/*
* Copyright (C) 2015 Michael Brown <mbrown@fensystems.co.uk>.
*
* 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 any later version.
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*
* You can also choose to distribute this program under the terms of
* the Unmodified Binary Distribution Licence (as given in the file
* COPYING.UBDL), provided that you have satisfied its requirements.
*/
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
/** @file
*
* AES algorithm
*
*/
#include <stdint.h>
#include <string.h>
#include <errno.h>
#include <assert.h>
#include <byteswap.h>
#include <ipxe/rotate.h>
#include <ipxe/crypto.h>
#include <ipxe/ecb.h>
#include <ipxe/cbc.h>
#include <ipxe/aes.h>
/** AES strides
*
* These are the strides (modulo 16) used to walk through the AES
* input state bytes in order of byte position after [Inv]ShiftRows.
*/
enum aes_stride {
/** Input stride for ShiftRows
*
* 0 4 8 c
* \ \ \
* 1 5 9 d
* \ \ \
* 2 6 a e
* \ \ \
* 3 7 b f
*/
AES_STRIDE_SHIFTROWS = +5,
/** Input stride for InvShiftRows
*
* 0 4 8 c
* / / /
* 1 5 9 d
* / / /
* 2 6 a e
* / / /
* 3 7 b f
*/
AES_STRIDE_INVSHIFTROWS = -3,
};
/** A single AES lookup table entry
*
* This represents the product (in the Galois field GF(2^8)) of an
* eight-byte vector multiplier with a single scalar multiplicand.
*
* The vector multipliers used for AES will be {1,1,1,3,2,1,1,3} for
* MixColumns and {1,9,13,11,14,9,13,11} for InvMixColumns. This
* allows for the result of multiplying any single column of the
* [Inv]MixColumns matrix by a scalar value to be obtained simply by
* extracting the relevant four-byte subset from the lookup table
* entry.
*
* For example, to find the result of multiplying the second column of
* the MixColumns matrix by the scalar value 0x80:
*
* MixColumns column[0]: { 2, 1, 1, 3 }
* MixColumns column[1]: { 3, 2, 1, 1 }
* MixColumns column[2]: { 1, 3, 2, 1 }
* MixColumns column[3]: { 1, 1, 3, 2 }
* Vector multiplier: { 1, 1, 1, 3, 2, 1, 1, 3 }
* Scalar multiplicand: 0x80
* Lookup table entry: { 0x80, 0x80, 0x80, 0x9b, 0x1b, 0x80, 0x80, 0x9b }
*
* The second column of the MixColumns matrix is {3,2,1,1}. The
* product of this column with the scalar value 0x80 can be obtained
* by extracting the relevant four-byte subset of the lookup table
* entry:
*
* MixColumns column[1]: { 3, 2, 1, 1 }
* Vector multiplier: { 1, 1, 1, 3, 2, 1, 1, 3 }
* Lookup table entry: { 0x80, 0x80, 0x80, 0x9b, 0x1b, 0x80, 0x80, 0x9b }
* Product: { 0x9b, 0x1b, 0x80, 0x80 }
*
* The column lookups require only seven bytes of the eight-byte
* entry: the remaining (first) byte is used to hold the scalar
* multiplicand itself (i.e. the first byte of the vector multiplier
* is always chosen to be 1).
*/
union aes_table_entry {
/** Viewed as an array of bytes */
uint8_t byte[8];
} __attribute__ (( packed ));
/** An AES lookup table
*
* This represents the products (in the Galois field GF(2^8)) of a
* constant eight-byte vector multiplier with all possible 256 scalar
* multiplicands.
*
* The entries are indexed by the AES [Inv]SubBytes S-box output
* values (denoted S(N)). This allows for the result of multiplying
* any single column of the [Inv]MixColumns matrix by S(N) to be
* obtained simply by extracting the relevant four-byte subset from
* the Nth table entry. For example:
*
* Input byte (N): 0x3a
* SubBytes output S(N): 0x80
* MixColumns column[1]: { 3, 2, 1, 1 }
* Vector multiplier: { 1, 1, 1, 3, 2, 1, 1, 3 }
* Table entry[0x3a]: { 0x80, 0x80, 0x80, 0x9b, 0x1b, 0x80, 0x80, 0x9b }
* Product: { 0x9b, 0x1b, 0x80, 0x80 }
*
* Since the first byte of the eight-byte vector multiplier is always
* chosen to be 1, the value of S(N) may be lookup up by extracting
* the first byte of the Nth table entry.
