cmdgen.c

/*
 * cmdgen.c - command-line form of PuTTYgen
 */

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <limits.h>
#include <assert.h>
#include <time.h>
#include <errno.h>
#include <string.h>

#include "putty.h"
#include "ssh.h"

struct progress {
    int phase, current;
};

static void progress_update(void *param, int action, int phase, int iprogress)
{
    struct progress *p = (struct progress *)param;
    if (action != PROGFN_PROGRESS)
        return;
    if (phase > p->phase) {
        if (p->phase >= 0)
            fputc('\n', stderr);
        p->phase = phase;
        if (iprogress >= 0)
            p->current = iprogress - 1;
        else
            p->current = iprogress;
    }
    while (p->current < iprogress) {
        fputc('+', stdout);
        p->current++;
    }
    fflush(stdout);
}

static void no_progress(void *param, int action, int phase, int iprogress)
{
}

/*
 * Stubs to let everything else link sensibly.
 */
char *x_get_default(const char *key)
{
    return NULL;
}
void sk_cleanup(void)
{
}

void showversion(void)
{
    char *buildinfo_text = buildinfo("\n");
    printf("puttygen: %s\n%s\n", ver, buildinfo_text);
    sfree(buildinfo_text);
}

void usage(bool standalone)
{
    fprintf(standalone ? stderr : stdout,
            "Usage: puttygen ( keyfile | -t type [ -b bits ] )\n"
            "                [ -C comment ] [ -P ] [ -q ]\n"
            "                [ -o output-keyfile ] [ -O type | -l | -L"
            " | -p ]\n");
    if (standalone)
        fprintf(stderr,
                "Use \"puttygen --help\" for more detail.\n");
}

void help(void)
{
    /*
     * Help message is an extended version of the usage message. So
     * start with that, plus a version heading.
     */
    printf("PuTTYgen: key generator and converter for the PuTTY tools\n"
           "%s\n", ver);
    usage(false);
    printf("  -t    specify key type when generating (ed25519, ecdsa, rsa, "
                                                        "dsa, rsa1)\n"
           "  -b    specify number of bits when generating key\n"
           "  -C    change or specify key comment\n"
           "  -P    change key passphrase\n"
           "  -q    quiet: do not display progress bar\n"
           "  -O    specify output type:\n"
           "           private             output PuTTY private key format\n"
           "           private-openssh     export OpenSSH private key\n"
           "           private-openssh-new export OpenSSH private key "
                                             "(force new format)\n"
           "           private-sshcom      export ssh.com private key\n"
           "           public              RFC 4716 / ssh.com public key\n"
           "           public-openssh      OpenSSH public key\n"
           "           fingerprint         output the key fingerprint\n"
           "  -o    specify output file\n"
           "  -l    equivalent to `-O fingerprint'\n"
           "  -L    equivalent to `-O public-openssh'\n"
           "  -p    equivalent to `-O public'\n"
           "  --old-passphrase file\n"
           "        specify file containing old key passphrase\n"
           "  --new-passphrase file\n"
           "        specify file containing new key passphrase\n"
           "  --random-device device\n"
           "        specify device to read entropy from (e.g. /dev/urandom)\n"
           );
}

static bool move(char *from, char *to)
{
    int ret;

    ret = rename(from, to);
    if (ret) {
        /*
         * This OS may require us to remove the original file first.
         */
        remove(to);
        ret = rename(from, to);
    }
    if (ret) {
        perror("puttygen: cannot move new file on to old one");
        return false;
    }
    return true;
}

static char *readpassphrase(const char *filename)
{
    FILE *fp;
    char *line;

    fp = fopen(filename, "r");
    if (!fp) {
        fprintf(stderr, "puttygen: cannot open %s: %s\n",
                filename, strerror(errno));
        return NULL;
    }
    line = fgetline(fp);
    if (line)
        line[strcspn(line, "\r\n")] = '\0';
    else if (ferror(fp))
        fprintf(stderr, "puttygen: error reading from %s: %s\n",
                filename, strerror(errno));
    else        /* empty file */
        line = dupstr("");
    fclose(fp);
    return line;
}

