Merge branch 'master' of http://lair.fifthhorseman.net/~dkg/git/monkeysphere

Conflicts:

	gpg2ssh/Makefile

4 files changed, 973 insertions, 0 deletions

diff --git a/src/keytrans/Makefile b/src/keytrans/Makefile
new file mode 100644
index 0000000..79602ef
--- /dev/null
+++ b/src/keytrans/Makefile
@@ -0,0 +1,12 @@
+all: openpgp2ssh
+
+openpgp2ssh: openpgp2ssh.c gnutls-helpers.o
+	gcc -g -Wall --pedantic -o openpgp2ssh openpgp2ssh.c `libgnutls-config --libs --cflags` gnutls-helpers.o
+
+%.o: %.c
+	gcc -g -Wall --pedantic -o $@ -c $<
+
+clean: 
+	rm -f openpgp2ssh *.o
+
+.PHONY: clean all
diff --git a/src/keytrans/gnutls-helpers.c b/src/keytrans/gnutls-helpers.c
new file mode 100644
index 0000000..5b4c46a
--- /dev/null
+++ b/src/keytrans/gnutls-helpers.c
@@ -0,0 +1,446 @@
+/* Author: Daniel Kahn Gillmor <dkg@fifthhorseman.net> */
+/* Date: Fri, 04 Apr 2008 19:31:16 -0400 */
+/* License: GPL v3 or later */
+
+#include "gnutls-helpers.h"
+/* for htonl() */
+#include <arpa/inet.h>
+
+/* for setlocale() */
+#include <locale.h>
+
+/* for isalnum() */
+#include <ctype.h>
+
+/* for exit() */
+#include <unistd.h>
+
+#include <assert.h>
+
+/* higher levels allow more frivolous error messages through. 
+   this is set with the MONKEYSPHERE_DEBUG variable */
+static int loglevel = 0;
+
+void err(int level, const char* fmt, ...) {
+  va_list ap;
+  if (level > loglevel)
+    return;
+  va_start(ap, fmt);
+  vfprintf(stderr, fmt, ap);
+  va_end(ap);
+  fflush(stderr);
+}
+
+void logfunc(int level, const char* string) {
+  fprintf(stderr, "GnuTLS Logging (%d): %s\n", level, string);
+}
+
+void init_keyid(gnutls_openpgp_keyid_t keyid) {
+  memset(keyid, 'x', sizeof(gnutls_openpgp_keyid_t));
+}
+
+
+
+void make_keyid_printable(printable_keyid out, gnutls_openpgp_keyid_t keyid)
+{
+  assert(sizeof(out) >= 2*sizeof(keyid));
+  hex_print_data((char*)out, (const char*)keyid, sizeof(keyid));
+}
+
+/* you must have twice as many bytes in the out buffer as in the in buffer */
+void hex_print_data(char* out, const char* in, size_t incount)
+{
+  static const char hex[16] = "0123456789ABCDEF";
+  unsigned int inix = 0, outix = 0;
+  
+  while (inix < incount) {
+    out[outix] = hex[(in[inix] >> 4) & 0x0f];
+    out[outix + 1] = hex[in[inix] & 0x0f];
+    inix++;
+    outix += 2;
+  }
+}
+
+unsigned char hex2bin(unsigned char x) {
+  if ((x >= '0') && (x <= '9')) 
+    return x - '0';
+  if ((x >= 'A') && (x <= 'F')) 
+    return 10 + x - 'A';
+  if ((x >= 'a') && (x <= 'f')) 
+    return 10 + x - 'a';
+  return 0xff;
+}
+
+void collapse_printable_keyid(gnutls_openpgp_keyid_t out, printable_keyid in) {
+  unsigned int pkix = 0, outkix = 0;
+  
+  while (pkix < sizeof(printable_keyid)) {
+    unsigned hi = hex2bin(in[pkix]);
+    unsigned lo = hex2bin(in[pkix + 1]);
+    if (hi == 0xff) {
+      err(0, "character '%c' is not a hex char\n", in[pkix]);
+      exit(1);
+    }
+    if (lo == 0xff) {
+      err(0, "character '%c' is not a hex char\n", in[pkix + 1]);
+      exit(1);
+    }
+    out[outkix] = lo | (hi << 4);
+
+    pkix += 2;
+    outkix++;
+  }
+}
+
+int convert_string_to_keyid(gnutls_openpgp_keyid_t out, const char* str) {
+  printable_keyid p;
+  int ret;
+
+  ret = convert_string_to_printable_keyid(p, str);
+  if (ret == 0) 
+    collapse_printable_keyid(out, p);
+  return ret;
+}
+int convert_string_to_printable_keyid(printable_keyid pkeyid, const char* str) {
+  int arglen, x;
+  arglen = 0;
+  x = 0;
+  while ((arglen <= sizeof(printable_keyid)) &&
+	 (str[x] != '\0')) {
+    if (isxdigit(str[x])) {
+      if (arglen == sizeof(printable_keyid)) {
+	err(0, "There are more than %d hex digits in the keyid '%s'\n", sizeof(printable_keyid), str);
+	return 1;
+      }
+      pkeyid[arglen] = str[x];
+      arglen++;
+    }
+    x++;
+  }
+  
+  if (arglen != sizeof(printable_keyid)) {
+    err(0, "Keyid '%s' is not %d hex digits in length\n", str, sizeof(printable_keyid));
+    return 1;
+  }
+  return 0;
