--- /dev/null
+/*
+ rsa.c -- RSA key handling
+ Copyright (C) 2007 Guus Sliepen <guus@tinc-vpn.org>
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of 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.
+
+ This program 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, write to the Free Software
+ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+ $Id$
+*/
+
+#include "system.h"
+
+#include <gcrypt.h>
+
+#include "logger.h"
+#include "rsa.h"
+
+// Base64 encoding/decoding tables
+
+static const uint8_t b64d[128] = {
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0x3e, 0xff, 0xff, 0xff, 0x3f,
+ 0x34, 0x35, 0x36, 0x37, 0x38, 0x39,
+ 0x3a, 0x3b, 0x3c, 0x3d, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0x00,
+ 0x01, 0x02, 0x03, 0x04, 0x05, 0x06,
+ 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c,
+ 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12,
+ 0x13, 0x14, 0x15, 0x16, 0x17, 0x18,
+ 0x19, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e,
+ 0x1f, 0x20, 0x21, 0x22, 0x23, 0x24,
+ 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a,
+ 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30,
+ 0x31, 0x32, 0x33, 0xff, 0xff, 0xff,
+ 0xff, 0xff
+};
+
+static const char b64e[64] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+
+// PEM encoding/decoding functions
+
+static bool pem_decode(FILE *fp, const char *header, uint8_t *buf, size_t size, size_t *outsize) {
+ bool decode = false;
+ char line[1024];
+ uint16_t word = 0;
+ int shift = 10;
+ size_t i, j = 0;
+
+ while(!feof(fp)) {
+ if(!fgets(line, sizeof line, fp))
+ return false;
+
+ if(!decode && !strncmp(line, "-----BEGIN ", 11)) {
+ if(!strncmp(line + 11, header, strlen(header)))
+ decode = true;
+ continue;
+ }
+
+ if(decode && !strncmp(line, "-----END", 8)) {
+ break;
+ }
+
+ if(!decode)
+ continue;
+
+ for(i = 0; line[i] >= ' '; i++) {
+ if(line[i] >= 128 || line[i] < 0 || b64d[(int)line[i]] == 0xff)
+ break;
+ word |= b64d[(int)line[i]] << shift;
+ shift -= 6;
+ if(shift <= 2) {
+ if(j > size) {
+ errno = ENOMEM;
+ return false;
+ }
+
+ buf[j++] = word >> 8;
+ word <<= 8;
+ shift += 8;
+ }
+ }
+ }
+
+ if(outsize)
+ *outsize = j;
+ return true;
+}
+
+
+// BER decoding functions
+
+static int ber_read_id(unsigned char **p, size_t *buflen) {
+ if(*buflen <= 0)
+ return -1;
+
+ if((**p & 0x1f) == 0x1f) {
+ int id = 0;
+ bool more;
+ while(*buflen > 0) {
+ id <<= 7;
+ id |= **p & 0x7f;
+ more = *(*p)++ & 0x80;
+ (*buflen)--;
+ if(!more)
+ break;
+ }
+ return id;
+ } else {
+ (*buflen)--;
+ return *(*p)++ & 0x1f;
+ }
+}
+
+static size_t ber_read_len(unsigned char **p, size_t *buflen) {
+ if(*buflen <= 0)
+ return -1;
+
+ if(**p & 0x80) {
+ size_t result = 0;
+ int len = *(*p)++ & 0x7f;
+ (*buflen)--;
+ if(len > *buflen)
+ return 0;
+
+ while(len--) {
+ result <<= 8;
+ result |= *(*p)++;
+ (*buflen)--;
+ }
+
+ return result;
+ } else {
+ (*buflen)--;
+ return *(*p)++;
+ }
+}
+
+
+static bool ber_read_sequence(unsigned char **p, size_t *buflen, size_t *result) {
+ int tag = ber_read_id(p, buflen);
+ size_t len = ber_read_len(p, buflen);
+
+ if(tag == 0x10) {
+ if(result)
+ *result = len;
+ return true;
+ } else {
+ return false;
+ }
+}
+
+static bool ber_read_mpi(unsigned char **p, size_t *buflen, gcry_mpi_t *mpi) {
+ int tag = ber_read_id(p, buflen);
+ size_t len = ber_read_len(p, buflen);
+ gcry_error_t err = 0;
+
+ if(tag != 0x02 || len > *buflen)
+ return false;
+
+ if(mpi)
