Add KDF support to pkeyutl. Update documentation.

Reviewed-by: Rich Salz <rsalz@openssl.org>

apps/pkeyutl.c

@@ -62,11 +62,12 @@
 #include <openssl/pem.h>
 #include <openssl/evp.h>
 
+#define KEY_NONE        0
 #define KEY_PRIVKEY     1
 #define KEY_PUBKEY      2
 #define KEY_CERT        3
 
-static EVP_PKEY_CTX *init_ctx(int *pkeysize,
+static EVP_PKEY_CTX *init_ctx(const char *kdfalg, int *pkeysize,
                               const char *keyfile, int keyform, int key_type,
                               char *passinarg, int pkey_op, ENGINE *e,
                               const int impl);
@@ -84,7 +85,7 @@ typedef enum OPTION_choice {
     OPT_PUBIN, OPT_CERTIN, OPT_ASN1PARSE, OPT_HEXDUMP, OPT_SIGN,
     OPT_VERIFY, OPT_VERIFYRECOVER, OPT_REV, OPT_ENCRYPT, OPT_DECRYPT,
     OPT_DERIVE, OPT_SIGFILE, OPT_INKEY, OPT_PEERKEY, OPT_PASSIN,
-    OPT_PEERFORM, OPT_KEYFORM, OPT_PKEYOPT
+    OPT_PEERFORM, OPT_KEYFORM, OPT_PKEYOPT, OPT_KDF, OPT_KDFLEN
 } OPTION_CHOICE;
 
 OPTIONS pkeyutl_options[] = {
@@ -103,6 +104,8 @@ OPTIONS pkeyutl_options[] = {
     {"encrypt", OPT_ENCRYPT, '-', "Encrypt input data with public key"},
     {"decrypt", OPT_DECRYPT, '-', "Decrypt input data with private key"},
     {"derive", OPT_DERIVE, '-', "Derive shared secret"},
+    {"kdf", OPT_KDF, 's', "Use KDF algorithm"},
+    {"kdflen", OPT_KDFLEN, 'p', "KDF algorithm output length"},
     {"sigfile", OPT_SIGFILE, '<', "Signature file (verify operation only)"},
     {"inkey", OPT_INKEY, 's', "Input private key file"},
     {"peerkey", OPT_PEERKEY, 's', "Peer key file used in key derivation"},
@@ -135,6 +138,8 @@ int pkeyutl_main(int argc, char **argv)
     size_t buf_outlen;
     const char *inkey = NULL;
     const char *peerkey = NULL;
+    const char *kdfalg = NULL;
+    int kdflen = 0;
     STACK_OF(OPENSSL_STRING) *pkeyopts = NULL;
 
     prog = opt_init(argc, argv, pkeyutl_options);
@@ -211,6 +216,14 @@ int pkeyutl_main(int argc, char **argv)
         case OPT_DERIVE:
             pkey_op = EVP_PKEY_OP_DERIVE;
             break;
+        case OPT_KDF:
+            pkey_op = EVP_PKEY_OP_DERIVE;
+            key_type = KEY_NONE;
+            kdfalg = opt_arg();
+            break;
+        case OPT_KDFLEN:
+            kdflen = atoi(opt_arg());
+            break;
         case OPT_REV:
             rev = 1;
             break;
@@ -228,11 +241,14 @@ int pkeyutl_main(int argc, char **argv)
     if (argc != 0)
         goto opthelp;
 
-    if (inkey == NULL ||
+    if (kdfalg != NULL) {
-        (peerkey != NULL && pkey_op != EVP_PKEY_OP_DERIVE))
+        if (kdflen == 0)
+            goto opthelp;
+    } else if ((inkey == NULL)
+            || (peerkey != NULL && pkey_op != EVP_PKEY_OP_DERIVE)) {
         goto opthelp;
-
+    }
-    ctx = init_ctx(&keysize, inkey, keyform, key_type,
+    ctx = init_ctx(kdfalg, &keysize, inkey, keyform, key_type,
                    passinarg, pkey_op, e, engine_impl);
     if (ctx == NULL) {
         BIO_printf(bio_err, "%s: Error initializing context\n", prog);
@@ -326,8 +342,13 @@ int pkeyutl_main(int argc, char **argv)
             BIO_puts(out, "Signature Verification Failure\n");
         goto end;
     }
-    rv = do_keyop(ctx, pkey_op, NULL, (size_t *)&buf_outlen,
+    if (kdflen != 0) {
-                  buf_in, (size_t)buf_inlen);
+        buf_outlen = kdflen;
+        rv = 1;
+    } else {
+        rv = do_keyop(ctx, pkey_op, NULL, (size_t *)&buf_outlen,
+                      buf_in, (size_t)buf_inlen);
+    }
     if (rv > 0 && buf_outlen != 0) {
         buf_out = app_malloc(buf_outlen, "buffer output");
         rv = do_keyop(ctx, pkey_op,
@@ -360,7 +381,7 @@ int pkeyutl_main(int argc, char **argv)
     return ret;
 }
 
