[PROV][KMGMT][KEXCH][EC] Implement EC keymgtm and ECDH

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/10631)

2 files changed, 535 insertions, 0 deletions

diff --git a/providers/implementations/exchange/build.info b/providers/implementations/exchange/build.info
index 51d32fc090..82b688def3 100644
--- a/providers/implementations/exchange/build.info
+++ b/providers/implementations/exchange/build.info
@@ -3,6 +3,7 @@
 
 $DH_GOAL=../../libimplementations.a
 $ECX_GOAL=../../libimplementations.a
+$ECDH_GOAL=../../libimplementations.a
 
 IF[{- !$disabled{dh} -}]
   SOURCE[$DH_GOAL]=dh_exch.c
@@ -21,4 +22,5 @@ ENDIF
 IF[{- !$disabled{ec} -}]
   SOURCE[$ECX_GOAL]=ecx_exch.c
   DEFINE[$ECX_GOAL]=$ECDEF
+  SOURCE[$ECDH_GOAL]=ecdh_exch.c
 ENDIF
diff --git a/providers/implementations/exchange/ecdh_exch.c b/providers/implementations/exchange/ecdh_exch.c
new file mode 100644
index 0000000000..bf353fa175
--- /dev/null
+++ b/providers/implementations/exchange/ecdh_exch.c
@@ -0,0 +1,533 @@
+/*
+ * Copyright 2020 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
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+/*
+ * ECDH low level APIs are deprecated for public use, but still ok for
+ * internal use.
+ */
+#include "internal/deprecated.h"
+
+#include <string.h>
+#include <openssl/crypto.h>
+#include <openssl/evp.h>
+#include <openssl/core_numbers.h>
+#include <openssl/core_names.h>
+#include <openssl/ec.h>
+#include <openssl/params.h>
+#include <openssl/err.h>
+#include "prov/provider_ctx.h"
+#include "prov/implementations.h"
+#include "crypto/ec.h" /* ecdh_KDF_X9_63() */
+
+static OSSL_OP_keyexch_newctx_fn ecdh_newctx;
+static OSSL_OP_keyexch_init_fn ecdh_init;
+static OSSL_OP_keyexch_set_peer_fn ecdh_set_peer;
+static OSSL_OP_keyexch_derive_fn ecdh_derive;
+static OSSL_OP_keyexch_freectx_fn ecdh_freectx;
+static OSSL_OP_keyexch_dupctx_fn ecdh_dupctx;
+static OSSL_OP_keyexch_set_ctx_params_fn ecdh_set_ctx_params;
+static OSSL_OP_keyexch_settable_ctx_params_fn ecdh_settable_ctx_params;
+static OSSL_OP_keyexch_get_ctx_params_fn ecdh_get_ctx_params;
+static OSSL_OP_keyexch_gettable_ctx_params_fn ecdh_gettable_ctx_params;
+
+enum kdf_type {
+    PROV_ECDH_KDF_NONE = 0,
+    PROV_ECDH_KDF_X9_63
+};
+
+/*
+ * What's passed as an actual key is defined by the KEYMGMT interface.
+ * We happen to know that our KEYMGMT simply passes EC_KEY structures, so
+ * we use that here too.