*/
struct aes_table {
/** Table entries, indexed by S(N) */
union aes_table_entry entry[256];
} __attribute__ (( aligned ( 8 ) ));
/** AES MixColumns lookup table */
static struct aes_table aes_mixcolumns;
/** AES InvMixColumns lookup table */
static struct aes_table aes_invmixcolumns;
/**
* Multiply [Inv]MixColumns matrix column by scalar multiplicand
*
* @v entry AES lookup table entry for scalar multiplicand
* @v column [Inv]MixColumns matrix column index
* @ret product Product of matrix column with scalar multiplicand
*/
static inline __attribute__ (( always_inline )) uint32_t
aes_entry_column ( const union aes_table_entry *entry, unsigned int column ) {
const union {
uint8_t byte;
uint32_t column;
} __attribute__ (( may_alias )) *product;
/* Locate relevant four-byte subset */
product = container_of ( &entry->byte[ 4 - column ],
typeof ( *product ), byte );
/* Extract this four-byte subset */
return product->column;
}
/**
* Multiply [Inv]MixColumns matrix column by S-boxed input byte
*
* @v table AES lookup table
* @v stride AES row shift stride
* @v in AES input state
* @v offset Output byte offset (after [Inv]ShiftRows)
* @ret product Product of matrix column with S(input byte)
*
* Note that the specified offset is not the offset of the input byte;
* it is the offset of the output byte which corresponds to the input
* byte. This output byte offset is used to calculate both the input
* byte offset and to select the appropriate matric column.
*
* With a compile-time constant offset, this function will optimise
* down to a single "movzbl" (to extract the input byte) and will
* generate a single x86 memory reference expression which can then be
* used directly within a single "xorl" instruction.
*/
static inline __attribute__ (( always_inline )) uint32_t
aes_column ( const struct aes_table *table, size_t stride,
const union aes_matrix *in, size_t offset ) {
const union aes_table_entry *entry;
unsigned int byte;
/* Extract input byte corresponding to this output byte offset
* (i.e. perform [Inv]ShiftRows).
*/
byte = in->byte[ ( stride * offset ) & 0xf ];
/* Locate lookup table entry for this input byte (i.e. perform
* [Inv]SubBytes).
*/
entry = &table->entry[byte];
/* Multiply appropriate matrix column by this input byte
* (i.e. perform [Inv]MixColumns).
*/
return aes_entry_column ( entry, ( offset & 0x3 ) );
}
/**
* Calculate intermediate round output column
*
* @v table AES lookup table
* @v stride AES row shift stride
* @v in AES input state
* @v key AES round key
* @v column Column index
* @ret output Output column value
*/
static inline __attribute__ (( always_inline )) uint32_t
aes_output ( const struct aes_table *table, size_t stride,
const union aes_matrix *in, const union aes_matrix *key,
unsigned int column ) {
size_t offset = ( column * 4 );
/* Perform [Inv]ShiftRows, [Inv]SubBytes, [Inv]MixColumns, and
* AddRoundKey for this column. The loop is unrolled to allow
* for the required compile-time constant optimisations.
*/
return ( aes_column ( table, stride, in, ( offset + 0 ) ) ^
aes_column ( table, stride, in, ( offset + 1 ) ) ^
aes_column ( table, stride, in, ( offset + 2 ) ) ^
aes_column ( table, stride, in, ( offset + 3 ) ) ^
key->column[column] );
}
/**
* Perform a single intermediate round
*
* @v table AES lookup table
* @v stride AES row shift stride
* @v in AES input state
* @v out AES output state
* @v key AES round key
*/
static inline __attribute__ (( always_inline )) void
aes_round ( const struct aes_table *table, size_t stride,
const union aes_matrix *in, union aes_matrix *out,
const union aes_matrix *key ) {
/* Perform [Inv]ShiftRows, [Inv]SubBytes, [Inv]MixColumns, and
* AddRoundKey for all columns. The loop is unrolled to allow
* for the required compile-time constant optimisations.
*/
out->column[0] = aes_output ( table, stride, in, key, 0 );
out->column[1] = aes_output ( table, stride, in, key, 1 );
out->column[2] = aes_output ( table, stride, in, key, 2 );
out->column[3] = aes_output ( table, stride, in, key, 3 );
}
/**
* Perform encryption intermediate rounds
*
* @v in AES input state
* @v out AES output state
* @v key Round keys
* @v rounds Number of rounds (must be odd)
*
* This function is deliberately marked as non-inlinable to ensure
* maximal availability of registers for GCC's register allocator,
* which has a tendency to otherwise spill performance-critical
* registers to the stack.
