fixes #4752 (Update libssh2 to 1.11.1)

1 files changed, 561 insertions, 0 deletions

diff --git a/libs/libssh2/src/wincng.h b/libs/libssh2/src/wincng.h
new file mode 100644
index 0000000000..a8d0d80575
--- /dev/null
+++ b/libs/libssh2/src/wincng.h
@@ -0,0 +1,561 @@
+#ifndef LIBSSH2_WINCNG_H
+#define LIBSSH2_WINCNG_H
+/*
+ * Copyright (C) Marc Hoersken <info@marc-hoersken.de>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms,
+ * with or without modification, are permitted provided
+ * that the following conditions are met:
+ *
+ *   Redistributions of source code must retain the above
+ *   copyright notice, this list of conditions and the
+ *   following disclaimer.
+ *
+ *   Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following
+ *   disclaimer in the documentation and/or other materials
+ *   provided with the distribution.
+ *
+ *   Neither the name of the copyright holder nor the names
+ *   of any other contributors may be used to endorse or
+ *   promote products derived from this software without
+ *   specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
+ * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
+ * OF SUCH DAMAGE.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#define LIBSSH2_CRYPTO_ENGINE libssh2_wincng
+
+/* required for cross-compilation against the w64 mingw-runtime package */
+#if defined(_WIN32_WINNT) && (_WIN32_WINNT < 0x0600)
+#undef _WIN32_WINNT
+#endif
+#ifndef _WIN32_WINNT
+#define _WIN32_WINNT 0x0600
+#endif
+
+#include <windows.h>
+#include <bcrypt.h>
+
+#define LIBSSH2_MD5 1
+
+#define LIBSSH2_HMAC_RIPEMD 0
+#define LIBSSH2_HMAC_SHA256 1
+#define LIBSSH2_HMAC_SHA512 1
+
+#define LIBSSH2_AES_CBC 1
+#define LIBSSH2_AES_CTR 1
+#define LIBSSH2_AES_GCM 0
+#define LIBSSH2_BLOWFISH 0
+#define LIBSSH2_RC4 1
+#define LIBSSH2_CAST 0
+#define LIBSSH2_3DES 1
+
+#define LIBSSH2_RSA 1
+#define LIBSSH2_RSA_SHA1 1
+#define LIBSSH2_RSA_SHA2 1
+#define LIBSSH2_DSA 1
+#define LIBSSH2_ED25519 0
+
+/*
+ * Conditionally enable ECDSA support.
+ *
+ * ECDSA support requires the use of
+ *
+ *   BCryptDeriveKey(..., BCRYPT_KDF_RAW_SECRET, ... )
+ *
+ * This functionality is only available as of Windows 10. To maintain
+ * backward compatibility, ECDSA support is therefore disabled
+ * by default and needs to be explicitly enabled using a build
+ * flag.
+ */
+#ifdef LIBSSH2_ECDSA_WINCNG
+#define LIBSSH2_ECDSA 1
+#else
+#define LIBSSH2_ECDSA 0
+#endif
+
+#include "crypto_config.h"
+
+#if LIBSSH2_MD5 || LIBSSH2_MD5_PEM
+#define MD5_DIGEST_LENGTH 16
+#endif
+#define SHA_DIGEST_LENGTH 20
+#define SHA256_DIGEST_LENGTH 32
+#define SHA384_DIGEST_LENGTH 48
+#define SHA512_DIGEST_LENGTH 64
+
+#define EC_MAX_POINT_LEN ((528 * 2 / 8) + 1)
+
+#if LIBSSH2_ECDSA
+#else
+#define _libssh2_ec_key void
+#endif
+
+/*******************************************************************/
+/*
+ * Windows CNG backend: Global context handles
+ */
+
+struct _libssh2_wincng_ctx {
+    BCRYPT_ALG_HANDLE hAlgRNG;
+    BCRYPT_ALG_HANDLE hAlgHashMD5;
+    BCRYPT_ALG_HANDLE hAlgHashSHA1;
+    BCRYPT_ALG_HANDLE hAlgHashSHA256;
+    BCRYPT_ALG_HANDLE hAlgHashSHA384;
+    BCRYPT_ALG_HANDLE hAlgHashSHA512;
+    BCRYPT_ALG_HANDLE hAlgHmacMD5;
+    BCRYPT_ALG_HANDLE hAlgHmacSHA1;
+    BCRYPT_ALG_HANDLE hAlgHmacSHA256;