+ */
+
+typedef struct {
+    OPENSSL_CTX *libctx;
+
+    EC_KEY *k;
+    EC_KEY *peerk;
+
+    /*
+     * ECDH cofactor mode:
+     *
+     *  . 0  disabled
+     *  . 1  enabled
+     *  . -1 use cofactor mode set for k
+     */
+    int cofactor_mode;
+
+    /************
+     * ECDH KDF *
+     ************/
+    /* KDF (if any) to use for ECDH */
+    enum kdf_type kdf_type;
+    /* Message digest to use for key derivation */
+    EVP_MD *kdf_md;
+    /* User key material */
+    unsigned char *kdf_ukm;
+    size_t kdf_ukmlen;
+    /* KDF output length */
+    size_t kdf_outlen;
+} PROV_ECDH_CTX;
+
+static
+void *ecdh_newctx(void *provctx)
+{
+    PROV_ECDH_CTX *pectx = OPENSSL_zalloc(sizeof(*pectx));
+
+    if (pectx == NULL)
+        return NULL;
+
+    pectx->libctx = PROV_LIBRARY_CONTEXT_OF(provctx);
+    pectx->cofactor_mode = -1;
+    pectx->kdf_type = PROV_ECDH_KDF_NONE;
+
+    return (void *)pectx;
+}
+
+static
+int ecdh_init(void *vpecdhctx, void *vecdh)
+{
+    PROV_ECDH_CTX *pecdhctx = (PROV_ECDH_CTX *)vpecdhctx;
+
+    if (pecdhctx == NULL || vecdh == NULL || !EC_KEY_up_ref(vecdh))
+        return 0;
+    EC_KEY_free(pecdhctx->k);
+    pecdhctx->k = vecdh;
+    pecdhctx->cofactor_mode = -1;
+    pecdhctx->kdf_type = PROV_ECDH_KDF_NONE;
+    return 1;
+}
+
+static
+int ecdh_set_peer(void *vpecdhctx, void *vecdh)
+{
+    PROV_ECDH_CTX *pecdhctx = (PROV_ECDH_CTX *)vpecdhctx;
+
+    if (pecdhctx == NULL || vecdh == NULL || !EC_KEY_up_ref(vecdh))
+        return 0;
+    EC_KEY_free(pecdhctx->peerk);
+    pecdhctx->peerk = vecdh;
+    return 1;
+}
+
+static
+void ecdh_freectx(void *vpecdhctx)
+{
+    PROV_ECDH_CTX *pecdhctx = (PROV_ECDH_CTX *)vpecdhctx;
+
+    EC_KEY_free(pecdhctx->k);
+    EC_KEY_free(pecdhctx->peerk);
+
+    EVP_MD_free(pecdhctx->kdf_md);
+    OPENSSL_clear_free(pecdhctx->kdf_ukm, pecdhctx->kdf_ukmlen);
+
+    OPENSSL_free(pecdhctx);
+}
+
+static
+void *ecdh_dupctx(void *vpecdhctx)
+{
+    PROV_ECDH_CTX *srcctx = (PROV_ECDH_CTX *)vpecdhctx;
+    PROV_ECDH_CTX *dstctx;
+
+    dstctx = OPENSSL_zalloc(sizeof(*srcctx));
+    if (dstctx == NULL)
+        return NULL;
+
+    *dstctx = *srcctx;
+
+    /* clear all pointers */
+
+    dstctx->k= NULL;
+    dstctx->peerk = NULL;
+    dstctx->kdf_md = NULL;
+    dstctx->kdf_ukm = NULL;
+
+    /* up-ref all ref-counted objects referenced in dstctx */
+
+    if (srcctx->k != NULL && !EC_KEY_up_ref(srcctx->k))
+        goto err;
+    else
+        dstctx->k = srcctx->k;
+
+    if (srcctx->peerk != NULL && !EC_KEY_up_ref(srcctx->peerk))
+        goto err;
+    else
+        dstctx->peerk = srcctx->peerk;
+
+    if (srcctx->kdf_md != NULL && !EVP_MD_up_ref(srcctx->kdf_md))
+        goto err;
+    else
+        dstctx->kdf_md = srcctx->kdf_md;
+
+    /* Duplicate UKM data if present */
+    if (srcctx->kdf_ukm != NULL && srcctx->kdf_ukmlen > 0) {
+        dstctx->kdf_ukm = OPENSSL_memdup(srcctx->kdf_ukm,
+                                         srcctx->kdf_ukmlen);
+        if (dstctx->kdf_ukm == NULL)
+            goto err;
+    }
+
+    return dstctx;
+
+ err:
+    ecdh_freectx(dstctx);
+    return NULL;
+}
+
+static
+int ecdh_set_ctx_params(void *vpecdhctx, const OSSL_PARAM params[])
+{
+    char name[80] = { '\0' }; /* should be big enough */
+    char *str = NULL;
+    PROV_ECDH_CTX *pectx = (PROV_ECDH_CTX *)vpecdhctx;
+    const OSSL_PARAM *p;
+
