Add X9.42 KDF.

Move the KDF code for CMS DH key agreement into an EVP_KDF object.
There are 2 specifications for X9.42 KDF. This implementation uses DER for
otherinfo which embeds the KDF loop counter inside the DER object.

Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/8898)

1 files changed, 31 insertions, 129 deletions

diff --git a/crypto/dh/dh_kdf.c b/crypto/dh/dh_kdf.c
index 2a01bfce46..03b1e4edd5 100644
--- a/crypto/dh/dh_kdf.c
+++ b/crypto/dh/dh_kdf.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2016 The OpenSSL Project Authors. All Rights Reserved.
+ * Copyright 2013-2019 The OpenSSL Project Authors. All Rights Reserved.
  *
  * Licensed under the Apache License 2.0 (the "License").  You may not use
  * this file except in compliance with the License.  You can obtain a copy
@@ -10,141 +10,43 @@
 #include "e_os.h"
 
 #ifndef OPENSSL_NO_CMS
-#include <string.h>
-#include <openssl/dh.h>
-#include <openssl/evp.h>
-#include <openssl/asn1.h>
-#include <openssl/cms.h>
-
-
-/* Key derivation from X9.42/RFC2631 */
-/* Uses CMS functions, hence the #ifdef wrapper. */
-
-#define DH_KDF_MAX      (1L << 30)
-
-/* Skip past an ASN1 structure: for OBJECT skip content octets too */
-
-static int skip_asn1(unsigned char **pp, long *plen, int exptag)
-{
-    const unsigned char *q = *pp;
-    int i, tag, xclass;
-    long tmplen;
-    i = ASN1_get_object(&q, &tmplen, &tag, &xclass, *plen);
-    if (i & 0x80)
-        return 0;
-    if (tag != exptag || xclass != V_ASN1_UNIVERSAL)
-        return 0;
-    if (tag == V_ASN1_OBJECT)
-        q += tmplen;
-    *plen -= q - *pp;
-    *pp = (unsigned char *)q;
-    return 1;
-}
-
-/*
- * Encode the DH shared info structure, return an offset to the counter value
- * so we can update the structure without reencoding it.
- */
-
-static int dh_sharedinfo_encode(unsigned char **pder, unsigned char **pctr,
-                                ASN1_OBJECT *key_oid, size_t outlen,
-                                const unsigned char *ukm, size_t ukmlen)
-{
-    unsigned char *p;
-    int derlen;
-    long tlen;
-    /* "magic" value to check offset is sane */
-    static unsigned char ctr[4] = { 0xF3, 0x17, 0x22, 0x53 };
-    X509_ALGOR atmp;
-    ASN1_OCTET_STRING ctr_oct, ukm_oct, *pukm_oct;
-    ASN1_TYPE ctr_atype;
-    if (ukmlen > DH_KDF_MAX || outlen > DH_KDF_MAX)
-        return 0;
-    ctr_oct.data = ctr;
-    ctr_oct.length = 4;
-    ctr_oct.flags = 0;
-    ctr_oct.type = V_ASN1_OCTET_STRING;
-    ctr_atype.type = V_ASN1_OCTET_STRING;
-    ctr_atype.value.octet_string = &ctr_oct;
-    atmp.algorithm = key_oid;
-    atmp.parameter = &ctr_atype;
-    if (ukm) {
-        ukm_oct.type = V_ASN1_OCTET_STRING;
-        ukm_oct.flags = 0;
-        ukm_oct.data = (unsigned char *)ukm;
-        ukm_oct.length = ukmlen;
-        pukm_oct = &ukm_oct;
-    } else
-        pukm_oct = NULL;
-    derlen = CMS_SharedInfo_encode(pder, &atmp, pukm_oct, outlen);
-    if (derlen <= 0)
-        return 0;
-    p = *pder;
-    tlen = derlen;
-    if (!skip_asn1(&p, &tlen, V_ASN1_SEQUENCE))
-        return 0;
-    if (!skip_asn1(&p, &tlen, V_ASN1_SEQUENCE))
-        return 0;
-    if (!skip_asn1(&p, &tlen, V_ASN1_OBJECT))
-        return 0;
-    if (!skip_asn1(&p, &tlen, V_ASN1_OCTET_STRING))
-        return 0;
-    if (CRYPTO_memcmp(p, ctr, 4))
-        return 0;
-    *pctr = p;
-    return derlen;
-}
+# include <string.h>
+# include <openssl/dh.h>
+# include <openssl/evp.h>
+# include <openssl/asn1.h>
+# include <openssl/kdf.h>
 
