- andreas@cvs.openbsd.org 2009/06/27 09:35:06

[openssh-git.git] / key.c

/* $OpenBSD: key.c,v 1.80 2008/10/10 05:00:12 stevesk Exp $ */
/*
 * read_bignum():
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *
 * As far as I am concerned, the code I have written for this software
 * can be used freely for any purpose.  Any derived versions of this
 * software must be clearly marked as such, and if the derived work is
 * incompatible with the protocol description in the RFC file, it must be
 * called by a name other than "ssh" or "Secure Shell".
 *
 *
 * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
 * Copyright (c) 2008 Alexander von Gernler.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "includes.h"

#include <sys/param.h>
#include <sys/types.h>

#include <openssl/evp.h>
#include <openbsd-compat/openssl-compat.h>

#include <stdarg.h>
#include <stdio.h>
#include <string.h>

#include "xmalloc.h"
#include "key.h"
#include "rsa.h"
#include "uuencode.h"
#include "buffer.h"
#include "log.h"

Key *
key_new(int type)
{
        Key *k;
        RSA *rsa;
        DSA *dsa;
        k = xcalloc(1, sizeof(*k));
        k->type = type;
        k->dsa = NULL;
        k->rsa = NULL;
        switch (k->type) {
        case KEY_RSA1:
        case KEY_RSA:
                if ((rsa = RSA_new()) == NULL)
                        fatal("key_new: RSA_new failed");
                if ((rsa->n = BN_new()) == NULL)
                        fatal("key_new: BN_new failed");
                if ((rsa->e = BN_new()) == NULL)
                        fatal("key_new: BN_new failed");
                k->rsa = rsa;
                break;
        case KEY_DSA:
                if ((dsa = DSA_new()) == NULL)
                        fatal("key_new: DSA_new failed");
                if ((dsa->p = BN_new()) == NULL)
                        fatal("key_new: BN_new failed");
                if ((dsa->q = BN_new()) == NULL)
                        fatal("key_new: BN_new failed");
                if ((dsa->g = BN_new()) == NULL)
                        fatal("key_new: BN_new failed");
                if ((dsa->pub_key = BN_new()) == NULL)
                        fatal("key_new: BN_new failed");
                k->dsa = dsa;
                break;
        case KEY_UNSPEC:
                break;
        default:
                fatal("key_new: bad key type %d", k->type);
                break;
        }
        return k;
}

Key *
key_new_private(int type)
{
        Key *k = key_new(type);
        switch (k->type) {
        case KEY_RSA1:
        case KEY_RSA:
                if ((k->rsa->d = BN_new()) == NULL)
                        fatal("key_new_private: BN_new failed");
                if ((k->rsa->iqmp = BN_new()) == NULL)
                        fatal("key_new_private: BN_new failed");
                if ((k->rsa->q = BN_new()) == NULL)
                        fatal("key_new_private: BN_new failed");
                if ((k->rsa->p = BN_new()) == NULL)
                        fatal("key_new_private: BN_new failed");
                if ((k->rsa->dmq1 = BN_new()) == NULL)
                        fatal("key_new_private: BN_new failed");
                if ((k->rsa->dmp1 = BN_new()) == NULL)
                        fatal("key_new_private: BN_new failed");
                break;
        case KEY_DSA:
                if ((k->dsa->priv_key = BN_new()) == NULL)
                        fatal("key_new_private: BN_new failed");
                break;
        case KEY_UNSPEC:
                break;
        default:
                break;
        }
        return k;
}

void
key_free(Key *k)
{
        if (k == NULL)
                fatal("key_free: key is NULL");
        switch (k->type) {
        case KEY_RSA1:
        case KEY_RSA:
                if (k->rsa != NULL)
                        RSA_free(k->rsa);
                k->rsa = NULL;
                break;
        case KEY_DSA:
                if (k->dsa != NULL)
                        DSA_free(k->dsa);
                k->dsa = NULL;
                break;
        case KEY_UNSPEC:
                break;
        default:
                fatal("key_free: bad key type %d", k->type);
                break;
        }
        xfree(k);
}