+}
+
+
+
+int init_gnutls() {
+  const char* version = NULL;
+  const char* debug_string = NULL;
+  int ret;
+
+  if (debug_string = getenv("MONKEYSPHERE_DEBUG"), debug_string) {
+    loglevel = atoi(debug_string);
+  }
+
+  if (ret = gnutls_global_init(), ret) {
+    err(0, "Failed to do gnutls_global_init() (error: %d)\n", ret);
+    return 1;
+  }
+
+  version = gnutls_check_version(NULL);
+
+  if (version) 
+    err(1, "gnutls version: %s\n", version);
+  else {
+    err(0, "no gnutls version found!\n");
+    return 1;
+  }
+
+  gnutls_global_set_log_function(logfunc);
+  
+  gnutls_global_set_log_level(loglevel);
+  err(1, "set log level to %d\n", loglevel);
+
+  return 0;
+}
+
+void init_datum(gnutls_datum_t* d) {
+  d->data = NULL;
+  d->size = 0;
+}
+void copy_datum(gnutls_datum_t* dest, const gnutls_datum_t* src) {
+  dest->data = gnutls_realloc(dest->data, src->size);
+  dest->size = src->size;
+  memcpy(dest->data, src->data, src->size);
+}
+int compare_data(const gnutls_datum_t* a, const gnutls_datum_t* b) {
+  if (a->size > b->size) {
+    err(0,"a is larger\n");
+    return 1;
+  }
+  if (a->size < b->size) {
+    err(0,"b is larger\n");
+    return -1;
+  }
+  return memcmp(a->data, b->data, a->size);
+}
+void free_datum(gnutls_datum_t* d) {
+  gnutls_free(d->data);
+  d->data = NULL;
+  d->size = 0;
+}
+
+/* read the passed-in string, store in a single datum */
+int set_datum_string(gnutls_datum_t* d, const char* s) {
+  unsigned int x = strlen(s)+1;
+  unsigned char* c = NULL;
+
+  c = gnutls_realloc(d->data, x);
+  if (NULL == c)
+    return -1;
+  d->data = c;
+  d->size = x;
+  memcpy(d->data, s, x);
+  return 0;
+}
+
+/* read the passed-in file descriptor until EOF, store in a single
+   datum */
+int set_datum_fd(gnutls_datum_t* d, int fd) {
+  unsigned int bufsize = 1024;
+  unsigned int len = 0;
+
+  FILE* f = fdopen(fd, "r");
+  if (bufsize > d->size) {
+    bufsize = 1024;
+    d->data = gnutls_realloc(d->data, bufsize);
+    if (d->data == NULL) {
+      err(0,"out of memory!\n");
+      return -1;
+    }
+    d->size = bufsize;
+  } else {
+    bufsize = d->size;
+  }
+  f = fdopen(fd, "r");
+  if (NULL == f) {
+    err(0,"could not fdopen FD %d\n", fd);
+  }
+  clearerr(f);
+  while (!feof(f) && !ferror(f)) { 
+    if (len == bufsize) {
+      /* allocate more space by doubling: */
+      bufsize *= 2;
+      d->data = gnutls_realloc(d->data, bufsize);
+      if (d->data == NULL) {
+	err(0,"out of memory!\n"); 
+	return -1;
+      };
+      d->size = bufsize;
+    }
+    len += fread(d->data + len, 1, bufsize - len, f);
+    /*     err(0,"read %d bytes\n", len); */
+  }
+  if (ferror(f)) {
+    err(0,"Error reading from fd %d (error: %d) (error: %d '%s')\n", fd, ferror(f), errno, strerror(errno));
+    return -1;
+  }
+    
+  /* touch up buffer size to match reality: */
+  d->data = gnutls_realloc(d->data, len);
+  d->size = len;
+  return 0;
+}
+
+/* read the file indicated (by name) in the fname parameter.  store
+   its entire contents in a single datum. */
+int set_datum_file(gnutls_datum_t* d, const char* fname) {
+  struct stat sbuf;
+  unsigned char* c = NULL;
+  FILE* file = NULL;
+  size_t x = 0;
+
+  if (0 != stat(fname, &sbuf)) {
+    err(0,"failed to stat '%s'\n", fname);
+    return -1;
+  }
+  
+  c = gnutls_realloc(d->data, sbuf.st_size);
+  if (NULL == c) {
+    err(0,"failed to allocate %d bytes for '%s'\n", sbuf.st_size, fname);
+    return -1;
+  }
+
+  d->data = c;
+  d->size = sbuf.st_size;
+  file = fopen(fname, "r");
+  if (NULL == file) {
+    err(0,"failed to open '%s' for reading\n",  fname);
+    return -1;
+  }
+
+  x = fread(d->data, d->size, 1, file);
+  if (x != 1) {
+    err(0,"tried to read %d bytes, read %d instead from '%s'\n", d->size, x, fname);
+    fclose(file);
+    return -1;
+  }
+  fclose(file);
+  return 0;
+}
+
+int write_datum_fd(int fd, const gnutls_datum_t* d) {
+  if (d->size != write(fd, d->data, d->size)) {