#define DEFAULT_RSADSA_BITS 2048

/* For Unix in particular, but harmless if this main() is reused elsewhere */
const bool buildinfo_gtk_relevant = false;

int main(int argc, char **argv)
{
    char *infile = NULL;
    Filename *infilename = NULL, *outfilename = NULL;
    LoadedFile *infile_lf = NULL;
    BinarySource *infile_bs = NULL;
    enum { NOKEYGEN, RSA1, RSA2, DSA, ECDSA, ED25519 } keytype = NOKEYGEN;
    char *outfile = NULL, *outfiletmp = NULL;
    enum { PRIVATE, PUBLIC, PUBLICO, FP, OPENSSH_AUTO,
           OPENSSH_NEW, SSHCOM } outtype = PRIVATE;
    int bits = -1;
    const char *comment = NULL;
    char *origcomment = NULL;
    bool change_passphrase = false;
    bool errs = false, nogo = false;
    int intype = SSH_KEYTYPE_UNOPENABLE;
    int sshver = 0;
    ssh2_userkey *ssh2key = NULL;
    RSAKey *ssh1key = NULL;
    strbuf *ssh2blob = NULL;
    char *ssh2alg = NULL;
    char *old_passphrase = NULL, *new_passphrase = NULL;
    bool load_encrypted;
    progfn_t progressfn = is_interactive() ? progress_update : no_progress;
    const char *random_device = NULL;
    int exit_status = 0;

    #define RETURN(status) do { exit_status = (status); goto out; } while (0)

    /* ------------------------------------------------------------------
     * Parse the command line to figure out what we've been asked to do.
     */

    /*
     * If run with no arguments at all, print the usage message and
     * return success.
     */
    if (argc <= 1) {
        usage(true);
        RETURN(0);
    }

    /*
     * Parse command line arguments.
     */
    while (--argc) {
        char *p = *++argv;
        if (p[0] == '-' && p[1]) {
            /*
             * An option.
             */
            while (p && *++p) {
                char c = *p;
                switch (c) {
                  case '-': {
                    /*
                     * Long option.
                     */
                    char *opt, *val;
                    opt = p++;     /* opt will have _one_ leading - */
                    while (*p && *p != '=')
                        p++;               /* find end of option */
                    if (*p == '=') {
                      *p++ = '\0';
                      val = p;
                    } else
                        val = NULL;