int
key_equal(const Key *a, const Key *b)
{
        if (a == NULL || b == NULL || a->type != b->type)
                return 0;
        switch (a->type) {
        case KEY_RSA1:
        case KEY_RSA:
                return a->rsa != NULL && b->rsa != NULL &&
                    BN_cmp(a->rsa->e, b->rsa->e) == 0 &&
                    BN_cmp(a->rsa->n, b->rsa->n) == 0;
        case KEY_DSA:
                return a->dsa != NULL && b->dsa != NULL &&
                    BN_cmp(a->dsa->p, b->dsa->p) == 0 &&
                    BN_cmp(a->dsa->q, b->dsa->q) == 0 &&
                    BN_cmp(a->dsa->g, b->dsa->g) == 0 &&
                    BN_cmp(a->dsa->pub_key, b->dsa->pub_key) == 0;
        default:
                fatal("key_equal: bad key type %d", a->type);
        }
        /* NOTREACHED */
}

u_char*
key_fingerprint_raw(const Key *k, enum fp_type dgst_type,
    u_int *dgst_raw_length)
{
        const EVP_MD *md = NULL;
        EVP_MD_CTX ctx;
        u_char *blob = NULL;
        u_char *retval = NULL;
        u_int len = 0;
        int nlen, elen;

        *dgst_raw_length = 0;

        switch (dgst_type) {
        case SSH_FP_MD5:
                md = EVP_md5();
                break;
        case SSH_FP_SHA1:
                md = EVP_sha1();
                break;
        default:
                fatal("key_fingerprint_raw: bad digest type %d",
                    dgst_type);
        }
        switch (k->type) {
        case KEY_RSA1:
                nlen = BN_num_bytes(k->rsa->n);
                elen = BN_num_bytes(k->rsa->e);
                len = nlen + elen;
                blob = xmalloc(len);
                BN_bn2bin(k->rsa->n, blob);
                BN_bn2bin(k->rsa->e, blob + nlen);
                break;
        case KEY_DSA:
        case KEY_RSA:
                key_to_blob(k, &blob, &len);
                break;
        case KEY_UNSPEC:
                return retval;
        default:
                fatal("key_fingerprint_raw: bad key type %d", k->type);
                break;
        }
        if (blob != NULL) {
                retval = xmalloc(EVP_MAX_MD_SIZE);
                EVP_DigestInit(&ctx, md);
                EVP_DigestUpdate(&ctx, blob, len);
                EVP_DigestFinal(&ctx, retval, dgst_raw_length);
                memset(blob, 0, len);
                xfree(blob);
        } else {
                fatal("key_fingerprint_raw: blob is null");
        }
        return retval;
}

static char *
key_fingerprint_hex(u_char *dgst_raw, u_int dgst_raw_len)
{
        char *retval;
        u_int i;

        retval = xcalloc(1, dgst_raw_len * 3 + 1);
        for (i = 0; i < dgst_raw_len; i++) {
                char hex[4];
                snprintf(hex, sizeof(hex), "%02x:", dgst_raw[i]);
                strlcat(retval, hex, dgst_raw_len * 3 + 1);
        }

        /* Remove the trailing ':' character */
        retval[(dgst_raw_len * 3) - 1] = '\0';
        return retval;
}

static char *
key_fingerprint_bubblebabble(u_char *dgst_raw, u_int dgst_raw_len)
{
        char vowels[] = { 'a', 'e', 'i', 'o', 'u', 'y' };
        char consonants[] = { 'b', 'c', 'd', 'f', 'g', 'h', 'k', 'l', 'm',
            'n', 'p', 'r', 's', 't', 'v', 'z', 'x' };
        u_int i, j = 0, rounds, seed = 1;
        char *retval;

        rounds = (dgst_raw_len / 2) + 1;
        retval = xcalloc((rounds * 6), sizeof(char));
        retval[j++] = 'x';
        for (i = 0; i < rounds; i++) {
                u_int idx0, idx1, idx2, idx3, idx4;
                if ((i + 1 < rounds) || (dgst_raw_len % 2 != 0)) {
                        idx0 = (((((u_int)(dgst_raw[2 * i])) >> 6) & 3) +
                            seed) % 6;
                        idx1 = (((u_int)(dgst_raw[2 * i])) >> 2) & 15;
                        idx2 = ((((u_int)(dgst_raw[2 * i])) & 3) +
                            (seed / 6)) % 6;
                        retval[j++] = vowels[idx0];
                        retval[j++] = consonants[idx1];
                        retval[j++] = vowels[idx2];
                        if ((i + 1) < rounds) {
                                idx3 = (((u_int)(dgst_raw[(2 * i) + 1])) >> 4) & 15;
                                idx4 = (((u_int)(dgst_raw[(2 * i) + 1]))) & 15;
                                retval[j++] = consonants[idx3];
                                retval[j++] = '-';
                                retval[j++] = consonants[idx4];
                                seed = ((seed * 5) +
                                    ((((u_int)(dgst_raw[2 * i])) * 7) +
                                    ((u_int)(dgst_raw[(2 * i) + 1])))) % 36;
                        }
                } else {
                        idx0 = seed % 6;
                        idx1 = 16;
                        idx2 = seed / 6;
                        retval[j++] = vowels[idx0];
                        retval[j++] = consonants[idx1];
                        retval[j++] = vowels[idx2];
                }
        }
        retval[j++] = 'x';
        retval[j++] = '\0';
        return retval;
}