*/
static __attribute__ (( noinline )) void
aes_encrypt_rounds ( union aes_matrix *in, union aes_matrix *out,
const union aes_matrix *key, unsigned int rounds ) {
union aes_matrix *tmp;
/* Perform intermediate rounds */
do {
/* Perform one intermediate round */
aes_round ( &aes_mixcolumns, AES_STRIDE_SHIFTROWS,
in, out, key++ );
/* Swap input and output states for next round */
tmp = in;
in = out;
out = tmp;
} while ( --rounds );
}
/**
* Perform decryption intermediate rounds
*
* @v in AES input state
* @v out AES output state
* @v key Round keys
* @v rounds Number of rounds (must be odd)
*
* As with aes_encrypt_rounds(), this function is deliberately marked
* as non-inlinable.
*
* This function could potentially use the same binary code as is used
* for encryption. To compensate for the difference between ShiftRows
* and InvShiftRows, half of the input byte offsets would have to be
* modifiable at runtime (half by an offset of +4/-4, half by an
* offset of -4/+4 for ShiftRows/InvShiftRows). This can be
* accomplished in x86 assembly within the number of available
* registers, but GCC's register allocator struggles to do so,
* resulting in a significant performance decrease due to registers
* being spilled to the stack. We therefore use two separate but very
* similar binary functions based on the same C source.
*/
static __attribute__ (( noinline )) void
aes_decrypt_rounds ( union aes_matrix *in, union aes_matrix *out,
const union aes_matrix *key, unsigned int rounds ) {
union aes_matrix *tmp;
/* Perform intermediate rounds */
do {
/* Perform one intermediate round */
aes_round ( &aes_invmixcolumns, AES_STRIDE_INVSHIFTROWS,
in, out, key++ );
/* Swap input and output states for next round */
tmp = in;
in = out;
out = tmp;
} while ( --rounds );
}
/**
* Perform standalone AddRoundKey
*
* @v state AES state
* @v key AES round key
*/
static inline __attribute__ (( always_inline )) void
aes_addroundkey ( union aes_matrix *state, const union aes_matrix *key ) {
state->column[0] ^= key->column[0];
state->column[1] ^= key->column[1];
state->column[2] ^= key->column[2];
state->column[3] ^= key->column[3];
}
/**
* Perform final round
*
* @v table AES lookup table
* @v stride AES row shift stride
* @v in AES input state
* @v out AES output state
* @v key AES round key
*/
static void aes_final ( const struct aes_table *table, size_t stride,
const union aes_matrix *in, union aes_matrix *out,
const union aes_matrix *key ) {
const union aes_table_entry *entry;
unsigned int byte;
size_t out_offset;
size_t in_offset;
/* Perform [Inv]ShiftRows and [Inv]SubBytes */
for ( out_offset = 0, in_offset = 0 ; out_offset < 16 ;
out_offset++, in_offset = ( ( in_offset + stride ) & 0xf ) ) {
/* Extract input byte (i.e. perform [Inv]ShiftRows) */
byte = in->byte[in_offset];
/* Locate lookup table entry for this input byte
* (i.e. perform [Inv]SubBytes).
*/
entry = &table->entry[byte];
/* Store output byte */
out->byte[out_offset] = entry->byte[0];
}
/* Perform AddRoundKey */
aes_addroundkey ( out, key );
}
/**
* Encrypt data
*
* @v ctx Context
* @v src Data to encrypt
* @v dst Buffer for encrypted data
* @v len Length of data
*/
static void aes_encrypt ( void *ctx, const void *src, void *dst, size_t len ) {
struct aes_context *aes = ctx;
union aes_matrix buffer[2];
union aes_matrix *in = &buffer[0];
union aes_matrix *out = &buffer[1];
unsigned int rounds = aes->rounds;
/* Sanity check */
assert ( len == sizeof ( *in ) );
/* Initialise input state */
memcpy ( in, src, sizeof ( *in ) );
/* Perform initial round (AddRoundKey) */
aes_addroundkey ( in, &aes->encrypt.key[0] );
/* Perform intermediate rounds (ShiftRows, SubBytes,
* MixColumns, AddRoundKey).