+    BCRYPT_ALG_HANDLE hAlgHmacSHA384;
+    BCRYPT_ALG_HANDLE hAlgHmacSHA512;
+    BCRYPT_ALG_HANDLE hAlgRSA;
+    BCRYPT_ALG_HANDLE hAlgDSA;
+    BCRYPT_ALG_HANDLE hAlgAES_CBC;
+    BCRYPT_ALG_HANDLE hAlgAES_ECB;
+    BCRYPT_ALG_HANDLE hAlgRC4_NA;
+    BCRYPT_ALG_HANDLE hAlg3DES_CBC;
+    BCRYPT_ALG_HANDLE hAlgDH;
+    BCRYPT_ALG_HANDLE hAlgChacha20;
+#if LIBSSH2_ECDSA
+    BCRYPT_ALG_HANDLE hAlgECDH[3];  /* indexed by libssh2_curve_type */
+    BCRYPT_ALG_HANDLE hAlgECDSA[3]; /* indexed by libssh2_curve_type */
+#endif
+    volatile int hasAlgDHwithKDF; /* -1=no, 0=maybe, 1=yes */
+};
+
+extern struct _libssh2_wincng_ctx _libssh2_wincng;
+
+
+/*******************************************************************/
+/*
+ * Windows CNG backend: Generic functions
+ */
+
+#define libssh2_crypto_init() \
+    _libssh2_wincng_init()
+#define libssh2_crypto_exit() \
+    _libssh2_wincng_free()
+
+#define _libssh2_random(buf, len) \
+    _libssh2_wincng_random(buf, len)
+
+#define libssh2_prepare_iovec(vec, len)  /* Empty. */
+
+
+/*******************************************************************/
+/*
+ * Windows CNG backend: Hash structure
+ */
+
+typedef struct __libssh2_wincng_hash_ctx {
+    BCRYPT_HASH_HANDLE hHash;
+    unsigned char *pbHashObject;
+    ULONG dwHashObject;
+    ULONG cbHash;
+} _libssh2_wincng_hash_ctx;
+
+/*
+ * Windows CNG backend: Hash functions
+ */
+
+#define libssh2_sha1_ctx _libssh2_wincng_hash_ctx
+#define libssh2_sha1_init(ctx) \
+    (_libssh2_wincng_hash_init(ctx, _libssh2_wincng.hAlgHashSHA1, \
+                               SHA_DIGEST_LENGTH, NULL, 0) == 0)
+#define libssh2_sha1_update(ctx, data, datalen) \
+    (_libssh2_wincng_hash_update(&ctx, data, (ULONG) datalen) == 0)
+#define libssh2_sha1_final(ctx, hash) \
+    (_libssh2_wincng_hash_final(&ctx, hash) == 0)
+#define libssh2_sha1(data, datalen, hash) \
+    _libssh2_wincng_hash(data, datalen, _libssh2_wincng.hAlgHashSHA1, \
+                         hash, SHA_DIGEST_LENGTH)
+
+#define libssh2_sha256_ctx _libssh2_wincng_hash_ctx
+#define libssh2_sha256_init(ctx) \
+    (_libssh2_wincng_hash_init(ctx, _libssh2_wincng.hAlgHashSHA256, \
+                               SHA256_DIGEST_LENGTH, NULL, 0) == 0)
+#define libssh2_sha256_update(ctx, data, datalen) \
+    (_libssh2_wincng_hash_update(&ctx, data, (ULONG) datalen) == 0)
+#define libssh2_sha256_final(ctx, hash) \
+    (_libssh2_wincng_hash_final(&ctx, hash) == 0)
+#define libssh2_sha256(data, datalen, hash) \
+    _libssh2_wincng_hash(data, datalen, _libssh2_wincng.hAlgHashSHA256, \
+                         hash, SHA256_DIGEST_LENGTH)
+
+#define libssh2_sha384_ctx _libssh2_wincng_hash_ctx
+#define libssh2_sha384_init(ctx) \
+    (_libssh2_wincng_hash_init(ctx, _libssh2_wincng.hAlgHashSHA384, \
+                               SHA384_DIGEST_LENGTH, NULL, 0) == 0)
+#define libssh2_sha384_update(ctx, data, datalen) \
+    (_libssh2_wincng_hash_update(&ctx, data, (ULONG) datalen) == 0)
+#define libssh2_sha384_final(ctx, hash) \
+    (_libssh2_wincng_hash_final(&ctx, hash) == 0)
+#define libssh2_sha384(data, datalen, hash) \
+    _libssh2_wincng_hash(data, datalen, _libssh2_wincng.hAlgHashSHA384, \
+                         hash, SHA384_DIGEST_LENGTH)
+
