Hi Jacob, thanks for the input.
On Tue 11 Dec, 2018, 4:24 PM Jakob Bohm via openssl-users, <openssl-users@xxxxxxxxxxx> wrote:
On 10/12/2018 11:30, Hemant Ranvir wrote:
> Dear all,
> After extracting openssl-1.1.1.tar.gz, openssl can be configured
> without asm by passing no-asm flag during config command.
>
> The expanded key can be obtained like follows:
> //Getting expanded key from inside openssl
> //Copied from crypto/evp/e_aes.c
> typedef struct {
> union {
> double align;
> AES_KEY ks;
> } ks;
> block128_f block;
> union {
> cbc128_f cbc;
> ctr128_f ctr;
> } stream;
> } EVP_AES_KEY;
>
> EVP_CIPHER_CTX *cipher_ctx = ssl->enc_write_ctx;
> EVP_AES_KEY * cipher_data = EVP_CIPHER_CTX_get_cipher_data(cipher_ctx);
> printf("Encrypted Expanded Key is : ");
> for(i=0;i<((cipher_ctx->cipher->key_len)/sizeof(cipher_data->ks.ks.rd_key[0])*11);i++)
> {
> printf("%08x", cipher_data->ks.ks.rd_key[i]);
> }
> printf("\n");
>
> To get the 128 bit encrypted key :
> unsigned char* key = unsigned char* malloc(16);
> int i;
> for (i=0; i<4; i++) {
> key[4*i] = cipher_data->ks.ks.rd_key[i] >> 24;
> key[4*i+1] = cipher_data->ks.ks.rd_key[i] >> 16;
> key[4*i+2] = cipher_data->ks.ks.rd_key[i] >> 8;
> key[4*i+3] = cipher_data->ks.ks.rd_key[i];
> }
>
> I am using this 128 bit key and using it in *Rijndael* Key Schedule
> function to get the expanded key. The expanded key will be 128*11 bit
> long.
> This expanded key is equal to the expanded key obtained from accessing
> structures inside openssl(shown in section "Getting expanded key from
> inside openssl" ) which is expected.
>
> Now if I configure openssl without no-asm flag and get the expanded
> key from inside openssl and compare it with the expanded key
> calculated using the function I wrote. They are not equal. As far as I
> know there is only one way to calculate expanded key. I have even
> checked whether the expanded key inside openssl is inverse cipher
> expanded key but yet it is different.
> Can someone point me in the right direction.
> Thanks!
>
>
There have always been multiple ways to store the expanded AES
key, each optimized a different implementation of the inner
loops in the encryption block function. It is highly likely
the assembler implementation for any given processor uses a
different inner loop, and thus a different expanded key data
layout, than the generic C code.
Enjoy
Jakob
--
Jakob Bohm, CIO, Partner, WiseMo A/S. https://www.wisemo.com
Transformervej 29, 2860 Søborg, Denmark. Direct +45 31 13 16 10
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