X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/22138a361cf0a32252034ae90ff2e91dec1f01c0..81fa3f37b8b594d312a65c0c5d59687d458d612b:/key.c

diff --git a/key.c b/key.c
index e01f2cc4..93b2d41f 100644
--- a/key.c
+++ b/key.c
@@ -1,3 +1,4 @@
+/* $OpenBSD: key.c,v 1.68 2006/11/06 21:25:28 markus Exp $ */
 /*
  * read_bignum():
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -9,7 +10,7 @@
  * called by a name other than "ssh" or "Secure Shell".
  *
  *
- * Copyright (c) 2000 Markus Friedl.  All rights reserved.
+ * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -31,19 +32,22 @@
  * (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"
-RCSID("$OpenBSD: key.c,v 1.22 2001/03/12 22:02:01 markus Exp $");
+
+#include <sys/types.h>
 
 #include <openssl/evp.h>
 
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+
 #include "xmalloc.h"
 #include "key.h"
 #include "rsa.h"
-#include "ssh-dss.h"
-#include "ssh-rsa.h"
 #include "uuencode.h"
 #include "buffer.h"
-#include "bufaux.h"
 #include "log.h"
 
 Key *
@@ -52,24 +56,32 @@ key_new(int type)
 	Key *k;
 	RSA *rsa;
 	DSA *dsa;
-	k = xmalloc(sizeof(*k));
+	k = xcalloc(1, sizeof(*k));
 	k->type = type;
 	k->dsa = NULL;
 	k->rsa = NULL;
 	switch (k->type) {
 	case KEY_RSA1:
 	case KEY_RSA:
-		rsa = RSA_new();
-		rsa->n = BN_new();
-		rsa->e = BN_new();
+		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:
-		dsa = DSA_new();
-		dsa->p = BN_new();
-		dsa->q = BN_new();
-		dsa->g = BN_new();
-		dsa->pub_key = BN_new();
+		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:
@@ -80,6 +92,7 @@ key_new(int type)
 	}
 	return k;
 }
+
 Key *
 key_new_private(int type)
 {
@@ -87,15 +100,22 @@ key_new_private(int type)
 	switch (k->type) {
 	case KEY_RSA1:
 	case KEY_RSA:
-		k->rsa->d = BN_new();
-		k->rsa->iqmp = BN_new();
-		k->rsa->q = BN_new();
-		k->rsa->p = BN_new();
-		k->rsa->dmq1 = BN_new();
-		k->rsa->dmp1 = BN_new();
+		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:
-		k->dsa->priv_key = BN_new();
+		if ((k->dsa->priv_key = BN_new()) == NULL)
+			fatal("key_new_private: BN_new failed");
 		break;
 	case KEY_UNSPEC:
 		break;
@@ -104,9 +124,12 @@ key_new_private(int type)
 	}
 	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:
@@ -127,8 +150,9 @@ key_free(Key *k)
 	}
 	xfree(k);
 }
+
 int
-key_equal(Key *a, Key *b)
+key_equal(const Key *a, const Key *b)
 {
 	if (a == NULL || b == NULL || a->type != b->type)
 		return 0;
@@ -138,14 +162,12 @@ key_equal(Key *a, Key *b)
 		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;
-		break;
 	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;
-		break;
 	default:
 		fatal("key_equal: bad key type %d", a->type);
 		break;
@@ -154,13 +176,14 @@ key_equal(Key *a, Key *b)
 }
 
 u_char*
-key_fingerprint_raw(Key *k, enum fp_type dgst_type, size_t *dgst_raw_length)
+key_fingerprint_raw(const Key *k, enum fp_type dgst_type,
+    u_int *dgst_raw_length)
 {
-	EVP_MD *md = NULL;
+	const EVP_MD *md = NULL;
 	EVP_MD_CTX ctx;
 	u_char *blob = NULL;
 	u_char *retval = NULL;
-	int len = 0;
+	u_int len = 0;
 	int nlen, elen;
 