/*
 * Draw an ASCII-Art representing the fingerprint so human brain can
 * profit from its built-in pattern recognition ability.
 * This technique is called "random art" and can be found in some
 * scientific publications like this original paper:
 *
 * "Hash Visualization: a New Technique to improve Real-World Security",
 * Perrig A. and Song D., 1999, International Workshop on Cryptographic
 * Techniques and E-Commerce (CrypTEC '99)
 * sparrow.ece.cmu.edu/~adrian/projects/validation/validation.pdf
 *
 * The subject came up in a talk by Dan Kaminsky, too.
 *
 * If you see the picture is different, the key is different.
 * If the picture looks the same, you still know nothing.
 *
 * The algorithm used here is a worm crawling over a discrete plane,
 * leaving a trace (augmenting the field) everywhere it goes.
 * Movement is taken from dgst_raw 2bit-wise.  Bumping into walls
 * makes the respective movement vector be ignored for this turn.
 * Graphs are not unambiguous, because circles in graphs can be
 * walked in either direction.
 */

/*
 * Field sizes for the random art.  Have to be odd, so the starting point
 * can be in the exact middle of the picture, and FLDBASE should be >=8 .
 * Else pictures would be too dense, and drawing the frame would
 * fail, too, because the key type would not fit in anymore.
 */
#define FLDBASE         8
#define FLDSIZE_Y       (FLDBASE + 1)
#define FLDSIZE_X       (FLDBASE * 2 + 1)
static char *
key_fingerprint_randomart(u_char *dgst_raw, u_int dgst_raw_len, const Key *k)
{
        /*
         * Chars to be used after each other every time the worm
         * intersects with itself.  Matter of taste.
         */
        char    *augmentation_string = " .o+=*BOX@%&#/^SE";
        char    *retval, *p;
        u_char   field[FLDSIZE_X][FLDSIZE_Y];
        u_int    i, b;
        int      x, y;
        size_t   len = strlen(augmentation_string) - 1;

        retval = xcalloc(1, (FLDSIZE_X + 3) * (FLDSIZE_Y + 2));

        /* initialize field */
        memset(field, 0, FLDSIZE_X * FLDSIZE_Y * sizeof(char));
        x = FLDSIZE_X / 2;
        y = FLDSIZE_Y / 2;

        /* process raw key */
        for (i = 0; i < dgst_raw_len; i++) {
                int input;
                /* each byte conveys four 2-bit move commands */
                input = dgst_raw[i];
                for (b = 0; b < 4; b++) {
                        /* evaluate 2 bit, rest is shifted later */
                        x += (input & 0x1) ? 1 : -1;
                        y += (input & 0x2) ? 1 : -1;

                        /* assure we are still in bounds */
                        x = MAX(x, 0);
                        y = MAX(y, 0);
                        x = MIN(x, FLDSIZE_X - 1);
                        y = MIN(y, FLDSIZE_Y - 1);

                        /* augment the field */
                        if (field[x][y] < len - 2)
                                field[x][y]++;
                        input = input >> 2;
                }
        }

        /* mark starting point and end point*/
        field[FLDSIZE_X / 2][FLDSIZE_Y / 2] = len - 1;
        field[x][y] = len;

        /* fill in retval */
        snprintf(retval, FLDSIZE_X, "+--[%4s %4u]", key_type(k), key_size(k));
        p = strchr(retval, '\0');

        /* output upper border */
        for (i = p - retval - 1; i < FLDSIZE_X; i++)
                *p++ = '-';
        *p++ = '+';
        *p++ = '\n';