+#define libssh2_sha512_ctx _libssh2_wincng_hash_ctx
+#define libssh2_sha512_init(ctx) \
+    (_libssh2_wincng_hash_init(ctx, _libssh2_wincng.hAlgHashSHA512, \
+                               SHA512_DIGEST_LENGTH, NULL, 0) == 0)
+#define libssh2_sha512_update(ctx, data, datalen) \
+    (_libssh2_wincng_hash_update(&ctx, data, (ULONG) datalen) == 0)
+#define libssh2_sha512_final(ctx, hash) \
+    (_libssh2_wincng_hash_final(&ctx, hash) == 0)
+#define libssh2_sha512(data, datalen, hash) \
+    _libssh2_wincng_hash(data, datalen, _libssh2_wincng.hAlgHashSHA512, \
+                         hash, SHA512_DIGEST_LENGTH)
+
+#if LIBSSH2_MD5 || LIBSSH2_MD5_PEM
+#define libssh2_md5_ctx _libssh2_wincng_hash_ctx
+#define libssh2_md5_init(ctx) \
+    (_libssh2_wincng_hash_init(ctx, _libssh2_wincng.hAlgHashMD5, \
+                               MD5_DIGEST_LENGTH, NULL, 0) == 0)
+#define libssh2_md5_update(ctx, data, datalen) \
+    (_libssh2_wincng_hash_update(&ctx, data, (ULONG) datalen) == 0)
+#define libssh2_md5_final(ctx, hash) \
+    (_libssh2_wincng_hash_final(&ctx, hash) == 0)
+#endif
+
+/*
+ * Windows CNG backend: HMAC functions
+ */
+
+#define libssh2_hmac_ctx _libssh2_wincng_hash_ctx
+
+
+/*******************************************************************/
+/*
+ * Windows CNG backend: Key Context structure
+ */
+
+typedef struct __libssh2_wincng_key_ctx {
+    BCRYPT_KEY_HANDLE hKey;
+    void *pbKeyObject;
+    DWORD cbKeyObject;
+} _libssh2_wincng_key_ctx;
+
+
+/*
+ * Windows CNG backend: RSA functions
+ */
+
+#define libssh2_rsa_ctx _libssh2_wincng_key_ctx
+#define _libssh2_rsa_new(rsactx, e, e_len, n, n_len, \
+                         d, d_len, p, p_len, q, q_len, \
+                         e1, e1_len, e2, e2_len, c, c_len) \
+    _libssh2_wincng_rsa_new(rsactx, e, e_len, n, n_len, \
+                            d, d_len, p, p_len, q, q_len, \
+                            e1, e1_len, e2, e2_len, c, c_len)
+#define _libssh2_rsa_new_private(rsactx, s, filename, passphrase) \
+    _libssh2_wincng_rsa_new_private(rsactx, s, filename, passphrase)
+#define _libssh2_rsa_new_private_frommemory(rsactx, s, filedata, \
+                                            filedata_len, passphrase) \
+    _libssh2_wincng_rsa_new_private_frommemory(rsactx, s, filedata, \
+                                               filedata_len, passphrase)
+#define _libssh2_rsa_sha1_sign(s, rsactx, hash, hash_len, sig, sig_len) \
+    _libssh2_wincng_rsa_sha1_sign(s, rsactx, hash, hash_len, sig, sig_len)
+#define _libssh2_rsa_sha2_sign(s, rsactx, hash, hash_len, sig, sig_len) \
+    _libssh2_wincng_rsa_sha2_sign(s, rsactx, hash, hash_len, sig, sig_len)
+#define _libssh2_rsa_sha1_verify(rsactx, sig, sig_len, m, m_len) \
+    _libssh2_wincng_rsa_sha1_verify(rsactx, sig, sig_len, m, m_len)
+#define _libssh2_rsa_sha2_verify(rsactx, hash_len, sig, sig_len, m, m_len) \
+    _libssh2_wincng_rsa_sha2_verify(rsactx, hash_len, sig, sig_len, m, m_len)
+#define _libssh2_rsa_free(rsactx) \
+    _libssh2_wincng_rsa_free(rsactx)
+
+/*
+ * Windows CNG backend: DSA functions
+ */
+
+#define libssh2_dsa_ctx _libssh2_wincng_key_ctx
+#define _libssh2_dsa_new(dsactx, p, p_len, q, q_len, \
+                         g, g_len, y, y_len, x, x_len) \
