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scd: Implement RSA signing for PIV cards.
* scd/app-piv.c (concat_tlv_list): New. (get_key_algorithm_by_dobj): Rename args for clarity. (do_auth): factor all code out to ... (do_sign): new. Implement RSA signing. Signed-off-by: Werner Koch <wk@gnupg.org>
This commit is contained in:
Werner Koch
parent
0328976c94
commit
53beea56af
332
scd/app-piv.c
332
scd/app-piv.c
@ -469,6 +469,107 @@ add_tlv (unsigned char *buffer, unsigned int tag, size_t length)
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}
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/* Function to build a list of TLV and return the result in a mallcoed
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* buffer. The varargs are tuples of (int,size_t,void) each with the
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* tag, the length and the actual data. A (0,0,NULL) tuple terminates
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* the list. Up to 10 tuples are supported. */
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static gpg_error_t
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concat_tlv_list (unsigned char **r_result, size_t *r_resultlen, ...)
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{
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gpg_error_t err;
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va_list arg_ptr;
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struct {
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int tag;
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unsigned int len;
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unsigned int contlen;
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const void *data;
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} argv[10];
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int i, j, argc;
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unsigned char *data = NULL;
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size_t datalen;
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unsigned char *p;
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size_t n;
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*r_result = NULL;
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*r_resultlen = 0;
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/* Collect all args. Check that length is <= 2^16 to match the
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* behaviour of add_tlv. */
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va_start (arg_ptr, r_resultlen);
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argc = 0;
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while (((argv[argc].tag = va_arg (arg_ptr, int))))
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{
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argv[argc].len = va_arg (arg_ptr, size_t);
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argv[argc].contlen = 0;
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argv[argc].data = va_arg (arg_ptr, const void *);
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if (argc >= DIM (argv)-1 || argv[argc].len > 0xffff)
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{
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va_end (arg_ptr);
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err = gpg_error (GPG_ERR_EINVAL);
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goto leave;
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}
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argc++;
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}
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va_end (arg_ptr);
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/* Compute the required buffer length and allocate the buffer. */
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datalen = 0;
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for (i=0; i < argc; i++)
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{
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if (!argv[i].len && !argv[i].data)
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{
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/* Constructed tag. Compute its length. Note that we
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* currently allow only one constructed tag in the list. */
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for (n=0, j = i + 1; j < argc; j++)
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{
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log_assert (!(!argv[j].len && !argv[j].data));
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n += add_tlv (NULL, argv[j].tag, argv[j].len);
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n += argv[j].len;
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}
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argv[i].contlen = n;
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datalen += add_tlv (NULL, argv[i].tag, n);
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}
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else
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{
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datalen += add_tlv (NULL, argv[i].tag, argv[i].len);
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datalen += argv[i].len;
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}
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}
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data = xtrymalloc (datalen);
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if (!data)
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{
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err = gpg_error_from_syserror ();
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goto leave;
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}
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/* Copy that data to the buffer. */
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p = data;
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for (i=0; i < argc; i++)
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{
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if (!argv[i].len && !argv[i].data)
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{
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/* Constructed tag. */
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p += add_tlv (p, argv[i].tag, argv[i].contlen);
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}
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else
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{
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p += add_tlv (p, argv[i].tag, argv[i].len);
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memcpy (p, argv[i].data, argv[i].len);
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p += argv[i].len;
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}
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}
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log_assert ( data + datalen == p );
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*r_result = data;
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data = NULL;
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*r_resultlen = datalen;
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err = 0;
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leave:
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xfree (data);
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return err;
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}
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/* Wrapper around iso7816_put_data_odd which also sets the tag into
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* the '5C' data object. The varargs are tuples of (int,size_t,void)
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* with the tag, the length and the actual data. A (0,0,NULL) tuple
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@ -1354,7 +1455,7 @@ do_readkey (app_t app, int advanced, const char *keyrefstr,
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* store it at R_ALGO. The algorithm is taken from the corresponding
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* certificate or from a cache. */
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static gpg_error_t
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get_key_algorithm_by_dobj (app_t app, data_object_t dobj, int *r_algo)
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get_key_algorithm_by_dobj (app_t app, data_object_t dobj, int *r_mechanism)
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{
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gpg_error_t err;
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unsigned char *certbuf = NULL;
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@ -1369,7 +1470,7 @@ get_key_algorithm_by_dobj (app_t app, data_object_t dobj, int *r_algo)
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size_t n;
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const char *curve_name;
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*r_algo = 0;
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*r_mechanism = 0;
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err = readcert_by_tag (app, dobj->tag, &certbuf, &certbuflen, &mechanism);
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if (err)
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@ -1382,7 +1483,7 @@ get_key_algorithm_by_dobj (app_t app, data_object_t dobj, int *r_algo)
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case PIV_ALGORITHM_RSA:
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case PIV_ALGORITHM_ECC_P256:
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case PIV_ALGORITHM_ECC_P384:
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*r_algo = mechanism;
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*r_mechanism = mechanism;
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break;
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default:
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@ -1468,7 +1569,7 @@ get_key_algorithm_by_dobj (app_t app, data_object_t dobj, int *r_algo)
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dobj->keyref, algoname, gpg_strerror (err));
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goto leave;
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}
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*r_algo = algo;
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*r_mechanism = algo;
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leave:
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gcry_free (algoname);
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@ -1862,10 +1963,11 @@ do_check_chv (app_t app, const char *pwidstr,
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* stored there and an error code returned. For ECDSA the result is
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* the simple concatenation of R and S without any DER encoding. R
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* and S are left extended with zeroes to make sure they have an equal
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* length.