        /* output content */
        for (y = 0; y < FLDSIZE_Y; y++) {
                *p++ = '|';
                for (x = 0; x < FLDSIZE_X; x++)
                        *p++ = augmentation_string[MIN(field[x][y], len)];
                *p++ = '|';
                *p++ = '\n';
        }

        /* output lower border */
        *p++ = '+';
        for (i = 0; i < FLDSIZE_X; i++)
                *p++ = '-';
        *p++ = '+';

        return retval;
}

char *
key_fingerprint(const Key *k, enum fp_type dgst_type, enum fp_rep dgst_rep)
{
        char *retval = NULL;
        u_char *dgst_raw;
        u_int dgst_raw_len;

        dgst_raw = key_fingerprint_raw(k, dgst_type, &dgst_raw_len);
        if (!dgst_raw)
                fatal("key_fingerprint: null from key_fingerprint_raw()");
        switch (dgst_rep) {
        case SSH_FP_HEX:
                retval = key_fingerprint_hex(dgst_raw, dgst_raw_len);
                break;
        case SSH_FP_BUBBLEBABBLE:
                retval = key_fingerprint_bubblebabble(dgst_raw, dgst_raw_len);
                break;
        case SSH_FP_RANDOMART:
                retval = key_fingerprint_randomart(dgst_raw, dgst_raw_len, k);
                break;
        default:
                fatal("key_fingerprint: bad digest representation %d",
                    dgst_rep);
                break;
        }
        memset(dgst_raw, 0, dgst_raw_len);
        xfree(dgst_raw);
        return retval;
}

/*
 * Reads a multiple-precision integer in decimal from the buffer, and advances
 * the pointer.  The integer must already be initialized.  This function is
 * permitted to modify the buffer.  This leaves *cpp to point just beyond the
 * last processed (and maybe modified) character.  Note that this may modify
 * the buffer containing the number.
 */
static int
read_bignum(char **cpp, BIGNUM * value)
{
        char *cp = *cpp;
        int old;

        /* Skip any leading whitespace. */
        for (; *cp == ' ' || *cp == '\t'; cp++)
                ;

        /* Check that it begins with a decimal digit. */
        if (*cp < '0' || *cp > '9')
                return 0;

        /* Save starting position. */
        *cpp = cp;

        /* Move forward until all decimal digits skipped. */
        for (; *cp >= '0' && *cp <= '9'; cp++)
                ;

        /* Save the old terminating character, and replace it by \0. */
        old = *cp;
        *cp = 0;

        /* Parse the number. */
        if (BN_dec2bn(&value, *cpp) == 0)
                return 0;

        /* Restore old terminating character. */
        *cp = old;

        /* Move beyond the number and return success. */
        *cpp = cp;
        return 1;
}

static int
write_bignum(FILE *f, BIGNUM *num)
{
        char *buf = BN_bn2dec(num);
        if (buf == NULL) {
                error("write_bignum: BN_bn2dec() failed");
                return 0;
        }
        fprintf(f, " %s", buf);
        OPENSSL_free(buf);
        return 1;
}

/* returns 1 ok, -1 error */
int
key_read(Key *ret, char **cpp)
{
        Key *k;
        int success = -1;
        char *cp, *space;
        int len, n, type;
        u_int bits;
        u_char *blob;

        cp = *cpp;