                    if (!strcmp(opt, "-help")) {
                      if (val) {
                        errs = true;
                        fprintf(stderr, "puttygen: option `-%s'"
                                " expects no argument\n", opt);
                      } else {
                        help();
                        nogo = true;
                      }
                    } else if (!strcmp(opt, "-version")) {
                      if (val) {
                        errs = true;
                        fprintf(stderr, "puttygen: option `-%s'"
                                " expects no argument\n", opt);
                      } else {
                        showversion();
                        nogo = true;
                      }
                    } else if (!strcmp(opt, "-pgpfp")) {
                      if (val) {
                        errs = true;
                        fprintf(stderr, "puttygen: option `-%s'"
                                " expects no argument\n", opt);
                      } else {
                        /* support --pgpfp for consistency */
                        pgp_fingerprints();
                        nogo = true;
                      }
                    } else if (!strcmp(opt, "-old-passphrase")) {
                      if (!val && argc > 1)
                          --argc, val = *++argv;
                      if (!val) {
                        errs = true;
                        fprintf(stderr, "puttygen: option `-%s'"
                                " expects an argument\n", opt);
                      } else {
                        old_passphrase = readpassphrase(val);
                        if (!old_passphrase)
                            errs = true;
                      }
                    } else if (!strcmp(opt, "-new-passphrase")) {
                      if (!val && argc > 1)
                          --argc, val = *++argv;
                      if (!val) {
                        errs = true;
                        fprintf(stderr, "puttygen: option `-%s'"
                                " expects an argument\n", opt);
                      } else {
                        new_passphrase = readpassphrase(val);
                        if (!new_passphrase)
                            errs = true;
                      }
                    } else if (!strcmp(opt, "-random-device")) {
                      if (!val && argc > 1)
                          --argc, val = *++argv;
                      if (!val) {
                        errs = true;
                        fprintf(stderr, "puttygen: option `-%s'"
                                " expects an argument\n", opt);
                      } else {
                        random_device = val;
                      }
                    } else {
                      errs = true;
                      fprintf(stderr,
                              "puttygen: no such option `-%s'\n", opt);
                    }
                    p = NULL;
                    break;
                  }
                  case 'h':
                  case 'V':
                  case 'P':
                  case 'l':
                  case 'L':
                  case 'p':
                  case 'q':
                    /*
                     * Option requiring no parameter.
                     */
                    switch (c) {
                      case 'h':
                        help();
                        nogo = true;
                        break;
                      case 'V':
                        showversion();
                        nogo = true;
                        break;
                      case 'P':
                        change_passphrase = true;
                        break;
                      case 'l':
                        outtype = FP;
                        break;
                      case 'L':
                        outtype = PUBLICO;
                        break;
                      case 'p':
                        outtype = PUBLIC;
                        break;
                      case 'q':
                        progressfn = no_progress;
                        break;
                    }
                    break;
                  case 't':
                  case 'b':
                  case 'C':
                  case 'O':
                  case 'o':
                    /*
                     * Option requiring parameter.
                     */
                    p++;
                    if (!*p && argc > 1)
                        --argc, p = *++argv;
                    else if (!*p) {
                        fprintf(stderr, "puttygen: option `-%c' expects a"
                                " parameter\n", c);
                        errs = true;
                    }
                    /*
                     * Now c is the option and p is the parameter.
                     */
                    switch (c) {
                      case 't':
                        if (!strcmp(p, "rsa") || !strcmp(p, "rsa2"))
                            keytype = RSA2, sshver = 2;
                        else if (!strcmp(p, "rsa1"))
                            keytype = RSA1, sshver = 1;
                        else if (!strcmp(p, "dsa") || !strcmp(p, "dss"))
                            keytype = DSA, sshver = 2;
                        else if (!strcmp(p, "ecdsa"))
                            keytype = ECDSA, sshver = 2;
                        else if (!strcmp(p, "ed25519"))
                            keytype = ED25519, sshver = 2;
                        else {
                            fprintf(stderr,
                                    "puttygen: unknown key type `%s'\n", p);
                            errs = true;
                        }
                        break;
                      case 'b':
                        bits = atoi(p);
                        break;
                      case 'C':
                        comment = p;
                        break;
                      case 'O':
                        if (!strcmp(p, "public"))
                            outtype = PUBLIC;
                        else if (!strcmp(p, "public-openssh"))
                            outtype = PUBLICO;
                        else if (!strcmp(p, "private"))
                            outtype = PRIVATE;
                        else if (!strcmp(p, "fingerprint"))
                            outtype = FP;
                        else if (!strcmp(p, "private-openssh"))
                            outtype = OPENSSH_AUTO, sshver = 2;
                        else if (!strcmp(p, "private-openssh-new"))
                            outtype = OPENSSH_NEW, sshver = 2;
                        else if (!strcmp(p, "private-sshcom"))
                            outtype = SSHCOM, sshver = 2;
                        else {
                            fprintf(stderr,
                                    "puttygen: unknown output type `%s'\n", p);
                            errs = true;
                        }
                        break;
                      case 'o':
                        outfile = p;
                        break;
                    }
                    p = NULL;          /* prevent continued processing */
                    break;
                  default:
                    /*
                     * Unrecognised option.
                     */
                    errs = true;
                    fprintf(stderr, "puttygen: no such option `-%c'\n", c);
                    break;
                }
            }
        } else {
            /*
             * A non-option argument.
             */
            if (!infile)
                infile = p;
            else {
                errs = true;
                fprintf(stderr, "puttygen: cannot handle more than one"
                        " input file\n");
            }
        }
    }

