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-rw-r--r--src/filters/modes/xts/xts.cpp208
-rw-r--r--src/filters/modes/xts/xts.h8
2 files changed, 129 insertions, 87 deletions
diff --git a/src/filters/modes/xts/xts.cpp b/src/filters/modes/xts/xts.cpp
index 67746d554..9615d26da 100644
--- a/src/filters/modes/xts/xts.cpp
+++ b/src/filters/modes/xts/xts.cpp
@@ -10,6 +10,8 @@
#include <algorithm>
#include <stdexcept>
+#include <stdio.h>
+
using namespace std::tr1::placeholders;
namespace Botan {
@@ -18,7 +20,7 @@ namespace {
void poly_double(byte tweak[], u32bit size)
{
- const byte polynomial = 0x87; // for 128 bit ciphers
+ const byte polynomial = (size == 16) ? 0x87 : 0x1B;
byte carry = 0;
for(u32bit i = 0; i != size; ++i)
@@ -41,9 +43,9 @@ XTS_Encryption::XTS_Encryption(BlockCipher* ciph) :
cipher(ciph),
buf_op(std::tr1::bind(&XTS_Encryption::xts_encrypt, this, _1, _2),
std::tr1::bind(&XTS_Encryption::xts_final, this, _1, _2),
- 2 * cipher->BLOCK_SIZE, 1)
+ 2 * cipher->BLOCK_SIZE, cipher->BLOCK_SIZE + 1)
{
- if(cipher->BLOCK_SIZE != 16)
+ if(cipher->BLOCK_SIZE != 8 && cipher->BLOCK_SIZE != 16)
throw std::invalid_argument("Bad cipher for XTS: " + cipher->name());
cipher2 = cipher->clone();
@@ -61,8 +63,8 @@ XTS_Encryption::XTS_Encryption(BlockCipher* ciph,
std::tr1::bind(&XTS_Encryption::xts_final, this, _1, _2),
2 * cipher->BLOCK_SIZE, cipher->BLOCK_SIZE + 1)
{
- if(cipher->BLOCK_SIZE != 16)
- throw std::invalid_argument("Bad cipher for XTS: " + cipher->name());
+ if(cipher->BLOCK_SIZE != 8 && cipher->BLOCK_SIZE != 16)
+ throw std::invalid_argument("Bad cipher for XTS: " + cipher->name());
cipher2 = cipher->clone();
tweak.resize(BOTAN_PARALLEL_BLOCKS_XTS * cipher->BLOCK_SIZE);
@@ -87,8 +89,19 @@ void XTS_Encryption::set_iv(const InitializationVector& iv)
if(iv.length() != cipher->BLOCK_SIZE)
throw Invalid_IV_Length(name(), iv.length());
- tweak = iv.bits_of();
+ const u32bit blocks_in_tweak = tweak.size() / cipher->BLOCK_SIZE;
+
+ tweak.copy(iv.begin(), iv.length());
cipher2->encrypt(tweak);
+
+ for(u32bit i = 1; i < blocks_in_tweak; ++i)
+ {
+ tweak.copy(i*cipher->BLOCK_SIZE,
+ tweak.begin() + (i-1)*cipher->BLOCK_SIZE,
+ cipher->BLOCK_SIZE);
+
+ poly_double(&tweak[i*cipher->BLOCK_SIZE], cipher->BLOCK_SIZE);
+ }
}
void XTS_Encryption::set_key(const SymmetricKey& key)
@@ -119,21 +132,39 @@ void XTS_Encryption::end_msg()
void XTS_Encryption::xts_encrypt(const byte input[], u32bit length)
{
+ const u32bit blocks_in_tweak = tweak.size() / cipher->BLOCK_SIZE;
u32bit blocks = length / cipher->BLOCK_SIZE;
- SecureVector<byte> temp(cipher->BLOCK_SIZE);
+ SecureVector<byte> temp(tweak.size());
- for(u32bit i = 0; i != blocks; ++i)
+ while(blocks)
{
- xor_buf(temp, input + i * cipher->BLOCK_SIZE, tweak,
- cipher->BLOCK_SIZE);
+ u32bit to_proc = std::min(blocks, blocks_in_tweak);
+ u32bit to_proc_bytes = to_proc * cipher->BLOCK_SIZE;
- cipher->encrypt(temp);
- xor_buf(temp, tweak, cipher->BLOCK_SIZE);
+ xor_buf(temp, input, tweak, to_proc_bytes);
- poly_double(tweak, cipher->BLOCK_SIZE);
+ cipher->encrypt_n(&temp[0], &temp[0], to_proc);
+
+ xor_buf(temp, tweak, to_proc_bytes);
+
+ send(temp, to_proc_bytes);
+
+ tweak.copy(&tweak[(to_proc-1)*cipher->BLOCK_SIZE],
+ cipher->BLOCK_SIZE);
+ poly_double(&tweak[0], cipher->BLOCK_SIZE);
+
+ for(u32bit i = 1; i < blocks_in_tweak; ++i)
+ {
+ tweak.copy(i*cipher->BLOCK_SIZE,
+ tweak.begin() + (i-1)*cipher->BLOCK_SIZE,
+ cipher->BLOCK_SIZE);
- send(temp, cipher->BLOCK_SIZE);
