eap_psk_common.c

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#include "includes.h"

#include "common.h"
#include "aes_wrap.h"
#include "eap_defs.h"
#include "eap_psk_common.h"

#define aes_block_size 16


int eap_psk_key_setup(const u8 *psk, u8 *ak, u8 *kdk)
{
        os_memset(ak, 0, aes_block_size);
        if (aes_128_encrypt_block(psk, ak, ak))
                return -1;
        os_memcpy(kdk, ak, aes_block_size);
        ak[aes_block_size - 1] ^= 0x01;
        kdk[aes_block_size - 1] ^= 0x02;
        if (aes_128_encrypt_block(psk, ak, ak) ||
            aes_128_encrypt_block(psk, kdk, kdk))
                return -1;
        return 0;
}


int eap_psk_derive_keys(const u8 *kdk, const u8 *rand_p, u8 *tek, u8 *msk,
                        u8 *emsk)
{
        u8 hash[aes_block_size];
        u8 counter = 1;
        int i;

        if (aes_128_encrypt_block(kdk, rand_p, hash))
                return -1;

        hash[aes_block_size - 1] ^= counter;
        if (aes_128_encrypt_block(kdk, hash, tek))
                return -1;
        hash[aes_block_size - 1] ^= counter;
        counter++;

        for (i = 0; i < EAP_MSK_LEN / aes_block_size; i++) {
                hash[aes_block_size - 1] ^= counter;
                if (aes_128_encrypt_block(kdk, hash, &msk[i * aes_block_size]))
                        return -1;
                hash[aes_block_size - 1] ^= counter;
                counter++;
        }

        for (i = 0; i < EAP_EMSK_LEN / aes_block_size; i++) {
                hash[aes_block_size - 1] ^= counter;
                if (aes_128_encrypt_block(kdk, hash,
                                          &emsk[i * aes_block_size]))
                        return -1;
                hash[aes_block_size - 1] ^= counter;
                counter++;
        }

        return 0;
}