/* openpgp-oids.c - OID helper for OpenPGP * Copyright (C) 2011 Free Software Foundation, Inc. * Copyright (C) 2013 Werner Koch * * This file is part of GnuPG. * * This file is free software; you can redistribute it and/or modify * it under the terms of either * * - the GNU Lesser General Public License as published by the Free * Software Foundation; either version 3 of the License, or (at * your option) any later version. * * or * * - the GNU General Public License as published by the Free * Software Foundation; either version 2 of the License, or (at * your option) any later version. * * or both in parallel, as here. * * This file is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, see . */ #include #include #include #include #include #include "util.h" #include "openpgpdefs.h" /* A table with all our supported OpenPGP curves. */ static struct { const char *name; /* Standard name. */ const char *oidstr; /* IETF formatted OID. */ unsigned int nbits; /* Nominal bit length of the curve. */ const char *alias; /* NULL or alternative name of the curve. */ int pubkey_algo; /* Required OpenPGP algo or 0 for ECDSA/ECDH. */ } oidtable[] = { { "Curve25519", "1.3.6.1.4.1.3029.1.5.1", 255, "cv25519", PUBKEY_ALGO_ECDH }, { "Ed25519", "1.3.6.1.4.1.11591.15.1", 255, "ed25519", PUBKEY_ALGO_EDDSA }, { "X448", "1.3.101.111", 448, "cv448", PUBKEY_ALGO_ECDH }, { "Ed448", "1.3.101.113", 456, "ed448", PUBKEY_ALGO_EDDSA }, { "NIST P-256", "1.2.840.10045.3.1.7", 256, "nistp256" }, { "NIST P-384", "1.3.132.0.34", 384, "nistp384" }, { "NIST P-521", "1.3.132.0.35", 521, "nistp521" }, { "brainpoolP256r1", "1.3.36.3.3.2.8.1.1.7", 256 }, { "brainpoolP384r1", "1.3.36.3.3.2.8.1.1.11", 384 }, { "brainpoolP512r1", "1.3.36.3.3.2.8.1.1.13", 512 }, { "secp256k1", "1.3.132.0.10", 256 }, { NULL, NULL, 0} }; /* The OID for Curve Ed25519 in OpenPGP format. */ static const char oid_ed25519[] = { 0x09, 0x2b, 0x06, 0x01, 0x04, 0x01, 0xda, 0x47, 0x0f, 0x01 }; /* The OID for Curve25519 in OpenPGP format. */ static const char oid_cv25519[] = { 0x0a, 0x2b, 0x06, 0x01, 0x04, 0x01, 0x97, 0x55, 0x01, 0x05, 0x01 }; /* The OID for X448 in OpenPGP format. */ /* * Here, we have a little semantic discrepancy. X448 is the name of * the ECDH computation and the OID is assigned to the algorithm in * RFC 8410. Note that this OID is not the one which is assigned to * the curve itself (originally in 8410). Nevertheless, we use "X448" * for the curve in libgcrypt. */ static const char oid_cv448[] = { 0x03, 0x2b, 0x65, 0x6f }; /* A table to store keyalgo strings like "rsa2048 or "ed25519" so that * we do not need to allocate them. This is currently a simple array * but may eventually be changed to a fast data structure. Noet that * unknown algorithms are stored with (NBITS,CURVE) set to (0,NULL). */ struct keyalgo_string_s { enum gcry_pk_algos algo; /* Mandatory. */ unsigned int nbits; /* Size for classical algos. */ char *curve; /* Curvename (OID) or NULL. */ char *name; /* Allocated name. */ }; static struct keyalgo_string_s *keyalgo_strings; /* The table. */ static size_t keyalgo_strings_size; /* Allocated size. */ static size_t keyalgo_strings_used; /* Used size. */ /* Helper for openpgp_oid_from_str. */ static size_t make_flagged_int (unsigned long value, char *buf, size_t buflen) { int more = 0; int shift; /* fixme: figure out the number of bits in an ulong and start with that value as