/*
* Copyright (C) 2013-2019 Tobias Brunner
* HSR Hochschule fuer Technik Rapperswil
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*/
#include <openssl/opensslv.h>
#if OPENSSL_VERSION_NUMBER >= 0x1000100fL
#include "openssl_aead.h"
#include <openssl/evp.h>
#include <crypto/iv/iv_gen_seq.h>
/* the generic AEAD identifiers were added with 1.1.0 */
#ifndef EVP_CTRL_AEAD_SET_IVLEN
#define EVP_CTRL_AEAD_SET_IVLEN EVP_CTRL_GCM_SET_IVLEN
#define EVP_CTRL_AEAD_SET_TAG EVP_CTRL_GCM_SET_TAG
#define EVP_CTRL_AEAD_GET_TAG EVP_CTRL_GCM_GET_TAG
#endif
/** as defined in RFC 4106 */
#define IV_LEN 8
#define SALT_LEN 4
#define NONCE_LEN (IV_LEN + SALT_LEN)
typedef struct private_aead_t private_aead_t;
/**
* Private data of aead_t
*/
struct private_aead_t {
/**
* Public interface
*/
aead_t public;
/**
* The encryption key
*/
chunk_t key;
/**
* Salt value
*/
char salt[SALT_LEN];
/**
* Size of the integrity check value
*/
size_t icv_size;
/**
* IV generator
*/
iv_gen_t *iv_gen;
/**
* The cipher to use
*/
const EVP_CIPHER *cipher;
};
/**
* Do the actual en/decryption in an EVP context
*/
static bool crypt(private_aead_t *this, chunk_t data, chunk_t assoc, chunk_t iv,
u_char *out, int enc)
{
EVP_CIPHER_CTX *ctx;
u_char nonce[NONCE_LEN];
bool success = FALSE;
int len;
memcpy(nonce, this->salt, SALT_LEN);
memcpy(nonce + SALT_LEN, iv.ptr, IV_LEN);
ctx = EVP_CIPHER_CTX_new();
EVP_CIPHER_CTX_set_padding(ctx, 0);
if (!EVP_CipherInit_ex(ctx, this->cipher, NULL, NULL, NULL, enc) ||
!EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, NONCE_LEN, NULL) ||
!EVP_CipherInit_ex(ctx, NULL, NULL, this->key.ptr, nonce, enc))
{
goto done;
}
if (!enc && !EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, this->icv_size,
data.ptr + data.len))
{ /* set ICV for verification on decryption */
goto done;
}
if (assoc.len && !EVP_CipherUpdate(ctx, NULL, &len, assoc.ptr, assoc.len))
{ /* set AAD if specified */
goto done;
}
if (!EVP_CipherUpdate(ctx, out, &len, data.ptr, data.len) ||
!EVP_CipherFinal_ex(ctx, out + len, &len))
{ /* EVP_CipherFinal_ex fails if ICV is incorrect on decryption */
goto done;
}
if (enc && !EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, this->icv_size,
out + data.len))
{ /* copy back the ICV when encrypting */
goto done;
}
success = TRUE;
done:
EVP_CIPHER_CTX_free(ctx);
return success;
}
METHOD(aead_t, encrypt, bool,
private_aead_t *this, chunk_t plain, chunk_t assoc, chunk_t iv,
chunk_t *encrypted)
{
u_char *out;
out = plain.ptr;
if (encrypted)
{
*encrypted = chunk_alloc(plain.len + this->icv_size);
out = encrypted->ptr;
}
return crypt(this, plain, assoc, iv, out, 1);
}
METHOD(aead_t, decrypt, bool,
private_aead_t *this, chunk_t encrypted, chunk_t assoc, chunk_t iv,
chunk_t *plain)
{
u_char *out;
if (encrypted.len < this->icv_size)
{
return FALSE;
}
encrypted.len -= this->icv_size;
out = encrypted.ptr;
if (plain)
{
*plain = chunk_alloc(encrypted.len);
out = plain->ptr;
}
return crypt(this, encrypted, assoc, iv, out, 0);
}
METHOD(aead_t, get_block_size, size_t,
private_aead_t *this)
{
return EVP_CIPHER_block_size(this->cipher);
}
METHOD(aead_t, get_icv_size, size_t,
private_aead_t *this)
{
return this->icv_size;
}
METHOD(aead_t, get_iv_size, size_t,
private_aead_t *this)
{
return IV_LEN;
}
METHOD(aead_t, get_iv_gen, iv_gen_t*,
private_aead_t *this)
{
return this->iv_gen;
}
METHOD(aead_t, get_key_size, size_t,
private_aead_t *this)
{
return this->key.len + SALT_LEN;
}
METHOD(aead_t, set_key, bool,
private_aead_t *this, chunk_t key)
{
if (key.len != get_key_size(this))
{
return FALSE;
}
memcpy(this->salt, key.ptr + key.len - SALT_LEN, SALT_LEN);
memcpy(this->key.ptr, key.ptr, this->key.len);
return TRUE;
}
METHOD(aead_t, destroy, void,
private_aead_t *this)
{
chunk_clear(&this->key);
this->iv_gen->destroy(this->iv_gen);
free(this);
}
/*
* Described in header
*/
aead_t *openssl_aead_create(encryption_algorithm_t algo,
size_t key_size, size_t salt_size)
{
private_aead_t *this;
INIT(this,
.public = {
.encrypt = _encrypt,
.decrypt = _decrypt,
.get_block_size = _get_block_size,
.get_icv_size = _get_icv_size,
.get_iv_size = _get_iv_size,
.get_iv_gen = _get_iv_gen,
.get_key_size = _get_key_size,
.set_key = _set_key,
.destroy = _destroy,
},
);
switch (algo)
{
case ENCR_AES_GCM_ICV8:
this->icv_size = 8;
break;
case ENCR_AES_GCM_ICV12:
this->icv_size = 12;
break;
case ENCR_AES_GCM_ICV16:
this->icv_size = 16;
break;
case ENCR_CHACHA20_POLY1305:
this->icv_size = 16;
break;
default:
free(this);
return NULL;
}
if (salt_size && salt_size != SALT_LEN)
{
/* currently not supported */
free(this);
return NULL;
}
switch (algo)
{
case ENCR_AES_GCM_ICV8:
case ENCR_AES_GCM_ICV12:
case ENCR_AES_GCM_ICV16:
switch (key_size)
{
case 0:
key_size = 16;
/* FALL */
case 16:
this->cipher = EVP_aes_128_gcm();
break;
case 24:
this->cipher = EVP_aes_192_gcm();
break;
case 32:
this->cipher = EVP_aes_256_gcm();
break;
default:
free(this);
return NULL;
}
break;
#if OPENSSL_VERSION_NUMBER >= 0x1010000fL && !defined(OPENSSL_NO_CHACHA)
case ENCR_CHACHA20_POLY1305:
switch (key_size)
{
case 0:
key_size = 32;
/* FALL */
case 32:
this->cipher = EVP_chacha20_poly1305();
break;
default:
free(this);
return NULL;
}
break;
#endif /* OPENSSL_NO_CHACHA */
default:
free(this);
return NULL;
}
if (!this->cipher)
{
free(this);
return NULL;
}
this->key = chunk_alloc(key_size);
this->iv_gen = iv_gen_seq_create();
return &this->public;
}
#endif /* OPENSSL_VERSION_NUMBER */
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