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Diffstat (limited to '')
| -rw-r--r-- | common/openpgp-oid.c | 464 |
1 files changed, 464 insertions, 0 deletions
diff --git a/common/openpgp-oid.c b/common/openpgp-oid.c new file mode 100644 index 0000000..18c5710 --- /dev/null +++ b/common/openpgp-oid.c @@ -0,0 +1,464 @@ +/* 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 <https://www.gnu.org/licenses/>. + */ + +#include <config.h> +#include <stdlib.h> +#include <errno.h> +#include <ctype.h> +#include <assert.h> + +#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 }, + + { "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 }; + + +/* 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)) + { + buf[buflen++] = 0x80 | (value >> 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 octect */ + 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; + } + + buf = gcry_mpi_get_opaque (a, &lengthi); + 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 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); +} + + +/* 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. */ +const char * +openpgp_curve_to_oid (const char *name, unsigned int *r_nbits) +{ + int i; + unsigned int nbits = 0; + const char *oidstr = NULL; + + 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; + 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; + break; + } + } + } + + if (r_nbits) + *r_nbits = nbits; + 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; +} + + +/* 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; +} |