+    if (pectx == NULL || params == NULL)
+        return 0;
+
+    p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_EC_ECDH_COFACTOR_MODE);
+    if (p != NULL) {
+        int mode;
+
+        if (!OSSL_PARAM_get_int(p, &mode))
+            return 0;
+
+        if (mode < -1 || mode > 1)
+            return 0;
+
+        pectx->cofactor_mode = mode;
+    }
+
+    p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_TYPE);
+    if (p != NULL) {
+        str = name;
+        if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
+            return 0;
+
+        if (name[0] == '\0')
+            pectx->kdf_type = PROV_ECDH_KDF_NONE;
+        else if (strcmp(name, OSSL_KDF_NAME_X963KDF) == 0)
+            pectx->kdf_type = PROV_ECDH_KDF_X9_63;
+        else
+            return 0;
+    }
+
+    p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_DIGEST);
+    if (p != NULL) {
+        char mdprops[80] = { '\0' }; /* should be big enough */
+
+        str = name;
+        if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
+            return 0;
+
+        str = mdprops;
+        p = OSSL_PARAM_locate_const(params,
+                                    OSSL_EXCHANGE_PARAM_KDF_DIGEST_PROPS);
+
+        if (p != NULL) {
+            if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(mdprops)))
+                return 0;
+        }
+
+        EVP_MD_free(pectx->kdf_md);
+        pectx->kdf_md = EVP_MD_fetch(pectx->libctx, name, mdprops);
+
+        if (pectx->kdf_md == NULL)
+            return 0;
+    }
+
+    p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_OUTLEN);
+    if (p != NULL) {
+        size_t outlen;
+
+        if (!OSSL_PARAM_get_size_t(p, &outlen))
+            return 0;
+        pectx->kdf_outlen = outlen;
+    }
+
+    p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_UKM);
+    if (p != NULL) {
+        void *tmp_ukm = NULL;
+        size_t tmp_ukmlen;
+
+        if (!OSSL_PARAM_get_octet_string(p, &tmp_ukm, 0, &tmp_ukmlen))
+            return 0;
+        OPENSSL_free(pectx->kdf_ukm);
+        pectx->kdf_ukm = tmp_ukm;
+        pectx->kdf_ukmlen = tmp_ukmlen;
+    }
+
+    return 1;
+}
+
+static const OSSL_PARAM known_settable_ctx_params[] = {
+    OSSL_PARAM_int(OSSL_EXCHANGE_PARAM_EC_ECDH_COFACTOR_MODE, NULL),
+    OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_TYPE, NULL, 0),
+    OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST, NULL, 0),
+    OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST_PROPS, NULL, 0),
+    OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_OUTLEN, NULL),
+    OSSL_PARAM_octet_string(OSSL_EXCHANGE_PARAM_KDF_UKM, NULL, 0),
+    OSSL_PARAM_END
+};
+
+static
+const OSSL_PARAM *ecdh_settable_ctx_params(void)
+{
+    return known_settable_ctx_params;
+}
+
+static
+int ecdh_get_ctx_params(void *vpecdhctx, OSSL_PARAM params[])
+{
+    PROV_ECDH_CTX *pectx = (PROV_ECDH_CTX *)vpecdhctx;
+    OSSL_PARAM *p;
+
+    if (pectx == NULL || params == NULL)
+        return 0;
+
+    p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_EC_ECDH_COFACTOR_MODE);
+    if (p != NULL) {
+        int mode = pectx->cofactor_mode;
+
+        if (mode == -1) {
+            /* check what is the default for pecdhctx->k */
+            mode = EC_KEY_get_flags(pectx->k) & EC_FLAG_COFACTOR_ECDH ? 1 : 0;
+        }
+
+        if (!OSSL_PARAM_set_int(p, mode))
+            return 0;
+    }
+