+    err(0,"failed to write body of datum.\n");
+    return -1;
+  }
+  return 0;
+}
+
+
+int write_datum_fd_with_length(int fd, const gnutls_datum_t* d) {
+  uint32_t len;
+  int looks_negative = (d->data[0] & 0x80);
+  unsigned char zero = 0;
+
+  /* if the first bit is 1, then the datum will appear negative in the
+     MPI encoding style used by OpenSSH.  In that case, we'll increase
+     the length by one, and dump out one more byte */
+
+  if (looks_negative) {
+    len = htonl(d->size + 1);
+  } else {
+    len = htonl(d->size);
+  }
+  if (write(fd, &len, sizeof(len)) != sizeof(len)) {
+    err(0,"failed to write size of datum.\n");
+    return -2;
+  }
+  if (looks_negative) {
+    if (write(fd, &zero, 1) != 1) {
+      err(0,"failed to write padding byte for MPI.\n");
+      return -2;
+    }
+  }
+  return write_datum_fd(fd, d);
+}
+
+int write_data_fd_with_length(int fd, const gnutls_datum_t** d, unsigned int num) {
+  unsigned int i;
+  int ret;
+
+  for (i = 0; i < num; i++)
+    if (ret = write_datum_fd_with_length(fd, d[i]), ret != 0)
+      return ret;
+
+  return 0;
+}
+
+
+int datum_from_string(gnutls_datum_t* d, const char* str) {
+  d->size = strlen(str);
+  d->data = gnutls_realloc(d->data, d->size);
+  if (d->data == 0)
+    return ENOMEM;
+  memcpy(d->data, str, d->size);
+  return 0;
+}
+
+
+int create_writing_pipe(pid_t* pid, const char* path, char* const argv[]) {
+  int p[2];
+  int ret;
+
+  if (pid == NULL) {
+    err(0,"bad pointer passed to create_writing_pipe()\n");
+    return -1;
+  }
+
+  if (ret = pipe(p), ret == -1) {
+    err(0,"failed to create a pipe (error: %d \"%s\")\n", errno, strerror(errno));
+    return -1;
+  }
+
+  *pid = fork();
+  if (*pid == -1) {
+    err(0,"Failed to fork (error: %d \"%s\")\n", errno, strerror(errno));
+    return -1;
+  }
+  if (*pid == 0) { /* this is the child */
+    close(p[1]); /* close unused write end */
+    
+    if (0 != dup2(p[0], 0)) { /* map the reading end into stdin */
+      err(0,"Failed to transfer reading file descriptor to stdin (error: %d \"%s\")\n", errno, strerror(errno));
+      exit(1);
+    }
+    execv(path, argv);
+    err(0,"exec %s failed (error: %d \"%s\")\n", path, errno, strerror(errno));
+    /* close the open file descriptors */
+    close(p[0]);
+    close(0);
+
+    exit(1);
+  } else { /* this is the parent */
+    close(p[0]); /* close unused read end */
+    return p[1];
+  }
+}
+
+int validate_ssh_host_userid(const char* userid) {
+  char* oldlocale = setlocale(LC_ALL, "C");
+  
+  /* choke if userid does not match the expected format
+     ("ssh://fully.qualified.domain.name") */
+  if (strncmp("ssh://", userid, strlen("ssh://")) != 0) {
+    err(0,"The user ID should start with ssh:// for a host key\n");
+    goto fail;
+  }
+  /* so that isalnum will work properly */
+  userid += strlen("ssh://");
+  while (0 != (*userid)) {
+    if (!isalnum(*userid)) {
+      err(0,"label did not start with a letter or a digit! (%s)\n", userid);
+      goto fail;
+    }
+    userid++;
+    while (isalnum(*userid) || ('-' == (*userid)))
+      userid++;
+    if (('.' == (*userid)) || (0 == (*userid))) { /* clean end of label:
+						 check last char
+						 isalnum */
+      if (!isalnum(*(userid - 1))) {
+	err(0,"label did not end with a letter or a digit!\n");
+	goto fail;
+      }
+      if ('.' == (*userid)) /* advance to the start of the next label */
+	userid++;
+    } else {
+      err(0,"invalid character in domain name: %c\n", *userid);
+      goto fail;
+    }
+  }
+  /* ensure that the last character is valid: */
+  if (!isalnum(*(userid - 1))) {
+    err(0,"hostname did not end with a letter or a digit!\n");
+    goto fail;
+  }
+  /* FIXME: fqdn's can be unicode now, thanks to RFC 3490 -- how do we
+     make sure that we've got an OK string? */
+
+  return 0;
+
+ fail:
+  setlocale(LC_ALL, oldlocale);
+  return 1;
+}
+
+/* http://tools.ietf.org/html/rfc4880#section-5.5.2 */