    if (bits == -1) {
        /*
         * No explicit key size was specified. Default varies
         * depending on key type.
         */
        switch (keytype) {
          case ECDSA:
            bits = 384;
            break;
          case ED25519:
            bits = 255;
            break;
          default:
            bits = DEFAULT_RSADSA_BITS;
            break;
        }
    }

    if (keytype == ECDSA && (bits != 256 && bits != 384 && bits != 521)) {
        fprintf(stderr, "puttygen: invalid bits for ECDSA, choose 256, 384 or 521\n");
        errs = true;
    }

    if (keytype == ED25519 && (bits != 255) && (bits != 256)) {
        fprintf(stderr, "puttygen: invalid bits for ED25519, choose 255\n");
        errs = true;
    }

    if (keytype == RSA2 || keytype == RSA1 || keytype == DSA) {
        if (bits < 256) {
            fprintf(stderr, "puttygen: cannot generate %s keys shorter than"
                    " 256 bits\n", (keytype == DSA ? "DSA" : "RSA"));
            errs = true;
        } else if (bits < DEFAULT_RSADSA_BITS) {
            fprintf(stderr, "puttygen: warning: %s keys shorter than"
                    " %d bits are probably not secure\n",
                    (keytype == DSA ? "DSA" : "RSA"), DEFAULT_RSADSA_BITS);
            /* but this is just a warning, so proceed anyway */
        }
    }

    if (errs)
        RETURN(1);

    if (nogo)
        RETURN(0);

    /*
     * If run with at least one argument _but_ not the required
     * ones, print the usage message and return failure.
     */
    if (!infile && keytype == NOKEYGEN) {
        usage(true);
        RETURN(1);
    }

    /* ------------------------------------------------------------------
     * Figure out further details of exactly what we're going to do.
     */

    /*
     * Bomb out if we've been asked to both load and generate a
     * key.
     */
    if (keytype != NOKEYGEN && infile) {
        fprintf(stderr, "puttygen: cannot both load and generate a key\n");
        RETURN(1);
    }

    /*
     * We must save the private part when generating a new key.
     */
    if (keytype != NOKEYGEN &&
        (outtype != PRIVATE && outtype != OPENSSH_AUTO &&
         outtype != OPENSSH_NEW && outtype != SSHCOM)) {
        fprintf(stderr, "puttygen: this would generate a new key but "
                "discard the private part\n");
        RETURN(1);
    }

    /*
     * Analyse the type of the input file, in case this affects our
     * course of action.
     */
    if (infile) {
        const char *load_error;

        infilename = filename_from_str(infile);
        if (!strcmp(infile, "-"))
            infile_lf = lf_load_keyfile_fp(stdin, &load_error);
        else
            infile_lf = lf_load_keyfile(infilename, &load_error);

        if (!infile_lf) {
            fprintf(stderr, "puttygen: unable to load file `%s': %s\n",
                    infile, load_error);
            RETURN(1);
        }

        infile_bs = BinarySource_UPCAST(infile_lf);
        intype = key_type_s(infile_bs);
        BinarySource_REWIND(infile_bs);

        switch (intype) {
          case SSH_KEYTYPE_UNOPENABLE:
          case SSH_KEYTYPE_UNKNOWN:
            fprintf(stderr, "puttygen: unable to load file `%s': %s\n",
                    infile, key_type_to_str(intype));
            RETURN(1);