        switch (ret->type) {
        case KEY_RSA1:
                /* Get number of bits. */
                if (*cp < '0' || *cp > '9')
                        return -1;      /* Bad bit count... */
                for (bits = 0; *cp >= '0' && *cp <= '9'; cp++)
                        bits = 10 * bits + *cp - '0';
                if (bits == 0)
                        return -1;
                *cpp = cp;
                /* Get public exponent, public modulus. */
                if (!read_bignum(cpp, ret->rsa->e))
                        return -1;
                if (!read_bignum(cpp, ret->rsa->n))
                        return -1;
                success = 1;
                break;
        case KEY_UNSPEC:
        case KEY_RSA:
        case KEY_DSA:
                space = strchr(cp, ' ');
                if (space == NULL) {
                        debug3("key_read: missing whitespace");
                        return -1;
                }
                *space = '\0';
                type = key_type_from_name(cp);
                *space = ' ';
                if (type == KEY_UNSPEC) {
                        debug3("key_read: missing keytype");
                        return -1;
                }
                cp = space+1;
                if (*cp == '\0') {
                        debug3("key_read: short string");
                        return -1;
                }
                if (ret->type == KEY_UNSPEC) {
                        ret->type = type;
                } else if (ret->type != type) {
                        /* is a key, but different type */
                        debug3("key_read: type mismatch");
                        return -1;
                }
                len = 2*strlen(cp);
                blob = xmalloc(len);
                n = uudecode(cp, blob, len);
                if (n < 0) {
                        error("key_read: uudecode %s failed", cp);
                        xfree(blob);
                        return -1;
                }
                k = key_from_blob(blob, (u_int)n);
                xfree(blob);
                if (k == NULL) {
                        error("key_read: key_from_blob %s failed", cp);
                        return -1;
                }
                if (k->type != type) {
                        error("key_read: type mismatch: encoding error");
                        key_free(k);
                        return -1;
                }
/*XXXX*/
                if (ret->type == KEY_RSA) {
                        if (ret->rsa != NULL)
                                RSA_free(ret->rsa);
                        ret->rsa = k->rsa;
                        k->rsa = NULL;
                        success = 1;
#ifdef DEBUG_PK
                        RSA_print_fp(stderr, ret->rsa, 8);
#endif
                } else {
                        if (ret->dsa != NULL)
                                DSA_free(ret->dsa);
                        ret->dsa = k->dsa;
                        k->dsa = NULL;
                        success = 1;
#ifdef DEBUG_PK
                        DSA_print_fp(stderr, ret->dsa, 8);
#endif
                }
/*XXXX*/
                key_free(k);
                if (success != 1)
                        break;
                /* advance cp: skip whitespace and data */
                while (*cp == ' ' || *cp == '\t')
                        cp++;
                while (*cp != '\0' && *cp != ' ' && *cp != '\t')
                        cp++;
                *cpp = cp;
                break;
        default:
                fatal("key_read: bad key type: %d", ret->type);
                break;
        }
        return success;
}

int
key_write(const Key *key, FILE *f)
{
        int n, success = 0;
        u_int len, bits = 0;
        u_char *blob;
        char *uu;

        if (key->type == KEY_RSA1 && key->rsa != NULL) {
                /* size of modulus 'n' */
                bits = BN_num_bits(key->rsa->n);
                fprintf(f, "%u", bits);
                if (write_bignum(f, key->rsa->e) &&
                    write_bignum(f, key->rsa->n)) {
                        success = 1;
                } else {
                        error("key_write: failed for RSA key");
                }
        } else if ((key->type == KEY_DSA && key->dsa != NULL) ||
            (key->type == KEY_RSA && key->rsa != NULL)) {
                key_to_blob(key, &blob, &len);
                uu = xmalloc(2*len);
                n = uuencode(blob, len, uu, 2*len);
                if (n > 0) {
                        fprintf(f, "%s %s", key_ssh_name(key), uu);
                        success = 1;
                }
                xfree(blob);
                xfree(uu);
        }
        return success;
}

const char *
key_type(const Key *k)
{
        switch (k->type) {
        case KEY_RSA1:
                return "RSA1";
        case KEY_RSA:
                return "RSA";
        case KEY_DSA:
                return "DSA";
        }
        return "unknown";
}

const char *
key_ssh_name(const Key *k)
{
        switch (k->type) {
        case KEY_RSA:
                return "ssh-rsa";
        case KEY_DSA:
                return "ssh-dss";
        }
        return "ssh-unknown";
}

u_int
key_size(const Key *k)
{
        switch (k->type) {
        case KEY_RSA1:
        case KEY_RSA:
                return BN_num_bits(k->rsa->n);
        case KEY_DSA:
                return BN_num_bits(k->dsa->p);
        }
        return 0;
}

static RSA *
rsa_generate_private_key(u_int bits)
{
        RSA *private;

        private = RSA_generate_key(bits, 35, NULL, NULL);
        if (private == NULL)
                fatal("rsa_generate_private_key: key generation failed.");
        return private;
}

static DSA*
dsa_generate_private_key(u_int bits)
{
        DSA *private = DSA_generate_parameters(bits, NULL, 0, NULL, NULL, NULL, NULL);

        if (private == NULL)
                fatal("dsa_generate_private_key: DSA_generate_parameters failed");
        if (!DSA_generate_key(private))
                fatal("dsa_generate_private_key: DSA_generate_key failed.");
        if (private == NULL)
                fatal("dsa_generate_private_key: NULL.");
        return private;
}

