Re: [PATCH v4 03/16] keytoc: fix ECDSA endianess problems

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

On 13.09.24 09:59, Sascha Hauer wrote:
> We print the ECDSA key values out as an uint32_t C array. They are used in
> barebox as a uint64_t C array, so when the endianess of the build system
> differs from the system barebox runs on we end up with the 32bit words
> swapped in the u64 array. Fix this by printing out the key values as
> an uint64_t array.
> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Acked-by: Ahmad Fatoum <a.fatoum@pengutronix.de>

Cool, thanks. Now we just need a tes and see it work on big-endian MIPS :-)

Cheers,
Ahmad

> ---
>  scripts/keytoc.c | 42 +++++++++++++++++++++---------------------
>  1 file changed, 21 insertions(+), 21 deletions(-)
> 
> diff --git a/scripts/keytoc.c b/scripts/keytoc.c
> index 7e73c786a3..b140160688 100644
> --- a/scripts/keytoc.c
> +++ b/scripts/keytoc.c
> @@ -315,12 +315,12 @@ static int rsa_get_params(EVP_PKEY *key, uint64_t *exponent, uint32_t *n0_invp,
>  
>  static FILE *outfilep;
>  
> -static int print_bignum(BIGNUM *num, int num_bits)
> +static int print_bignum(BIGNUM *num, int num_bits, int width)
>  {
>  	BIGNUM *tmp, *big2, *big32, *big2_32;
>  	BN_CTX *ctx;
>  	int i;
> -	uint32_t *arr;
> +	uint64_t *arr;
>  
>  	tmp = BN_new();
>  	big2 = BN_new();
> @@ -345,34 +345,34 @@ static int print_bignum(BIGNUM *num, int num_bits)
>  		return -ENOMEM;
>  	}
>  	BN_set_word(big2, 2L);
> -	BN_set_word(big32, 32L);
> -	BN_exp(big2_32, big2, big32, ctx); /* B = 2^32 */
> +	BN_set_word(big32, width);
> +	BN_exp(big2_32, big2, big32, ctx); /* B = 2^width */
>  
> -	arr = malloc(num_bits / 32 * sizeof(uint32_t));
> +	arr = malloc(num_bits / width * sizeof(*arr));
>  
> -	for (i = 0; i < num_bits / 32; i++) {
> +	for (i = 0; i < num_bits / width; i++) {
>  		BN_mod(tmp, num, big2_32, ctx); /* n = N mod B */
>  		arr[i] = BN_get_word(tmp);
> -		BN_rshift(num, num, 32); /*  N = N/B */
> +		BN_rshift(num, num, width); /*  N = N/B */
>  	}
>  
>  	if (dts) {
> -		for (i = 0; i < num_bits / 32; i++) {
> +		for (i = 0; i < num_bits / width; i++) {
>  			if (i % 4)
>  				fprintf(outfilep, " ");
>  			else
>  				fprintf(outfilep, "\n\t\t\t\t");
> -			fprintf(outfilep, "0x%08x", arr[num_bits / 32 - 1 - i]);
> -			BN_rshift(num, num, 32); /*  N = N/B */
> +			fprintf(outfilep, "0x%0*jx", width / 4, arr[num_bits / width - 1 - i]);
> +			BN_rshift(num, num, width); /*  N = N/B */
>  		}
>  	} else {
> -		for (i = 0; i < num_bits / 32; i++) {
> +		for (i = 0; i < num_bits / width; i++) {
>  			if (i % 4)
>  				fprintf(outfilep, " ");
>  			else
>  				fprintf(outfilep, "\n\t");
> -			fprintf(outfilep, "0x%08x,", arr[i]);
> -			BN_rshift(num, num, 32); /*  N = N/B */
> +			fprintf(outfilep, "0x%0*jx,", width / 4, arr[i]);
> +			BN_rshift(num, num, width); /*  N = N/B */
>  		}
>  	}
>  
> @@ -473,12 +473,12 @@ static int gen_key_ecdsa(EVP_PKEY *key, const char *key_name, const char *key_na
>  		fprintf(stderr, "ERROR: generating a dts snippet for ECDSA keys is not yet supported\n");
>  		return -EOPNOTSUPP;
>  	} else {
> -		fprintf(outfilep, "\nstatic uint32_t %s_x[] = {", key_name_c);
> -		print_bignum(key_x, bits);
> +		fprintf(outfilep, "\nstatic uint64_t %s_x[] = {", key_name_c);
> +		print_bignum(key_x, bits, 64);
>  		fprintf(outfilep, "\n};\n\n");
>  
> -		fprintf(outfilep, "static uint32_t %s_y[] = {", key_name_c);
> -		print_bignum(key_y, bits);
> +		fprintf(outfilep, "static uint64_t %s_y[] = {", key_name_c);
> +		print_bignum(key_y, bits, 64);
>  		fprintf(outfilep, "\n};\n\n");
>  
>  		fprintf(outfilep, "static struct ecdsa_public_key %s = {\n", key_name_c);
> @@ -512,10 +512,10 @@ static int gen_key_rsa(EVP_PKEY *key, const char *key_name, const char *key_name
>  	if (dts) {
>  		fprintf(outfilep, "\t\tkey-%s {\n", key_name_c);
>  		fprintf(outfilep, "\t\t\trsa,r-squared = <");
> -		print_bignum(r_squared, bits);
> +		print_bignum(r_squared, bits, 32);
>  		fprintf(outfilep, ">;\n");
>  		fprintf(outfilep, "\t\t\trsa,modulus= <");
> -		print_bignum(modulus, bits);
> +		print_bignum(modulus, bits, 32);
>  		fprintf(outfilep, ">;\n");
>  		fprintf(outfilep, "\t\t\trsa,exponent = <0x%0lx 0x%lx>;\n",
>  			(exponent >> 32) & 0xffffffff,
> @@ -526,11 +526,11 @@ static int gen_key_rsa(EVP_PKEY *key, const char *key_name, const char *key_name
>  		fprintf(outfilep, "\t\t};\n");
>  	} else {
>  		fprintf(outfilep, "\nstatic uint32_t %s_modulus[] = {", key_name_c);
> -		print_bignum(modulus, bits);
> +		print_bignum(modulus, bits, 32);
>  		fprintf(outfilep, "\n};\n\n");
>  
>  		fprintf(outfilep, "static uint32_t %s_rr[] = {", key_name_c);
> -		print_bignum(r_squared, bits);
> +		print_bignum(r_squared, bits, 32);
>  		fprintf(outfilep, "\n};\n\n");
>  
>  		if (standalone) {


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