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aes: xts: Add new context structure

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Add a new context structure for XTS. Adjust the API for XTS to use the new
context structure, including tests suites and the benchmark program. Update
Doxgen documentation accordingly.
This commit is contained in:
Jaeden Amero 2018-05-29 18:55:17 +01:00
parent e22ba80e7b
commit 9366feb504
4 changed files with 214 additions and 57 deletions
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118
include/mbedtls/aes.h
View File

@ -89,6 +89,19 @@ typedef struct
}
mbedtls_aes_context;
#if defined(MBEDTLS_CIPHER_MODE_XTS)
/**
* \brief The AES XTS context-type definition.
*/
typedef struct
{
mbedtls_aes_context crypt; /*!< The AES context to use for AES block
encryption or decryption. */
mbedtls_aes_context tweak; /*!< The AES context used for tweak
computation. */
} mbedtls_aes_xts_context;
#endif /* MBEDTLS_CIPHER_MODE_XTS */
#else /* MBEDTLS_AES_ALT */
#include "aes_alt.h"
#endif /* MBEDTLS_AES_ALT */
@ -110,6 +123,25 @@ void mbedtls_aes_init( mbedtls_aes_context *ctx );
*/
void mbedtls_aes_free( mbedtls_aes_context *ctx );
#if defined(MBEDTLS_CIPHER_MODE_XTS)
/**
* \brief This function initializes the specified AES XTS context.
*
* It must be the first API called before using
* the context.
*
* \param ctx The AES XTS context to initialize.
*/
void mbedtls_aes_xts_init( mbedtls_aes_xts_context *ctx );
/**
* \brief This function releases and clears the specified AES XTS context.
*
* \param ctx The AES XTS context to clear.
*/
void mbedtls_aes_xts_free( mbedtls_aes_xts_context *ctx );
#endif /* MBEDTLS_CIPHER_MODE_XTS */
/**
* \brief This function sets the encryption key.
*
@ -142,6 +174,44 @@ int mbedtls_aes_setkey_enc( mbedtls_aes_context *ctx, const unsigned char *key,
int mbedtls_aes_setkey_dec( mbedtls_aes_context *ctx, const unsigned char *key,
unsigned int keybits );
#if defined(MBEDTLS_CIPHER_MODE_XTS)
/**
* \brief This function prepares an XTS context for encryption and
* sets the encryption key.
*
* \param ctx The AES XTS context to which the key should be bound.
* \param key The encryption key. This is comprised of the XTS key1
* concatenated with the XTS key2.
* \param keybits The size of \p key passed in bits. Valid options are:
* <ul><li>256 bits (each of key1 and key2 is a 128-bit key)</li>
* <li>512 bits (each of key1 and key2 is a 256-bit key)</li></ul>
*
* \return \c 0 on success.
* \return #MBEDTLS_ERR_AES_INVALID_KEY_LENGTH on failure.
*/
int mbedtls_aes_xts_setkey_enc( mbedtls_aes_xts_context *ctx,
const unsigned char *key,
unsigned int keybits );
/**
* \brief This function prepares an XTS context for decryption and
* sets the decryption key.
*
* \param ctx The AES XTS context to which the key should be bound.
* \param key The decryption key. This is comprised of the XTS key1
* concatenated with the XTS key2.
* \param keybits The size of \p key passed in bits. Valid options are:
* <ul><li>256 bits (each of key1 and key2 is a 128-bit key)</li>
* <li>512 bits (each of key1 and key2 is a 256-bit key)</li></ul>
*
* \return \c 0 on success.
* \return #MBEDTLS_ERR_AES_INVALID_KEY_LENGTH on failure.
*/
int mbedtls_aes_xts_setkey_dec( mbedtls_aes_xts_context *ctx,
const unsigned char *key,
unsigned int keybits );
#endif /* MBEDTLS_CIPHER_MODE_XTS */
/**
* \brief This function performs an AES single-block encryption or
* decryption operation.
@ -215,30 +285,38 @@ int mbedtls_aes_crypt_cbc( mbedtls_aes_context *ctx,
#if defined(MBEDTLS_CIPHER_MODE_XTS)
/**
* \brief AES-XTS buffer encryption/decryption
* Length should be greater or equal than the block size (16
* bytes, 128 bits)
* \brief This function performs an AES-XTS encryption or decryption
* operation for an entire XTS data unit.
*
* Warning: The bits_length parameter must given be in bits, not bytes like the
* other modes
* AES-XTS encrypts or decrypts blocks based on their location as
* defined by a data unit number. The data unit number must be
* provided by \p iv.
*
* \param crypt_ctx AES context for encrypting data
* \param tweak_ctx AES context for xor-ing with data
* \param mode MBEDTLS_AES_ENCRYPT or MBEDTLS_AES_DECRYPT
* \param bits_length length of the input data (in bits)
* \param iv initialization vector
* \param input buffer holding the input data
* \param output buffer holding the output data
* \param ctx The AES XTS context to use for AES XTS operations.
* \param mode The AES operation: #MBEDTLS_AES_ENCRYPT or
* #MBEDTLS_AES_DECRYPT.
* \param bits_length The length of a data unit in bits.
* \param iv The address of the data unit encoded as an array of 16
* bytes in little-endian format. For disk encryption, this
* is typically the index of the block device sector that
* contains the data.
* \param input The buffer holding the input data (which is an entire
* data unit). This function reads \p length bytes from \p
* input.
* \param output The buffer holding the output data (which is an entire
* data unit). This function writes \p length bytes to \p
* output.
*
* \return 0 if successful, or MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH
* \return \c 0 on success.
* \return #MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH if \p length is
* smaller than an AES block in size (16 bytes).
*/
int mbedtls_aes_crypt_xts( mbedtls_aes_context *crypt_ctx,
mbedtls_aes_context *tweak_ctx,
int mode,
size_t bits_length,
unsigned char iv[16],
const unsigned char *input,
unsigned char *output );
int mbedtls_aes_crypt_xts( mbedtls_aes_xts_context *ctx,
int mode,
size_t bits_length,
const unsigned char iv[16],
const unsigned char *input,
unsigned char *output );
#endif /* MBEDTLS_CIPHER_MODE_XTS */
#if defined(MBEDTLS_CIPHER_MODE_CFB)

