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/*
* Cipher Modes via OpenSSL
* (C) 1999-2010,2015 Jack Lloyd
* (C) 2017 Alexander Bluhm (genua GmbH)
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/cipher_mode.h>
#include <botan/internal/rounding.h>
#include <botan/internal/openssl.h>
#include <openssl/evp.h>
#include <limits.h>
namespace Botan {
namespace {
class OpenSSL_Cipher_Mode final : public Cipher_Mode
{
public:
OpenSSL_Cipher_Mode(const std::string& name,
const EVP_CIPHER* cipher,
Cipher_Dir direction);
~OpenSSL_Cipher_Mode();
std::string provider() const override { return "openssl"; }
std::string name() const override { return m_mode_name; }
void start_msg(const uint8_t nonce[], size_t nonce_len) override;
size_t process(uint8_t msg[], size_t msg_len) override;
void finish(secure_vector<uint8_t>& final_block, size_t offset0) override;
size_t output_length(size_t input_length) const override;
size_t update_granularity() const override;
size_t minimum_final_size() const override;
size_t default_nonce_length() const override;
bool valid_nonce_length(size_t nonce_len) const override;
void clear() override;
void reset() override;
Key_Length_Specification key_spec() const override;
private:
void key_schedule(const uint8_t key[], size_t length) override;
const std::string m_mode_name;
const Cipher_Dir m_direction;
size_t m_block_size;
EVP_CIPHER_CTX* m_cipher;
bool m_key_set;
bool m_nonce_set;
};
OpenSSL_Cipher_Mode::OpenSSL_Cipher_Mode(const std::string& name,
const EVP_CIPHER* algo,
Cipher_Dir direction) :
m_mode_name(name),
m_direction(direction),
m_key_set(false),
m_nonce_set(false)
{
m_block_size = EVP_CIPHER_block_size(algo);
if(EVP_CIPHER_mode(algo) != EVP_CIPH_CBC_MODE)
throw Invalid_Argument("OpenSSL_BlockCipher: Non-CBC EVP was passed in");
m_cipher = EVP_CIPHER_CTX_new();
if (m_cipher == nullptr)
throw OpenSSL_Error("Can't allocate new context", ERR_get_error());
EVP_CIPHER_CTX_init(m_cipher);
if(!EVP_CipherInit_ex(m_cipher, algo, nullptr, nullptr, nullptr,
m_direction == ENCRYPTION ? 1 : 0))
throw OpenSSL_Error("EVP_CipherInit_ex", ERR_get_error());
if(!EVP_CIPHER_CTX_set_padding(m_cipher, 0))
throw OpenSSL_Error("EVP_CIPHER_CTX_set_padding", ERR_get_error());
}
OpenSSL_Cipher_Mode::~OpenSSL_Cipher_Mode()
{
EVP_CIPHER_CTX_free(m_cipher);
}
void OpenSSL_Cipher_Mode::start_msg(const uint8_t nonce[], size_t nonce_len)
{
verify_key_set(m_key_set);
if(!valid_nonce_length(nonce_len))
throw Invalid_IV_Length(name(), nonce_len);
if(nonce_len)
{
if(!EVP_CipherInit_ex(m_cipher, nullptr, nullptr, nullptr, nonce, -1))
throw OpenSSL_Error("EVP_CipherInit_ex nonce", ERR_get_error());
}
else if(m_nonce_set == false)
{
const std::vector<uint8_t> zeros(m_block_size);
if(!EVP_CipherInit_ex(m_cipher, nullptr, nullptr, nullptr, zeros.data(), -1))
throw OpenSSL_Error("EVP_CipherInit_ex nonce", ERR_get_error());
}
// otherwise existing CBC state left unchanged
m_nonce_set = true;
}
size_t OpenSSL_Cipher_Mode::process(uint8_t msg[], size_t msg_len)
{
verify_key_set(m_key_set);
BOTAN_STATE_CHECK(m_nonce_set);
if(msg_len == 0)
return 0;
if(msg_len > INT_MAX)
throw Internal_Error("msg_len overflow");
int outl = msg_len;
secure_vector<uint8_t> out(outl);
