Re: [U-Boot] [PATCH 2/4] aes: Move the AES-128-CBC encryption function to common code

16 Feb 2014

Hi Marek,
On 5 February 2014 20:44, Marek Vasut marex@denx.de wrote:
...
Move the AES-128-CBC encryption function implemented in tegra20-common/crypto.c
into lib/aes.c . This is well re-usable common code. Moreover, clean the code up
a bit and fix the kerneldoc-style annotations.
Signed-off-by: Marek Vasut marex@denx.de
arch/arm/cpu/tegra20-common/crypto.c | 72 +-----------------------------------
 include/aes.h                        | 10 +++++
 lib/aes.c                            | 59 +++++++++++++++++++++++++++++
 3 files changed, 71 insertions(+), 70 deletions(-)

diff --git a/arch/arm/cpu/tegra20-common/crypto.c b/arch/arm/cpu/tegra20-common/crypto.c
index 8209f76..b18e67c 100644
--- a/arch/arm/cpu/tegra20-common/crypto.c
+++ b/arch/arm/cpu/tegra20-common/crypto.c
@@ -19,74 +19,6 @@ enum security_op {
        SECURITY_ENCRYPT        = 1 << 1,       /* Encrypt the data */
 };
-static void debug_print_vector(char *name, u32 num_bytes, u8 *data)
-{

  u32 i;



  debug("%s [%d] @0x%08x", name, num_bytes, (u32)data);


  for (i = 0; i < num_bytes; i++) {


          if (i % 16 == 0)


                  debug(" = ");


          debug("%02x", data[i]);


          if ((i+1) % 16 != 0)


                  debug(" ");


  }


  debug("\n");



-}



-/**


Apply chain data to the destination using EOR







Each array is of length AES_AES_KEY_LENGTH.



AES_KEY_LENGTH
...






\param cbc_chain_data       Chain data



\param src                  Source data



\param dst                  Destination data, which is modified here


*/

-static void apply_cbc_chain_data(u8 *cbc_chain_data, u8 *src, u8 *dst)
-{

  int i;



  for (i = 0; i < 16; i++)



AES_KEY_LENGTH?
...

          *dst++ = *src++ ^ *cbc_chain_data++;



-}



-/**


Encrypt some data with AES.







\param key_schedule         Expanded key to use



\param src                  Source data to encrypt



\param dst                  Destination buffer



\param num_aes_blocks       Number of AES blocks to encrypt


*/

-static void encrypt_object(u8 *key_schedule, u8 *src, u8 *dst,

                     u32 num_aes_blocks)



-{

  u8 tmp_data[AES_KEY_LENGTH];


  u8 *cbc_chain_data;


  u32 i;



  cbc_chain_data = zero_key;      /* Convenient array of 0's for IV */



  for (i = 0; i < num_aes_blocks; i++) {


          debug("encrypt_object: block %d of %d\n", i, num_aes_blocks);


          debug_print_vector("AES Src", AES_KEY_LENGTH, src);



          /* Apply the chain data */


          apply_cbc_chain_data(cbc_chain_data, src, tmp_data);


          debug_print_vector("AES Xor", AES_KEY_LENGTH, tmp_data);



          /* encrypt the AES block */


          aes_encrypt(tmp_data, key_schedule, dst);


          debug_print_vector("AES Dst", AES_KEY_LENGTH, dst);



          /* Update pointers for next loop. */


          cbc_chain_data = dst;


          src += AES_KEY_LENGTH;


          dst += AES_KEY_LENGTH;


  }



-}



/**

Shift a vector left by one bit


@@ -129,7 +61,7 @@ static void sign_object(u8 *key, u8 *key_schedule, u8 *src, u8 *dst,
        for (i = 0; i < AES_KEY_LENGTH; i++)
                tmp_data[i] = 0;

  encrypt_object(key_schedule, tmp_data, left, 1);




  aes_cbc_encrypt_blocks(key_schedule, tmp_data, left, 1);
  debug_print_vector("AES(key, nonce)", AES_KEY_LENGTH, left);

  left_shift_vector(left, k1, sizeof(left));



