 0, attachment)
, m_state(WAITING_FOR_KEYCHECK)
, m_passphrase((const byte *)p, strlen(p))
, m_throwException(throwException)
{
}
DefaultDecryptor::DefaultDecryptor(const byte *passphrase, size_t passphraseLength, BufferedTransformation *attachment, bool throwException)
: ProxyFilter(NULL, SALTLENGTH+BLOCKSIZE, 0, attachment)
, m_state(WAITING_FOR_KEYCHECK)
, m_passphrase(passphrase, passphraseLength)
, m_throwException(throwException)
{
}
void DefaultDecryptor::FirstPut(const byte *inString)
{
CheckKey(inString, inString+SALTLENGTH);
}
void DefaultDecryptor::LastPut(const byte *inString, size_t length)
{
if (m_filter.get() == NULL)
{
m_state = KEY_BAD;
if (m_throwException)
throw KeyBadErr();
}
else
{
m_filter->MessageEnd();
m_state = WAITING_FOR_KEYCHECK;
}
}
void DefaultDecryptor::CheckKey(const byte *salt, const byte *keyCheck)
{
SecByteBlock check(STDMAX((unsigned int)2*BLOCKSIZE, (unsigned int)DefaultHashModule::DIGESTSIZE));
DefaultHashModule hash;
hash.Update(m_passphrase, m_passphrase.size());
hash.Update(salt, SALTLENGTH);
hash.Final(check);
SecByteBlock key(KEYLENGTH);
SecByteBlock IV(BLOCKSIZE);
GenerateKeyIV(m_passphrase, m_passphrase.size(), salt, SALTLENGTH, key, IV);
m_cipher.SetKeyWithIV(key, key.size(), IV);
std::auto_ptr<StreamTransformationFilter> decryptor(new StreamTransformationFilter(m_cipher));
decryptor->Put(keyCheck, BLOCKSIZE);
decryptor->ForceNextPut();
decryptor->Get(check+BLOCKSIZE, BLOCKSIZE);
SetFilter(decryptor.release());
if (!VerifyBufsEqual(check, check+BLOCKSIZE, BLOCKSIZE))
{
m_state = KEY_BAD;
if (m_throwException)
throw KeyBadErr();
}
else
m_state = KEY_GOOD;
}
// ********************************************************
static DefaultMAC * NewDefaultEncryptorMAC(const byte *passphrase, size_t passphraseLength)
{
size_t macKeyLength = DefaultMAC::StaticGetValidKeyLength(16);
SecByteBlock macKey(macKeyLength);
// since the MAC is encrypted there is no reason to mash the passphrase for many iterations
Mash(passphrase, passphraseLength, macKey, macKeyLength, 1);
return new DefaultMAC(macKey, macKeyLength);
}
DefaultEncryptorWithMAC::DefaultEncryptorWithMAC(const char *passphrase, BufferedTransformation *attachment)
: ProxyFilter(NULL, 0, 0, attachment)
, m_mac(NewDefaultEncryptorMAC((const byte *)passphrase, strlen(passphrase)))
{
SetFilter(new HashFilter(*m_mac, new DefaultEncryptor(passphrase), true));
}
DefaultEncryptorWithMAC::DefaultEncryptorWithMAC(const byte *passphrase, size_t passphraseLength, BufferedTransformation *attachment)
: ProxyFilter(NULL, 0, 0, attachment)
, m_mac(NewDefaultEncryptorMAC(passphrase, passphraseLength))
{
SetFilter(new HashFilter(*m_mac, new DefaultEncryptor(passphrase, passphraseLength), true));
}
void DefaultEncryptorWithMAC::LastPut(const byte *inString, size_t length)
{
m_filter->MessageEnd();
}
// ********************************************************
DefaultDecryptorWithMAC::DefaultDecryptorWithMAC(const char *passphrase, BufferedTransformation *attachment, bool throwException)
: ProxyFilter(NULL, 0, 0, attachment)
, m_mac(NewDefaultEncryptorMAC((const byte *)passphrase, strlen(passphrase)))
, m_throwException(throwException)
{
SetFilter(new DefaultDecryptor(passphrase, m_hashVerifier=new HashVerifier(*m_mac, NULL, HashVerifier::PUT_MESSAGE), throwException));
}
DefaultDecryptorWithMAC::DefaultDecryptorWithMAC(const byte *passphrase, size_t passphraseLength, BufferedTransformation *attachment, bool throwException)
: ProxyFilter(NULL, 0, 0, attachment)
, m_mac(NewDefaultEncryptorMAC(passphrase, passphraseLength))
, m_throwException(throwException)
{
SetFilter(new DefaultDecryptor(passphrase, passphraseLength, m_hashVerifier=new HashVerifier(*m_mac, NULL, HashVerifier::PUT_MESSAGE), throwException));
}
DefaultDecryptor::State DefaultDecryptorWithMAC::CurrentState() const
{
return static_cast<const DefaultDecryptor *>(m_filter.get())->CurrentState();
}
bool DefaultDecryptorWithMAC::CheckLastMAC() const
{
return m_hashVerifier->GetLastResult();
}
void DefaultDecryptorWithMAC::LastPut(const byte *inString, size_t length)
{
m_filter->MessageEnd();
if (m_throwException && !CheckLastMAC())
throw MACBadErr();
}
NAMESPACE_END
|