-static EVP_PKEY_CTX *init_ctx(int *pkeysize,
+static EVP_PKEY_CTX *init_ctx(const char *kdfalg, int *pkeysize,
                               const char *keyfile, int keyform, int key_type,
                               char *passinarg, int pkey_op, ENGINE *e,
                               const int engine_impl)
@@ -373,7 +394,7 @@ static EVP_PKEY_CTX *init_ctx(int *pkeysize,
     X509 *x;
     if (((pkey_op == EVP_PKEY_OP_SIGN) || (pkey_op == EVP_PKEY_OP_DECRYPT)
          || (pkey_op == EVP_PKEY_OP_DERIVE))
-        && (key_type != KEY_PRIVKEY)) {
+        && (key_type != KEY_PRIVKEY && kdfalg == NULL)) {
         BIO_printf(bio_err, "A private key is needed for this operation\n");
         goto end;
     }
@@ -398,21 +419,28 @@ static EVP_PKEY_CTX *init_ctx(int *pkeysize,
         }
         break;
 
+    case KEY_NONE:
+        break;
+
     }
 
-    *pkeysize = EVP_PKEY_size(pkey);
-
-    if (!pkey)
-        goto end;
-
 #ifndef OPENSSL_NO_ENGINE
     if (engine_impl)
         impl = e;
 #endif
-    
-    ctx = EVP_PKEY_CTX_new(pkey, impl);
 
-    EVP_PKEY_free(pkey);
+    if (kdfalg) {
+        int kdfnid = OBJ_sn2nid(kdfalg);
+        if (kdfnid == NID_undef)
+            goto end;
+        ctx = EVP_PKEY_CTX_new_id(kdfnid, impl);
+    } else {
+        if (pkey == NULL)
+            goto end;
+        *pkeysize = EVP_PKEY_size(pkey);
+        ctx = EVP_PKEY_CTX_new(pkey, impl);
+        EVP_PKEY_free(pkey);
+    }
 
     if (ctx == NULL)
         goto end;

doc/apps/pkeyutl.pod

@@ -25,6 +25,8 @@ B<openssl> B<pkeyutl>
 [B<-encrypt>]
 [B<-decrypt>]
 [B<-derive>]
+[B<-kdf algorithm>]
+[B<-kdflen length>]
 [B<-pkeyopt opt:value>]
 [B<-hexdump>]
 [B<-asn1parse>]
@@ -119,6 +121,15 @@ decrypt the input data using a private key.
 
 derive a shared secret using the peer key.
 
+=item B<-kdf algorithm>
+
+Use key derivation function B<algorithm>. Note: additional paramers
+will normally have to be set and the KDF output length for this to work.
+
+=item B<-kdflen length>
+
+Set the ouput length for KDF.
+
 =item B<-pkeyopt opt:value>
 
 Public key options specified as opt:value. See NOTES below for more details.
@@ -249,6 +260,12 @@ Derive a shared secret value:
 
  openssl pkeyutl -derive -inkey key.pem -peerkey pubkey.pem -out secret
 
+Hexdump 48 bytes of TLS1 PRF using digest B<SHA256> and shared secret and
+seed consisting of the single byte 0xFF.
+
+ openssl pkeyutl -kdf TLS1-PRF -kdflen 48 -pkeyopt md:SHA256 \
+    -pkeyopt hexsecret:ff -pkeyopt hexseed:ff -hexdump
+
 =head1 SEE ALSO
 
 L<genpkey(1)>, L<pkey(1)>, L<rsautl(1)>