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WIP: swtpm_cert: Enable CAs with ML-DSA key to sign a certifcate #1064

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stefanberger wants to merge 1 commit into from
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WIP: swtpm_cert: Enable CAs with ML-DSA key to sign a certifcate #1064

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19 changes: 19 additions & 0 deletions configure.ac
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Original file line number Diff line number Diff line change
Expand Up @@ -220,6 +220,25 @@ AS_IF([test "x$with_gnutls" != "xno"],
[with_gnutls=no]
)
AS_IF([test "x$with_gnutls" != "xno"],[with_gnutls="yes"])
AS_IF([test "x$with_gnutls" = "xyes"],
[AC_COMPILE_IFELSE(
[AC_LANG_PROGRAM(
[[
#include <gnutls/gnutls.h>
#include <stdio.h>
]],
[[
printf("%d", GNUTLS_PK_MLDSA44);
]]
)],
[
AC_MSG_RESULT("GnuTLS has ML-DSA support")
AC_DEFINE_UNQUOTED([GNUTLS_SUPPORTS_MLDSA], 1,
[whether GnuTLS support ML-DSA signing algorithm])
],
[AC_MSG_RESULT("GnuTLS has no ML-DSA support")],
)]
)
]
)

Expand Down
29 changes: 25 additions & 4 deletions src/swtpm_cert/ek-cert.c
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Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,8 @@
* in section 3.5
*/

#include "config.h"

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
Expand Down Expand Up @@ -984,6 +986,26 @@ static char *get_password(const char *password)
return result;
}

/*
* Get the hash algorithm for signing. TPM 1.2 used SHA1 and TPM 2 SHA256.
* For an ML-DSA signing key only shake-256 is allowed.
*/
static int get_signing_hashalgo(int flags, gnutls_x509_privkey_t sigkey)
{
if (flags & CERT_TYPE_TPM2_F) {
#ifdef GNUTLS_SUPPORTS_MLDSA
int keyalgo = gnutls_x509_privkey_get_pk_algorithm2(sigkey, NULL);

if (keyalgo == GNUTLS_PK_MLDSA44 ||
keyalgo == GNUTLS_PK_MLDSA65 ||
keyalgo == GNUTLS_PK_MLDSA87)
return GNUTLS_DIG_SHAKE_256;
#endif
return GNUTLS_DIG_SHA256;
}
return GNUTLS_DIG_SHA1;
}

static void capabilities_print_json(void)
{
fprintf(stdout,
Expand Down Expand Up @@ -1018,7 +1040,7 @@ main(int argc, char *argv[])
int ecc_y_len = 0;
const char *ecc_curveid = NULL;
gnutls_datum_t datum = { NULL, 0}, out = { NULL, 0};
gnutls_digest_algorithm_t hashAlgo = GNUTLS_DIG_SHA1;
gnutls_digest_algorithm_t hashAlgo;
mpz_t serial;
time_t now;
int err;
Expand Down Expand Up @@ -1261,9 +1283,6 @@ main(int argc, char *argv[])
}
}

if (flags & CERT_TYPE_TPM2_F)
hashAlgo = GNUTLS_DIG_SHA256;

if ((mpz_sizeinbase(serial, 2) + 7) / 8 > sizeof(ser_number) - 1) {
fprintf(stderr, "Serial number is too large.\n");
goto cleanup;
Expand Down Expand Up @@ -1704,6 +1723,8 @@ if (_err != GNUTLS_E_SUCCESS) { \
CHECK_GNUTLS_ERROR(err, "Could not set public EK on CRT: %s\n",
gnutls_strerror(err))

hashAlgo = get_signing_hashalgo(flags, sigkey);

/* sign cert */
if (sigkey) {
err = gnutls_x509_crt_sign2(crt, sigcert, sigkey, hashAlgo, 0);
Expand Down