@@ -193,7 +125,7 @@ static int encrypt_and_sign(u8 *key, enum security_op oper, u8 *src,
        if (oper & SECURITY_ENCRYPT) {
                /* Perform this in place, resulting in src being encrypted. */
                debug("encrypt_and_sign: begin encryption\n");

          encrypt_object(key_schedule, src, src, num_aes_blocks);




          aes_cbc_encrypt_blocks(key_schedule, src, src, num_aes_blocks);
          debug("encrypt_and_sign: end encryption\n");
  }




diff --git a/include/aes.h b/include/aes.h
index c70eda6..d9bb387 100644
--- a/include/aes.h
+++ b/include/aes.h
@@ -53,4 +53,14 @@ void aes_encrypt(u8 *in, u8 *expkey, u8 *out);
  */
 void aes_decrypt(u8 *in, u8 *expkey, u8 *out);
+/**


aes_cbc_encrypt_blocks() - Encrypt multiple blocks of data with AES CBC.







@key_exp            Expanded key to use



@src                        Source data to encrypt



@dst                        Destination buffer



@num_aes_blocks     Number of AES blocks to encrypt


*/

+void aes_cbc_encrypt_blocks(u8 *key_exp, u8 *src, u8 *dst, u32 num_aes_blocks);



#endif /* _AES_REF_H_ */
diff --git a/lib/aes.c b/lib/aes.c
index e996b27..4df5dae 100644
--- a/lib/aes.c
+++ b/lib/aes.c
@@ -580,3 +580,62 @@ void aes_decrypt(u8 *in, u8 *expkey, u8 *out)
    memcpy(out, state, sizeof(state));

}



+static void debug_print_vector(char *name, u32 num_bytes, u8 *data)
+{

  u32 i;



  debug("%s [%d] @0x%08x", name, num_bytes, (u32)data);


  for (i = 0; i < num_bytes; i++) {


          if (i % 16 == 0)


                  debug(" = ");


          debug("%02x", data[i]);


          if ((i+1) % 16 != 0)


                  debug(" ");


  }


  debug("\n");



Can we use print_buffer() here?
...
+}



+/**


Apply chain data to the destination using EOR







Each array is of length AES_AES_KEY_LENGTH.







@cbc_chain_data     Chain data



@src                        Source data



@dst                        Destination data, which is modified here


*/

+static void apply_cbc_chain_data(u8 *cbc_chain_data, u8 *src, u8 *dst)
+{

  int i;



  for (i = 0; i < 16; i++)


          *dst++ = *src++ ^ *cbc_chain_data++;



+}



+void aes_cbc_encrypt_blocks(u8 *key_exp, u8 *src, u8 *dst, u32 num_aes_blocks)
+{

  u8 zero_key[AES_KEY_LENGTH] = { 0 };


  u8 tmp_data[AES_KEY_LENGTH];


  /* Convenient array of 0's for IV */


  u8 *cbc_chain_data = zero_key;


  u32 i;



  for (i = 0; i < num_aes_blocks; i++) {


          debug("encrypt_object: block %d of %d\n", i, num_aes_blocks);


          debug_print_vector("AES Src", AES_KEY_LENGTH, src);



          /* Apply the chain data */


          apply_cbc_chain_data(cbc_chain_data, src, tmp_data);


          debug_print_vector("AES Xor", AES_KEY_LENGTH, tmp_data);



          /* Encrypt the AES block */


          aes_encrypt(tmp_data, key_exp, dst);


          debug_print_vector("AES Dst", AES_KEY_LENGTH, dst);



          /* Update pointers for next loop. */


          cbc_chain_data = dst;


          src += AES_KEY_LENGTH;


          dst += AES_KEY_LENGTH;


  }



+}
1.8.5.3

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Regards,
Simon

    

Re: [U-Boot] [PATCH 2/4] aes: Move the AES-128-CBC encryption function to common code

Simon Glass

Signed-off-by: Marek Vasut marex@denx.de

+}