+ poly_double(&tweak[i*cipher->BLOCK_SIZE], cipher->BLOCK_SIZE);
+ }
+
+ input += to_proc * cipher->BLOCK_SIZE;
+ blocks -= to_proc;
}
}
@@ -142,7 +173,7 @@ void XTS_Encryption::xts_encrypt(const byte input[], u32bit length)
*/
void XTS_Encryption::xts_final(const byte input[], u32bit length)
{
- if(length < cipher->BLOCK_SIZE)
+ if(length <= cipher->BLOCK_SIZE)
throw Exception("XTS_Encryption: insufficient data to encrypt");
if(length % cipher->BLOCK_SIZE == 0)
@@ -175,13 +206,14 @@ void XTS_Encryption::xts_final(const byte input[], u32bit length)
/*
* XTS_Decryption constructor
*/
-XTS_Decryption::XTS_Decryption(BlockCipher* ciph)
+XTS_Decryption::XTS_Decryption(BlockCipher* ciph) :
+ buf_op(std::tr1::bind(&XTS_Decryption::buffered_proc_block, this, _1, _2),
+ std::tr1::bind(&XTS_Decryption::buffered_final, this, _1, _2),
+ 2 * ciph->BLOCK_SIZE, 1)
{
cipher = ciph;
cipher2 = ciph->clone();
- tweak.resize(cipher->BLOCK_SIZE);
- buffer.resize(2 * cipher->BLOCK_SIZE);
- position = 0;
+ tweak.resize(BOTAN_PARALLEL_BLOCKS_XTS * cipher->BLOCK_SIZE);
}
/*
@@ -189,13 +221,14 @@ XTS_Decryption::XTS_Decryption(BlockCipher* ciph)
*/
XTS_Decryption::XTS_Decryption(BlockCipher* ciph,
const SymmetricKey& key,
- const InitializationVector& iv)
+ const InitializationVector& iv) :
+ buf_op(std::tr1::bind(&XTS_Decryption::buffered_proc_block, this, _1, _2),
+ std::tr1::bind(&XTS_Decryption::buffered_final, this, _1, _2),
+ 2 * ciph->BLOCK_SIZE, 1)
{
cipher = ciph;
cipher2 = ciph->clone();
- tweak.resize(cipher->BLOCK_SIZE);
- buffer.resize(2 * cipher->BLOCK_SIZE);
- position = 0;
+ tweak.resize(BOTAN_PARALLEL_BLOCKS_XTS * cipher->BLOCK_SIZE);
set_key(key);
set_iv(iv);
@@ -214,11 +247,22 @@ std::string XTS_Decryption::name() const
*/
void XTS_Decryption::set_iv(const InitializationVector& iv)
{
- if(iv.length() != tweak.size())
+ if(iv.length() != cipher->BLOCK_SIZE)
throw Invalid_IV_Length(name(), iv.length());
- tweak = iv.bits_of();
+ const u32bit blocks_in_tweak = tweak.size() / cipher->BLOCK_SIZE;
+
+ tweak.copy(iv.begin(), iv.length());
cipher2->encrypt(tweak);
+
+ for(u32bit i = 1; i < blocks_in_tweak; ++i)
+ {
+ tweak.copy(i*cipher->BLOCK_SIZE,
+ tweak.begin() + (i-1)*cipher->BLOCK_SIZE,
+ cipher->BLOCK_SIZE);
+
+ poly_double(&tweak[i*cipher->BLOCK_SIZE], cipher->BLOCK_SIZE);
+ }
}
void XTS_Decryption::set_key(const SymmetricKey& key)
@@ -233,94 +277,90 @@ void XTS_Decryption::set_key(const SymmetricKey& key)
}
/*
-* Decrypt a block
+* Decrypt in XTS mode
*/
-void XTS_Decryption::decrypt(const byte block[])
+void XTS_Decryption::write(const byte input[], u32bit length)
{
- xor_buf(buffer, block, tweak, cipher->BLOCK_SIZE);
- cipher->decrypt(buffer);
- xor_buf(buffer, tweak, cipher->BLOCK_SIZE);
-
- poly_double(tweak, cipher->BLOCK_SIZE);
-
- send(buffer, cipher->BLOCK_SIZE);
+ buf_op.write(input, length);
}
/*
-* Decrypt in XTS mode
+* Finish decrypting in XTS mode
*/
-void XTS_Decryption::write(const byte input[], u32bit length)
+void XTS_Decryption::end_msg()
{
- const u32bit BLOCK_SIZE = cipher->BLOCK_SIZE;
+ buf_op.final();
+ }
- u32bit copied = std::min(buffer.size() - position, length);
- buffer.copy(position, input, copied);
- length -= copied;
- input += copied;
- position += copied;
+void XTS_Decryption::buffered_proc_block(const byte input[], u32bit input_length)
+ {
+ const u32bit blocks_in_tweak = tweak.size() / cipher->BLOCK_SIZE;
+ u32bit blocks = input_length / cipher->BLOCK_SIZE;