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* length. If HASHALGO is not zero, the function prepends the hash's
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* OID to the indata or checks that it is consistent.
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*/
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static gpg_error_t
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do_auth (app_t app, const char *keyidstr,
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do_sign (app_t app, const char *keyidstr, int hashalgo,
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gpg_error_t (*pincb)(void*, const char *, char **),
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void *pincb_arg,
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const void *indata_arg, size_t indatalen,
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@ -1874,13 +1976,16 @@ do_auth (app_t app, const char *keyidstr,
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const unsigned char *indata = indata_arg;
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gpg_error_t err;
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data_object_t dobj;
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unsigned char tmpl[2+2+2+128];
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size_t tmpllen;
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unsigned char oidbuf[64];
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size_t oidbuflen;
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unsigned char *outdata = NULL;
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size_t outdatalen;
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const unsigned char *s;
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size_t n;
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int keyref, algo;
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int keyref, mechanism;
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unsigned char *indata_buffer = NULL; /* Malloced helper. */
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unsigned char *apdudata = NULL;
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size_t apdudatalen;
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if (!keyidstr || !*keyidstr)
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{
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@ -1888,9 +1993,6 @@ do_auth (app_t app, const char *keyidstr,
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goto leave;
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}
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/* Fixme: Shall we support the KEYID/FINGERPRINT syntax? Does it
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* make sense for X.509 certs? */
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dobj = find_dobj_by_keyref (app, keyidstr);
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if ((keyref = keyref_from_dobj (dobj)) == -1)
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{
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@ -1898,69 +2000,141 @@ do_auth (app_t app, const char *keyidstr,
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goto leave;
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}
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err = get_key_algorithm_by_dobj (app, dobj, &algo);
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err = get_key_algorithm_by_dobj (app, dobj, &mechanism);
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if (err)
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goto leave;
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/* We need to remove the ASN.1 prefix from INDATA. We use TEMPL as
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* a temporary buffer for the OID. */
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if (algo == PIV_ALGORITHM_ECC_P256)
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/* For ECC we need to remove the ASN.1 prefix from INDATA. For RSA
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* we need to add the padding and possible also the ASN.1 prefix. */
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if (mechanism == PIV_ALGORITHM_ECC_P256
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|| mechanism == PIV_ALGORITHM_ECC_P384)
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{
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tmpllen = sizeof tmpl;
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err = gcry_md_get_asnoid (GCRY_MD_SHA256, &tmpl, &tmpllen);
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int need_algo, need_digestlen;
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if (mechanism == PIV_ALGORITHM_ECC_P256)
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{
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need_algo = GCRY_MD_SHA256;
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need_digestlen = 32;
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}
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else
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{
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need_algo = GCRY_MD_SHA384;
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need_digestlen = 48;
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}
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if (hashalgo && hashalgo != need_algo)
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{
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err = gpg_error (GPG_ERR_UNSUPPORTED_ALGORITHM);
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log_error ("piv: hash algo %d does not match mechanism %d\n",
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need_algo, mechanism);
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goto leave;
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}
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if (indatalen > need_digestlen)
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{
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oidbuflen = sizeof oidbuf;
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err = gcry_md_get_asnoid (need_algo, &oidbuf, &oidbuflen);
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if (err)
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{
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err = gpg_error (GPG_ERR_INTERNAL);
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log_debug ("piv: no OID for hash algo %d\n", GCRY_MD_SHA256);
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log_debug ("piv: no OID for hash algo %d\n", need_algo);
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goto leave;
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}
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if (indatalen != tmpllen + 32 || memcmp (indata, tmpl, tmpllen))
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if (indatalen != oidbuflen + need_digestlen
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|| memcmp (indata, oidbuf, oidbuflen))
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{
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err = GPG_ERR_INV_VALUE;
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log_error ("piv: bad formatted input for ECC-P256 auth\n");
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err = gpg_error (GPG_ERR_INV_VALUE);
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log_error ("piv: bad input for signing with mechanism %d\n",
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mechanism);
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goto leave;
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}
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indata +=tmpllen;
