208 lines
8.3 KiB
C++
208 lines
8.3 KiB
C++
// chachapoly.cpp - written and placed in the public domain by Jeffrey Walton
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// RFC 8439, Section 2.8, AEAD Construction, http://tools.ietf.org/html/rfc8439
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#include "pch.h"
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#include "chachapoly.h"
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#include "algparam.h"
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#include "misc.h"
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NAMESPACE_BEGIN(CryptoPP)
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////////////////////////////// IETF ChaChaTLS //////////////////////////////
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// RekeyCipherAndMac is heavier-weight than we like. The Authenc framework was
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// predicated on BlockCiphers, where the key and key schedule could be
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// calculated independent of the IV being used. However, the ChaCha and
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// ChaCha20Poly1305 construction combines key setup and IV. That is, both are
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// needed to key or rekey the cipher. Even a simple Resync() requires us to
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// regenerate the initial state for both ChaCha20 and Poly1305.
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void ChaCha20Poly1305_Base::RekeyCipherAndMac(const byte *userKey, size_t keylength, const NameValuePairs ¶ms)
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{
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// Derive MAC key
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AlgorithmParameters block0 = MakeParameters("InitialBlock", (word64)0, true);
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AccessSymmetricCipher().SetKey(userKey, keylength, CombinedNameValuePairs(params, block0));
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// Only the first 256-bits are used to key the MAC
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SecByteBlock derived(NULLPTR, 32);
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AccessSymmetricCipher().ProcessString(derived, derived.size());
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// Key the Poly1305 MAC
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AccessMAC().SetKey(derived, derived.size(), params);
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// Key the ChaCha20 cipher
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AlgorithmParameters block1 = MakeParameters("InitialBlock", (word64)1, true);
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AccessSymmetricCipher().SetKey(userKey, keylength, CombinedNameValuePairs(params, block1));
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}
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void ChaCha20Poly1305_Base::SetKeyWithoutResync(const byte *userKey, size_t userKeyLength, const NameValuePairs ¶ms)
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{
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CRYPTOPP_ASSERT(userKey && userKeyLength == 32);
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m_userKey.Assign(userKey, userKeyLength);
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// ChaCha/Poly1305 initial state depends on both the key and IV. The
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// IV may or may not be present during the call to SetKeyWithoutResync.
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// If the IV is present, the framework will call SetKeyWithoutResync
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// followed by Resynchronize which calls Resync. In this case we defer
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// calculating the initial state until the call to Resynchronize.
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// If the IV is not present, it avoids calling ChaCha's SetKey without
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// an IV, which results in an exception. In this case the user will need
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// to call Resynchronize to key ChaCha and Poly1305.
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// RekeyCipherAndMac(userKey, userKeyLength, params);
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CRYPTOPP_UNUSED(params);
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}
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void ChaCha20Poly1305_Base::Resync(const byte *iv, size_t len)
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{
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CRYPTOPP_ASSERT(iv && len == 12);
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RekeyCipherAndMac(m_userKey, m_userKey.SizeInBytes(),
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MakeParameters(Name::IV(), ConstByteArrayParameter(iv,len)));
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}
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size_t ChaCha20Poly1305_Base::AuthenticateBlocks(const byte *data, size_t len)
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{
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AccessMAC().Update(data, len);
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return 0;
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}
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void ChaCha20Poly1305_Base::AuthenticateLastHeaderBlock()
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{
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// Pad to a multiple of 16 or 0
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const byte zero[16] = {0};
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size_t pad = (16 - (m_totalHeaderLength % 16)) % 16;
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AccessMAC().Update(zero, pad);
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}
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void ChaCha20Poly1305_Base::AuthenticateLastConfidentialBlock()
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{
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// Pad to a multiple of 16 or 0
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const byte zero[16] = {0};
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size_t pad = (16 - (m_totalMessageLength % 16)) % 16;
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AccessMAC().Update(zero, pad);
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}
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void ChaCha20Poly1305_Base::AuthenticateLastFooterBlock(byte *mac, size_t macSize)
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{
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CRYPTOPP_ALIGN_DATA(8) byte length[2*sizeof(word64)];
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PutWord(true, LITTLE_ENDIAN_ORDER, length+0, m_totalHeaderLength);
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PutWord(true, LITTLE_ENDIAN_ORDER, length+8, m_totalMessageLength);
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AccessMAC().Update(length, sizeof(length));
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AccessMAC().TruncatedFinal(mac, macSize);
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m_state = State_KeySet;
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}
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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)
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{
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Resynchronize(iv, ivLength);
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Update(aad, aadLength);
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ProcessString(ciphertext, message, messageLength);
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TruncatedFinal(mac, macSize);
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}
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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)
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{
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Resynchronize(iv, ivLength);
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Update(aad, aadLength);
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ProcessString(message, ciphertext, ciphertextLength);
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return TruncatedVerify(mac, macLength);
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}
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////////////////////////////// IETF XChaCha20 draft //////////////////////////////
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// RekeyCipherAndMac is heavier-weight than we like. The Authenc framework was
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// predicated on BlockCiphers, where the key and key schedule could be
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// calculated independent of the IV being used. However, the ChaCha and
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// ChaCha20Poly1305 construction combines key setup and IV. That is, both are
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// needed to key or rekey the cipher. Even a simple Resync() requires us to
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// regenerate the initial state for both ChaCha20 and Poly1305.