- if(length == 0) return;
+ SecureVector<byte> temp(tweak.size());
- decrypt(buffer);
- if(length > BLOCK_SIZE)
+ while(blocks)
{
- decrypt(buffer + BLOCK_SIZE);
- while(length > 2*BLOCK_SIZE)
+ u32bit to_proc = std::min(blocks, blocks_in_tweak);
+ u32bit to_proc_bytes = to_proc * cipher->BLOCK_SIZE;
+
+ xor_buf(temp, input, tweak, to_proc_bytes);
+
+ cipher->decrypt_n(&temp[0], &temp[0], to_proc);
+
+ xor_buf(temp, tweak, to_proc_bytes);
+
+ send(temp, to_proc_bytes);
+
+ tweak.copy(&tweak[(to_proc-1)*cipher->BLOCK_SIZE],
+ cipher->BLOCK_SIZE);
+ poly_double(&tweak[0], cipher->BLOCK_SIZE);
+
+ for(u32bit i = 1; i < blocks_in_tweak; ++i)
{
- decrypt(input);
- length -= BLOCK_SIZE;
- input += BLOCK_SIZE;
+ tweak.copy(i*cipher->BLOCK_SIZE,
+ tweak.begin() + (i-1)*cipher->BLOCK_SIZE,
+ cipher->BLOCK_SIZE);
+
+ poly_double(&tweak[i*cipher->BLOCK_SIZE], cipher->BLOCK_SIZE);
}
- position = 0;
- }
- else
- {
- copy_mem(buffer.begin(), buffer + BLOCK_SIZE, BLOCK_SIZE);
- position = BLOCK_SIZE;
+
+ input += to_proc * cipher->BLOCK_SIZE;
+ blocks -= to_proc;
}
- buffer.copy(position, input, length);
- position += length;
}
-/*
-* Finish decrypting in XTS mode
-*/
-void XTS_Decryption::end_msg()
+void XTS_Decryption::buffered_final(const byte input[], u32bit input_length)
{
- const u32bit BLOCK_SIZE = cipher->BLOCK_SIZE;
-
- if(position < BLOCK_SIZE)
+ if(input_length <= cipher->BLOCK_SIZE)
throw Exception("XTS_Decryption: insufficient data to decrypt");
- else if(position == BLOCK_SIZE)
- {
- decrypt(buffer);
- }
- else if(position == 2*BLOCK_SIZE)
+
+ if(input_length % cipher->BLOCK_SIZE == 0)
{
- decrypt(buffer);
- decrypt(buffer + BLOCK_SIZE);
+ buffered_proc_block(input, input_length);
}
else
{
- SecureVector<byte> tweak2 = tweak;
+ SecureVector<byte> temp(input, input_length);
+ SecureVector<byte> tweak_copy(&tweak[0], cipher->BLOCK_SIZE);
- poly_double(tweak2, cipher->BLOCK_SIZE);
+ poly_double(tweak_copy, cipher->BLOCK_SIZE);
- xor_buf(buffer, tweak2, cipher->BLOCK_SIZE);
- cipher->decrypt(buffer);
- xor_buf(buffer, tweak2, cipher->BLOCK_SIZE);
+ xor_buf(temp, tweak_copy, cipher->BLOCK_SIZE);
+ cipher->decrypt(temp);
+ xor_buf(temp, tweak_copy, cipher->BLOCK_SIZE);
- for(u32bit i = 0; i != position - cipher->BLOCK_SIZE; ++i)
- std::swap(buffer[i], buffer[i + cipher->BLOCK_SIZE]);
+ for(u32bit i = 0; i != input_length - cipher->BLOCK_SIZE; ++i)
+ std::swap(temp[i], temp[i + cipher->BLOCK_SIZE]);
- xor_buf(buffer, tweak, cipher->BLOCK_SIZE);
- cipher->decrypt(buffer);
- xor_buf(buffer, tweak, cipher->BLOCK_SIZE);
+ xor_buf(temp, tweak, cipher->BLOCK_SIZE);
+ cipher->decrypt(temp);
+ xor_buf(temp, tweak, cipher->BLOCK_SIZE);
- send(buffer, position);
+ send(temp, input_length);
}
- position = 0;
+ buf_op.reset();
}
}
diff --git a/src/filters/modes/xts/xts.h b/src/filters/modes/xts/xts.h
index 3abe6be3e..4ee00efe7 100644
--- a/src/filters/modes/xts/xts.h
+++ b/src/filters/modes/xts/xts.h
@@ -71,13 +71,15 @@ class BOTAN_DLL XTS_Decryption : public Keyed_Filter
private:
void write(const byte[], u32bit);
void end_msg();
- void decrypt(const byte[]);
+
+ void buffered_proc_block(const byte input[], u32bit input_length);
+ void buffered_final(const byte input[], u32bit input_length);
BlockCipher* cipher;
BlockCipher* cipher2;
SecureVector<byte> tweak;
- SecureVector<byte> buffer;
- u32bit position;
+
+ Buffered_Operation buf_op;
};
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-28 07:29:45 +0000