 	*dgst_raw_length = 0;
@@ -191,7 +214,6 @@ key_fingerprint_raw(Key *k, enum fp_type dgst_type, size_t *dgst_raw_length)
 		break;
 	case KEY_UNSPEC:
 		return retval;
-		break;
 	default:
 		fatal("key_fingerprint_raw: bad key type %d", k->type);
 		break;
@@ -200,8 +222,7 @@ key_fingerprint_raw(Key *k, enum fp_type dgst_type, size_t *dgst_raw_length)
 		retval = xmalloc(EVP_MAX_MD_SIZE);
 		EVP_DigestInit(&ctx, md);
 		EVP_DigestUpdate(&ctx, blob, len);
-		EVP_DigestFinal(&ctx, retval, NULL);
-		*dgst_raw_length = md->md_size;
+		EVP_DigestFinal(&ctx, retval, dgst_raw_length);
 		memset(blob, 0, len);
 		xfree(blob);
 	} else {
@@ -210,25 +231,26 @@ key_fingerprint_raw(Key *k, enum fp_type dgst_type, size_t *dgst_raw_length)
 	return retval;
 }
 
-char*
-key_fingerprint_hex(u_char* dgst_raw, size_t dgst_raw_len) 
+static char *
+key_fingerprint_hex(u_char *dgst_raw, u_int dgst_raw_len)
 {
 	char *retval;
-	int i;
+	u_int i;
 
-	retval = xmalloc(dgst_raw_len * 3);
-	retval[0] = '\0';
-	for(i = 0; i < dgst_raw_len; 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);
+		strlcat(retval, hex, dgst_raw_len * 3 + 1);
 	}
+
+	/* Remove the trailing ':' character */
 	retval[(dgst_raw_len * 3) - 1] = '\0';
 	return retval;
 }
 
-char*
-key_fingerprint_bubblebabble(u_char* dgst_raw, size_t dgst_raw_len) 
+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',
@@ -237,7 +259,7 @@ key_fingerprint_bubblebabble(u_char* dgst_raw, size_t dgst_raw_len)
 	char *retval;
 
 	rounds = (dgst_raw_len / 2) + 1;
-	retval = xmalloc(sizeof(char) * (rounds*6));
+	retval = xcalloc((rounds * 6), sizeof(char));
 	retval[j++] = 'x';
 	for (i = 0; i < rounds; i++) {
 		u_int idx0, idx1, idx2, idx3, idx4;
@@ -274,17 +296,17 @@ key_fingerprint_bubblebabble(u_char* dgst_raw, size_t dgst_raw_len)
 	return retval;
 }
 
-char*
-key_fingerprint(Key *k, enum fp_type dgst_type, enum fp_rep dgst_rep)
+char *
+key_fingerprint(const Key *k, enum fp_type dgst_type, enum fp_rep dgst_rep)
 {
-	char *retval = NULL; 
+	char *retval = NULL;
 	u_char *dgst_raw;
-	size_t dgst_raw_len; 
-	
+	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) {
+	switch (dgst_rep) {
 	case SSH_FP_HEX:
 		retval = key_fingerprint_hex(dgst_raw, dgst_raw_len);
 		break;
@@ -308,7 +330,7 @@ key_fingerprint(Key *k, enum fp_type dgst_type, enum fp_rep dgst_rep)
  * last processed (and maybe modified) character.  Note that this may modify
  * the buffer containing the number.
  */
-int
+static int
 read_bignum(char **cpp, BIGNUM * value)
 {
 	char *cp = *cpp;
@@ -344,7 +366,8 @@ read_bignum(char **cpp, BIGNUM * value)
 	*cpp = cp;
 	return 1;
 }
-int
+
+static int
 write_bignum(FILE *f, BIGNUM *num)
 {
 	char *buf = BN_bn2dec(num);
@@ -353,11 +376,11 @@ write_bignum(FILE *f, BIGNUM *num)
 		return 0;
 	}
 	fprintf(f, " %s", buf);
-	xfree(buf);
+	OPENSSL_free(buf);
 	return 1;
 }
 
-/* returns 1 ok, -1 error, 0 type mismatch */
+/* returns 1 ok, -1 error */
 int
 key_read(Key *ret, char **cpp)
 {
@@ -370,7 +393,7 @@ key_read(Key *ret, char **cpp)
 
 	cp = *cpp;
 