+    p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_TYPE);
+    if (p != NULL) {
+        const char *kdf_type = NULL;
+
+        switch (pectx->kdf_type) {
+            case PROV_ECDH_KDF_NONE:
+                kdf_type = "";
+                break;
+            case PROV_ECDH_KDF_X9_63:
+                kdf_type = OSSL_KDF_NAME_X963KDF;
+                break;
+            default:
+                return 0;
+        }
+
+        if (!OSSL_PARAM_set_utf8_string(p, kdf_type))
+            return 0;
+    }
+
+    p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_DIGEST);
+    if (p != NULL
+            && !OSSL_PARAM_set_utf8_string(p, pectx->kdf_md == NULL
+                                           ? ""
+                                           : EVP_MD_name(pectx->kdf_md))){
+        return 0;
+    }
+
+    p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_OUTLEN);
+    if (p != NULL && !OSSL_PARAM_set_size_t(p, pectx->kdf_outlen))
+        return 0;
+
+    p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_UKM);
+    if (p != NULL && !OSSL_PARAM_set_octet_ptr(p, pectx->kdf_ukm, 0))
+        return 0;
+
+    p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_UKM_LEN);
+    if (p != NULL && !OSSL_PARAM_set_size_t(p, pectx->kdf_ukmlen))
+        return 0;
+
+    return 1;
+}
+
+static const OSSL_PARAM known_gettable_ctx_params[] = {
+    OSSL_PARAM_int(OSSL_EXCHANGE_PARAM_EC_ECDH_COFACTOR_MODE, NULL),
+    OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_TYPE, NULL, 0),
+    OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST, NULL, 0),
+    OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_OUTLEN, NULL),
+    OSSL_PARAM_DEFN(OSSL_EXCHANGE_PARAM_KDF_UKM, OSSL_PARAM_OCTET_PTR,
+                    NULL, 0),
+    OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_UKM_LEN, NULL),
+    OSSL_PARAM_END
+};
+
+static
+const OSSL_PARAM *ecdh_gettable_ctx_params(void)
+{
+    return known_gettable_ctx_params;
+}
+
+static ossl_inline
+size_t ecdh_size(const EC_KEY *k)
+{
+    size_t degree = 0;
+    const EC_GROUP *group;
+
+    if (k == NULL
+            || (group = EC_KEY_get0_group(k)) == NULL)
+        return 0;
+
+    degree = EC_GROUP_get_degree(group);
+
+    return (degree + 7) / 8;
+}
+
+static ossl_inline
+int ecdh_plain_derive(void *vpecdhctx, unsigned char *secret,
+                      size_t *psecretlen, size_t outlen)
+{
+    PROV_ECDH_CTX *pecdhctx = (PROV_ECDH_CTX *)vpecdhctx;
+    int retlen, ret = 0;
+    size_t ecdhsize, size;
+    const EC_POINT *ppubkey = NULL;
+    EC_KEY *privk = NULL;
+    const EC_GROUP *group;
+    const BIGNUM *cofactor;
+    int key_cofactor_mode;
+
+    if (pecdhctx->k == NULL || pecdhctx->peerk == NULL) {
+        ERR_raise(ERR_LIB_PROV, EC_R_KEYS_NOT_SET);
+        return 0;
+    }
+
+    ecdhsize = ecdh_size(pecdhctx->k);
+    if (secret == NULL) {
+        *psecretlen = ecdhsize;
+        return 1;
+    }
+
+    if ((group = EC_KEY_get0_group(pecdhctx->k)) == NULL
+            || (cofactor = EC_GROUP_get0_cofactor(group)) == NULL )
+        return 0;
+
+    /*
+     * NB: unlike PKCS#3 DH, if outlen is less than maximum size this is not
+     * an error, the result is truncated.
+     */
+    size = outlen < ecdhsize ? outlen : ecdhsize;
+
+    /*
+     * The ctx->cofactor_mode flag has precedence over the
+     * cofactor_mode flag set on ctx->k.