 int DH_KDF_X9_42(unsigned char *out, size_t outlen,
                  const unsigned char *Z, size_t Zlen,
                  ASN1_OBJECT *key_oid,
                  const unsigned char *ukm, size_t ukmlen, const EVP_MD *md)
 {
-    EVP_MD_CTX *mctx = NULL;
-    int rv = 0;
-    unsigned int i;
-    size_t mdlen;
-    unsigned char *der = NULL, *ctr;
-    int derlen;
-    if (Zlen > DH_KDF_MAX)
+    int ret = 0, nid;
+    EVP_KDF_CTX *kctx = NULL;
+    const EVP_KDF *kdf = NULL;
+    const char *oid_sn;
+
+    nid = OBJ_obj2nid(key_oid);
+    if (nid == NID_undef)
         return 0;
-    mctx = EVP_MD_CTX_new();
-    if (mctx == NULL)
+    oid_sn = OBJ_nid2sn(nid);
+    if (oid_sn == NULL)
         return 0;
-    mdlen = EVP_MD_size(md);
-    derlen = dh_sharedinfo_encode(&der, &ctr, key_oid, outlen, ukm, ukmlen);
-    if (derlen == 0)
+
+    kdf = EVP_get_kdfbyname(SN_x942kdf);
+    if (kdf == NULL)
         goto err;
-    for (i = 1;; i++) {
-        unsigned char mtmp[EVP_MAX_MD_SIZE];
-        if (!EVP_DigestInit_ex(mctx, md, NULL)
-            || !EVP_DigestUpdate(mctx, Z, Zlen))
-            goto err;
-        ctr[3] = i & 0xFF;
-        ctr[2] = (i >> 8) & 0xFF;
-        ctr[1] = (i >> 16) & 0xFF;
-        ctr[0] = (i >> 24) & 0xFF;
-        if (!EVP_DigestUpdate(mctx, der, derlen))
-            goto err;
-        if (outlen >= mdlen) {
-            if (!EVP_DigestFinal(mctx, out, NULL))
-                goto err;
-            outlen -= mdlen;
-            if (outlen == 0)
-                break;
-            out += mdlen;
-        } else {
-            if (!EVP_DigestFinal(mctx, mtmp, NULL))
-                goto err;
-            memcpy(out, mtmp, outlen);
-            OPENSSL_cleanse(mtmp, mdlen);
-            break;
-        }
-    }
-    rv = 1;
- err:
-    OPENSSL_free(der);
-    EVP_MD_CTX_free(mctx);
-    return rv;
+    kctx = EVP_KDF_CTX_new(kdf);
+    ret =
+        kctx != NULL
+        && EVP_KDF_ctrl(kctx, EVP_KDF_CTRL_SET_MD, md) > 0
+        && EVP_KDF_ctrl(kctx, EVP_KDF_CTRL_SET_KEY, Z, Zlen) > 0
+        && (ukm == NULL
+            || EVP_KDF_ctrl(kctx, EVP_KDF_CTRL_SET_UKM, ukm, ukmlen) > 0)
+        && EVP_KDF_ctrl(kctx, EVP_KDF_CTRL_SET_CEK_ALG, oid_sn) > 0
+        && EVP_KDF_derive(kctx, out, outlen) > 0;
+err:
+    EVP_KDF_CTX_free(kctx);
+    return ret;
 }
-#endif
+#endif /* OPENSSL_NO_CMS */