if(!EVP_CipherUpdate(m_cipher, out.data(), &outl, msg, msg_len))
throw OpenSSL_Error("EVP_CipherUpdate", ERR_get_error());
copy_mem(msg, out.data(), outl);
return outl;
}
void OpenSSL_Cipher_Mode::finish(secure_vector<uint8_t>& buffer,
size_t offset)
{
verify_key_set(m_key_set);
BOTAN_STATE_CHECK(m_nonce_set);
BOTAN_ASSERT(buffer.size() >= offset, "Offset ok");
uint8_t* buf = buffer.data() + offset;
const size_t buf_size = buffer.size() - offset;
size_t written = process(buf, buf_size);
int outl = buf_size - written;
secure_vector<uint8_t> out(outl);
if(!EVP_CipherFinal_ex(m_cipher, out.data(), &outl))
throw OpenSSL_Error("EVP_CipherFinal_ex", ERR_get_error());
copy_mem(buf + written, out.data(), outl);
written += outl;
buffer.resize(offset + written);
}
size_t OpenSSL_Cipher_Mode::update_granularity() const
{
return m_block_size * BOTAN_BLOCK_CIPHER_PAR_MULT;
}
size_t OpenSSL_Cipher_Mode::minimum_final_size() const
{
return 0; // no padding
}
size_t OpenSSL_Cipher_Mode::default_nonce_length() const
{
return m_block_size;
}
bool OpenSSL_Cipher_Mode::valid_nonce_length(size_t nonce_len) const
{
return (nonce_len == 0 || nonce_len == m_block_size);
}
size_t OpenSSL_Cipher_Mode::output_length(size_t input_length) const
{
if(input_length == 0)
return m_block_size;
else
return round_up(input_length, m_block_size);
}
void OpenSSL_Cipher_Mode::clear()
{
m_key_set = false;
m_nonce_set = false;
const EVP_CIPHER* algo = EVP_CIPHER_CTX_cipher(m_cipher);
if(!EVP_CIPHER_CTX_cleanup(m_cipher))
throw OpenSSL_Error("EVP_CIPHER_CTX_cleanup", ERR_get_error());
EVP_CIPHER_CTX_init(m_cipher);
if(!EVP_CipherInit_ex(m_cipher, algo, nullptr, nullptr, nullptr,
m_direction == ENCRYPTION ? 1 : 0))
throw OpenSSL_Error("EVP_CipherInit_ex clear", ERR_get_error());
if(!EVP_CIPHER_CTX_set_padding(m_cipher, 0))
throw OpenSSL_Error("EVP_CIPHER_CTX_set_padding clear", ERR_get_error());
}
void OpenSSL_Cipher_Mode::reset()
{
if(!EVP_CipherInit_ex(m_cipher, nullptr, nullptr, nullptr, nullptr, -1))
throw OpenSSL_Error("EVP_CipherInit_ex clear", ERR_get_error());
m_nonce_set = false;
}
Key_Length_Specification OpenSSL_Cipher_Mode::key_spec() const
{
return Key_Length_Specification(EVP_CIPHER_CTX_key_length(m_cipher));
}
void OpenSSL_Cipher_Mode::key_schedule(const uint8_t key[], size_t length)
{
if(!EVP_CIPHER_CTX_set_key_length(m_cipher, length))
throw OpenSSL_Error("EVP_CIPHER_CTX_set_key_length", ERR_get_error());
if(!EVP_CipherInit_ex(m_cipher, nullptr, nullptr, key, nullptr, -1))
throw OpenSSL_Error("EVP_CipherInit_ex key", ERR_get_error());
m_key_set = true;
m_nonce_set = false;
}
}
Cipher_Mode*
make_openssl_cipher_mode(const std::string& name, Cipher_Dir direction)
{
#define MAKE_OPENSSL_MODE(evp_fn) \
new OpenSSL_Cipher_Mode(name, (evp_fn)(), direction)
#if defined(BOTAN_HAS_AES) && defined(BOTAN_HAS_MODE_CBC) && !defined(OPENSSL_NO_AES)
if(name == "AES-128/CBC/NoPadding")
return MAKE_OPENSSL_MODE(EVP_aes_128_cbc);
if(name == "AES-192/CBC/NoPadding")
return MAKE_OPENSSL_MODE(EVP_aes_192_cbc);
if(name == "AES-256/CBC/NoPadding")
return MAKE_OPENSSL_MODE(EVP_aes_256_cbc);
#endif
#undef MAKE_OPENSSL_MODE
return nullptr;
}
}
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