          case SSH_KEYTYPE_SSH1:
          case SSH_KEYTYPE_SSH1_PUBLIC:
            if (sshver == 2) {
                fprintf(stderr, "puttygen: conversion from SSH-1 to SSH-2 keys"
                        " not supported\n");
                RETURN(1);
            }
            sshver = 1;
            break;

          case SSH_KEYTYPE_SSH2:
          case SSH_KEYTYPE_SSH2_PUBLIC_RFC4716:
          case SSH_KEYTYPE_SSH2_PUBLIC_OPENSSH:
          case SSH_KEYTYPE_OPENSSH_PEM:
          case SSH_KEYTYPE_OPENSSH_NEW:
          case SSH_KEYTYPE_SSHCOM:
            if (sshver == 1) {
                fprintf(stderr, "puttygen: conversion from SSH-2 to SSH-1 keys"
                        " not supported\n");
                RETURN(1);
            }
            sshver = 2;
            break;

          case SSH_KEYTYPE_OPENSSH_AUTO:
          default:
            unreachable("Should never see these types on an input file");
        }
    }

    /*
     * Determine the default output file, if none is provided.
     *
     * This will usually be equal to stdout, except that if the
     * input and output file formats are the same then the default
     * output is to overwrite the input.
     *
     * Also in this code, we bomb out if the input and output file
     * formats are the same and no other action is performed.
     */
    if ((intype == SSH_KEYTYPE_SSH1 && outtype == PRIVATE) ||
        (intype == SSH_KEYTYPE_SSH2 && outtype == PRIVATE) ||
        (intype == SSH_KEYTYPE_OPENSSH_PEM && outtype == OPENSSH_AUTO) ||
        (intype == SSH_KEYTYPE_OPENSSH_NEW && outtype == OPENSSH_NEW) ||
        (intype == SSH_KEYTYPE_SSHCOM && outtype == SSHCOM)) {
        if (!outfile) {
            outfile = infile;
            outfiletmp = dupcat(outfile, ".tmp");
        }

        if (!change_passphrase && !comment) {
            fprintf(stderr, "puttygen: this command would perform no useful"
                    " action\n");
            RETURN(1);
        }
    } else {
        if (!outfile) {
            /*
             * Bomb out rather than automatically choosing to write
             * a private key file to stdout.
             */
            if (outtype == PRIVATE || outtype == OPENSSH_AUTO ||
                outtype == OPENSSH_NEW || outtype == SSHCOM) {
                fprintf(stderr, "puttygen: need to specify an output file\n");
                RETURN(1);
            }
        }
    }

    /*
     * Figure out whether we need to load the encrypted part of the
     * key. This will be the case if either (a) we need to write
     * out a private key format, or (b) the entire input key file
     * is encrypted.
     */
    if (outtype == PRIVATE || outtype == OPENSSH_AUTO ||
        outtype == OPENSSH_NEW || outtype == SSHCOM ||
        intype == SSH_KEYTYPE_OPENSSH_PEM ||
        intype == SSH_KEYTYPE_OPENSSH_NEW ||
        intype == SSH_KEYTYPE_SSHCOM)
        load_encrypted = true;
    else
        load_encrypted = false;

    if (load_encrypted && (intype == SSH_KEYTYPE_SSH1_PUBLIC ||
                           intype == SSH_KEYTYPE_SSH2_PUBLIC_RFC4716 ||
                           intype == SSH_KEYTYPE_SSH2_PUBLIC_OPENSSH)) {
        fprintf(stderr, "puttygen: cannot perform this action on a "
                "public-key-only input file\n");
        RETURN(1);
    }

    /* ------------------------------------------------------------------
     * Now we're ready to actually do some stuff.
     */