109
library/aes.c
View File

@ -521,6 +521,20 @@ void mbedtls_aes_free( mbedtls_aes_context *ctx )
mbedtls_platform_zeroize( ctx, sizeof( mbedtls_aes_context ) );
}
#if defined(MBEDTLS_CIPHER_MODE_XTS)
void mbedtls_aes_xts_init( mbedtls_aes_xts_context *ctx )
{
mbedtls_aes_init( &ctx->crypt );
mbedtls_aes_init( &ctx->tweak );
}
void mbedtls_aes_xts_free( mbedtls_aes_xts_context *ctx )
{
mbedtls_aes_free( &ctx->crypt );
mbedtls_aes_free( &ctx->tweak );
}
#endif /* MBEDTLS_CIPHER_MODE_XTS */
/*
* AES key schedule (encryption)
*/
@ -702,6 +716,78 @@ exit:
return( ret );
}
#if defined(MBEDTLS_CIPHER_MODE_XTS)
static int mbedtls_aes_xts_decode_keys( const unsigned char *key,
unsigned int keybits,
const unsigned char **key1,
unsigned int *key1bits,
const unsigned char **key2,
unsigned int *key2bits )
{
const unsigned int half_keybits = keybits / 2;
const unsigned int half_keybytes = half_keybits / 8;
switch( keybits )
{
case 256: break;
case 512: break;
default : return( MBEDTLS_ERR_AES_INVALID_KEY_LENGTH );
}
*key1bits = half_keybits;
*key2bits = half_keybits;
*key1 = &key[0];
*key2 = &key[half_keybytes];
return 0;
}
int mbedtls_aes_xts_setkey_enc( mbedtls_aes_xts_context *ctx,
const unsigned char *key,
unsigned int keybits)
{
int ret;
const unsigned char *key1, *key2;
unsigned int key1bits, key2bits;
ret = mbedtls_aes_xts_decode_keys( key, keybits, &key1, &key1bits,
&key2, &key2bits );
if( ret != 0 )
return( ret );
/* Set the tweak key. Always set tweak key for the encryption mode. */
ret = mbedtls_aes_setkey_enc( &ctx->tweak, key2, key2bits );
if( ret != 0 )
return( ret );
/* Set crypt key for encryption. */
return mbedtls_aes_setkey_enc( &ctx->crypt, key1, key1bits );
}
int mbedtls_aes_xts_setkey_dec( mbedtls_aes_xts_context *ctx,
const unsigned char *key,
unsigned int keybits)
{
int ret;
const unsigned char *key1, *key2;
unsigned int key1bits, key2bits;
ret = mbedtls_aes_xts_decode_keys( key, keybits, &key1, &key1bits,
&key2, &key2bits );
if( ret != 0 )
return( ret );
/* Set the tweak key. Always set tweak key for encryption. */
ret = mbedtls_aes_setkey_enc( &ctx->tweak, key2, key2bits );
if( ret != 0 )
return( ret );
/* Set crypt key for decryption. */
return mbedtls_aes_setkey_dec( &ctx->crypt, key1, key1bits );
}
#endif /* MBEDTLS_CIPHER_MODE_XTS */
#endif /* !MBEDTLS_AES_SETKEY_DEC_ALT */