+size_t get_openpgp_mpi_size(gnutls_datum_t* d) {
+  return 2 + d->size;
+}
+
+int write_openpgp_mpi_to_fd(int fd, gnutls_datum_t* d) {
+  uint16_t x;
+
+  x = d->size * 8;
+  x = htons(x);
+  
+  write(fd, &x, sizeof(x));
+  write(fd, d->data, d->size);
+  
+  return 0;
+}
diff --git a/src/keytrans/gnutls-helpers.h b/src/keytrans/gnutls-helpers.h
new file mode 100644
index 0000000..f196456
--- /dev/null
+++ b/src/keytrans/gnutls-helpers.h
@@ -0,0 +1,78 @@
+/* Author: Daniel Kahn Gillmor <dkg@fifthhorseman.net> */
+/* Date: Fri, 04 Apr 2008 19:31:16 -0400 */
+/* License: GPL v3 or later */
+
+
+#include <gnutls/gnutls.h>
+#include <gnutls/openpgp.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <stdarg.h>
+
+/* Functions to help dealing with GnuTLS for monkeysphere key
+   translation projects: */
+
+/* set everything up, including logging levels.  Return 0 on
+   success */
+int init_gnutls();
+
+/* logging and output functions: */
+
+void err(int level, const char* fmt, ...);
+void logfunc(int level, const char* string);
+
+/* basic datum manipulations: */
+
+void init_datum(gnutls_datum_t* d);
+void copy_datum(gnutls_datum_t* dest, const gnutls_datum_t* src);
+int compare_data(const gnutls_datum_t* a, const gnutls_datum_t* b);
+void free_datum(gnutls_datum_t* d);
+int write_datum_fd(int fd, const gnutls_datum_t* d);
+int write_datum_fd_with_length(int fd, const gnutls_datum_t* d);
+int write_data_fd_with_length(int fd, const gnutls_datum_t** d, unsigned int num);
+
+/* set up a datum from a null-terminated string */
+int datum_from_string(gnutls_datum_t* d, const char* str);
+
+/* keyid manipulations: */
+typedef unsigned char printable_keyid[16];
+
+void init_keyid(gnutls_openpgp_keyid_t keyid);
+void make_keyid_printable(printable_keyid out, gnutls_openpgp_keyid_t keyid);
+void collapse_printable_keyid(gnutls_openpgp_keyid_t out, printable_keyid in);
+int convert_string_to_keyid(gnutls_openpgp_keyid_t out, const char* str);
+int convert_string_to_printable_keyid(printable_keyid out, const char* str);
+
+/* you must have twice as many bytes in the out buffer as in the in buffer */
+void hex_print_data(char* out, const char* in, size_t incount);
+
+/* functions to get data into datum objects: */
+
+/* read the passed-in string, store in a single datum */
+int set_datum_string(gnutls_datum_t* d, const char* s);
+
+/* read the passed-in file descriptor until EOF, store in a single
+   datum */
+int set_datum_fd(gnutls_datum_t* d, int fd);
+
+/* read the file indicated (by name) in the fname parameter.  store
+   its entire contents in a single datum. */
+int set_datum_file(gnutls_datum_t* d, const char* fname);
+
+/* set up file descriptor pipe for writing (child process pid gets
+   stored in pid, fd is returned)*/
+int create_writing_pipe(pid_t* pid, const char* path, char* const argv[]);
+
+/* return 0 if userid matches the monkeysphere spec for ssh host user IDs */
+int validate_ssh_host_userid(const char* userid);
+
+/* how many bytes will it take to write out this datum in OpenPGP MPI form? */
+size_t get_openpgp_mpi_size(gnutls_datum_t* d);
+
+/* write the MPI stored in gnutls_datum_t to file descriptor fd: */
+int write_openpgp_mpi_to_fd(int fd, gnutls_datum_t* d);
diff --git a/src/keytrans/openpgp2ssh.c b/src/keytrans/openpgp2ssh.c
new file mode 100644
index 0000000..511af71
--- /dev/null
+++ b/src/keytrans/openpgp2ssh.c
@@ -0,0 +1,437 @@
+#include "gnutls-helpers.h"
+
+#include <gnutls/openpgp.h>
+#include <gnutls/x509.h>
+
+/* for waitpid() */
+#include <sys/types.h>
+#include <sys/wait.h>
+
+/* 
+   Author: Daniel Kahn Gillmor <dkg@fifthhorseman.net>
+   Date: 2008-06-12 13:47:41-0400
+   License: GPL v3 or later
+
+   monkeysphere key translator: execute this with an OpenPGP key on
+   stdin, (please indicate the specific keyid that you want as the
+   first argument if there are subkeys).  At the moment, only public
+   keys and passphraseless secret keys work.
