diff --git a/kdc/pkinit.c b/kdc/pkinit.c
index 87621e371..66c27504a 100644
--- a/kdc/pkinit.c
+++ b/kdc/pkinit.c
@@ -1370,16 +1370,86 @@ _kdc_pk_mk_pa_reply(krb5_context context,
 	    if (rep.u.encKeyPack.length != size)
 		krb5_abortx(context, "Internal ASN.1 encoder error");
 
-	    /* XXX KRB-FX-CF2 */
-	    ret = krb5_generate_random_keyblock(context, sessionetype,
-						sessionkey);
-	    if (ret) {
-		free_PA_PK_AS_REP(&rep);
-		goto out;
+	    /* generate the session key using the method from RFC6112 */
+	    {
+		krb5_keyblock kdc_contribution_key;
+		krb5_crypto reply_crypto;
+		krb5_crypto kdccont_crypto;
+		krb5_data p1 = { strlen("PKINIT"), "PKINIT"};
+		krb5_data p2 = { strlen("KEYEXCHANGE"), "KEYEXCHANGE"};
+		void *kckdata;
+		size_t kcklen;
+		EncryptedData kx;
+		void *kxdata;
+		size_t kxlen;
+
+		ret = krb5_generate_random_keyblock(context, sessionetype,
+						&kdc_contribution_key);
+		if (ret) {
+		    free_PA_PK_AS_REP(&rep);
+		    goto out;
+		}
+		ret = krb5_crypto_init(context, &cp->reply_key, enctype, &reply_crypto);
+		if (ret) {
+		    krb5_free_keyblock_contents(context, &kdc_contribution_key);
+		    free_PA_PK_AS_REP(&rep);
+		    goto out;
+		}
+		ret = krb5_crypto_init(context, &kdc_contribution_key, sessionetype, &kdccont_crypto);
+		if (ret) {
+		    krb5_crypto_destroy(context, reply_crypto);
+		    krb5_free_keyblock_contents(context, &kdc_contribution_key);
+		    free_PA_PK_AS_REP(&rep);
+		    goto out;
+		}
+		/* KRB-FX-CF2 */
+		ret = krb5_crypto_fx_cf2(context, kdccont_crypto, reply_crypto,
+					 &p1, &p2, sessionetype, sessionkey);
+		krb5_crypto_destroy(context, kdccont_crypto);
+		if (ret) {
+		    krb5_crypto_destroy(context, reply_crypto);
+		    krb5_free_keyblock_contents(context, &kdc_contribution_key);
+		    free_PA_PK_AS_REP(&rep);
+		    goto out;
+		}
+		ASN1_MALLOC_ENCODE(EncryptionKey, kckdata, kcklen,
+				   &kdc_contribution_key, &size, ret);
+		krb5_free_keyblock_contents(context, &kdc_contribution_key);
+		if (ret) {
+		    krb5_set_error_message(context, ret, "encoding of PKINIT-KX Key failed %d", ret);
+		    krb5_crypto_destroy(context, reply_crypto);
+		    free_PA_PK_AS_REP(&rep);
+		    goto out;
+		}
+		if (kcklen != size)
+		    krb5_abortx(context, "Internal ASN.1 encoder error");
+		ret = krb5_encrypt_EncryptedData(context, reply_crypto, KRB5_KU_PA_PKINIT_KX,
+					kckdata, kcklen, 0, &kx);
+		krb5_crypto_destroy(context, reply_crypto);
+		free(kckdata);
+		if (ret) {
+		    free_PA_PK_AS_REP(&rep);
+		    goto out;
+		}
+		ASN1_MALLOC_ENCODE(EncryptedData, kxdata, kxlen,
+				   &kx, &size, ret);
+		free_EncryptedData(&kx);
+		if (ret) {
+		    krb5_set_error_message(context, ret, "encoding of PKINIT-KX failed %d", ret);
+		    free_PA_PK_AS_REP(&rep);
+		    goto out;
+		}
+		if (kxlen != size)
+		    krb5_abortx(context, "Internal ASN.1 encoder error");
+		/* Add PA-PKINIT-KX */
+		ret = krb5_padata_add(context, md, KRB5_PADATA_PKINIT_KX, kxdata, kxlen);
+		if (ret) {
+		    krb5_set_error_message(context, ret,
+					   "Failed adding PKINIT-KX %d", ret);
+		    free(buf);
+		    goto out;
+		}
 	    }
-
-	    /* XXX Add PA-PKINIT-KX */
-
 	}
 
 #define use_btmm_with_enckey 0