    /*
     * Either load or generate a key.
     */
    if (keytype != NOKEYGEN) {
        char *entropy;
        char default_comment[80];
        struct tm tm;
        struct progress prog;

        prog.phase = -1;
        prog.current = -1;

        tm = ltime();
        if (keytype == DSA)
            strftime(default_comment, 30, "dsa-key-%Y%m%d", &tm);
        else if (keytype == ECDSA)
            strftime(default_comment, 30, "ecdsa-key-%Y%m%d", &tm);
        else if (keytype == ED25519)
            strftime(default_comment, 30, "ed25519-key-%Y%m%d", &tm);
        else
            strftime(default_comment, 30, "rsa-key-%Y%m%d", &tm);

        entropy = get_random_data(bits / 8, random_device);
        if (!entropy) {
            fprintf(stderr, "puttygen: failed to collect entropy, "
                    "could not generate key\n");
            RETURN(1);
        }
        random_setup_special();
        random_reseed(make_ptrlen(entropy, bits / 8));
        smemclr(entropy, bits/8);
        sfree(entropy);

        if (keytype == DSA) {
            struct dss_key *dsskey = snew(struct dss_key);
            dsa_generate(dsskey, bits, progressfn, &prog);
            ssh2key = snew(ssh2_userkey);
            ssh2key->key = &dsskey->sshk;
            ssh1key = NULL;
        } else if (keytype == ECDSA) {
            struct ecdsa_key *ek = snew(struct ecdsa_key);
            ecdsa_generate(ek, bits, progressfn, &prog);
            ssh2key = snew(ssh2_userkey);
            ssh2key->key = &ek->sshk;
            ssh1key = NULL;
        } else if (keytype == ED25519) {
            struct eddsa_key *ek = snew(struct eddsa_key);
            eddsa_generate(ek, bits, progressfn, &prog);
            ssh2key = snew(ssh2_userkey);
            ssh2key->key = &ek->sshk;
            ssh1key = NULL;
        } else {
            RSAKey *rsakey = snew(RSAKey);
            rsa_generate(rsakey, bits, progressfn, &prog);
            rsakey->comment = NULL;
            if (keytype == RSA1) {
                ssh1key = rsakey;
            } else {
                ssh2key = snew(ssh2_userkey);
                ssh2key->key = &rsakey->sshk;
            }
        }
        progressfn(&prog, PROGFN_PROGRESS, INT_MAX, -1);

        if (ssh2key)
            ssh2key->comment = dupstr(default_comment);
        if (ssh1key)
            ssh1key->comment = dupstr(default_comment);

    } else {
        const char *error = NULL;
        bool encrypted;

        assert(infile != NULL);

        sfree(origcomment);
        origcomment = NULL;

        /*
         * Find out whether the input key is encrypted.
         */
        if (intype == SSH_KEYTYPE_SSH1)
            encrypted = rsa1_encrypted_s(infile_bs, &origcomment);
        else if (intype == SSH_KEYTYPE_SSH2)
            encrypted = ppk_encrypted_s(infile_bs, &origcomment);
        else
            encrypted = import_encrypted_s(infilename, infile_bs,
                                           intype, &origcomment);
        BinarySource_REWIND(infile_bs);

        /*
         * If so, ask for a passphrase.
         */
        if (encrypted && load_encrypted) {
            if (!old_passphrase) {
                prompts_t *p = new_prompts();
                int ret;
                p->to_server = false;
                p->from_server = false;
                p->name = dupstr("SSH key passphrase");
                add_prompt(p, dupstr("Enter passphrase to load key: "), false);
                ret = console_get_userpass_input(p);
                assert(ret >= 0);
                if (!ret) {
                    free_prompts(p);
                    perror("puttygen: unable to read passphrase");
                    RETURN(1);
                } else {
                    old_passphrase = prompt_get_result(p->prompts[0]);
                    free_prompts(p);
                }
            }
        } else {
            old_passphrase = NULL;
        }

        switch (intype) {
            int ret;

          case SSH_KEYTYPE_SSH1:
          case SSH_KEYTYPE_SSH1_PUBLIC:
            ssh1key = snew(RSAKey);
            memset(ssh1key, 0, sizeof(RSAKey));
            if (!load_encrypted) {
                strbuf *blob;
                BinarySource src[1];