shift (after making it a multiple of 7) a more straigtforward implementation is to do it in reverse order using a temporary buffer - saves a lot of compares */ for (more=0, shift=28; shift > 0; shift -= 7) { if (more || value >= (1<> shift); value -= (value >> shift) << shift; more = 1; } } buf[buflen++] = value; return buflen; } /* Convert the OID given in dotted decimal form in STRING to an DER * encoding and store it as an opaque value at R_MPI. The format of * the DER encoded is not a regular ASN.1 object but the modified * format as used by OpenPGP for the ECC curve description. On error * the function returns and error code an NULL is stored at R_BUG. * Note that scanning STRING stops at the first white space * character. */ gpg_error_t openpgp_oid_from_str (const char *string, gcry_mpi_t *r_mpi) { unsigned char *buf; size_t buflen; unsigned long val1, val; const char *endp; int arcno; *r_mpi = NULL; if (!string || !*string) return gpg_error (GPG_ERR_INV_VALUE); /* We can safely assume that the encoded OID is shorter than the string. */ buf = xtrymalloc (1 + strlen (string) + 2); if (!buf) return gpg_error_from_syserror (); /* Save the first byte for the length. */ buflen = 1; val1 = 0; /* Avoid compiler warning. */ arcno = 0; do { arcno++; val = strtoul (string, (char**)&endp, 10); if (!digitp (string) || !(*endp == '.' || !*endp)) { xfree (buf); return gpg_error (GPG_ERR_INV_OID_STRING); } if (*endp == '.') string = endp+1; if (arcno == 1) { if (val > 2) break; /* Not allowed, error caught below. */ val1 = val; } else if (arcno == 2) { /* Need to combine the first two arcs in one octet. */ if (val1 < 2) { if (val > 39) { xfree (buf); return gpg_error (GPG_ERR_INV_OID_STRING); } buf[buflen++] = val1*40 + val; } else { val += 80; buflen = make_flagged_int (val, buf, buflen); } } else { buflen = make_flagged_int (val, buf, buflen); } } while (*endp == '.'); if (arcno == 1 || buflen < 2 || buflen > 254 ) { /* It is not possible to encode only the first arc. */ xfree (buf); return gpg_error (GPG_ERR_INV_OID_STRING); } *buf = buflen - 1; *r_mpi = gcry_mpi_set_opaque (NULL, buf, buflen * 8); if (!*r_mpi) { xfree (buf); return gpg_error_from_syserror (); } return 0; } /* Return a malloced string representation of the OID in the buffer * (BUF,LEN). In case of an error NULL is returned and ERRNO is set. * As per OpenPGP spec the first byte of the buffer is the length of * the rest; the function performs a consistency check. */ char * openpgp_oidbuf_to_str (const unsigned char *buf, size_t len) { char *string, *p; int n = 0; unsigned long val, valmask; valmask = (unsigned long)0xfe << (8 * (sizeof (valmask) - 1)); /* The first bytes gives the length; check consistency. */ if (!len || buf[0] != len -1) { gpg_err_set_errno (EINVAL); return NULL; } /* Skip length byte. */ len--; buf++; /* To calculate the length of the string we can safely assume an upper limit of 3 decimal characters per byte. Two extra bytes account for the special first octet */ string = p = xtrymalloc (len*(1+3)+2+1); if (!string) return NULL; if (!len) { *p = 0; return string; } if (buf[0] < 40) p += sprintf (p, "0.%d", buf[n]); else if (buf[0] < 80) p += sprintf (p, "1.%d", buf[n]-40); else { val = buf[n] & 0x7f; while ( (buf[n]&0x80) && ++n < len ) { if ( (val & valmask) ) goto badoid; /* Overflow. */ val <<= 7; val |= buf[n] & 0x7f; } if (val < 80) goto badoid; val -= 80; sprintf (p, "2.