*/
aes_encrypt_rounds ( in, out, &aes->encrypt.key[1], ( rounds - 2 ) );
in = out;
/* Perform final round (ShiftRows, SubBytes, AddRoundKey) */
out = dst;
aes_final ( &aes_mixcolumns, AES_STRIDE_SHIFTROWS, in, out,
&aes->encrypt.key[ rounds - 1 ] );
}
/**
* Decrypt data
*
* @v ctx Context
* @v src Data to decrypt
* @v dst Buffer for decrypted data
* @v len Length of data
*/
static void aes_decrypt ( void *ctx, const void *src, void *dst, size_t len ) {
struct aes_context *aes = ctx;
union aes_matrix buffer[2];
union aes_matrix *in = &buffer[0];
union aes_matrix *out = &buffer[1];
unsigned int rounds = aes->rounds;
/* Sanity check */
assert ( len == sizeof ( *in ) );
/* Initialise input state */
memcpy ( in, src, sizeof ( *in ) );
/* Perform initial round (AddRoundKey) */
aes_addroundkey ( in, &aes->decrypt.key[0] );
/* Perform intermediate rounds (InvShiftRows, InvSubBytes,
* InvMixColumns, AddRoundKey).
*/
aes_decrypt_rounds ( in, out, &aes->decrypt.key[1], ( rounds - 2 ) );
in = out;
/* Perform final round (InvShiftRows, InvSubBytes, AddRoundKey) */
out = dst;
aes_final ( &aes_invmixcolumns, AES_STRIDE_INVSHIFTROWS, in, out,
&aes->decrypt.key[ rounds - 1 ] );
}
/**
* Multiply a polynomial by (x) modulo (x^8 + x^4 + x^3 + x^2 + 1) in GF(2^8)
*
* @v poly Polynomial to be multiplied
* @ret result Result
*/
static __attribute__ (( const )) unsigned int aes_double ( unsigned int poly ) {
/* Multiply polynomial by (x), placing the resulting x^8
* coefficient in the LSB (i.e. rotate byte left by one).
*/
poly = rol8 ( poly, 1 );
/* If coefficient of x^8 (in LSB) is non-zero, then reduce by
* subtracting (x^8 + x^4 + x^3 + x^2 + 1) in GF(2^8).
*/
if ( poly & 0x01 ) {
poly ^= 0x01; /* Subtract x^8 (currently in LSB) */
poly ^= 0x1b; /* Subtract (x^4 + x^3 + x^2 + 1) */
}
return poly;
}
/**
* Fill in MixColumns lookup table entry
*
* @v entry AES lookup table entry for scalar multiplicand
*
* The MixColumns lookup table vector multiplier is {1,1,1,3,2,1,1,3}.
*/
static void aes_mixcolumns_entry ( union aes_table_entry *entry ) {
unsigned int scalar_x_1;
unsigned int scalar_x;
unsigned int scalar;
/* Retrieve scalar multiplicand */
scalar = entry->byte[0];
entry->byte[1] = scalar;
entry->byte[2] = scalar;
entry->byte[5] = scalar;
entry->byte[6] = scalar;
/* Calculate scalar multiplied by (x) */
scalar_x = aes_double ( scalar );
entry->byte[4] = scalar_x;
/* Calculate scalar multiplied by (x + 1) */
scalar_x_1 = ( scalar_x ^ scalar );
entry->byte[3] = scalar_x_1;
entry->byte[7] = scalar_x_1;
}
/**
* Fill in InvMixColumns lookup table entry
*
* @v entry AES lookup table entry for scalar multiplicand
*
* The InvMixColumns lookup table vector multiplier is {1,9,13,11,14,9,13,11}.