+
+   For secret keys, it will spit out a PEM-encoded version of the key
+   on stdout, which can be fed into ssh-add like this:
+
+    gpg --export-secret-keys $KEYID | openpgp2ssh $KEYID | ssh-add -c /dev/stdin
+
+   For public keys, it will spit out a single line of text that can
+   (with some massaging) be used in an openssh known_hosts or
+   authorized_keys file.  For example:
+
+    echo server.example.org $(gpg --export $KEYID | openpgp2ssh $KEYID) >> ~/.ssh/known_hosts
+
+   Requirements: I've only built this so far with GnuTLS v2.3.x.
+   GnuTLS 2.2.x does not contain the appropriate functionality.
+
+ */
+
+
+/* FIXME: keyid should be const as well */
+int convert_private_pgp_to_x509(gnutls_x509_privkey_t* output, const gnutls_openpgp_privkey_t* pgp_privkey, gnutls_openpgp_keyid_t* keyid) {
+  gnutls_datum_t m, e, d, p, q, u, g, y, x;
+  gnutls_pk_algorithm_t pgp_algo;
+  unsigned int pgp_bits;
+  int ret;
+  gnutls_openpgp_keyid_t curkeyid;
+  int subkeyidx;
+  int subkeycount;
+  int found = 0;
+
+  init_datum(&m);
+  init_datum(&e);
+  init_datum(&d);
+  init_datum(&p);
+  init_datum(&q);
+  init_datum(&u);
+  init_datum(&g);
+  init_datum(&y);
+  init_datum(&x);
+
+  subkeycount = gnutls_openpgp_privkey_get_subkey_count(*pgp_privkey);
+  if (subkeycount < 0) {
+    err(0,"Could not determine subkey count (got value %d)\n", subkeycount);
+    return 1;
+  }
+
+  if ((keyid == NULL) && 
+      (subkeycount > 0)) {
+    err(0,"No keyid passed in, but there were %d keys to choose from\n", subkeycount + 1);
+    return 1;
+  }
+
+  if (keyid != NULL) {
+    ret = gnutls_openpgp_privkey_get_key_id(*pgp_privkey, curkeyid);
+    if (ret) {
+      err(0,"Could not get keyid (error: %d)\n", ret);
+      return 1;
+    }
+  }
+  if ((keyid == NULL) || (memcmp(*keyid, curkeyid, sizeof(gnutls_openpgp_keyid_t)) == 0)) {
+    /* we want to export the primary key: */
+    err(0,"exporting primary key\n");
+
+    /* FIXME: this is almost identical to the block below for subkeys.