+     *
+     * - if ctx->cofactor_mode == -1, use ctx->k directly
+     * - if ctx->cofactor_mode == key_cofactor_mode, use ctx->k directly
+     * - if ctx->cofactor_mode != key_cofactor_mode:
+     *     - if ctx->k->cofactor == 1, the cofactor_mode flag is irrelevant, use
+     *          ctx->k directly
+     *     - if ctx->k->cofactor != 1, use a duplicate of ctx->k with the flag
+     *          set to ctx->cofactor_mode
+     */
+    key_cofactor_mode =
+        (EC_KEY_get_flags(pecdhctx->k) & EC_FLAG_COFACTOR_ECDH) ? 1 : 0;
+    if (pecdhctx->cofactor_mode != -1
+            && pecdhctx->cofactor_mode != key_cofactor_mode
+            && !BN_is_one(cofactor)) {
+        if ((privk = EC_KEY_dup(pecdhctx->k)) == NULL)
+            return 0;
+
+        if (pecdhctx->cofactor_mode == 1)
+            EC_KEY_set_flags(privk, EC_FLAG_COFACTOR_ECDH);
+        else
+            EC_KEY_clear_flags(privk, EC_FLAG_COFACTOR_ECDH);
+    } else {
+        privk = pecdhctx->k;
+    }
+
+    ppubkey = EC_KEY_get0_public_key(pecdhctx->peerk);
+
+    retlen = ECDH_compute_key(secret, size, ppubkey, privk, NULL);
+
+    if (retlen <= 0)
+        goto end;
+
+    *psecretlen = retlen;
+    ret = 1;
+
+ end:
+    if (privk != pecdhctx->k)
+        EC_KEY_free(privk);
+    return ret;
+}
+
+static ossl_inline
+int ecdh_X9_63_kdf_derive(void *vpecdhctx, unsigned char *secret,
+                          size_t *psecretlen, size_t outlen)
+{
+    PROV_ECDH_CTX *pecdhctx = (PROV_ECDH_CTX *)vpecdhctx;
+    unsigned char *stmp = NULL;
+    size_t stmplen;
+    int ret = 0;
+
+    if (secret == NULL) {
+        *psecretlen = pecdhctx->kdf_outlen;
+        return 1;
+    }
+
+    if (pecdhctx->kdf_outlen > outlen)
+        return 0;
+    if (!ecdh_plain_derive(vpecdhctx, NULL, &stmplen, 0))
+        return 0;
+    if ((stmp = OPENSSL_secure_malloc(stmplen)) == NULL) {
+        ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
+        return 0;
+    }
+    if (!ecdh_plain_derive(vpecdhctx, stmp, &stmplen, stmplen))
+        goto err;
+
+    /* Do KDF stuff */
+    if (!ecdh_KDF_X9_63(secret, pecdhctx->kdf_outlen,
+                        stmp, stmplen,
+                        pecdhctx->kdf_ukm,
+                        pecdhctx->kdf_ukmlen,
+                        pecdhctx->kdf_md))
+        goto err;
+    *psecretlen = pecdhctx->kdf_outlen;
+    ret = 1;
+
+ err:
+    OPENSSL_secure_clear_free(stmp, stmplen);
+    return ret;
+}
+
+static
+int ecdh_derive(void *vpecdhctx, unsigned char *secret,
+                size_t *psecretlen, size_t outlen)
+{
+    PROV_ECDH_CTX *pecdhctx = (PROV_ECDH_CTX *)vpecdhctx;
+
+    switch (pecdhctx->kdf_type) {
+        case PROV_ECDH_KDF_NONE:
+            return ecdh_plain_derive(vpecdhctx, secret, psecretlen, outlen);
+        case PROV_ECDH_KDF_X9_63:
+            return ecdh_X9_63_kdf_derive(vpecdhctx, secret, psecretlen, outlen);
+    }
+
+    return 0;
+}
+
+
+
+const OSSL_DISPATCH ecdh_keyexch_functions[] = {
+    { OSSL_FUNC_KEYEXCH_NEWCTX, (void (*)(void))ecdh_newctx },
+    { OSSL_FUNC_KEYEXCH_INIT, (void (*)(void))ecdh_init },
+    { OSSL_FUNC_KEYEXCH_DERIVE, (void (*)(void))ecdh_derive },
+    { OSSL_FUNC_KEYEXCH_SET_PEER, (void (*)(void))ecdh_set_peer },
+    { OSSL_FUNC_KEYEXCH_FREECTX, (void (*)(void))ecdh_freectx },
+    { OSSL_FUNC_KEYEXCH_DUPCTX, (void (*)(void))ecdh_dupctx },
+    { OSSL_FUNC_KEYEXCH_SET_CTX_PARAMS, (void (*)(void))ecdh_set_ctx_params },
+    { OSSL_FUNC_KEYEXCH_SETTABLE_CTX_PARAMS,
+      (void (*)(void))ecdh_settable_ctx_params },
+    { OSSL_FUNC_KEYEXCH_GET_CTX_PARAMS, (void (*)(void))ecdh_get_ctx_params },
+    { OSSL_FUNC_KEYEXCH_GETTABLE_CTX_PARAMS,
+      (void (*)(void))ecdh_gettable_ctx_params },
+    { 0, NULL }
+};