Key *
key_generate(int type, u_int bits)
{
        Key *k = key_new(KEY_UNSPEC);
        switch (type) {
        case KEY_DSA:
                k->dsa = dsa_generate_private_key(bits);
                break;
        case KEY_RSA:
        case KEY_RSA1:
                k->rsa = rsa_generate_private_key(bits);
                break;
        default:
                fatal("key_generate: unknown type %d", type);
        }
        k->type = type;
        return k;
}

Key *
key_from_private(const Key *k)
{
        Key *n = NULL;
        switch (k->type) {
        case KEY_DSA:
                n = key_new(k->type);
                if ((BN_copy(n->dsa->p, k->dsa->p) == NULL) ||
                    (BN_copy(n->dsa->q, k->dsa->q) == NULL) ||
                    (BN_copy(n->dsa->g, k->dsa->g) == NULL) ||
                    (BN_copy(n->dsa->pub_key, k->dsa->pub_key) == NULL))
                        fatal("key_from_private: BN_copy failed");
                break;
        case KEY_RSA:
        case KEY_RSA1:
                n = key_new(k->type);
                if ((BN_copy(n->rsa->n, k->rsa->n) == NULL) ||
                    (BN_copy(n->rsa->e, k->rsa->e) == NULL))
                        fatal("key_from_private: BN_copy failed");
                break;
        default:
                fatal("key_from_private: unknown type %d", k->type);
                break;
        }
        return n;
}

int
key_type_from_name(char *name)
{
        if (strcmp(name, "rsa1") == 0) {
                return KEY_RSA1;
        } else if (strcmp(name, "rsa") == 0) {
                return KEY_RSA;
        } else if (strcmp(name, "dsa") == 0) {
                return KEY_DSA;
        } else if (strcmp(name, "ssh-rsa") == 0) {
                return KEY_RSA;
        } else if (strcmp(name, "ssh-dss") == 0) {
                return KEY_DSA;
        }
        debug2("key_type_from_name: unknown key type '%s'", name);
        return KEY_UNSPEC;
}

int
key_names_valid2(const char *names)
{
        char *s, *cp, *p;

        if (names == NULL || strcmp(names, "") == 0)
                return 0;
        s = cp = xstrdup(names);
        for ((p = strsep(&cp, ",")); p && *p != '\0';
            (p = strsep(&cp, ","))) {
                switch (key_type_from_name(p)) {
                case KEY_RSA1:
                case KEY_UNSPEC:
                        xfree(s);
                        return 0;
                }
        }
        debug3("key names ok: [%s]", names);
        xfree(s);
        return 1;
}

Key *
key_from_blob(const u_char *blob, u_int blen)
{
        Buffer b;
        int rlen, type;
        char *ktype = NULL;
        Key *key = NULL;

#ifdef DEBUG_PK
        dump_base64(stderr, blob, blen);
#endif
        buffer_init(&b);
        buffer_append(&b, blob, blen);
        if ((ktype = buffer_get_string_ret(&b, NULL)) == NULL) {
                error("key_from_blob: can't read key type");
                goto out;
        }

        type = key_type_from_name(ktype);

        switch (type) {
        case KEY_RSA:
                key = key_new(type);
                if (buffer_get_bignum2_ret(&b, key->rsa->e) == -1 ||
                    buffer_get_bignum2_ret(&b, key->rsa->n) == -1) {
                        error("key_from_blob: can't read rsa key");
                        key_free(key);
                        key = NULL;
                        goto out;
                }
#ifdef DEBUG_PK
                RSA_print_fp(stderr, key->rsa, 8);
#endif
                break;
        case KEY_DSA:
                key = key_new(type);
                if (buffer_get_bignum2_ret(&b, key->dsa->p) == -1 ||
                    buffer_get_bignum2_ret(&b, key->dsa->q) == -1 ||
                    buffer_get_bignum2_ret(&b, key->dsa->g) == -1 ||
                    buffer_get_bignum2_ret(&b, key->dsa->pub_key) == -1) {
                        error("key_from_blob: can't read dsa key");
                        key_free(key);
                        key = NULL;
                        goto out;
                }
#ifdef DEBUG_PK
                DSA_print_fp(stderr, key->dsa, 8);
#endif
                break;
        case KEY_UNSPEC:
                key = key_new(type);
                break;
        default:
                error("key_from_blob: cannot handle type %s", ktype);
                goto out;
        }
        rlen = buffer_len(&b);
        if (key != NULL && rlen != 0)
                error("key_from_blob: remaining bytes in key blob %d", rlen);
 out:
        if (ktype != NULL)
                xfree(ktype);
        buffer_free(&b);
        return key;
}