+       This clumsiness seems inherent in the gnutls OpenPGP API,
+       though.  ugh. */
+    pgp_algo = gnutls_openpgp_privkey_get_pk_algorithm(*pgp_privkey, &pgp_bits);
+    if (pgp_algo < 0) {
+      err(0, "failed to get OpenPGP key algorithm (error: %d)\n", pgp_algo);
+      return 1;
+    }
+    if (pgp_algo == GNUTLS_PK_RSA) {
+      err(0,"OpenPGP RSA Key, with %d bits\n", pgp_bits);
+      ret = gnutls_openpgp_privkey_export_rsa_raw(*pgp_privkey, &m, &e, &d, &p, &q, &u);
+      if (GNUTLS_E_SUCCESS != ret) {
+	err(0, "failed to export RSA key parameters (error: %d)\n", ret);
+	return 1;
+      }
+      
+    } else if (pgp_algo == GNUTLS_PK_DSA) {
+      err(0,"OpenPGP DSA Key, with %d bits\n", pgp_bits);
+      ret = gnutls_openpgp_privkey_export_dsa_raw(*pgp_privkey, &p, &q, &g, &y, &x);
+      if (GNUTLS_E_SUCCESS != ret) {
+	err(0,"failed to export DSA key parameters (error: %d)\n", ret);
+	return 1;
+      }
+    }
+    found = 1;
+  } else {
+    /* lets trawl through the subkeys until we find the one we want: */
+    for (subkeyidx = 0; (subkeyidx < subkeycount) && !found; subkeyidx++) {
+      ret = gnutls_openpgp_privkey_get_subkey_id(*pgp_privkey, subkeyidx, curkeyid);
+      if (ret) {
+	err(0,"Could not get keyid of subkey with index %d (error: %d)\n", subkeyidx, ret);
+	return 1;
+      }
+      if (memcmp(*keyid, curkeyid, sizeof(gnutls_openpgp_keyid_t)) == 0) {
+	err(0,"exporting subkey index %d\n", subkeyidx);
+
+	/* FIXME: this is almost identical to the block above for the
+	   primary key. */
+	pgp_algo = gnutls_openpgp_privkey_get_subkey_pk_algorithm(*pgp_privkey, subkeyidx, &pgp_bits);
+	if (pgp_algo < 0) {
+	  err(0,"failed to get the algorithm of the OpenPGP public key (error: %d)\n", pgp_algo);
+	  return pgp_algo;
+	} else if (pgp_algo == GNUTLS_PK_RSA) {
+	  err(0,"OpenPGP RSA key, with %d bits\n", pgp_bits);
+	  ret = gnutls_openpgp_privkey_export_subkey_rsa_raw(*pgp_privkey, subkeyidx, &m, &e, &d, &p, &q, &u);
+	  if (GNUTLS_E_SUCCESS != ret) {
+	    err(0,"failed to export RSA key parameters (error: %d)\n", ret);
+	    return 1;
+	  }
+	} else if (pgp_algo == GNUTLS_PK_DSA) {
+	  err(0,"OpenPGP DSA Key, with %d bits\n", pgp_bits);
+	  ret = gnutls_openpgp_privkey_export_subkey_dsa_raw(*pgp_privkey, subkeyidx, &p, &q, &g, &y, &x);
+	  if (GNUTLS_E_SUCCESS != ret) {
+	    err(0,"failed to export DSA key parameters (error: %d)\n", ret);
+	    return 1;
+	  }
+	}
+	found = 1;
+      }
+    }
+  }
+
+  if (!found) {
+    err(0,"Could not find key in input\n");
+    return 1;
+  }
+
+  if (pgp_algo == GNUTLS_PK_RSA) {
+    ret = gnutls_x509_privkey_import_rsa_raw (*output, &m, &e, &d, &p, &q, &u); 
+    if (GNUTLS_E_SUCCESS != ret) {
+      err(0, "failed to import RSA key parameters (error: %d)\n", ret);
+      return 1;
+    }
+  } else if (pgp_algo == GNUTLS_PK_DSA) {
+    ret = gnutls_x509_privkey_import_dsa_raw (*output, &p, &q, &g, &y, &x); 
+    if (GNUTLS_E_SUCCESS != ret) {
+      err(0,"failed to import DSA key parameters (error: %d)\n", ret);
+      return 1;
+    }
+  } else {
+    err(0,"OpenPGP Key was not RSA or DSA -- can't deal! (actual algorithm was: %d)\n", pgp_algo);
+    return 1;
+  }
+  
+  ret = gnutls_x509_privkey_fix(*output);
+  if (ret != 0) {
+    err(0,"failed to fix up the private key in X.509 format (error: %d)\n", ret);
+    return 1; 
+  }
+
+  return 0;
+}
+
+/* FIXME: keyid should be const also */
+int emit_public_openssh_from_pgp(const gnutls_openpgp_crt_t* pgp_crt, gnutls_openpgp_keyid_t* keyid) {
+  gnutls_openpgp_keyid_t curkeyid;
+  int ret;
+  int subkeyidx;
+  int subkeycount;
+  int found = 0;
+  gnutls_datum_t m, e, p, q, g, y, algolabel;
+  unsigned int bits;
+  gnutls_pk_algorithm_t algo;
+  const gnutls_datum_t* all[5];
+  const char* algoname;
+  int mpicount;
+  /* output_data must be at least 2 chars longer than the maximum possible
+     algorithm name: */
+  char output_data[20];
+
+  /* variables for the output conversion: */
+  int pipestatus;
+  int pipefd, child_pid;
+  char* const b64args[] = {"/usr/bin/base64", "--wrap=0", NULL};
+
+  init_datum(&m);
+  init_datum(&e);
+  init_datum(&p);
+  init_datum(&q);
+  init_datum(&g);
+  init_datum(&algolabel);
+
+
+  /* figure out if we've got the right thing: */
+  subkeycount = gnutls_openpgp_crt_get_subkey_count(*pgp_crt);
+  if (subkeycount < 0) {
+    err(0,"Could not determine subkey count (got value %d)\n", subkeycount);
+    return 1;
+  }
+
+  if ((keyid == NULL) && 
+      (subkeycount > 0)) {
+    err(0,"No keyid passed in, but there were %d keys to choose from\n", subkeycount + 1);
+    return 1;
+  }
+
+  if (keyid != NULL) {
+    ret = gnutls_openpgp_crt_get_key_id(*pgp_crt, curkeyid);
+    if (ret) {
+      err(0,"Could not get keyid (error: %d)\n", ret);
+      return 1;
+    }
+  }
+  if ((keyid == NULL) || (memcmp(*keyid, curkeyid, sizeof(gnutls_openpgp_keyid_t)) == 0)) {
+    /* we want to export the primary key: */
+    err(0,"exporting primary key\n");
+
+    /* FIXME: this is almost identical to the block below for subkeys.