%lu", val); p += strlen (p); } for (n++; n < len; n++) { val = buf[n] & 0x7f; while ( (buf[n]&0x80) && ++n < len ) { if ( (val & valmask) ) goto badoid; /* Overflow. */ val <<= 7; val |= buf[n] & 0x7f; } sprintf (p, ".%lu", val); p += strlen (p); } *p = 0; return string; badoid: /* Return a special OID (gnu.gnupg.badoid) to indicate the error case. The OID is broken and thus we return one which can't do any harm. Formally this does not need to be a bad OID but an OID with an arc that can't be represented in a 32 bit word is more than likely corrupt. */ xfree (string); return xtrystrdup ("1.3.6.1.4.1.11591.2.12242973"); } /* Return a malloced string representation of the OID in the opaque * MPI A. In case of an error NULL is returned and ERRNO is set. */ char * openpgp_oid_to_str (gcry_mpi_t a) { const unsigned char *buf; unsigned int lengthi; if (!a || !gcry_mpi_get_flag (a, GCRYMPI_FLAG_OPAQUE) || !(buf = gcry_mpi_get_opaque (a, &lengthi))) { gpg_err_set_errno (EINVAL); return NULL; } return openpgp_oidbuf_to_str (buf, (lengthi+7)/8); } /* Return true if (BUF,LEN) represents the OID for Ed25519. */ int openpgp_oidbuf_is_ed25519 (const void *buf, size_t len) { return (buf && len == DIM (oid_ed25519) && !memcmp (buf, oid_ed25519, DIM (oid_ed25519))); } /* Return true if A represents the OID for Ed25519. */ int openpgp_oid_is_ed25519 (gcry_mpi_t a) { const unsigned char *buf; unsigned int nbits; if (!a || !gcry_mpi_get_flag (a, GCRYMPI_FLAG_OPAQUE)) return 0; buf = gcry_mpi_get_opaque (a, &nbits); return openpgp_oidbuf_is_ed25519 (buf, (nbits+7)/8); } /* Return true if (BUF,LEN) represents the OID for Curve25519. */ int openpgp_oidbuf_is_cv25519 (const void *buf, size_t len) { return (buf && len == DIM (oid_cv25519) && !memcmp (buf, oid_cv25519, DIM (oid_cv25519))); } /* Return true if (BUF,LEN) represents the OID for X448. */ static int openpgp_oidbuf_is_cv448 (const void *buf, size_t len) { return (buf && len == DIM (oid_cv448) && !memcmp (buf, oid_cv448, DIM (oid_cv448))); } /* Return true if the MPI A represents the OID for Curve25519. */ int openpgp_oid_is_cv25519 (gcry_mpi_t a) { const unsigned char *buf; unsigned int nbits; if (!a || !gcry_mpi_get_flag (a, GCRYMPI_FLAG_OPAQUE)) return 0; buf = gcry_mpi_get_opaque (a, &nbits); return openpgp_oidbuf_is_cv25519 (buf, (nbits+7)/8); } /* Return true if the MPI A represents the OID for X448. */ int openpgp_oid_is_cv448 (gcry_mpi_t a) { const unsigned char *buf; unsigned int nbits; if (!a || !gcry_mpi_get_flag (a, GCRYMPI_FLAG_OPAQUE)) return 0; buf = gcry_mpi_get_opaque (a, &nbits); return openpgp_oidbuf_is_cv448 (buf, (nbits+7)/8); } /* Map the Libgcrypt ECC curve NAME to an OID. If R_NBITS is not NULL store the bit size of the curve there. Returns NULL for unknown curve names. If R_ALGO is not NULL and a specific ECC algorithm is required for this curve its OpenPGP algorithm number is stored there; otherwise 0 is stored which indicates that ECDSA or ECDH can be used. */ const char * openpgp_curve_to_oid (const char *name, unsigned int *r_nbits, int *r_algo) { int i; unsigned int nbits = 0; const char *oidstr = NULL; int algo = 0; if (name) { for (i=0; oidtable[i].name; i++) if (!strcmp (oidtable[i].name, name) || (oidtable[i].alias && !strcmp (oidtable[i].alias, name))) { oidstr = oidtable[i].oidstr; nbits = oidtable[i].nbits; algo = oidtable[i].pubkey_algo; break; } if (!oidtable[i].name) { /* If not found assume the input is already an OID and check whether we support it. */ for (i=0; oidtable[i].name; i++) if (!strcmp (name, oidtable[i].oidstr)) { oidstr = oidtable[i].oidstr; nbits = oidtable[i].nbits; algo = oidtable[i].pubkey_algo; break; } } } if (r_nbits) *r_nbits = nbits; if (r_algo) *r_algo = algo; return oidstr; } /* Map an OpenPGP OID to the Libgcrypt curve name. Returns NULL for * unknown curve names. Unless CANON is set we prefer an alias name * here which is more suitable for printing. */ const char * openpgp_oid_to_curve (const char *oidstr, int canon) { int i; if (!oidstr) return NULL; for (i=0; oidtable[i].name; i++) if (!strcmp (oidtable[i].oidstr, oidstr)) return !canon && oidtable[i].alias? oidtable[i].alias : oidtable[i].name; return NULL; } /* Map an OpenPGP OID, name or alias to the Libgcrypt curve name. * Returns NULL for unknown curve names. Unless CANON is set we * prefer an alias name here which is more suitable for printing. */ const char * openpgp_oid_or_name_to_curve (const char *oidname, int canon) { int i; if (!oidname) return NULL; for (i=0; oidtable[i].name; i++) if (!strcmp (oidtable[i].oidstr, oidname) || !strcmp (oidtable[i].name, oidname) || (oidtable[i].alias &&!strcmp (oidtable[i].alias, oidname))) return !canon && oidtable[i].alias? oidtable[i].alias : oidtable[i].name; return NULL; } /* Return true if the curve with NAME is supported. */ static int curve_supported_p (const char *name) { int result = 0; gcry_sexp_t keyparms; if (!gcry_sexp_build (&keyparms, NULL, "(public-key(ecc(curve %s)))", name)) { result = !!gcry_pk_get_curve (keyparms, 0, NULL); gcry_sexp_release (keyparms); } return result; } /* Enumerate available and supported OpenPGP curves. The caller needs to set the integer variable at ITERP to zero and keep on calling this function until NULL is returned. */ const char * openpgp_enum_curves (int *iterp) { int idx = *iterp; while (idx >= 0 && idx < DIM (oidtable) && oidtable[idx].name) { if (curve_supported_p (oidtable[idx].name)) { *iterp = idx + 1; return oidtable[idx].alias? oidtable[idx].alias : oidtable[idx].name; } idx++; } *iterp = idx; return NULL; } /* Return the Libgcrypt name for the gpg curve NAME if supported. If * R_ALGO is not NULL the required OpenPGP public key algo or 0 is * stored at that address. If R_NBITS is not NULL the nominal bitsize * of the curves is stored there. NULL is returned if the curve is * not supported. */ const char * openpgp_is_curve_supported (const char *name, int *r_algo, unsigned int *r_nbits) { int idx; if (r_algo) *r_algo = 0; if (r_nbits) *r_nbits = 0; for (idx = 0; idx < DIM (oidtable) && oidtable[idx].name; idx++) { if ((!strcmp (name, oidtable[idx].name) || (oidtable[idx].alias && !strcmp (name, (oidtable[idx].alias)))) && curve_supported_p (oidtable[idx].name)) { if (r_algo) *r_algo = oidtable[idx].pubkey_algo; if (r_nbits) *r_nbits = oidtable[idx].nbits; return oidtable[idx].name; } } return NULL; } /* Map a Gcrypt public key algorithm number to the used by OpenPGP. * Returns 0 for unknown gcry algorithm. */ pubkey_algo_t map_gcry_pk_to_openpgp (enum gcry_pk_algos algo) { switch (algo) { case GCRY_PK_EDDSA: return PUBKEY_ALGO_EDDSA; case GCRY_PK_ECDSA: return PUBKEY_ALGO_ECDSA; case GCRY_PK_ECDH: return PUBKEY_ALGO_ECDH; default: return algo < 110 ? (pubkey_algo_t)algo : 0; } } /* Map an OpenPGP public