*/
static void aes_invmixcolumns_entry ( union aes_table_entry *entry ) {
unsigned int scalar_x3_x2_x;
unsigned int scalar_x3_x2_1;
unsigned int scalar_x3_x2;
unsigned int scalar_x3_x_1;
unsigned int scalar_x3_1;
unsigned int scalar_x3;
unsigned int scalar_x2;
unsigned int scalar_x;
unsigned int scalar;
/* Retrieve scalar multiplicand */
scalar = entry->byte[0];
/* Calculate scalar multiplied by (x) */
scalar_x = aes_double ( scalar );
/* Calculate scalar multiplied by (x^2) */
scalar_x2 = aes_double ( scalar_x );
/* Calculate scalar multiplied by (x^3) */
scalar_x3 = aes_double ( scalar_x2 );
/* Calculate scalar multiplied by (x^3 + 1) */
scalar_x3_1 = ( scalar_x3 ^ scalar );
entry->byte[1] = scalar_x3_1;
entry->byte[5] = scalar_x3_1;
/* Calculate scalar multiplied by (x^3 + x + 1) */
scalar_x3_x_1 = ( scalar_x3_1 ^ scalar_x );
entry->byte[3] = scalar_x3_x_1;
entry->byte[7] = scalar_x3_x_1;
/* Calculate scalar multiplied by (x^3 + x^2) */
scalar_x3_x2 = ( scalar_x3 ^ scalar_x2 );
/* Calculate scalar multiplied by (x^3 + x^2 + 1) */
scalar_x3_x2_1 = ( scalar_x3_x2 ^ scalar );
entry->byte[2] = scalar_x3_x2_1;
entry->byte[6] = scalar_x3_x2_1;
/* Calculate scalar multiplied by (x^3 + x^2 + x) */
scalar_x3_x2_x = ( scalar_x3_x2 ^ scalar_x );
entry->byte[4] = scalar_x3_x2_x;
}
/**
* Generate AES lookup tables
*
*/
static void aes_generate ( void ) {
union aes_table_entry *entry;
union aes_table_entry *inventry;
unsigned int poly = 0x01;
unsigned int invpoly = 0x01;
unsigned int transformed;
unsigned int i;
/* Iterate over non-zero values of GF(2^8) using generator (x + 1) */
do {
/* Multiply polynomial by (x + 1) */
poly ^= aes_double ( poly );
/* Divide inverse polynomial by (x + 1). This code
* fragment is taken directly from the Wikipedia page
* on the Rijndael S-box. An explanation of why it
* works would be greatly appreciated.
*/
invpoly ^= ( invpoly << 1 );
invpoly ^= ( invpoly << 2 );
invpoly ^= ( invpoly << 4 );
if ( invpoly & 0x80 )
invpoly ^= 0x09;
invpoly &= 0xff;
/* Apply affine transformation */
transformed = ( 0x63 ^ invpoly ^ rol8 ( invpoly, 1 ) ^
rol8 ( invpoly, 2 ) ^ rol8 ( invpoly, 3 ) ^
rol8 ( invpoly, 4 ) );
/* Populate S-box (within MixColumns lookup table) */
aes_mixcolumns.entry[poly].byte[0] = transformed;
} while ( poly != 0x01 );
/* Populate zeroth S-box entry (which has no inverse) */
aes_mixcolumns.entry[0].byte[0] = 0x63;
/* Fill in MixColumns and InvMixColumns lookup tables */
for ( i = 0 ; i < 256 ; i++ ) {
/* Fill in MixColumns lookup table entry */
entry = &aes_mixcolumns.entry[i];
aes_mixcolumns_entry ( entry );
/* Populate inverse S-box (within InvMixColumns lookup table) */
inventry = &aes_invmixcolumns.entry[ entry->byte[0] ];
inventry->byte[0] = i;
/* Fill in InvMixColumns lookup table entry */
aes_invmixcolumns_entry ( inventry );
}
}
/**
* Rotate key column
*
* @v column Key column
* @ret column Updated key column
*/
static inline __attribute__ (( always_inline )) uint32_t
aes_key_rotate ( uint32_t column ) {
return ( ( __BYTE_ORDER == __LITTLE_ENDIAN ) ?
ror32 ( column, 8 ) : rol32 ( column, 8 ) );
}
/**
* Apply S-box to key column
*
* @v column Key column
* @ret column Updated key column
*/
static uint32_t aes_key_sbox ( uint32_t column ) {
unsigned int i;
uint8_t byte;
for ( i = 0 ; i < 4 ; i++ ) {
byte = ( column & 0xff );
byte = aes_mixcolumns.entry[byte].byte[0];
column = ( ( column & ~0xff ) | byte );
column = rol32 ( column, 8 );
}
return column;
}
/**
* Apply schedule round constant to key column
*
* @v column Key column
* @v rcon Round constant
* @ret column Updated key column
*/
static inline __attribute__ (( always_inline )) uint32_t
aes_key_rcon ( uint32_t column, unsigned int rcon ) {
return ( ( __BYTE_ORDER == __LITTLE_ENDIAN ) ?