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indatalen -= tmpllen;
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indata += oidbuflen;
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indatalen -= oidbuflen;
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}
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else if (algo == PIV_ALGORITHM_ECC_P384)
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{
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tmpllen = sizeof tmpl;
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err = gcry_md_get_asnoid (GCRY_MD_SHA384, &tmpl, &tmpllen);
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if (err)
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{
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err = gpg_error (GPG_ERR_INTERNAL);
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log_debug ("piv: no OID for hash algo %d\n", GCRY_MD_SHA384);
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goto leave;
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}
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if (indatalen != tmpllen + 48 || memcmp (indata, tmpl, tmpllen))
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else if (mechanism == PIV_ALGORITHM_RSA)
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{
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err = GPG_ERR_INV_VALUE;
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log_error ("piv: bad formatted input for ECC-P384 auth\n");
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goto leave;
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}
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indata += tmpllen;
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indatalen -= tmpllen;
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}
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else if (algo == PIV_ALGORITHM_RSA)
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/* PIV requires 2048 bit RSA. */
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unsigned int framelen = 2048 / 8;
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unsigned char *frame;
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int i;
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oidbuflen = sizeof oidbuf;
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if (!hashalgo)
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{
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err = gpg_error (GPG_ERR_NOT_IMPLEMENTED);
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log_error ("piv: FIXME: implement RSA authentication\n");
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/* We assume that indata already has the required
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* digestinfo; thus merely prepend the padding below. */
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}
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else if ((err = gcry_md_get_asnoid (hashalgo, &oidbuf, &oidbuflen)))
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{
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log_debug ("piv: no OID for hash algo %d\n", hashalgo);
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goto leave;
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}
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else
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{
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err = gpg_error (GPG_ERR_INTERNAL);
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log_debug ("piv: unknown PIV algo %d from helper function\n", algo);
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unsigned int digestlen = gcry_md_get_algo_dlen (hashalgo);
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if (indatalen == digestlen)
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{
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/* Plain hash in INDATA; prepend the digestinfo. */
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indata_buffer = xtrymalloc (oidbuflen + indatalen);
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if (!indata_buffer)
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{
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err = gpg_error_from_syserror ();
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goto leave;
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}
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/* Because we don't have a dynamic template builder we make sure
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* that we can encode all lengths in one octet. FIXME: Use add_tls
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* from app-openpgp as a base for an strconcat like function. */
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if (indatalen >= 100)
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memcpy (indata_buffer, oidbuf, oidbuflen);
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memcpy (indata_buffer+oidbuflen, indata, indatalen);
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indata = indata_buffer;
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indatalen = oidbuflen + indatalen;
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}
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else if (indatalen == oidbuflen + digestlen
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&& !memcmp (indata, oidbuf, oidbuflen))
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; /* Correct prefix. */
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else
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{
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err = gpg_error (GPG_ERR_TOO_LARGE);
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err = gpg_error (GPG_ERR_INV_VALUE);
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log_error ("piv: bad input for signing with RSA and hash %d\n",
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hashalgo);
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goto leave;
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}
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}
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/* Now prepend the pkcs#v1.5 padding. We require at least 8
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* byte of padding and 3 extra bytes for the prefix and the
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* delimiting nul. */
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if (!indatalen || indatalen + 8 + 4 > framelen)
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{
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err = gpg_error (GPG_ERR_INV_VALUE);
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log_error ("piv: input does not fit into a %u bit PKCS#v1.5 frame\n",
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8*framelen);
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goto leave;
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}
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frame = xtrymalloc (framelen);
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if (!frame)
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{
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err = gpg_error_from_syserror ();
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goto leave;
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}
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n = 0;
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frame[n++] = 0;
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frame[n++] = 1; /* Block type. */
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i = framelen - indatalen - 3 ;