-	switch(ret->type) {
+	switch (ret->type) {
 	case KEY_RSA1:
 		/* Get number of bits. */
 		if (*cp < '0' || *cp > '9')
@@ -392,14 +415,14 @@ key_read(Key *ret, char **cpp)
 	case KEY_DSA:
 		space = strchr(cp, ' ');
 		if (space == NULL) {
-			debug3("key_read: no space");
+			debug3("key_read: missing whitespace");
 			return -1;
 		}
 		*space = '\0';
 		type = key_type_from_name(cp);
 		*space = ' ';
 		if (type == KEY_UNSPEC) {
-			debug3("key_read: no key found");
+			debug3("key_read: missing keytype");
 			return -1;
 		}
 		cp = space+1;
@@ -412,21 +435,22 @@ key_read(Key *ret, char **cpp)
 		} else if (ret->type != type) {
 			/* is a key, but different type */
 			debug3("key_read: type mismatch");
-			return 0;
+			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, n);
+		k = key_from_blob(blob, (u_int)n);
+		xfree(blob);
 		if (k == NULL) {
 			error("key_read: key_from_blob %s failed", cp);
 			return -1;
 		}
-		xfree(blob);
 		if (k->type != type) {
 			error("key_read: type mismatch: encoding error");
 			key_free(k);
@@ -453,9 +477,9 @@ key_read(Key *ret, char **cpp)
 #endif
 		}
 /*XXXX*/
+		key_free(k);
 		if (success != 1)
 			break;
-		key_free(k);
 		/* advance cp: skip whitespace and data */
 		while (*cp == ' ' || *cp == '\t')
 			cp++;
@@ -469,11 +493,14 @@ key_read(Key *ret, char **cpp)
 	}
 	return success;
 }
+
 int
-key_write(Key *key, FILE *f)
+key_write(const Key *key, FILE *f)
 {
-	int success = 0;
-	u_int bits = 0;
+	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' */
@@ -487,8 +514,6 @@ key_write(Key *key, FILE *f)
 		}
 	} else if ((key->type == KEY_DSA && key->dsa != NULL) ||
 	    (key->type == KEY_RSA && key->rsa != NULL)) {
-		int len, n;
-		u_char *blob, *uu;
 		key_to_blob(key, &blob, &len);
 		uu = xmalloc(2*len);
 		n = uuencode(blob, len, uu, 2*len);
@@ -501,63 +526,62 @@ key_write(Key *key, FILE *f)
 	}
 	return success;
 }
-char *
-key_type(Key *k)
+
+const char *
+key_type(const Key *k)
 {
 	switch (k->type) {
 	case KEY_RSA1:
 		return "RSA1";
-		break;
 	case KEY_RSA:
 		return "RSA";
-		break;
 	case KEY_DSA:
 		return "DSA";
-		break;
 	}
 	return "unknown";
 }
-char *
-key_ssh_name(Key *k)
+
+const char *
+key_ssh_name(const Key *k)
 {
 	switch (k->type) {
 	case KEY_RSA:
 		return "ssh-rsa";
-		break;
 	case KEY_DSA:
 		return "ssh-dss";
-		break;
 	}
 	return "ssh-unknown";
 }
+
 u_int
-key_size(Key *k){
+key_size(const Key *k)
+{
 	switch (k->type) {
 	case KEY_RSA1:
 	case KEY_RSA:
 		return BN_num_bits(k->rsa->n);
-		break;
 	case KEY_DSA:
 		return BN_num_bits(k->dsa->p);
-		break;
 	}
 	return 0;
 }
 
-RSA *
+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;
 }
 
-DSA*
+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))
@@ -587,22 +611,24 @@ key_generate(int type, u_int bits)
 }
 
 Key *
-key_from_private(Key *k)
+key_from_private(const Key *k)
 {
 	Key *n = NULL;
 	switch (k->type) {
 	case KEY_DSA:
 		n = key_new(k->type);
-		BN_copy(n->dsa->p, k->dsa->p);
-		BN_copy(n->dsa->q, k->dsa->q);
-		BN_copy(n->dsa->g, k->dsa->g);
-		BN_copy(n->dsa->pub_key, k->dsa->pub_key);
+		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);
-		BN_copy(n->rsa->n, k->rsa->n);
-		BN_copy(n->rsa->e, k->rsa->e);
+		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);
@@ -614,27 +640,49 @@ key_from_private(Key *k)
 int
 key_type_from_name(char *name)
 {
-	if (strcmp(name, "rsa1") == 0){
+	if (strcmp(name, "rsa1") == 0) {
 		return KEY_RSA1;
-	} else if (strcmp(name, "rsa") == 0){
+	} else if (strcmp(name, "rsa") == 0) {
 		return KEY_RSA;
-	} else if (strcmp(name, "dsa") == 0){
+	} else if (strcmp(name, "dsa") == 0) {
 		return KEY_DSA;
-	} else if (strcmp(name, "ssh-rsa") == 0){
+	} else if (strcmp(name, "ssh-rsa") == 0) {
 		return KEY_RSA;
-	} else if (strcmp(name, "ssh-dss") == 0){
+	} 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(char *blob, int blen)
+key_from_blob(const u_char *blob, u_int blen)
 {
 	Buffer b;
-	char *ktype;
 	int rlen, type;
+	char *ktype = NULL;
 	Key *key = NULL;
 