key algorithm number to the one used by * Libgcrypt. Returns 0 for unknown gcry algorithm. */ enum gcry_pk_algos map_openpgp_pk_to_gcry (pubkey_algo_t algo) { switch (algo) { case PUBKEY_ALGO_EDDSA: return GCRY_PK_EDDSA; case PUBKEY_ALGO_ECDSA: return GCRY_PK_ECDSA; case PUBKEY_ALGO_ECDH: return GCRY_PK_ECDH; default: return algo < 110 ? (enum gcry_pk_algos)algo : 0; } } /* Return a string describing the public key algorithm and the * keysize. For elliptic curves the function prints the name of the * curve because the keysize is a property of the curve. ALGO is the * Gcrypt algorithm number, CURVE is either NULL or gives the OID of * the curve, NBITS is either 0 or the size for algorithms like RSA. * The returned string is taken from permanent table. Examples * for the output are: * * "rsa3072" - RSA with 3072 bit * "elg1024" - Elgamal with 1024 bit * "ed25519" - ECC using the curve Ed25519. * "E_1.2.3.4" - ECC using the unsupported curve with OID "1.2.3.4". * "E_1.3.6.1.4.1.11591.2.12242973" - ECC with a bogus OID. * "unknown_N" - Unknown OpenPGP algorithm N. * If N is > 110 this is a gcrypt algo. */ const char * get_keyalgo_string (enum gcry_pk_algos algo, unsigned int nbits, const char *curve) { const char *prefix; int i; char *name, *curvebuf; switch (algo) { case GCRY_PK_RSA: prefix = "rsa"; break; case GCRY_PK_ELG: prefix = "elg"; break; case GCRY_PK_DSA: prefix = "dsa"; break; case GCRY_PK_ECC: case GCRY_PK_ECDH: case GCRY_PK_ECDSA: case GCRY_PK_EDDSA: prefix = ""; break; default: prefix = NULL; break; } if (prefix && *prefix && nbits) { for (i=0; i < keyalgo_strings_used; i++) { if (keyalgo_strings[i].algo == algo && keyalgo_strings[i].nbits && keyalgo_strings[i].nbits == nbits) return keyalgo_strings[i].name; } /* Not yet in the table - add it. */ name = xasprintf ("%s%u", prefix, nbits); nbits = nbits? nbits : 1; /* No nbits - oops - use 1 instead. */ curvebuf = NULL; } else if (prefix && !*prefix) { const char *curvename; for (i=0; i < keyalgo_strings_used; i++) { if (keyalgo_strings[i].algo == algo && keyalgo_strings[i].curve && !strcmp (keyalgo_strings[i].curve, curve)) return keyalgo_strings[i].name; } /* Not yet in the table - add it. */ curvename = openpgp_oid_or_name_to_curve (curve, 0); if (curvename) name = xasprintf ("%s", curvename); else if (curve) name = xasprintf ("E_%s", curve); else name = xasprintf ("E_error"); nbits = 0; curvebuf = xstrdup (curve); } else { for (i=0; i < keyalgo_strings_used; i++) { if (keyalgo_strings[i].algo == algo && !keyalgo_strings[i].nbits && !keyalgo_strings[i].curve) return keyalgo_strings[i].name; } /* Not yet in the table - add it. */ name = xasprintf ("unknown_%u", (unsigned int)algo); nbits = 0; curvebuf = NULL; } /* Store a new entry. This is a loop because of a possible nPth * thread switch during xrealloc. */ while (keyalgo_strings_used >= keyalgo_strings_size) { keyalgo_strings_size += 10; if (keyalgo_strings_size > 1024*1024) log_fatal ("%s: table getting too large - possible DoS\n", __func__); keyalgo_strings = xrealloc (keyalgo_strings, (keyalgo_strings_size * sizeof *keyalgo_strings)); } keyalgo_strings[keyalgo_strings_used].algo = algo; keyalgo_strings[keyalgo_strings_used].nbits = nbits; keyalgo_strings[keyalgo_strings_used].curve = curvebuf; keyalgo_strings[keyalgo_strings_used].name = name; keyalgo_strings_used++; return name; /* Note that this is in the table. */ }