+    _libssh2_wincng_dsa_new(dsactx, p, p_len, q, q_len, \
+                            g, g_len, y, y_len, x, x_len)
+#define _libssh2_dsa_new_private(dsactx, s, filename, passphrase) \
+    _libssh2_wincng_dsa_new_private(dsactx, s, filename, passphrase)
+#define _libssh2_dsa_new_private_frommemory(dsactx, s, filedata, \
+                                            filedata_len, passphrase) \
+    _libssh2_wincng_dsa_new_private_frommemory(dsactx, s, filedata, \
+                                               filedata_len, passphrase)
+#define _libssh2_dsa_sha1_sign(dsactx, hash, hash_len, sig) \
+    _libssh2_wincng_dsa_sha1_sign(dsactx, hash, hash_len, sig)
+#define _libssh2_dsa_sha1_verify(dsactx, sig, m, m_len) \
+    _libssh2_wincng_dsa_sha1_verify(dsactx, sig, m, m_len)
+#define _libssh2_dsa_free(dsactx) \
+    _libssh2_wincng_dsa_free(dsactx)
+
+
+/*
+ * Windows CNG backend: ECDSA functions
+ */
+
+typedef enum {
+    LIBSSH2_EC_CURVE_NISTP256 = 0,
+    LIBSSH2_EC_CURVE_NISTP384 = 1,
+    LIBSSH2_EC_CURVE_NISTP521 = 2,
+} libssh2_curve_type;
+
+typedef struct __libssh2_wincng_ecdsa_ctx {
+    BCRYPT_KEY_HANDLE handle;
+    libssh2_curve_type curve;
+} _libssh2_wincng_ecdsa_key;
+
+#define libssh2_ecdsa_ctx _libssh2_wincng_ecdsa_key
+
+#if LIBSSH2_ECDSA
+#define _libssh2_ec_key _libssh2_wincng_ecdsa_key
+#endif
+
+void
+_libssh2_wincng_ecdsa_free(libssh2_ecdsa_ctx* ctx);
+
+#define _libssh2_ecdsa_create_key(session, privkey, pubkey_octal, \
+                                  pubkey_octal_len, curve) \
+    _libssh2_wincng_ecdh_create_key(session, privkey, pubkey_octal, \
+                                    pubkey_octal_len, curve)
+
+#define _libssh2_ecdsa_curve_name_with_octal_new(ctx, k, k_len, curve) \
+    _libssh2_wincng_ecdsa_curve_name_with_octal_new(ctx, k, k_len, curve)
+
+#define _libssh2_ecdh_gen_k(k, privkey, server_pubkey, server_pubkey_len) \
+    _libssh2_wincng_ecdh_gen_k(k, privkey, server_pubkey, server_pubkey_len)
+
+#define _libssh2_ecdsa_verify(ctx, r, r_len, s, s_len, m, m_len) \
+    _libssh2_wincng_ecdsa_verify(ctx, r, r_len, s, s_len, m, m_len)
+
+#define _libssh2_ecdsa_new_private(ctx, session, filename, passphrase) \
+    _libssh2_wincng_ecdsa_new_private(ctx, session, filename, passphrase)
+
+#define _libssh2_ecdsa_new_private_frommemory(ctx, session, filedata, \
+                                              filedata_len, passphrase) \
+    _libssh2_wincng_ecdsa_new_private_frommemory(ctx, session, filedata, \
+                                                 filedata_len, passphrase)
+
+#define _libssh2_ecdsa_sign(session, ctx, hash, hash_len, sign, sign_len) \
+    _libssh2_wincng_ecdsa_sign(session, ctx, hash, hash_len, sign, sign_len)
+
+#define _libssh2_ecdsa_get_curve_type(ctx) \
+    _libssh2_wincng_ecdsa_get_curve_type(ctx)
+
+#define _libssh2_ecdsa_free(ecdsactx) \
+    _libssh2_wincng_ecdsa_free(ecdsactx)
+
+
+/*
+ * Windows CNG backend: Key functions
+ */
+
+#define _libssh2_pub_priv_keyfile(s, m, m_len, p, p_len, pk, pw) \
+    _libssh2_wincng_pub_priv_keyfile(s, m, m_len, p, p_len, pk, pw)
+#define _libssh2_pub_priv_keyfilememory(s, m, m_len, p, p_len, \
+                                        pk, pk_len, pw) \
+    _libssh2_wincng_pub_priv_keyfilememory(s, m, m_len, p, p_len, \
