- markus@cvs.openbsd.org 2002/06/08 05:07:56

[openssh.git] / ssh-rsa.c

diff --git a/ssh-rsa.c b/ssh-rsa.c
index 9de0e7b0890ee625330f89ac1dbb56823a9dff0d..458c9c840efab6d4375b655de7ce18d2a3090059 100644 (file)
--- a/ssh-rsa.c
+++ b/ssh-rsa.c
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: ssh-rsa.c,v 1.6 2001/02/08 19:30:52 itojun Exp $");
+RCSID("$OpenBSD: ssh-rsa.c,v 1.19 2002/05/31 13:20:50 markus Exp $");
 
 #include <openssl/evp.h>
 #include <openssl/err.h>
@@ -34,37 +34,41 @@ RCSID("$OpenBSD: ssh-rsa.c,v 1.6 2001/02/08 19:30:52 itojun Exp $");
 #include "bufaux.h"
 #include "key.h"
 #include "ssh-rsa.h"
+#include "compat.h"
+#include "ssh.h"
 
 /* RSASSA-PKCS1-v1_5 (PKCS #1 v2.0 signature) with SHA1 */
 int
 ssh_rsa_sign(
     Key *key,
-    u_char **sigp, int *lenp,
-    u_char *data, int datalen)
+    u_char **sigp, u_int *lenp,
+    u_char *data, u_int datalen)
 {
-       EVP_MD *evp_md = EVP_sha1();
+       const EVP_MD *evp_md;
        EVP_MD_CTX md;
-       u_char *digest, *sig, *ret;
+       u_char digest[EVP_MAX_MD_SIZE], *sig, *ret;
        u_int slen, dlen, len;
-       int ok;
+       int ok, nid;
        Buffer b;
 
        if (key == NULL || key->type != KEY_RSA || key->rsa == NULL) {
                error("ssh_rsa_sign: no RSA key");
                return -1;
        }
-       slen = RSA_size(key->rsa);
-       sig = xmalloc(slen);
-
-       dlen = evp_md->md_size;
-       digest = xmalloc(dlen);
+       nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1;
+       if ((evp_md = EVP_get_digestbynid(nid)) == NULL) {
+               error("ssh_rsa_sign: EVP_get_digestbynid %d failed", nid);
+               return -1;
+       }
        EVP_DigestInit(&md, evp_md);
        EVP_DigestUpdate(&md, data, datalen);
-       EVP_DigestFinal(&md, digest, NULL);
+       EVP_DigestFinal(&md, digest, &dlen);
 
-       ok = RSA_sign(NID_sha1, digest, dlen, sig, &len, key->rsa);
-       memset(digest, 'd', dlen);
-       xfree(digest);
+       slen = RSA_size(key->rsa);
+       sig = xmalloc(slen);
+
+       ok = RSA_sign(nid, digest, dlen, sig, &len, key->rsa);
+       memset(digest, 'd', sizeof(digest));
 
        if (ok != 1) {
                int ecode = ERR_get_error();
@@ -97,36 +101,34 @@ ssh_rsa_sign(
                *lenp = len;
        if (sigp != NULL)
                *sigp = ret;
-       debug2("ssh_rsa_sign: done");
        return 0;
 }
 
 int
 ssh_rsa_verify(
     Key *key,
-    u_char *signature, int signaturelen,
-    u_char *data, int datalen)
+    u_char *signature, u_int signaturelen,
+    u_char *data, u_int datalen)
 {
        Buffer b;
-       EVP_MD *evp_md = EVP_sha1();
+       const EVP_MD *evp_md;
        EVP_MD_CTX md;
        char *ktype;
-       u_char *sigblob, *digest;
-       u_int len, dlen;
-       int rlen;
-       int ret;
+       u_char digest[EVP_MAX_MD_SIZE], *sigblob;
+       u_int len, dlen, modlen;
+       int rlen, ret, nid;
 
        if (key == NULL || key->type != KEY_RSA || key->rsa == NULL) {
                error("ssh_rsa_verify: no RSA key");
                return -1;
        }
-       if (BN_num_bits(key->rsa->n) < 768) {
+       if (BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE) {
                error("ssh_rsa_verify: n too small: %d bits",
                    BN_num_bits(key->rsa->n));
                return -1;
        }
        buffer_init(&b);
-       buffer_append(&b, (char *) signature, signaturelen);
+       buffer_append(&b, signature, signaturelen);
        ktype = buffer_get_string(&b, NULL);
        if (strcmp("ssh-rsa", ktype) != 0) {
                error("ssh_rsa_verify: cannot handle type %s", ktype);
@@ -135,23 +137,41 @@ ssh_rsa_verify(
                return -1;
        }
        xfree(ktype);
-       sigblob = (u_char *)buffer_get_string(&b, &len);
+       sigblob = buffer_get_string(&b, &len);
        rlen = buffer_len(&b);
        buffer_free(&b);
-       if(rlen != 0) {
+       if (rlen != 0) {
                error("ssh_rsa_verify: remaining bytes in signature %d", rlen);
+               xfree(sigblob);
+               return -1;
+       }
+       /* RSA_verify expects a signature of RSA_size */
+       modlen = RSA_size(key->rsa);
+       if (len > modlen) {
+               error("ssh_rsa_verify: len %d > modlen %d", len, modlen);
+               xfree(sigblob);
+               return -1;
+       } else if (len < modlen) {
+               int diff = modlen - len;
+               debug("ssh_rsa_verify: add padding: modlen %d > len %d",
+                   modlen, len);
+               sigblob = xrealloc(sigblob, modlen);
+               memmove(sigblob + diff, sigblob, len);
+               memset(sigblob, 0, diff);
+               len = modlen;
+       }
+       nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1;
+       if ((evp_md = EVP_get_digestbynid(nid)) == NULL) {
+               error("ssh_rsa_verify: EVP_get_digestbynid %d failed", nid);
+               xfree(sigblob);
                return -1;
        }
-
-       dlen = evp_md->md_size;
-       digest = xmalloc(dlen);
        EVP_DigestInit(&md, evp_md);
        EVP_DigestUpdate(&md, data, datalen);
-       EVP_DigestFinal(&md, digest, NULL);
+       EVP_DigestFinal(&md, digest, &dlen);
 
-       ret = RSA_verify(NID_sha1, digest, dlen, sigblob, len, key->rsa);
-       memset(digest, 'd', dlen);
-       xfree(digest);
+       ret = RSA_verify(nid, digest, dlen, sigblob, len, key->rsa);
+       memset(digest, 'd', sizeof(digest));
        memset(sigblob, 's', len);
        xfree(sigblob);
        if (ret == 0) {