int
key_to_blob(const Key *key, u_char **blobp, u_int *lenp)
{
        Buffer b;
        int len;

        if (key == NULL) {
                error("key_to_blob: key == NULL");
                return 0;
        }
        buffer_init(&b);
        switch (key->type) {
        case KEY_DSA:
                buffer_put_cstring(&b, key_ssh_name(key));
                buffer_put_bignum2(&b, key->dsa->p);
                buffer_put_bignum2(&b, key->dsa->q);
                buffer_put_bignum2(&b, key->dsa->g);
                buffer_put_bignum2(&b, key->dsa->pub_key);
                break;
        case KEY_RSA:
                buffer_put_cstring(&b, key_ssh_name(key));
                buffer_put_bignum2(&b, key->rsa->e);
                buffer_put_bignum2(&b, key->rsa->n);
                break;
        default:
                error("key_to_blob: unsupported key type %d", key->type);
                buffer_free(&b);
                return 0;
        }
        len = buffer_len(&b);
        if (lenp != NULL)
                *lenp = len;
        if (blobp != NULL) {
                *blobp = xmalloc(len);
                memcpy(*blobp, buffer_ptr(&b), len);
        }
        memset(buffer_ptr(&b), 0, len);
        buffer_free(&b);
        return len;
}

int
key_sign(
    const Key *key,
    u_char **sigp, u_int *lenp,
    const u_char *data, u_int datalen)
{
        switch (key->type) {
        case KEY_DSA:
                return ssh_dss_sign(key, sigp, lenp, data, datalen);
        case KEY_RSA:
                return ssh_rsa_sign(key, sigp, lenp, data, datalen);
        default:
                error("key_sign: invalid key type %d", key->type);
                return -1;
        }
}

/*
 * key_verify returns 1 for a correct signature, 0 for an incorrect signature
 * and -1 on error.
 */
int
key_verify(
    const Key *key,
    const u_char *signature, u_int signaturelen,
    const u_char *data, u_int datalen)
{
        if (signaturelen == 0)
                return -1;

        switch (key->type) {
        case KEY_DSA:
                return ssh_dss_verify(key, signature, signaturelen, data, datalen);
        case KEY_RSA:
                return ssh_rsa_verify(key, signature, signaturelen, data, datalen);
        default:
                error("key_verify: invalid key type %d", key->type);
                return -1;
        }
}

/* Converts a private to a public key */
Key *
key_demote(const Key *k)
{
        Key *pk;

        pk = xcalloc(1, sizeof(*pk));
        pk->type = k->type;
        pk->flags = k->flags;
        pk->dsa = NULL;
        pk->rsa = NULL;

        switch (k->type) {
        case KEY_RSA1:
        case KEY_RSA:
                if ((pk->rsa = RSA_new()) == NULL)
                        fatal("key_demote: RSA_new failed");
                if ((pk->rsa->e = BN_dup(k->rsa->e)) == NULL)
                        fatal("key_demote: BN_dup failed");
                if ((pk->rsa->n = BN_dup(k->rsa->n)) == NULL)
                        fatal("key_demote: BN_dup failed");
                break;
        case KEY_DSA:
                if ((pk->dsa = DSA_new()) == NULL)
                        fatal("key_demote: DSA_new failed");
                if ((pk->dsa->p = BN_dup(k->dsa->p)) == NULL)
                        fatal("key_demote: BN_dup failed");
                if ((pk->dsa->q = BN_dup(k->dsa->q)) == NULL)
                        fatal("key_demote: BN_dup failed");
                if ((pk->dsa->g = BN_dup(k->dsa->g)) == NULL)
                        fatal("key_demote: BN_dup failed");
                if ((pk->dsa->pub_key = BN_dup(k->dsa->pub_key)) == NULL)
                        fatal("key_demote: BN_dup failed");
                break;
        default:
                fatal("key_free: bad key type %d", k->type);
                break;
        }

        return (pk);
}