+                                           pk, pk_len, pw)
+#define _libssh2_sk_pub_keyfilememory(s, m, m_len, p, p_len, alg, app, \
+                                      f, kh, kh_len, pk, pk_len, pw) \
+    _libssh2_wincng_sk_pub_keyfilememory(s, m, m_len, p, p_len, alg, app, \
+                                         f, kh, kh_len, pk, pk_len, pw)
+
+/*******************************************************************/
+/*
+ * Windows CNG backend: Cipher Context structure
+ */
+
+struct _libssh2_wincng_cipher_ctx {
+    BCRYPT_KEY_HANDLE hKey;
+    unsigned char *pbKeyObject;
+    unsigned char *pbIV;
+    unsigned char *pbCtr;
+    ULONG dwKeyObject;
+    ULONG dwIV;
+    ULONG dwBlockLength;
+    ULONG dwCtrLength;
+};
+
+#define _libssh2_cipher_ctx struct _libssh2_wincng_cipher_ctx
+
+/*
+ * Windows CNG backend: Cipher Type structure
+ */
+
+struct _libssh2_wincng_cipher_type {
+    BCRYPT_ALG_HANDLE *phAlg;
+    ULONG dwKeyLength;
+    int useIV;      /* TODO: Convert to bool when a C89 compatible bool type
+                       is defined */
+    int ctrMode;
+};
+
+#define _libssh2_cipher_type(type) struct _libssh2_wincng_cipher_type type
+
+#define _libssh2_cipher_aes256ctr { &_libssh2_wincng.hAlgAES_ECB, 32, 0, 1 }
+#define _libssh2_cipher_aes192ctr { &_libssh2_wincng.hAlgAES_ECB, 24, 0, 1 }
+#define _libssh2_cipher_aes128ctr { &_libssh2_wincng.hAlgAES_ECB, 16, 0, 1 }
+#define _libssh2_cipher_aes256    { &_libssh2_wincng.hAlgAES_CBC, 32, 1, 0 }
+#define _libssh2_cipher_aes192    { &_libssh2_wincng.hAlgAES_CBC, 24, 1, 0 }
+#define _libssh2_cipher_aes128    { &_libssh2_wincng.hAlgAES_CBC, 16, 1, 0 }
+#define _libssh2_cipher_arcfour   { &_libssh2_wincng.hAlgRC4_NA, 16, 0, 0 }
+#define _libssh2_cipher_3des      { &_libssh2_wincng.hAlg3DES_CBC, 24, 1, 0 }
+#define _libssh2_cipher_chacha20  { &_libssh2_wincng.hAlgChacha20, 24, 1, 0 }
+
+/*
+ * Windows CNG backend: Cipher functions
+ */
+
+#define _libssh2_cipher_init(ctx, type, iv, secret, encrypt) \
+    _libssh2_wincng_cipher_init(ctx, type, iv, secret, encrypt)
+#define _libssh2_cipher_crypt(ctx, type, encrypt, block, blocklen, fl) \
+    _libssh2_wincng_cipher_crypt(ctx, type, encrypt, block, blocklen, fl)
+#define _libssh2_cipher_dtor(ctx) \
+    _libssh2_wincng_cipher_dtor(ctx)
+
+/*******************************************************************/
+/*
+ * Windows CNG backend: BigNumber Context
+ */
+
+#define _libssh2_bn_ctx int /* not used */
+#define _libssh2_bn_ctx_new() 0 /* not used */
+#define _libssh2_bn_ctx_free(bnctx) ((void)0) /* not used */
+
+
+/*******************************************************************/
+/*
+ * Windows CNG backend: BigNumber structure
+ */
+
+struct _libssh2_wincng_bignum {
+    unsigned char *bignum;
+    ULONG length;
+};
+
+#define _libssh2_bn struct _libssh2_wincng_bignum
+
+/*
+ * Windows CNG backend: BigNumber functions
+ */
+
+#define _libssh2_bn_init() \
+    _libssh2_wincng_bignum_init()
+#define _libssh2_bn_init_from_bin() \
+    _libssh2_bn_init()
+#define _libssh2_bn_set_word(bn, word) \
+    _libssh2_wincng_bignum_set_word(bn, word)
+#define _libssh2_bn_from_bin(bn, len, bin) \
+    _libssh2_wincng_bignum_from_bin(bn, (ULONG) len, bin)
+#define _libssh2_bn_to_bin(bn, bin) \