#define AES_FROUND(X0,X1,X2,X3,Y0,Y1,Y2,Y3) \
@ -1042,13 +1128,12 @@ static void mbedtls_gf128mul_x_ble( unsigned char r[16],
/*
* AES-XTS buffer encryption/decryption
*/
int mbedtls_aes_crypt_xts( mbedtls_aes_context *crypt_ctx,
mbedtls_aes_context *tweak_ctx,
int mode,
size_t bits_length,
unsigned char iv[16],
const unsigned char *input,
unsigned char *output )
int mbedtls_aes_crypt_xts( mbedtls_aes_xts_context *ctx,
int mode,
size_t bits_length,
const unsigned char iv[16],
const unsigned char *input,
unsigned char *output )
{
union xts_buf128 {
uint8_t u8[16];
@ -1075,7 +1160,7 @@ int mbedtls_aes_crypt_xts( mbedtls_aes_context *crypt_ctx,
return( MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH );
mbedtls_aes_crypt_ecb( tweak_ctx, MBEDTLS_AES_ENCRYPT, iv, t_buf.u8 );
mbedtls_aes_crypt_ecb( &ctx->tweak, MBEDTLS_AES_ENCRYPT, iv, t_buf.u8 );
if( mode == MBEDTLS_AES_DECRYPT && remn )
{
@ -1096,7 +1181,7 @@ first:
scratch.u64[1] = (uint64_t)( inbuf->u64[1] ^ t_buf.u64[1] );
/* CC <- E(Key2,PP) */
mbedtls_aes_crypt_ecb( crypt_ctx, mode, scratch.u8, outbuf->u8 );
mbedtls_aes_crypt_ecb( &ctx->crypt, mode, scratch.u8, outbuf->u8 );
/* C <- T xor CC */
outbuf->u64[0] = (uint64_t)( outbuf->u64[0] ^ t_buf.u64[0] );
@ -1127,7 +1212,7 @@ first:
scratch.u64[1] = (uint64_t)( cts_scratch.u64[1] ^ t_buf.u64[1] );
/* CC <- E(Key2,PP) */
mbedtls_aes_crypt_ecb( crypt_ctx, mode, scratch.u8, scratch.u8 );
mbedtls_aes_crypt_ecb( &ctx->crypt, mode, scratch.u8, scratch.u8 );
/* C <- T xor CC */
outbuf[nblk - 1].u64[0] = (uint64_t)( scratch.u64[0] ^ t_buf.u64[0] );
@ -1148,7 +1233,7 @@ decrypt_only_one_full_block:
scratch.u64[1] = (uint64_t)( inbuf[nblk - 1].u64[1] ^ t_buf.u64[1] );
/* CC <- E(Key2,PP) */
mbedtls_aes_crypt_ecb( crypt_ctx, mode, scratch.u8, scratch.u8 );
mbedtls_aes_crypt_ecb( &ctx->crypt, mode, scratch.u8, scratch.u8 );
/* C <- T xor CC */
cts_scratch.u64[0] = (uint64_t)( scratch.u64[0] ^ t_buf.u64[0] );
@ -1165,7 +1250,7 @@ decrypt_only_one_full_block:
scratch.u64[1] = (uint64_t)( inbuf[nblk - 1].u64[1] ^ cts_t_buf.u64[1] );
/* CC <- E(Key2,PP) */
mbedtls_aes_crypt_ecb( crypt_ctx, mode, scratch.u8, scratch.u8 );
mbedtls_aes_crypt_ecb( &ctx->crypt, mode, scratch.u8, scratch.u8 );
/* C <- T xor CC */
outbuf[nblk - 1].u64[0] = (uint64_t)( scratch.u64[0] ^ cts_t_buf.u64[0] );