                sfree(origcomment);
                origcomment = NULL;

                blob = strbuf_new();

                ret = rsa1_loadpub_s(infile_bs, BinarySink_UPCAST(blob),
                                     &origcomment, &error);
                BinarySource_BARE_INIT(src, blob->u, blob->len);
                get_rsa_ssh1_pub(src, ssh1key, RSA_SSH1_EXPONENT_FIRST);
                strbuf_free(blob);

                ssh1key->comment = dupstr(origcomment);
                ssh1key->private_exponent = NULL;
                ssh1key->p = NULL;
                ssh1key->q = NULL;
                ssh1key->iqmp = NULL;
            } else {
                ret = rsa1_load_s(infile_bs, ssh1key, old_passphrase, &error);
            }
            BinarySource_REWIND(infile_bs);
            if (ret > 0)
                error = NULL;
            else if (!error)
                error = "unknown error";
            break;

          case SSH_KEYTYPE_SSH2:
          case SSH_KEYTYPE_SSH2_PUBLIC_RFC4716:
          case SSH_KEYTYPE_SSH2_PUBLIC_OPENSSH:
            if (!load_encrypted) {
                sfree(origcomment);
                origcomment = NULL;
                ssh2blob = strbuf_new();
                if (ppk_loadpub_s(infile_bs, &ssh2alg,
                                  BinarySink_UPCAST(ssh2blob),
                                  &origcomment, &error)) {
                    const ssh_keyalg *alg = find_pubkey_alg(ssh2alg);
                    if (alg)
                        bits = ssh_key_public_bits(
                            alg, ptrlen_from_strbuf(ssh2blob));
                    else
                        bits = -1;
                } else {
                    strbuf_free(ssh2blob);
                    ssh2blob = NULL;
                }
                sfree(ssh2alg);
            } else {
                ssh2key = ppk_load_s(infile_bs, old_passphrase, &error);
            }
            BinarySource_REWIND(infile_bs);
            if ((ssh2key && ssh2key != SSH2_WRONG_PASSPHRASE) || ssh2blob)
                error = NULL;
            else if (!error) {
                if (ssh2key == SSH2_WRONG_PASSPHRASE)
                    error = "wrong passphrase";
                else
                    error = "unknown error";
            }
            break;

          case SSH_KEYTYPE_OPENSSH_PEM:
          case SSH_KEYTYPE_OPENSSH_NEW:
          case SSH_KEYTYPE_SSHCOM:
            ssh2key = import_ssh2_s(infile_bs, intype, old_passphrase, &error);
            if (ssh2key) {
                if (ssh2key != SSH2_WRONG_PASSPHRASE)
                    error = NULL;
                else
                    error = "wrong passphrase";
            } else if (!error)
                error = "unknown error";
            break;

          default:
            unreachable("bad input key type");
        }

        if (error) {
            fprintf(stderr, "puttygen: error loading `%s': %s\n",
                    infile, error);
            RETURN(1);
        }
    }

    /*
     * Change the comment if asked to.
     */
    if (comment) {
        if (sshver == 1) {
            assert(ssh1key);
            sfree(ssh1key->comment);
            ssh1key->comment = dupstr(comment);
        } else {
            assert(ssh2key);
            sfree(ssh2key->comment);
            ssh2key->comment = dupstr(comment);
        }
    }

    /*
     * Unless we're changing the passphrase, the old one (if any) is a
     * reasonable default.
     */
    if (!change_passphrase && old_passphrase && !new_passphrase)
        new_passphrase = dupstr(old_passphrase);