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void XChaCha20Poly1305_Base::RekeyCipherAndMac(const byte *userKey, size_t keylength, const NameValuePairs ¶ms)
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{
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// Derive MAC key
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AlgorithmParameters block0 = MakeParameters("InitialBlock", (word64)0, true);
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AccessSymmetricCipher().SetKey(userKey, keylength, CombinedNameValuePairs(params, block0));
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// Only the first 256-bits are used to key the MAC
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SecByteBlock derived(NULLPTR, 32);
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AccessSymmetricCipher().ProcessString(derived, derived.size());
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// Key the Poly1305 MAC
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AccessMAC().SetKey(derived, derived.size(), params);
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// Key the ChaCha20 cipher
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AlgorithmParameters block1 = MakeParameters("InitialBlock", (word64)1, true);
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AccessSymmetricCipher().SetKey(userKey, keylength, CombinedNameValuePairs(params, block1));
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}
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void XChaCha20Poly1305_Base::SetKeyWithoutResync(const byte *userKey, size_t userKeyLength, const NameValuePairs ¶ms)
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{
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CRYPTOPP_ASSERT(userKey && userKeyLength == 32);
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m_userKey.Assign(userKey, userKeyLength);
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// XChaCha20/Poly1305 initial state depends on both the key and IV. The
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// IV may or may not be present during the call to SetKeyWithoutResync.
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// If the IV is present, the framework will call SetKeyWithoutResync
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// followed by Resynchronize which calls Resync. In this case we defer
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// calculating the initial state until the call to Resynchronize.
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// If the IV is not present, it avoids calling ChaCha's SetKey without
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// an IV, which results in an exception. In this case the user will need
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// to call Resynchronize to key ChaCha and Poly1305.
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// RekeyCipherAndMac(userKey, userKeyLength, params);
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CRYPTOPP_UNUSED(params);
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}
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void XChaCha20Poly1305_Base::Resync(const byte *iv, size_t len)
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{
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CRYPTOPP_ASSERT(iv && len == 24);
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RekeyCipherAndMac(m_userKey, m_userKey.SizeInBytes(),
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MakeParameters(Name::IV(), ConstByteArrayParameter(iv,len)));
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}
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size_t XChaCha20Poly1305_Base::AuthenticateBlocks(const byte *data, size_t len)
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{
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AccessMAC().Update(data, len);
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return 0;
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}
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void XChaCha20Poly1305_Base::AuthenticateLastHeaderBlock()
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{
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// Pad to a multiple of 16 or 0
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const byte zero[16] = {0};
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size_t pad = (16 - (m_totalHeaderLength % 16)) % 16;
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AccessMAC().Update(zero, pad);
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}
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void XChaCha20Poly1305_Base::AuthenticateLastConfidentialBlock()
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{
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// Pad to a multiple of 16 or 0
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const byte zero[16] = {0};
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size_t pad = (16 - (m_totalMessageLength % 16)) % 16;
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AccessMAC().Update(zero, pad);
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}
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void XChaCha20Poly1305_Base::AuthenticateLastFooterBlock(byte *mac, size_t macSize)
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{
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CRYPTOPP_ALIGN_DATA(8) byte length[2*sizeof(word64)];
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PutWord(true, LITTLE_ENDIAN_ORDER, length+0, m_totalHeaderLength);
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PutWord(true, LITTLE_ENDIAN_ORDER, length+8, m_totalMessageLength);
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AccessMAC().Update(length, sizeof(length));
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AccessMAC().TruncatedFinal(mac, macSize);
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m_state = State_KeySet;
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}
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void XChaCha20Poly1305_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)
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{
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Resynchronize(iv, ivLength);
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Update(aad, aadLength);
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ProcessString(ciphertext, message, messageLength);
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TruncatedFinal(mac, macSize);
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}
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bool XChaCha20Poly1305_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)
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{
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Resynchronize(iv, ivLength);
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Update(aad, aadLength);
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ProcessString(message, ciphertext, ciphertextLength);
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return TruncatedVerify(mac, macLength);
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}
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NAMESPACE_END
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