18
programs/test/benchmark.c
View File

@ -432,23 +432,23 @@ int main( int argc, char *argv[] )
if( todo.aes_xts )
{
int keysize;
mbedtls_aes_context crypt_ctx, tweak_ctx;
mbedtls_aes_init( &crypt_ctx );
mbedtls_aes_init( &tweak_ctx );
for( keysize = 128; keysize <= 256; keysize += 64 )
mbedtls_aes_xts_context ctx;
mbedtls_aes_xts_init( &ctx );
for( keysize = 128; keysize <= 256; keysize += 128 )
{
mbedtls_snprintf( title, sizeof( title ), "AES-XTS-%d", keysize );
memset( buf, 0, sizeof( buf ) );
memset( tmp, 0, sizeof( tmp ) );
mbedtls_aes_setkey_enc( &crypt_ctx, tmp, keysize );
mbedtls_aes_setkey_enc( &tweak_ctx, tmp, keysize );
mbedtls_aes_xts_setkey_enc( &ctx, tmp, keysize * 2 );
TIME_AND_TSC( title,
mbedtls_aes_crypt_xts( &crypt_ctx, &tweak_ctx, MBEDTLS_AES_ENCRYPT, BUFSIZE * 8, tmp, buf, buf ) );
mbedtls_aes_crypt_xts( &ctx, MBEDTLS_AES_ENCRYPT, BUFSIZE,
tmp, buf, buf ) );
mbedtls_aes_xts_free( &ctx );
}
mbedtls_aes_free( &crypt_ctx );
mbedtls_aes_free( &tweak_ctx );
}
#endif
#if defined(MBEDTLS_GCM_C)

26
tests/suites/test_suite_aes.function
View File

@ -161,20 +161,18 @@ void aes_encrypt_xts( char *hex_key_string, char *hex_iv_string,
unsigned char src_str[100] = { 0, };
unsigned char dst_str[100] = { 0, };
unsigned char output[100] = { 0, };
mbedtls_aes_context crypt_ctx, tweak_ctx;
mbedtls_aes_xts_context ctx;
int key_len, data_len;
mbedtls_aes_init( &crypt_ctx );
mbedtls_aes_init( &tweak_ctx );
mbedtls_aes_xts_init( &ctx );
key_len = unhexify( key_str, hex_key_string );
unhexify( iv_str, hex_iv_string );
data_len = unhexify( src_str, hex_src_string );
mbedtls_aes_setkey_enc( &crypt_ctx, key_str, ( key_len * 8 ) / 2 );
mbedtls_aes_setkey_enc( &tweak_ctx, key_str + key_len / 2, ( key_len * 8 ) / 2 );
mbedtls_aes_xts_setkey_enc( &ctx, key_str, key_len * 8 );
TEST_ASSERT( mbedtls_aes_crypt_xts( &crypt_ctx, &tweak_ctx, MBEDTLS_AES_ENCRYPT, data_unit_len, iv_str, src_str, output ) == xts_result );
TEST_ASSERT( mbedtls_aes_crypt_xts( &ctx, MBEDTLS_AES_ENCRYPT, data_unit_len, iv_str, src_str, output ) == xts_result );
if( xts_result == 0 )
{
hexify( dst_str, output, data_len );
@ -183,8 +181,7 @@ void aes_encrypt_xts( char *hex_key_string, char *hex_iv_string,
}
exit:
mbedtls_aes_free( &crypt_ctx );
mbedtls_aes_free( &tweak_ctx );
mbedtls_aes_xts_free( &ctx );
}
/* END_CASE */
@ -198,20 +195,18 @@ void aes_decrypt_xts( char *hex_key_string, char *hex_iv_string,
unsigned char src_str[100] = { 0, };
unsigned char dst_str[100] = { 0, };
unsigned char output[100] = { 0, };
mbedtls_aes_context crypt_ctx, tweak_ctx;
mbedtls_aes_xts_context ctx;
int key_len, data_len;
mbedtls_aes_init( &crypt_ctx );
mbedtls_aes_init( &tweak_ctx );
mbedtls_aes_xts_init( &ctx );
key_len = unhexify( key_str, hex_key_string );
unhexify( iv_str, hex_iv_string );
data_len = unhexify( src_str, hex_src_string );
mbedtls_aes_setkey_dec( &crypt_ctx, key_str, ( key_len * 8 ) / 2 );
mbedtls_aes_setkey_enc( &tweak_ctx, key_str + key_len / 2, ( key_len * 8 ) / 2 );
mbedtls_aes_xts_setkey_dec( &ctx, key_str, key_len * 8 );
TEST_ASSERT( mbedtls_aes_crypt_xts( &crypt_ctx, &tweak_ctx, MBEDTLS_AES_DECRYPT, data_unit_len, iv_str, src_str, output ) == xts_result );
TEST_ASSERT( mbedtls_aes_crypt_xts( &ctx, MBEDTLS_AES_DECRYPT, data_unit_len, iv_str, src_str, output ) == xts_result );
if( xts_result == 0 )
{
hexify( dst_str, output, data_len );
@ -220,8 +215,7 @@ void aes_decrypt_xts( char *hex_key_string, char *hex_iv_string,
}
exit:
mbedtls_aes_free( &crypt_ctx );
mbedtls_aes_free( &tweak_ctx );
mbedtls_aes_xts_free( &ctx );
}
/* END_CASE */