Commit 0f409b05 authored by Fabio Utzig's avatar Fabio Utzig Committed by Fabio Utzig
Browse files

ext: tinycrypt: update ctr mode to stream 



Add an offset parameter to mode ctr so it can be properly used as a
streaming cipher, like required by the flash encryption algorithm.

Signed-off-by: default avatarFabio Utzig <fabio.utzig@nordicsemi.no>
parent d3838989

boot/bootutil/include/bootutil/crypto/aes_ctr.h

+2 −24
Original line number Diff line number Diff line
@@ -96,33 +96,11 @@ static inline int bootutil_aes_ctr_set_key(bootutil_aes_ctr_context *ctx, const 


static int _bootutil_aes_ctr_crypt(bootutil_aes_ctr_context *ctx, uint8_t *counter, const uint8_t *in, uint32_t inlen, uint32_t blk_off, uint8_t *out)

{

    uint8_t buf[16];

    uint32_t buflen;

    int rc;

    if (blk_off == 0) {

        rc = tc_ctr_mode(out, inlen, in, inlen, counter, ctx);

    rc = tc_ctr_mode(out, inlen, in, inlen, counter, &blk_off, ctx);

    if (rc != TC_CRYPTO_SUCCESS) {

        return -1;

    }

    } else if (blk_off < 16) {

        buflen = ((inlen + blk_off <= 16) ? inlen : (16 - blk_off));

        inlen -= buflen;

        memcpy(&buf[blk_off], &in[0], buflen);

        rc = tc_ctr_mode(buf, 16, buf, 16, counter, ctx);

        if (rc != TC_CRYPTO_SUCCESS) {

            return -1;

        }

        memcpy(&out[0], &buf[blk_off], buflen);

        memset(&buf[0], 0, 16);

        if (inlen > 0) {

            rc = tc_ctr_mode(&out[buflen], inlen, &in[buflen], inlen, counter, ctx);

        }

        if (rc != TC_CRYPTO_SUCCESS) {

            return -1;

        }

    } else {

        return -1;

    }

    return 0;

}

ext/tinycrypt/lib/include/tinycrypt/ctr_mode.h

+3 −1
Original line number Diff line number Diff line
@@ -96,10 +96,12 @@ extern "C" { 
 * @param in IN -- data to encrypt (or decrypt)

 * @param inlen IN -- length of input data in bytes

 * @param ctr IN/OUT -- the current counter value

 * @param blk_off IN/OUT -- the offset in the block

 * @param sched IN -- an initialized AES key schedule

 */

int tc_ctr_mode(uint8_t *out, unsigned int outlen, const uint8_t *in,

		unsigned int inlen, uint8_t *ctr, const TCAesKeySched_t sched);

		unsigned int inlen, uint8_t *ctr, uint32_t *blk_off,

		const TCAesKeySched_t sched);



#ifdef __cplusplus

}

ext/tinycrypt/lib/source/ctr_mode.c

+9 −3
Original line number Diff line number Diff line
@@ -35,18 +35,21 @@ 
#include <tinycrypt/utils.h>



int tc_ctr_mode(uint8_t *out, unsigned int outlen, const uint8_t *in,

		unsigned int inlen, uint8_t *ctr, const TCAesKeySched_t sched)

		unsigned int inlen, uint8_t *ctr, uint32_t *blk_off,

		const TCAesKeySched_t sched)

{



	uint8_t buffer[TC_AES_BLOCK_SIZE];

	uint8_t nonce[TC_AES_BLOCK_SIZE];

	unsigned int block_num;

	unsigned int i;

	uint32_t n;



	/* input sanity check: */

	if (out == (uint8_t *) 0 ||

	    in == (uint8_t *) 0 ||

	    ctr == (uint8_t *) 0 ||

	    blk_off == (uint32_t *) 0 ||

	    sched == (TCAesKeySched_t) 0 ||

	    inlen == 0 ||

	    outlen == 0 ||
@@ -60,8 +63,9 @@ int tc_ctr_mode(uint8_t *out, unsigned int outlen, const uint8_t *in, 
	/* select the last 4 bytes of the nonce to be incremented */

	block_num = (nonce[12] << 24) | (nonce[13] << 16) |

		    (nonce[14] << 8) | (nonce[15]);

	n = *blk_off;

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

		if ((i % (TC_AES_BLOCK_SIZE)) == 0) {

		if (n == 0) {

			/* encrypt data using the current nonce */

			if (tc_aes_encrypt(buffer, nonce, sched)) {

				block_num++;
@@ -74,8 +78,10 @@ int tc_ctr_mode(uint8_t *out, unsigned int outlen, const uint8_t *in, 
			}

		}

		/* update the output */

		*out++ = buffer[i%(TC_AES_BLOCK_SIZE)] ^ *in++;

		*out++ = buffer[n] ^ *in++;

		n = (n + 1) % TC_AES_BLOCK_SIZE;

	}

	*blk_off = n;



	/* update the counter */

	ctr[12] = nonce[12]; ctr[13] = nonce[13];

ext/tinycrypt/tests/test_ctr_mode.c

+15 −3
Original line number Diff line number Diff line
@@ -81,30 +81,42 @@ unsigned int test_1_and_2(void) 
        uint8_t out[80];

        uint8_t decrypted[64];

        unsigned int result = TC_PASS;

        uint32_t off = 0;



        TC_PRINT("CTR test #1 (encryption SP 800-38a tests):\n");

        (void)tc_aes128_set_encrypt_key(&sched, key);



        (void)memcpy(out, ctr, sizeof(ctr));

        if (tc_ctr_mode(&out[TC_AES_BLOCK_SIZE], sizeof(plaintext), plaintext,

			sizeof(plaintext), ctr, &sched) == 0) {

			sizeof(plaintext), ctr, &off, &sched) == 0) {

                TC_ERROR("CTR test #1 (encryption SP 800-38a tests) failed in %s.\n", __func__);

                result = TC_FAIL;

                goto exitTest1;

        }



        if (off != 0) {

            TC_ERROR("CTR test #1 invalid block offset (%u).\n", off);

            result = TC_FAIL;

            goto exitTest1;

        }

        result = check_result(1, ciphertext, sizeof(out), out, sizeof(out));

        TC_END_RESULT(result);



        TC_PRINT("CTR test #2 (decryption SP 800-38a tests):\n");

        (void) memcpy(ctr, out, sizeof(ctr));

        off = 0;

        if (tc_ctr_mode(decrypted, sizeof(decrypted), &out[TC_AES_BLOCK_SIZE],

                        sizeof(decrypted), ctr, &sched) == 0) {

                        sizeof(decrypted), ctr, &off, &sched) == 0) {

                TC_ERROR("CTR test #2 (decryption SP 800-38a tests) failed in %s.\n", __func__);

                result = TC_FAIL;

                goto exitTest1;

        }



        if (off != 0) {

            TC_ERROR("CTR test #2 invalid block offset (%u).\n", off);

            result = TC_FAIL;

            goto exitTest1;

        }

        result = check_result(2, plaintext, sizeof(plaintext),

			      decrypted, sizeof(plaintext));
@@ -126,7 +138,7 @@ int main(void) 
        TC_PRINT("Performing CTR tests:\n");

        result = test_1_and_2();

        if (result == TC_FAIL) { /* terminate test */

                TC_ERROR("CBC test #1 failed.\n");

                TC_ERROR("CTR test #1 failed.\n");

                goto exitTest;

        }

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