 #ifdef DEBUG_PK
@@ -642,24 +690,38 @@ key_from_blob(char *blob, int blen)
 #endif
 	buffer_init(&b);
 	buffer_append(&b, blob, blen);
-	ktype = buffer_get_string(&b, NULL);
+	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){
+	switch (type) {
 	case KEY_RSA:
 		key = key_new(type);
-		buffer_get_bignum2(&b, key->rsa->e);
-		buffer_get_bignum2(&b, key->rsa->n);
+		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);
-		buffer_get_bignum2(&b, key->dsa->p);
-		buffer_get_bignum2(&b, key->dsa->q);
-		buffer_get_bignum2(&b, key->dsa->g);
-		buffer_get_bignum2(&b, key->dsa->pub_key);
+		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
@@ -669,29 +731,30 @@ key_from_blob(char *blob, int blen)
 		break;
 	default:
 		error("key_from_blob: cannot handle type %s", ktype);
-		break;
+		goto out;
 	}
 	rlen = buffer_len(&b);
 	if (key != NULL && rlen != 0)
 		error("key_from_blob: remaining bytes in key blob %d", rlen);
-	xfree(ktype);
+ out:
+	if (ktype != NULL)
+		xfree(ktype);
 	buffer_free(&b);
 	return key;
 }
 
 int
-key_to_blob(Key *key, u_char **blobp, u_int *lenp)
+key_to_blob(const Key *key, u_char **blobp, u_int *lenp)
 {
 	Buffer b;
 	int len;
-	u_char *buf;
 
 	if (key == NULL) {
 		error("key_to_blob: key == NULL");
 		return 0;
 	}
 	buffer_init(&b);
-	switch(key->type){
+	switch (key->type) {
 	case KEY_DSA:
 		buffer_put_cstring(&b, key_ssh_name(key));
 		buffer_put_bignum2(&b, key->dsa->p);
@@ -705,57 +768,101 @@ key_to_blob(Key *key, u_char **blobp, u_int *lenp)
 		buffer_put_bignum2(&b, key->rsa->n);
 		break;
 	default:
-		error("key_to_blob: illegal key type %d", key->type);
-		break;
+		error("key_to_blob: unsupported key type %d", key->type);
+		buffer_free(&b);
+		return 0;
 	}
 	len = buffer_len(&b);
-	buf = xmalloc(len);
-	memcpy(buf, buffer_ptr(&b), len);
-	memset(buffer_ptr(&b), 0, len);
-	buffer_free(&b);
 	if (lenp != NULL)
 		*lenp = len;
-	if (blobp != NULL)
-		*blobp = buf;
+	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(
-    Key *key,
-    u_char **sigp, int *lenp,
-    u_char *data, int datalen)
+    const Key *key,
+    u_char **sigp, u_int *lenp,
+    const u_char *data, u_int datalen)
 {
-	switch(key->type){
+	switch (key->type) {
 	case KEY_DSA:
 		return ssh_dss_sign(key, sigp, lenp, data, datalen);
-		break;
 	case KEY_RSA:
 		return ssh_rsa_sign(key, sigp, lenp, data, datalen);
-		break;
 	default:
-		error("key_sign: illegal key type %d", key->type);
+		error("key_sign: invalid key type %d", key->type);
 		return -1;
-		break;
 	}
 }
 
+/*
+ * key_verify returns 1 for a correct signature, 0 for an incorrect signature
+ * and -1 on error.
+ */
 int
 key_verify(
-    Key *key,
-    u_char *signature, int signaturelen,
-    u_char *data, int datalen)
+    const Key *key,
+    const u_char *signature, u_int signaturelen,
+    const u_char *data, u_int datalen)
 {
-	switch(key->type){
+	if (signaturelen == 0)
+		return -1;
+
+	switch (key->type) {
 	case KEY_DSA:
 		return ssh_dss_verify(key, signature, signaturelen, data, datalen);
-		break;
 	case KEY_RSA:
 		return ssh_rsa_verify(key, signature, signaturelen, data, datalen);
-		break;
 	default:
-		error("key_verify: illegal key type %d", key->type);
+		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);
 }