src/usr.bin/ssh/ssh-rsa.c - diff

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Diff for /src/usr.bin/ssh/ssh-rsa.c between version 1.24 and 1.25

-version 1.24, 2002/08/02 21:23:41
+version 1.25, 2002/08/02 22:20:30
 Line 37
 Line 37
 Line 37
  #include "compat.h"
  #include "ssh.h"
+ static int openssh_RSA_verify(int, u_char *, u_int, u_char *, u_int , RSA *);
  /* RSASSA-PKCS1-v1_5 (PKCS #1 v2.0 signature) with SHA1 */
  int
  ssh_rsa_sign(Key *key, u_char **sigp, u_int *lenp,
-Line 167
+Line 169
 Line 167
 Line 169
          EVP_DigestUpdate(&md, data, datalen);
          EVP_DigestFinal(&md, digest, &dlen);
-         ret = RSA_verify(nid, digest, dlen, sigblob, len, key->rsa);
+         ret = openssh_RSA_verify(nid, digest, dlen, sigblob, len, key->rsa);
          memset(digest, 'd', sizeof(digest));
          memset(sigblob, 's', len);
          xfree(sigblob);
-         if (ret == 0) {
-                 int ecode = ERR_get_error();
-                 error("ssh_rsa_verify: RSA_verify failed: %s",
-                     ERR_error_string(ecode, NULL));
-         }
          debug("ssh_rsa_verify: signature %scorrect", (ret==0) ? "in" : "");
+         return ret;
+ }
+ /*
+  * See:
+  * http://www.rsasecurity.com/rsalabs/pkcs/pkcs-1/
+  * ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1/pkcs-1v2-1.asn
+  */
+ /*
+  * id-sha1 OBJECT IDENTIFIER ::= { iso(1) identified-organization(3)
+  *      oiw(14) secsig(3) algorithms(2) 26 }
+  */
+ static const u_char id_sha1[] = {
+x30, 0x21, /* type Sequence, length 0x21 (33) */
+x30, 0x09, /* type Sequence, length 0x09 */
+x06, 0x05, /* type OID, length 0x05 */
+x2b, 0x0e, 0x03, 0x02, 0x1a, /* id-sha1 OID */
+x05, 0x00, /* NULL */
+x04, 0x14  /* Octet string, length 0x14 (20), followed by sha1 hash */
+ };
+ /*
+  * id-md5 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)
+  *      rsadsi(113549) digestAlgorithm(2) 5 }
+  */
+ static const u_char id_md5[] = {
+x30, 0x20, /* type Sequence, length 0x20 (32) */
+x30, 0x0c, /* type Sequence, length 0x09 */
+x06, 0x08, /* type OID, length 0x05 */
+x2a, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x02, 0x05, /* id-md5 */
+x05, 0x00, /* NULL */
+x04, 0x10  /* Octet string, length 0x10 (16), followed by md5 hash */
+ };
+ static int
+ openssh_RSA_verify(int type, u_char *hash, u_int hashlen,
+     u_char *sigbuf, u_int siglen, RSA *rsa)
+ {
+         u_int ret, rsasize, len, oidlen = 0, hlen = 0;
+         const u_char *oid = NULL;
+         u_char *decrypted = NULL;
+         ret = 0;
+         switch (type) {
+         case NID_sha1:
+                 oid = id_sha1;
+                 oidlen = sizeof(id_sha1);
+                 hlen = 20;
+                 break;
+         case NID_md5:
+                 oid = id_md5;
+                 oidlen = sizeof(id_md5);
+                 hlen = 16;
+                 break;
+         default:
+                 goto done;
+                 break;
+         }
+         if (hashlen != hlen) {
+                 error("bad hashlen");
+                 goto done;
+         }
+         rsasize = RSA_size(rsa);
+         if (siglen == 0 || siglen > rsasize) {
+                 error("bad siglen");
+                 goto done;
+         }
+         decrypted = xmalloc(rsasize);
+         if ((len = RSA_public_decrypt(siglen, sigbuf, decrypted, rsa,
+             RSA_PKCS1_PADDING)) < 0) {
+                 error("RSA_public_decrypt failed: %s",
+                     ERR_error_string(ERR_get_error(), NULL));
+                 goto done;
+         }
+         if (len != hlen + oidlen) {
+                 error("bad decrypted len: %d != %d + %d", len, hlen, oidlen);
+                 goto done;
+         }
+         if (memcmp(decrypted, oid, oidlen) != 0) {
+                 error("oid mismatch");
+                 goto done;
+         }
+         if (memcmp(decrypted + oidlen, hash, hlen) != 0) {
+                 error("hash mismatch");
+                 goto done;
+         }
+         ret = 1;
+ done:
+         if (decrypted)
+                 xfree(decrypted);
          return ret;
  }