+    _libssh2_wincng_bignum_to_bin(bn, bin)
+#define _libssh2_bn_bytes(bn) bn->length
+#define _libssh2_bn_bits(bn) \
+    _libssh2_wincng_bignum_bits(bn)
+#define _libssh2_bn_free(bn) \
+    _libssh2_wincng_bignum_free(bn)
+
+/*
+ * Windows CNG backend: Diffie-Hellman support
+ */
+
+/* Default generate and safe prime sizes for
+   diffie-hellman-group-exchange-sha1 */
+#define LIBSSH2_DH_GEX_MINGROUP     2048
+#define LIBSSH2_DH_GEX_OPTGROUP     4096
+#define LIBSSH2_DH_GEX_MAXGROUP     4096
+
+#define LIBSSH2_DH_MAX_MODULUS_BITS 16384
+
+typedef struct {
+    /* holds our private and public key components */
+    BCRYPT_KEY_HANDLE dh_handle;
+    /* records the parsed out modulus and generator
+     * parameters that are shared  with the peer */
+    BCRYPT_DH_PARAMETER_HEADER *dh_params;
+    /* records the parsed out private key component for
+     * fallback if the DH API raw KDF is not supported */
+    struct _libssh2_wincng_bignum *dh_privbn;
+} _libssh2_dh_ctx;
+
+#define libssh2_dh_init(dhctx) _libssh2_dh_init(dhctx)
+#define libssh2_dh_key_pair(dhctx, public, g, p, group_order, bnctx) \
+    _libssh2_dh_key_pair(dhctx, public, g, p, group_order)
+#define libssh2_dh_secret(dhctx, secret, f, p, bnctx) \
+    _libssh2_dh_secret(dhctx, secret, f, p)
+#define libssh2_dh_dtor(dhctx) _libssh2_dh_dtor(dhctx)
+
+/*******************************************************************/
+/*
+ * Windows CNG backend: forward declarations
+ */
+void _libssh2_wincng_init(void);
+void _libssh2_wincng_free(void);
+int _libssh2_wincng_random(void *buf, size_t len);
+
+int
+_libssh2_wincng_hash_init(_libssh2_wincng_hash_ctx *ctx,
+                          BCRYPT_ALG_HANDLE hAlg, ULONG hashlen,
+                          unsigned char *key, ULONG keylen);
+int
+_libssh2_wincng_hash_update(_libssh2_wincng_hash_ctx *ctx,
+                            const void *data, ULONG datalen);
+int
+_libssh2_wincng_hash_final(_libssh2_wincng_hash_ctx *ctx,
+                           unsigned char *hash);
+int
+_libssh2_wincng_hash(const unsigned char *data, ULONG datalen,
+                     BCRYPT_ALG_HANDLE hAlg,
+                     unsigned char *hash, ULONG hashlen);
+
+void
+_libssh2_wincng_rsa_free(libssh2_rsa_ctx *rsa);
+
+#if LIBSSH2_DSA
+void
+_libssh2_wincng_dsa_free(libssh2_dsa_ctx *dsa);
+#endif
+
+void
+_libssh2_wincng_cipher_dtor(_libssh2_cipher_ctx *ctx);
+
+_libssh2_bn *
+_libssh2_wincng_bignum_init(void);
+int
+_libssh2_wincng_bignum_set_word(_libssh2_bn *bn, ULONG word);
+ULONG
+_libssh2_wincng_bignum_bits(const _libssh2_bn *bn);
+int
+_libssh2_wincng_bignum_from_bin(_libssh2_bn *bn, ULONG len,
+                                const unsigned char *bin);
+int
+_libssh2_wincng_bignum_to_bin(const _libssh2_bn *bn, unsigned char *bin);
+void
+_libssh2_wincng_bignum_free(_libssh2_bn *bn);
+extern void
+_libssh2_dh_init(_libssh2_dh_ctx *dhctx);
+extern int
+_libssh2_dh_key_pair(_libssh2_dh_ctx *dhctx, _libssh2_bn *public,
+                     _libssh2_bn *g, _libssh2_bn *p, int group_order);
+extern int
+_libssh2_dh_secret(_libssh2_dh_ctx *dhctx, _libssh2_bn *secret,
+                   _libssh2_bn *f, _libssh2_bn *p);
+extern void
+_libssh2_dh_dtor(_libssh2_dh_ctx *dhctx);
+
+#endif /* LIBSSH2_WINCNG_H */