Update documentation

1 files changed, 5 insertions, 10 deletions

diff --git a/chachapoly.cpp b/chachapoly.cpp
index ee49b4e6..6d4d395e 100644
--- a/chachapoly.cpp
+++ b/chachapoly.cpp
@@ -14,14 +14,14 @@ void ChaCha20Poly1305_Base::RekeyCipherAndMac(const byte *userKey, size_t keylen
 	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

+	// Only the first 256-bits are used to key the MAC

 	SecByteBlock derived(NULLPTR, 32);

 	AccessSymmetricCipher().ProcessString(derived, derived.size());

 

-	// Set the Poly1305 key

+	// Key the Poly1305 MAC

 	AccessMAC().SetKey(derived, derived.size(), params);

 

-	// Key Cipher for bulk encryption

+	// Key the ChaCha20 cipher

 	AlgorithmParameters block1 = MakeParameters("InitialBlock", (word64)1, true);

 	AccessSymmetricCipher().SetKey(userKey, keylength, CombinedNameValuePairs(params, block1));

 }

@@ -30,14 +30,12 @@ void ChaCha20Poly1305_Base::SetKeyWithoutResync(const byte *userKey, size_t user
 {

 	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)));

 }

@@ -52,8 +50,7 @@ void ChaCha20Poly1305_Base::AuthenticateLastHeaderBlock()
 {

 	// Pad to a multiple of 16 or 0

 	const byte zero[16] = {0};

-	size_t rem = m_totalHeaderLength % 16;

-	size_t pad = rem ? 16 - rem : 0;

+	size_t pad = (16 - (m_totalHeaderLength % 16)) % 16;

 	AccessMAC().Update(zero, pad);

 }

 

@@ -61,8 +58,7 @@ void ChaCha20Poly1305_Base::AuthenticateLastConfidentialBlock()
 {

 	// Pad to a multiple of 16 or 0

 	const byte zero[16] = {0};

-	size_t rem = m_totalMessageLength % 16;

-	size_t pad = rem ? 16 - rem : 0;

+	size_t pad = (16 - (m_totalMessageLength % 16)) % 16;

 	AccessMAC().Update(zero, pad);

 }

 

@@ -72,7 +68,6 @@ void ChaCha20Poly1305_Base::AuthenticateLastFooterBlock(byte *mac, size_t macSiz
 	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);

 }