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memset (frame+n, 0xff, i);
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n += i;
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frame[n++] = 0; /* Delimiter. */
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memcpy (frame+n, indata, indatalen);
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n += indatalen;
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log_assert (n == framelen);
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/* And now put it into the indata_buffer. */
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xfree (indata_buffer);
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indata_buffer = frame;
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indata = indata_buffer;
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indatalen = framelen;
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}
|
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else
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{
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err = gpg_error (GPG_ERR_INTERNAL);
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log_debug ("piv: unknown PIV mechanism %d while signing\n", mechanism);
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goto leave;
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}
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@ -1970,19 +2144,18 @@ do_auth (app_t app, const char *keyidstr,
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return err;
|
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|
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/* Build the Dynamic Authentication Template. */
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tmpl[0] = 0x7c;
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tmpl[1] = indatalen + 4;
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tmpl[2] = 0x82; /* Response. */
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tmpl[3] = 0; /* Must be 0 to get the tag in the answer. */
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tmpl[4] = 0x81; /* Challenge. */
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tmpl[5] = indatalen;
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memcpy (tmpl+6, indata, indatalen);
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tmpllen = indatalen + 6;
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err = concat_tlv_list (&apdudata, &apdudatalen,
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(int)0x7c, (size_t)0, NULL, /* Constructed. */
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(int)0x82, (size_t)0, "",
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(int)0x81, (size_t)indatalen, indata,
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(int)0, (size_t)0, NULL);
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if (err)
|
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goto leave;
|
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|
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/* Note: the -1 requests command chaining. */
|
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err = iso7816_general_authenticate (app->slot, -1,
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algo, keyref,
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tmpl, (int)tmpllen, 0,
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mechanism, keyref,
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apdudata, (int)apdudatalen, 0,
|
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&outdata, &outdatalen);
|
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if (err)
|
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goto leave;
|
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@ -1990,15 +2163,22 @@ do_auth (app_t app, const char *keyidstr,
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/* Parse the response. */
|
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if (outdatalen && *outdata == 0x7c
|
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&& (s = find_tlv (outdata, outdatalen, 0x82, &n)))
|
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{
|
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if (mechanism == PIV_ALGORITHM_RSA)
|
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{
|
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memmove (outdata, outdata + (s - outdata), n);
|
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outdatalen = n;
|
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}
|
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else /* ECC */
|
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{
|
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const unsigned char *rval, *sval;
|
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size_t rlen, rlenx, slen, slenx, resultlen;
|
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char *result;
|
||||
/* The result of an ECDSA signature is
|
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* SEQUENCE { r INTEGER, s INTEGER }
|
||||
* We re-pack that by concatenating R and S and making sure that
|
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* both have the same length. We simplify parsing by using
|
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* find_tlv and not a proper DER parser. */
|
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* We re-pack that by concatenating R and S and making sure
|
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* that both have the same length. We simplify parsing by
|
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* using find_tlv and not a proper DER parser. */
|
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s = find_tlv (s, n, 0x30, &n);
|
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if (!s)
|
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goto bad_der;
|
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@ -2028,6 +2208,7 @@ do_auth (app_t app, const char *keyidstr,
|
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outdata = result;
|
||||
outdatalen = resultlen;
|
||||
}
|
||||
}
|
||||
else
|
||||
{
|
||||
bad_der:
|
||||
@ -2048,10 +2229,29 @@ do_auth (app_t app, const char *keyidstr,
|
||||
*r_outdata = outdata;
|
||||
*r_outdatalen = outdatalen;
|
||||
}
|
||||
xfree (apdudata);
|
||||
xfree (indata_buffer);
|
||||
return err;
|
||||
}
|
||||
|
||||
|
||||
/* AUTH for PIV cards is actually the same as SIGN. The difference
|
||||
* between AUTH and SIGN is that AUTH expects that pkcs#1.5 padding
|
||||
* for RSA has already been done (digestInfo part w/o the padding)
|
||||
* whereas SIGN may accept a plain digest and does the padding if
|
||||
* needed. This is also the reason why SIGN takes a hashalgo. */
|
||||
static gpg_error_t
|
||||
do_auth (app_t app, const char *keyidstr,
|
||||
gpg_error_t (*pincb)(void*, const char *, char **),
|
||||
void *pincb_arg,
|
||||
const void *indata, size_t indatalen,
|
||||
unsigned char **r_outdata, size_t *r_outdatalen)
|
||||
{
|
||||
return do_sign (app, keyidstr, 0, pincb, pincb_arg, indata, indatalen,
|
||||
r_outdata, r_outdatalen);
|
||||
}
|
||||
|
||||
|
||||
/* Check whether a key for DOBJ already exists. We detect this by
|
||||
* reading the certificate described by DOBJ. If FORCE is TRUE a
|
||||
* diagnositic will be printed but no error returned if the key
|
||||
@ -2464,7 +2664,7 @@ app_select_piv (app_t app)
|
||||
app->fnc.writecert = do_writecert;
|
||||
/* app->fnc.writekey = do_writekey; */
|
||||
app->fnc.genkey = do_genkey;
|
||||
/* app->fnc.sign = do_sign; */
|
||||
app->fnc.sign = do_sign;
|
||||
app->fnc.auth = do_auth;
|
||||
/* app->fnc.decipher = do_decipher; */
|
||||
app->fnc.change_pin = do_change_chv;
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user