+ err = gcry_mpi_scan(mpi, GCRYMPI_FMT_USG, *p, len, NULL);
+
+ *p += len;
+ *buflen -= len;
+
+ return mpi ? !err : true;
+}
+
+bool rsa_set_hex_public_key(rsa_t *rsa, char *n, char *e) {
+ gcry_error_t err = 0;
+
+ err = gcry_mpi_scan(&rsa->n, GCRY_FMT_HEX, n, 0, NULL)
+ ?: gcry_mpi_scan(&rsa->e, GCRY_FMT_HEX, n, 0, NULL);
+
+ if(err) {
+ logger(LOG_ERR, _("Error while reading RSA public key: %s"), gcry_strerror(errno));
+ return false;
+ }
+}
+
+bool rsa_set_hex_private_key(rsa_t *rsa, char *n, char *e, char *d) {
+ gcry_error_t err = 0;
+
+ err = gcry_mpi_scan(&rsa->n, GCRY_FMT_HEX, n, 0, NULL)
+ ?: gcry_mpi_scan(&rsa->e, GCRY_FMT_HEX, n, 0, NULL)
+ ?: gcry_mpi_scan(&rsa->d, GCRY_FMT_HEX, n, 0, NULL);
+
+ if(err) {
+ logger(LOG_ERR, _("Error while reading RSA public key: %s"), gcry_strerror(errno));
+ return false;
+ }
+}
+
+// Read PEM RSA keys
+
+bool read_pem_rsa_public_key(rsa_t *rsa, FILE *fp) {
+ uint8_t derbuf[8096], *derp = derbuf;
+ size_t derlen;
+
+ if(!pem_decode(fp, "RSA PUBLIC KEY", derbuf, sizeof derbuf, &derlen)) {
+ logger(LOG_ERR, _("Unable to read RSA public key: %s"), strerror(errno));
+ return NULL;
+ }
+
+ if(!ber_read_sequence(&derp, &derlen, NULL)
+ || !ber_read_mpi(&derp, &derlen, &rsa->n)
+ || !ber_read_mpi(&derp, &derlen, &rsa->e)
+ || derlen) {
+ logger(LOG_ERR, _("Error while decoding RSA public key"));
+ return NULL;
+ }
+
+ return true;
+}
+
+bool read_pem_rsa_private_key(rsa_t *rsa, FILE *fp) {
+ uint8_t derbuf[8096], *derp = derbuf;
+ size_t derlen;
+
+ if(!pem_decode(fp, "RSA PRIVATE KEY", derbuf, sizeof derbuf, &derlen)) {
+ logger(LOG_ERR, _("Unable to read RSA private key: %s"), strerror(errno));
+ return NULL;
+ }
+
+ if(!ber_read_sequence(&derp, &derlen, NULL)
+ || !ber_read_mpi(&derp, &derlen, NULL)
+ || !ber_read_mpi(&derp, &derlen, &rsa->n)
+ || !ber_read_mpi(&derp, &derlen, &rsa->e)
+ || !ber_read_mpi(&derp, &derlen, &rsa->d)
+ || !ber_read_mpi(&derp, &derlen, NULL) // p
+ || !ber_read_mpi(&derp, &derlen, NULL) // q
+ || !ber_read_mpi(&derp, &derlen, NULL)
+ || !ber_read_mpi(&derp, &derlen, NULL)
+ || !ber_read_mpi(&derp, &derlen, NULL) // u
+ || derlen) {
+ logger(LOG_ERR, _("Error while decoding RSA private key"));
+ return NULL;
+ }
+
+ return true;
+}
+
+size_t rsa_size(rsa_t *rsa) {
+ return (gcry_mpi_get_nbits(rsa->n) + 7) / 8;
+}
+
+/* Well, libgcrypt has functions to handle RSA keys, but they suck.
+ * So we just use libgcrypt's mpi functions, and do the math ourselves.
+ */
+
+// TODO: get rid of this macro, properly clean up gcry_ structures after use
+#define check(foo) { gcry_error_t err = (foo); if(err) {logger(LOG_ERR, "gcrypt error %s/%s at %s:%d\n", gcry_strsource(err), gcry_strerror(err), __FILE__, __LINE__); return false; }}
+
+bool rsa_public_encrypt(rsa_t *rsa, void *in, size_t len, void *out) {
+ gcry_mpi_t inmpi;
+ check(gcry_mpi_scan(&inmpi, GCRYMPI_FMT_USG, in, len, NULL));
+
+ gcry_mpi_t outmpi = gcry_mpi_new(len * 8);
+ gcry_mpi_powm(outmpi, inmpi, rsa->e, rsa->n);
+
+ check(gcry_mpi_print(GCRYMPI_FMT_USG, out,len, NULL, outmpi));
+
+ return true;
+}
+
+bool rsa_public_decrypt(rsa_t *rsa, void *in, size_t len, void *out) {
+ gcry_mpi_t inmpi;
+ check(gcry_mpi_scan(&inmpi, GCRYMPI_FMT_USG, in, len, NULL));
+
+ gcry_mpi_t outmpi = gcry_mpi_new(len * 8);
+ gcry_mpi_powm(outmpi, inmpi, rsa->d, rsa->n);
+
+ check(gcry_mpi_print(GCRYMPI_FMT_USG, out,len, NULL, outmpi));
+
+ return true;
+}
projects / meshlink / blobdiff