( column ^ rcon ) : ( column ^ ( rcon << 24 ) ) );
}
/**
* Set key
*
* @v ctx Context
* @v key Key
* @v keylen Key length
* @ret rc Return status code
*/
static int aes_setkey ( void *ctx, const void *key, size_t keylen ) {
struct aes_context *aes = ctx;
union aes_matrix *enc;
union aes_matrix *dec;
union aes_matrix temp;
union aes_matrix zero;
unsigned int rcon = 0x01;
unsigned int rounds;
size_t offset = 0;
uint32_t *prev;
uint32_t *next;
uint32_t *end;
uint32_t tmp;
/* Generate lookup tables, if not already done */
if ( ! aes_mixcolumns.entry[0].byte[0] )
aes_generate();
/* Validate key length and calculate number of intermediate rounds */
switch ( keylen ) {
case ( 128 / 8 ) :
rounds = 11;
break;
case ( 192 / 8 ) :
rounds = 13;
break;
case ( 256 / 8 ) :
rounds = 15;
break;
default:
DBGC ( aes, "AES %p unsupported key length (%zd bits)\n",
aes, ( keylen * 8 ) );
return -EINVAL;
}
aes->rounds = rounds;
enc = aes->encrypt.key;
end = enc[rounds].column;
/* Copy raw key */
memcpy ( enc, key, keylen );
prev = enc->column;
next = ( ( ( void * ) prev ) + keylen );
tmp = next[-1];
/* Construct expanded key */
while ( next < end ) {
/* If this is the first column of an expanded key
* block, or the middle column of an AES-256 key
* block, then apply the S-box.
*/
if ( ( offset == 0 ) || ( ( offset | keylen ) == 48 ) )
tmp = aes_key_sbox ( tmp );
/* If this is the first column of an expanded key
* block then rotate and apply the round constant.
*/
if ( offset == 0 ) {
tmp = aes_key_rotate ( tmp );
tmp = aes_key_rcon ( tmp, rcon );
rcon = aes_double ( rcon );
}
/* XOR with previous key column */
tmp ^= *prev;
/* Store column */
*next = tmp;
/* Move to next column */
offset += sizeof ( *next );
if ( offset == keylen )
offset = 0;
next++;
prev++;
}
DBGC2 ( aes, "AES %p expanded %zd-bit key:\n", aes, ( keylen * 8 ) );
DBGC2_HDA ( aes, 0, &aes->encrypt, ( rounds * sizeof ( *enc ) ) );
/* Convert to decryption key */
memset ( &zero, 0, sizeof ( zero ) );
dec = &aes->decrypt.key[ rounds - 1 ];
memcpy ( dec--, enc++, sizeof ( *dec ) );
while ( dec > aes->decrypt.key ) {
/* Perform InvMixColumns (by reusing the encryption
* final-round code to perform ShiftRows+SubBytes and
* reusing the decryption intermediate-round code to
* perform InvShiftRows+InvSubBytes+InvMixColumns, all
* with a zero encryption key).
*/
aes_final ( &aes_mixcolumns, AES_STRIDE_SHIFTROWS,
enc++, &temp, &zero );
aes_decrypt_rounds ( &temp, dec--, &zero, 1 );
}
memcpy ( dec--, enc++, sizeof ( *dec ) );
DBGC2 ( aes, "AES %p inverted %zd-bit key:\n", aes, ( keylen * 8 ) );
DBGC2_HDA ( aes, 0, &aes->decrypt, ( rounds * sizeof ( *dec ) ) );
return 0;
}
/**
* Set initialisation vector
*
* @v ctx Context
* @v iv Initialisation vector
*/
static void aes_setiv ( void *ctx __unused, const void *iv __unused ) {
/* Nothing to do */
}
/** Basic AES algorithm */
struct cipher_algorithm aes_algorithm = {
.name = "aes",
.ctxsize = sizeof ( struct aes_context ),
.blocksize = AES_BLOCKSIZE,
.setkey = aes_setkey,
.setiv = aes_setiv,
.encrypt = aes_encrypt,
.decrypt = aes_decrypt,
};
/* AES in Electronic Codebook mode */
ECB_CIPHER ( aes_ecb, aes_ecb_algorithm,
aes_algorithm, struct aes_context, AES_BLOCKSIZE );
/* AES in Cipher Block Chaining mode */
CBC_CIPHER ( aes_cbc, aes_cbc_algorithm,
aes_algorithm, struct aes_context, AES_BLOCKSIZE );