+       This clumsiness seems inherent in the gnutls OpenPGP API,
+       though.  ugh. */
+    algo = gnutls_openpgp_crt_get_pk_algorithm(*pgp_crt, &bits);
+    if (algo < 0) {
+      err(0,"failed to get the algorithm of the OpenPGP public key (error: %d)\n", algo);
+      return algo;
+    } else if (algo == GNUTLS_PK_RSA) {
+      err(0,"OpenPGP RSA certificate, with %d bits\n", bits);
+      ret = gnutls_openpgp_crt_get_pk_rsa_raw(*pgp_crt, &m, &e);
+      if (GNUTLS_E_SUCCESS != ret) {
+	err(0,"failed to export RSA certificate parameters (error: %d)\n", ret);
+	return 1;
+      }
+    } else if (algo == GNUTLS_PK_DSA) {
+      err(0,"OpenPGP DSA certificate, with %d bits\n", bits);
+      ret = gnutls_openpgp_crt_get_pk_dsa_raw(*pgp_crt, &p, &q, &g, &y);
+      if (GNUTLS_E_SUCCESS != ret) {
+	err(0,"failed to export DSA certificate parameters (error: %d)\n", ret);
+	return 1;
+      }
+    }
+    found = 1;
+
+  } else {
+    /* lets trawl through the subkeys until we find the one we want: */
+    for (subkeyidx = 0; (subkeyidx < subkeycount) && !found; subkeyidx++) {
+      ret = gnutls_openpgp_crt_get_subkey_id(*pgp_crt, subkeyidx, curkeyid);
+      if (ret) {
+	err(0,"Could not get keyid of subkey with index %d (error: %d)\n", subkeyidx, ret);
+	return 1;
+      }
+      if (memcmp(*keyid, curkeyid, sizeof(gnutls_openpgp_keyid_t)) == 0) {
+	err(0,"exporting subkey index %d\n", subkeyidx);
+
+	/* FIXME: this is almost identical to the block above for the
+	   primary key. */
+	algo = gnutls_openpgp_crt_get_subkey_pk_algorithm(*pgp_crt, subkeyidx, &bits);
+	if (algo < 0) {
+	  err(0,"failed to get the algorithm of the OpenPGP public key (error: %d)\n", algo);
+	  return algo;
+	} else if (algo == GNUTLS_PK_RSA) {
+	  err(0,"OpenPGP RSA certificate, with %d bits\n", bits);
+	  ret = gnutls_openpgp_crt_get_subkey_pk_rsa_raw(*pgp_crt, subkeyidx, &m, &e);
+	  if (GNUTLS_E_SUCCESS != ret) {
+	    err(0,"failed to export RSA certificate parameters (error: %d)\n", ret);
+	    return 1;
+	  }
+	} else if (algo == GNUTLS_PK_DSA) {
+	  err(0,"OpenPGP DSA certificate, with %d bits\n", bits);
+	  ret = gnutls_openpgp_crt_get_subkey_pk_dsa_raw(*pgp_crt, subkeyidx, &p, &q, &g, &y);
+	  if (GNUTLS_E_SUCCESS != ret) {
+	    err(0,"failed to export DSA certificate parameters (error: %d)\n", ret);
+	    return 1;
+	  }
+	}
+	found = 1;
+	
+      }
+    }
+  }
+
+  if (!found) {
+    err(0,"Could not find key in input\n");
+    return 1;
+  }
+
+  /* if we made it this far, we've got MPIs, and we've got the
+     algorithm, so we just need to emit the info */
+  if (algo == GNUTLS_PK_RSA) {
+    algoname = "ssh-rsa";
+    mpicount = 3;
+
+    all[0] = &algolabel;
+    all[1] = &e;
+    all[2] = &m;
+  } else if (algo == GNUTLS_PK_DSA) {
+    algoname = "ssh-dss";
+    mpicount = 5;
+
+    all[0] = &algolabel;
+    all[1] = &p;
+    all[2] = &q;
+    all[3] = &g;
+    all[4] = &y;
+  } else {
+    err(0,"Key algorithm was neither DSA nor RSA (it was %d).  Can't deal.  Sorry!\n", algo);
+    return 1;
+  }
+
+  if (ret = datum_from_string(&algolabel, algoname), ret) {
+    err(0,"couldn't label string (error: %d)\n", ret);
+    return ret;
+  }
+
+  snprintf(output_data, sizeof(output_data), "%s ", algoname);
+