    /*
     * Prompt for a new passphrase if we have been asked to, or if
     * we have just generated a key.
     */
    if (!new_passphrase && (change_passphrase || keytype != NOKEYGEN)) {
        prompts_t *p = new_prompts();
        int ret;

        p->to_server = false;
        p->from_server = false;
        p->name = dupstr("New SSH key passphrase");
        add_prompt(p, dupstr("Enter passphrase to save key: "), false);
        add_prompt(p, dupstr("Re-enter passphrase to verify: "), false);
        ret = console_get_userpass_input(p);
        assert(ret >= 0);
        if (!ret) {
            free_prompts(p);
            perror("puttygen: unable to read new passphrase");
            RETURN(1);
        } else {
            if (strcmp(prompt_get_result_ref(p->prompts[0]),
                       prompt_get_result_ref(p->prompts[1]))) {
                free_prompts(p);
                fprintf(stderr, "puttygen: passphrases do not match\n");
                RETURN(1);
            }
            new_passphrase = prompt_get_result(p->prompts[0]);
            free_prompts(p);
        }
    }
    if (new_passphrase && !*new_passphrase) {
        sfree(new_passphrase);
        new_passphrase = NULL;
    }

    /*
     * Write output.
     *
     * (In the case where outfile and outfiletmp are both NULL,
     * there is no semantic reason to initialise outfilename at
     * all; but we have to write _something_ to it or some compiler
     * will probably complain that it might be used uninitialised.)
     */
    if (outfiletmp)
        outfilename = filename_from_str(outfiletmp);
    else
        outfilename = filename_from_str(outfile ? outfile : "");

    switch (outtype) {
        bool ret;
        int real_outtype;

      case PRIVATE:
        random_ref(); /* we'll need a few random bytes in the save file */
        if (sshver == 1) {
            assert(ssh1key);
            ret = rsa1_save_f(outfilename, ssh1key, new_passphrase);
            if (!ret) {
                fprintf(stderr, "puttygen: unable to save SSH-1 private key\n");
                RETURN(1);
            }
        } else {
            assert(ssh2key);
            ret = ppk_save_f(outfilename, ssh2key, new_passphrase);
            if (!ret) {
                fprintf(stderr, "puttygen: unable to save SSH-2 private key\n");
                RETURN(1);
            }
        }
        if (outfiletmp) {
            if (!move(outfiletmp, outfile))
                RETURN(1);              /* rename failed */
        }
        break;

      case PUBLIC:
      case PUBLICO: {
        FILE *fp;

        if (outfile) {
          fp = f_open(outfilename, "w", false);
          if (!fp) {
            fprintf(stderr, "unable to open output file\n");
            exit(1);
          }
        } else {
          fp = stdout;
        }

        if (sshver == 1) {
          ssh1_write_pubkey(fp, ssh1key);
        } else {
          if (!ssh2blob) {
            assert(ssh2key);
            ssh2blob = strbuf_new();
            ssh_key_public_blob(ssh2key->key, BinarySink_UPCAST(ssh2blob));
          }

          ssh2_write_pubkey(fp, ssh2key ? ssh2key->comment : origcomment,
                            ssh2blob->s, ssh2blob->len,
                            (outtype == PUBLIC ?
                             SSH_KEYTYPE_SSH2_PUBLIC_RFC4716 :
                             SSH_KEYTYPE_SSH2_PUBLIC_OPENSSH));
        }

        if (outfile)
            fclose(fp);

        break;
      }

      case FP: {
        FILE *fp;
        char *fingerprint;

        if (sshver == 1) {
          assert(ssh1key);
          fingerprint = rsa_ssh1_fingerprint(ssh1key);
        } else {
          if (ssh2key) {
            fingerprint = ssh2_fingerprint(ssh2key->key);
          } else {
            assert(ssh2blob);
            fingerprint = ssh2_fingerprint_blob(
                ptrlen_from_strbuf(ssh2blob));
          }
        }

        if (outfile) {
          fp = f_open(outfilename, "w", false);
          if (!fp) {
            fprintf(stderr, "unable to open output file\n");
            exit(1);
          }