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/*
* ECB Mode
* (C) 1999-2007 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#include <botan/ecb.h>
namespace Botan {
namespace {
const u32bit PARALLEL_BLOCKS = BOTAN_PARALLEL_BLOCKS_ECB;
}
/*
* ECB_Encryption Constructor
*/
ECB_Encryption::ECB_Encryption(BlockCipher* ciph,
BlockCipherModePaddingMethod* pad)
{
cipher = ciph;
padder = pad;
plaintext.resize(cipher->BLOCK_SIZE);
ciphertext.resize(cipher->BLOCK_SIZE * PARALLEL_BLOCKS);
position = 0;
}
/*
* ECB_Encryption Constructor
*/
ECB_Encryption::ECB_Encryption(BlockCipher* ciph,
BlockCipherModePaddingMethod* pad,
const SymmetricKey& key)
{
cipher = ciph;
padder = pad;
plaintext.resize(cipher->BLOCK_SIZE);
ciphertext.resize(cipher->BLOCK_SIZE * PARALLEL_BLOCKS);
position = 0;
cipher->set_key(key);
}
/*
* ECB_Encryption Destructor
*/
ECB_Encryption::~ECB_Encryption()
{
delete cipher;
delete padder;
}
/*
* Return an ECB mode name
*/
std::string ECB_Encryption::name() const
{
return (cipher->name() + "/ECB/" + padder->name());
}
/*
* Encrypt in ECB mode
*/
void ECB_Encryption::write(const byte input[], u32bit length)
{
const u32bit BLOCK_SIZE = cipher->BLOCK_SIZE;
if(position)
{
plaintext.copy(position, input, length);
if(position + length >= BLOCK_SIZE)
{
cipher->encrypt(plaintext, ciphertext);
send(ciphertext, BLOCK_SIZE);
input += (BLOCK_SIZE - position);
length -= (BLOCK_SIZE - position);
position = 0;
}
}
while(length >= BLOCK_SIZE)
{
const u32bit to_proc =
std::min<u32bit>(length, ciphertext.size()) / BLOCK_SIZE;
cipher->encrypt_n(input, ciphertext, to_proc);
send(ciphertext, to_proc * BLOCK_SIZE);
input += to_proc * BLOCK_SIZE;
length -= to_proc * BLOCK_SIZE;
}
plaintext.copy(position, input, length);
position += length;
}
/*
* Finish encrypting in ECB mode
*/
void ECB_Encryption::end_msg()
{
const u32bit BLOCK_SIZE = cipher->BLOCK_SIZE;
SecureVector<byte> padding(BLOCK_SIZE);
padder->pad(padding, padding.size(), position);
write(padding, padder->pad_bytes(BLOCK_SIZE, position));
if(position != 0)
throw Encoding_Error(name() + ": Did not pad to full blocksize");
}
/*
* ECB_Decryption Constructor
*/
ECB_Decryption::ECB_Decryption(BlockCipher* ciph,
BlockCipherModePaddingMethod* pad)
{
cipher = ciph;
padder = pad;
ciphertext.resize(cipher->BLOCK_SIZE);
plaintext.resize(cipher->BLOCK_SIZE * PARALLEL_BLOCKS);
position = 0;
}
/*
* ECB_Decryption Constructor
*/
ECB_Decryption::ECB_Decryption(BlockCipher* ciph,
BlockCipherModePaddingMethod* pad,
const SymmetricKey& key)
{
cipher = ciph;
padder = pad;
ciphertext.resize(cipher->BLOCK_SIZE);
plaintext.resize(cipher->BLOCK_SIZE * PARALLEL_BLOCKS);
position = 0;
cipher->set_key(key);
}
/*
* ECB_Decryption Destructor
*/
ECB_Decryption::~ECB_Decryption()
{
delete cipher;
delete padder;
}
/*
* Return an ECB mode name
*/
std::string ECB_Decryption::name() const
{
return (cipher->name() + "/ECB/" + padder->name());
}
/*
* Decrypt in ECB mode
*/
void ECB_Decryption::write(const byte input[], u32bit length)
{
const u32bit BLOCK_SIZE = cipher->BLOCK_SIZE;
if(position)
{
ciphertext.copy(position, input, length);
if(position + length > BLOCK_SIZE)
{
cipher->decrypt(ciphertext, plaintext);
send(plaintext, BLOCK_SIZE);
input += (BLOCK_SIZE - position);
length -= (BLOCK_SIZE - position);
position = 0;
}
}
while(length > BLOCK_SIZE)
{
/* Always leave at least 1 byte left over, to ensure that (as long
as the input message actually is a multiple of the block size)
we will have the full final block left over in end_msg so as
to remove the padding
*/
const u32bit to_proc =
std::min<u32bit>(length - 1, plaintext.size()) / BLOCK_SIZE;
cipher->decrypt_n(input, plaintext, to_proc);
send(plaintext, to_proc * BLOCK_SIZE);
input += to_proc * BLOCK_SIZE;
length -= to_proc * BLOCK_SIZE;
}
ciphertext.copy(position, input, length);
position += length;
}
/*
* Finish decrypting in ECB mode
*/
void ECB_Decryption::end_msg()
{
if(position != cipher->BLOCK_SIZE)
throw Decoding_Error(name());
cipher->decrypt(ciphertext);
send(ciphertext, padder->unpad(ciphertext, cipher->BLOCK_SIZE));
position = 0;
}
}
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