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Update documentation

pull/794/head
Jeffrey Walton 2019-02-06 00:52:41 -05:00
parent df8abd5f00
commit 483bb4a8e7
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GPG Key ID: B36AB348921B1838
2 changed files with 28 additions and 19 deletions
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29
chacha.cpp
View File

@ -39,6 +39,7 @@ void ChaCha_TestInstantiations()
{
ChaCha::Encryption x;
ChaChaTLS::Encryption y;
XChaCha20::Encryption z;
}
#endif
@ -424,19 +425,14 @@ void ChaChaTLS_Policy::CipherSetKey(const NameValuePairs &params, const byte *ke
// the function, so we have to use the heavier-weight SetKey to change it.
word64 block;
if (params.GetValue("InitialBlock", block))
m_state[16] = static_cast<word32>(block);
m_state[CTR] = static_cast<word32>(block);
else
m_state[16] = 0;
// State words are defined in RFC 8439, Section 2.3.
m_state[0] = 0x61707865;
m_state[1] = 0x3320646e;
m_state[2] = 0x79622d32;
m_state[3] = 0x6b206574;
m_state[CTR] = 0;
// State words are defined in RFC 8439, Section 2.3. Key is 32-bytes.
GetBlock<word32, LittleEndian> get(key);
get(m_state[4])(m_state[5])(m_state[6])(m_state[7])(m_state[8])(m_state[9])(m_state[10])(m_state[11]);
get(m_state[KEY+0])(m_state[KEY+1])(m_state[KEY+2])(m_state[KEY+3])
(m_state[KEY+4])(m_state[KEY+5])(m_state[KEY+6])(m_state[KEY+7]);
}
void ChaChaTLS_Policy::CipherResynchronize(byte *keystreamBuffer, const byte *IV, size_t length)
@ -444,9 +440,16 @@ void ChaChaTLS_Policy::CipherResynchronize(byte *keystreamBuffer, const byte *IV
CRYPTOPP_UNUSED(keystreamBuffer), CRYPTOPP_UNUSED(length);
CRYPTOPP_ASSERT(length==12);
// State words are defined in RFC 8439, Section 2.3.
m_state[0] = 0x61707865; m_state[1] = 0x3320646e;
m_state[2] = 0x79622d32; m_state[3] = 0x6b206574;
// Copy saved key into state
std::memcpy(m_state+4, m_state+KEY, 8*sizeof(word32));
// State words are defined in RFC 8439, Section 2.3
GetBlock<word32, LittleEndian> get(IV);
m_state[12] = m_state[16];
m_state[12] = m_state[CTR];
get(m_state[13])(m_state[14])(m_state[15]);
}
@ -510,9 +513,9 @@ void XChaCha20_Policy::CipherSetKey(const NameValuePairs &params, const byte *ke
word64 block;
if (params.GetValue("InitialBlock", block))
m_state[24] = static_cast<word32>(block);
m_state[CTR] = static_cast<word32>(block);
else
m_state[24] = 1;
m_state[CTR] = 1;
// Stash key away for use in CipherResynchronize
GetBlock<word32, LittleEndian> get(key);
@ -545,7 +548,7 @@ void XChaCha20_Policy::CipherResynchronize(byte *keystreamBuffer, const byte *iv
m_state[2] = 0x79622d32; m_state[3] = 0x6b206574;
// Setup new IV
m_state[12] = m_state[24];
m_state[12] = m_state[CTR];
m_state[13] = 0;
m_state[14] = GetWord<word32>(false, LITTLE_ENDIAN_ORDER, iv+16);
m_state[15] = GetWord<word32>(false, LITTLE_ENDIAN_ORDER, iv+20);

18
chacha.h
View File

@ -5,10 +5,10 @@
// The library added Bernstein's ChaCha classses at Crypto++ 5.6.4. The IETF
// uses a slightly different implementation than Bernstein, and the IETF
// classes were added at Crypto++ 8.1. We wanted to maintain ABI compatibility
// at the 8.1 release so the original ChaCha classes were not disturbed.
// Instead new classes were added for IETF ChaCha. The back-end implementation
// shares code as expected, however.
// ChaCha and XChaCha classes were added at Crypto++ 8.1. We wanted to maintain
// ABI compatibility at the 8.1 release so the original ChaCha classes were not
// disturbed. Instead new classes were added for IETF ChaCha. The back-end
// implementation shares code as expected, however.
/// \file chacha.h
/// \brief Classes for ChaCha8, ChaCha12 and ChaCha20 stream ciphers
@ -20,7 +20,10 @@
/// implementation for cipher suites
/// <tt>TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256</tt>,
/// <tt>TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256</tt>,
/// and <tt>TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256</tt>.
/// and <tt>TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256</tt>. Finally,
/// the library provides <a
/// href="https://tools.ietf.org/html/draft-arciszewski-xchacha">XChaCha:
/// eXtended-nonce ChaCha and AEAD_XChaCha20_Poly1305 (rev. 03)</a>.
/// \since ChaCha since Crypto++ 5.6.4, ChaChaTLS and XChaCha20 since Crypto++ 8.1
#ifndef CRYPTOPP_CHACHA_H
@ -125,8 +128,10 @@ protected:
std::string AlgorithmName() const;
std::string AlgorithmProvider() const;
FixedSizeAlignedSecBlock<word32, 16+1> m_state;
FixedSizeAlignedSecBlock<word32, 16+8+1> m_state;
CRYPTOPP_CONSTANT(ROUNDS = ChaChaTLS_Info::ROUNDS)
CRYPTOPP_CONSTANT(KEY = 16) // Index into m_state
CRYPTOPP_CONSTANT(CTR = 24) // Index into m_state
};
/// \brief ChaCha-TLS stream cipher
@ -191,6 +196,7 @@ protected:
FixedSizeAlignedSecBlock<word32, 16+8+1> m_state;
CRYPTOPP_CONSTANT(ROUNDS = XChaCha20_Info::ROUNDS)
CRYPTOPP_CONSTANT(KEY = 16) // Index into m_state
CRYPTOPP_CONSTANT(CTR = 24) // Index into m_state
};
/// \brief XChaCha stream cipher