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/*
* ECB Mode
* (C) 1999-2009,2013 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#include <botan/ecb.h>
#include <botan/loadstor.h>
#include <botan/internal/xor_buf.h>
#include <botan/internal/rounding.h>
namespace Botan {
ECB_Mode::ECB_Mode(BlockCipher* cipher, BlockCipherModePaddingMethod* padding) :
m_cipher(cipher),
m_padding(padding)
{
if(!m_padding->valid_blocksize(cipher->block_size()))
throw std::invalid_argument("Padding " + m_padding->name() +
" cannot be used with " +
cipher->name() + "/ECB");
}
void ECB_Mode::clear()
{
m_cipher->clear();
}
std::string ECB_Mode::name() const
{
return cipher().name() + "/ECB/" + padding().name();
}
size_t ECB_Mode::update_granularity() const
{
return cipher().parallel_bytes();
}
Key_Length_Specification ECB_Mode::key_spec() const
{
return cipher().key_spec();
}
size_t ECB_Mode::default_nonce_size() const
{
return 0;
}
bool ECB_Mode::valid_nonce_length(size_t n) const
{
return (n == 0);
}
void ECB_Mode::key_schedule(const byte key[], size_t length)
{
m_cipher->set_key(key, length);
}
secure_vector<byte> ECB_Mode::start(const byte nonce[], size_t nonce_len)
{
if(!valid_nonce_length(nonce_len))
throw Invalid_IV_Length(name(), nonce_len);
return secure_vector<byte>();
}
size_t ECB_Encryption::minimum_final_size() const
{
return 0;
}
size_t ECB_Encryption::output_length(size_t input_length) const
{
return round_up(input_length, cipher().block_size());
}
void ECB_Encryption::update(secure_vector<byte>& buffer, size_t offset)
{
BOTAN_ASSERT(buffer.size() >= offset, "Offset is sane");
const size_t sz = buffer.size() - offset;
byte* buf = &buffer[offset];
const size_t BS = cipher().block_size();
BOTAN_ASSERT(sz % BS == 0, "ECB input is full blocks");
const size_t blocks = sz / BS;
cipher().encrypt_n(&buf[0], &buf[0], blocks);
}
void ECB_Encryption::finish(secure_vector<byte>& buffer, size_t offset)
{
BOTAN_ASSERT(buffer.size() >= offset, "Offset is sane");
const size_t sz = buffer.size() - offset;
//byte* buf = &buffer[offset];
const size_t BS = cipher().block_size();
const size_t bytes_in_final_block = sz % BS;
const size_t pad_bytes = padding().pad_bytes(BS, bytes_in_final_block);
if((pad_bytes + bytes_in_final_block) % BS)
throw std::runtime_error("Did not pad to full block size in " + name());
#if 0
const size_t pad_offset = buffer.size();
//buffer.resize(checked_add(buffer.size() + pad_bytes));
buffer.resize(buffer.size() + pad_bytes);
padder().pad(&buffer[pad_offset], BS, bytes_in_final_block);
#else
std::vector<byte> pad(BS);
padding().pad(&pad[0], BS, bytes_in_final_block);
buffer.insert(buffer.end(), pad.begin(), pad.begin() + pad_bytes);
#endif
update(buffer, offset);
}
size_t ECB_Decryption::output_length(size_t input_length) const
{
return input_length;
}
size_t ECB_Decryption::minimum_final_size() const
{
return cipher().block_size();
}
void ECB_Decryption::update(secure_vector<byte>& buffer, size_t offset)
{
BOTAN_ASSERT(buffer.size() >= offset, "Offset is sane");
const size_t sz = buffer.size() - offset;
byte* buf = &buffer[offset];
const size_t BS = cipher().block_size();
BOTAN_ASSERT(sz % BS == 0, "Input is full blocks");
size_t blocks = sz / BS;
cipher().decrypt_n(&buf[0], &buf[0], blocks);
}
void ECB_Decryption::finish(secure_vector<byte>& buffer, size_t offset)
{
BOTAN_ASSERT(buffer.size() >= offset, "Offset is sane");
const size_t sz = buffer.size() - offset;
const size_t BS = cipher().block_size();
if(sz == 0 || sz % BS)
throw Decoding_Error(name() + ": Ciphertext not a multiple of block size");
update(buffer, offset);
const size_t pad_bytes = BS - padding().unpad(&buffer[buffer.size()-BS], BS);
buffer.resize(buffer.size() - pad_bytes); // remove padding
}
}
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