diff options
Diffstat (limited to 'common/sexputil.c')
| -rw-r--r-- | common/sexputil.c | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/common/sexputil.c b/common/sexputil.c index 4ff7b4955..7c6cb6af5 100644 --- a/common/sexputil.c +++ b/common/sexputil.c @@ -32,6 +32,7 @@ #endif #include "util.h" +#include "tlv.h" #include "sexp-parse.h" @@ -225,3 +226,163 @@ hash_algo_from_sigval (const unsigned char *sigval) return gcry_md_map_name (buffer); } + +/* Create a public key S-expression for an RSA public key from the + modulus M with length MLEN and the public exponent E with length + ELEN. Returns a newly allocated buffer of NULL in case of a memory + allocation problem. If R_LEN is not NULL, the length of the + canonical S-expression is stored there. */ +unsigned char * +make_canon_sexp_from_rsa_pk (const void *m_arg, size_t mlen, + const void *e_arg, size_t elen, + size_t *r_len) +{ + const unsigned char *m = m_arg; + const unsigned char *e = e_arg; + int m_extra = 0; + int e_extra = 0; + char mlen_str[35]; + char elen_str[35]; + unsigned char *keybuf, *p; + const char const part1[] = "(10:public-key(3:rsa(1:n"; + const char const part2[] = ")(1:e"; + const char const part3[] = ")))"; + + /* Remove leading zeroes. */ + for (; mlen && !*m; mlen--, m++) + ; + for (; elen && !*e; elen--, e++) + ; + + /* Insert a leading zero if the number would be zero or interpreted + as negative. */ + if (!mlen || (m[0] & 0x80)) + m_extra = 1; + if (!elen || (e[0] & 0x80)) + e_extra = 1; + + /* Build the S-expression. */ + snprintf (mlen_str, sizeof mlen_str, "%u:", (unsigned int)mlen+m_extra); + snprintf (elen_str, sizeof elen_str, "%u:", (unsigned int)elen+e_extra); + + keybuf = xtrymalloc (strlen (part1) + strlen (mlen_str) + mlen + m_extra + + strlen (part2) + strlen (elen_str) + elen + e_extra + + strlen (part3) + 1); + if (!keybuf) + return NULL; + + p = stpcpy (keybuf, part1); + p = stpcpy (p, mlen_str); + if (m_extra) + *p++ = 0; + memcpy (p, m, mlen); + p += mlen; + p = stpcpy (p, part2); + p = stpcpy (p, elen_str); + if (e_extra) + *p++ = 0; + memcpy (p, e, elen); + p += elen; + p = stpcpy (p, part3); + + if (r_len) + *r_len = p - keybuf; + + return keybuf; +} + + +/* Return the so called "keygrip" which is the SHA-1 hash of the + public key parameters expressed in a way depended on the algorithm. + + KEY is expected to be an canonical encoded S-expression with a + public or private key. KEYLEN is the length of that buffer. + + GRIP must be at least 20 bytes long. On success 0 is returned, on + error an error code. */ +gpg_error_t +get_rsa_pk_from_canon_sexp (const unsigned char *keydata, size_t keydatalen, + unsigned char const **r_n, size_t *r_nlen, + unsigned char const **r_e, size_t *r_elen) +{ + gpg_error_t err; + const unsigned char *buf, *tok; + size_t buflen, toklen; + int depth, last_depth1, last_depth2; + const unsigned char *rsa_n = NULL; + const unsigned char *rsa_e = NULL; + size_t rsa_n_len, rsa_e_len; + + *r_n = NULL; + *r_nlen = 0; + *r_e = NULL; + *r_elen = 0; + + buf = keydata; + buflen = keydatalen; + depth = 0; + if ((err = parse_sexp (&buf, &buflen, &depth, &tok, &toklen))) + return err; + if ((err = parse_sexp (&buf, &buflen, &depth, &tok, &toklen))) + return err; + if (!tok || toklen != 10 || memcmp ("public-key", tok, toklen)) + return gpg_error (GPG_ERR_BAD_PUBKEY); + if ((err = parse_sexp (&buf, &buflen, &depth, &tok, &toklen))) + return err; + if ((err = parse_sexp (&buf, &buflen, &depth, &tok, &toklen))) + return err; + if (!tok || toklen != 3 || memcmp ("rsa", tok, toklen)) + return gpg_error (GPG_ERR_WRONG_PUBKEY_ALGO); + + last_depth1 = depth; + while (!(err = parse_sexp (&buf, &buflen, &depth, &tok, &toklen)) + && depth && depth >= last_depth1) + { + if (tok) + return gpg_error (GPG_ERR_UNKNOWN_SEXP); + if ((err = parse_sexp (&buf, &buflen, &depth, &tok, &toklen))) + return err; + if (tok && toklen == 1) + { + const unsigned char **mpi; + size_t *mpi_len; + + switch (*tok) + { + case 'n': mpi = &rsa_n; mpi_len = &rsa_n_len; break; + case 'e': mpi = &rsa_e; mpi_len = &rsa_e_len; break; + default: mpi = NULL; mpi_len = NULL; break; + } + if (mpi && *mpi) + return gpg_error (GPG_ERR_DUP_VALUE); + + if ((err = parse_sexp (&buf, &buflen, &depth, &tok, &toklen))) + return err; + if (tok && mpi) + { + /* Strip off leading zero bytes and save. */ + for (;toklen && !*tok; toklen--, tok++) + ; + *mpi = tok; + *mpi_len = toklen; + } + } + + /* Skip to the end of the list. */ + last_depth2 = depth; + while (!(err = parse_sexp (&buf, &buflen, &depth, &tok, &toklen)) + && depth && depth >= last_depth2) + ; + if (err) + return err; + } + + if (!rsa_n || !rsa_n_len || !rsa_e || !rsa_e_len) + return gpg_error (GPG_ERR_BAD_PUBKEY); + + *r_n = rsa_n; + *r_nlen = rsa_n_len; + *r_e = rsa_e; + *r_elen = rsa_e_len; + return 0; +} |