+  pipefd = create_writing_pipe(&child_pid, b64args[0], b64args);
+  if (pipefd < 0) {
+    err(0,"failed to create a writing pipe (returned %d)\n", pipefd);
+    return pipefd;
+  }
+    
+  write(1, output_data, strlen(output_data));
+
+  if (0 != write_data_fd_with_length(pipefd, all, mpicount)) {
+    err(0,"was not able to write out RSA key data\n");
+    return 1;
+  }
+  close(pipefd);
+  if (child_pid != waitpid(child_pid, &pipestatus, 0)) {
+    err(0,"could not wait for child process to return for some reason.\n");
+    return 1;
+  }
+  if (pipestatus != 0) {
+    err(0,"base64 pipe died with return code %d\n", pipestatus);
+    return pipestatus;
+  }
+
+  write(1, "\n", 1);
+  
+  return 0;
+}
+
+int main(int argc, char* argv[]) {
+  gnutls_datum_t data;
+  int ret;
+  gnutls_x509_privkey_t x509_privkey;
+  gnutls_openpgp_privkey_t pgp_privkey;
+  gnutls_openpgp_crt_t pgp_crt;
+
+  char output_data[10240];
+  size_t ods = sizeof(output_data);
+  
+  gnutls_openpgp_keyid_t keyid;
+  gnutls_openpgp_keyid_t* use_keyid;
+
+  init_gnutls();
+
+  /* figure out what keyid we should be looking for: */
+  use_keyid = NULL;
+  if (argv[1] != NULL) {
+    ret = convert_string_to_keyid(keyid, argv[1]);
+    if (ret != 0)
+      return ret;
+    use_keyid = &keyid;
+  }
+
+  
+  init_datum(&data);
+
+  /* slurp in the key from stdin */
+  if (ret = set_datum_fd(&data, 0), ret) {
+    err(0,"didn't read file descriptor 0\n");
+    return 1;
+  }
+
+
+  if (ret = gnutls_openpgp_privkey_init(&pgp_privkey), ret) {
+    err(0,"Failed to initialized OpenPGP private key (error: %d)\n", ret);
+    return 1;
+  }
+  /* check whether it's a private key or a public key, by trying them: */
+  if ((gnutls_openpgp_privkey_import(pgp_privkey, &data, GNUTLS_OPENPGP_FMT_RAW, NULL, 0) == 0) || 
+      (gnutls_openpgp_privkey_import(pgp_privkey, &data, GNUTLS_OPENPGP_FMT_BASE64, NULL, 0) == 0)) {
+    /* we're dealing with a private key */
+    err(0,"Translating private key\n");
+    if (ret = gnutls_x509_privkey_init(&x509_privkey), ret) {
+      err(0,"Failed to initialize X.509 private key for output (error: %d)\n", ret);
+      return 1;
+    }
+    
+    ret = convert_private_pgp_to_x509(&x509_privkey, &pgp_privkey, use_keyid);
+
+    gnutls_openpgp_privkey_deinit(pgp_privkey);
+    if (ret)
+      return ret;
+
+    ret = gnutls_x509_privkey_export (x509_privkey,
+				      GNUTLS_X509_FMT_PEM,
+				      output_data,
+				      &ods);
+    if (ret == 0) {
+      write(1, output_data, ods);
+    }
+    gnutls_x509_privkey_deinit(x509_privkey);
+  
+  } else {
+    if (ret = gnutls_openpgp_crt_init(&pgp_crt), ret) {
+      err(0,"Failed to initialized OpenPGP certificate (error: %d)\n", ret);
+      return 1;
+    }
+    
+    if ((gnutls_openpgp_crt_import(pgp_crt, &data, GNUTLS_OPENPGP_FMT_RAW) == 0) || 
+	(gnutls_openpgp_crt_import(pgp_crt, &data, GNUTLS_OPENPGP_FMT_BASE64) == 0)) {
+      /* we're dealing with a public key */
+      err(0,"Translating public key\n");
+
+      ret = emit_public_openssh_from_pgp(&pgp_crt, use_keyid);
+      
+    } else {
+      /* we have no idea what kind of key this is at all anyway! */
+      err(0,"Input does contain any form of OpenPGP key I recognize.\n");
+      return 1;
+    }
+  }
+
+  gnutls_global_deinit();
+  return 0;
+}