/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 *    Copyright 2020 (c) Wind River Systems, Inc.
 *    Copyright 2020 (c) basysKom GmbH
 */

#include <open62541/plugin/securitypolicy_default.h>
#include <open62541/util.h>

#if defined(UA_ENABLE_ENCRYPTION_OPENSSL) || defined(UA_ENABLE_ENCRYPTION_LIBRESSL)

#include "securitypolicy_openssl_common.h"

#include <openssl/hmac.h>
#include <openssl/sha.h>
#include <openssl/rsa.h>
#include <openssl/x509.h>
#include <openssl/rand.h>
#include <openssl/rsa.h>

#define UA_SHA256_LENGTH 32    /* 256 bit */
#define UA_SECURITYPOLICY_BASIC256SHA256_RSAPADDING_LEN 42
#define UA_SECURITYPOLICY_BASIC256SHA256_SYM_SIGNING_KEY_LENGTH 32
#define UA_SECURITYPOLICY_BASIC256SHA256_SYM_ENCRYPTION_KEY_LENGTH 32
#define UA_SECURITYPOLICY_BASIC256SHA256_SYM_ENCRYPTION_BLOCK_SIZE 16
#define UA_SECURITYPOLICY_BASIC256SHA256_SYM_PLAIN_TEXT_BLOCK_SIZE 16
#define UA_SECURITYPOLICY_BASIC256SHA256_MINASYMKEYLENGTH 256
#define UA_SECURITYPOLICY_BASIC256SHA256_MAXASYMKEYLENGTH 512

typedef struct {
    EVP_PKEY *localPrivateKey;
    UA_ByteString localCertThumbprint;
    const UA_Logger *logger;    
} Policy_Context_Basic256Sha256;

typedef struct {
    UA_ByteString localSymSigningKey;  
    UA_ByteString localSymEncryptingKey; 
    UA_ByteString localSymIv; 
    UA_ByteString remoteSymSigningKey;
    UA_ByteString remoteSymEncryptingKey;
    UA_ByteString remoteSymIv;

    Policy_Context_Basic256Sha256 *policyContext;
    UA_ByteString remoteCertificate;
    X509 *remoteCertificateX509; /* X509 */      
} Channel_Context_Basic256Sha256;

/* create the policy context */

static UA_StatusCode 
UA_Policy_New_Context(UA_SecurityPolicy * securityPolicy,
                       const UA_ByteString localPrivateKey,
                       const UA_Logger *logger) {
    Policy_Context_Basic256Sha256 *context = (Policy_Context_Basic256Sha256 *)
        UA_malloc(sizeof(Policy_Context_Basic256Sha256));
    if(context == NULL)
        return UA_STATUSCODE_BADOUTOFMEMORY;
    context->localPrivateKey = UA_OpenSSL_LoadPrivateKey(&localPrivateKey);

    if(!context->localPrivateKey) {
        UA_free(context);
        return UA_STATUSCODE_BADINVALIDARGUMENT;
    }

    UA_StatusCode retval =
        UA_Openssl_X509_GetCertificateThumbprint(&securityPolicy->localCertificate,
                                                 &context->localCertThumbprint, true);
    if(retval != UA_STATUSCODE_GOOD) {
        EVP_PKEY_free(context->localPrivateKey);
        UA_free(context);
        return retval; 
    }

    context->logger = logger;
    securityPolicy->policyContext = context;
    return UA_STATUSCODE_GOOD;
}

/* Clear the policy context */
static void
UA_Policy_Clear_Context(UA_SecurityPolicy *policy) {
    if(policy == NULL)
        return;

    UA_ByteString_clear(&policy->localCertificate);

    /* Delete all allocated members in the context */
    Policy_Context_Basic256Sha256 *pc =
        (Policy_Context_Basic256Sha256 *) policy->policyContext;
    EVP_PKEY_free(pc->localPrivateKey);
    UA_ByteString_clear(&pc->localCertThumbprint);
    UA_free(pc);        
    return;
}

/* create the channel context */

static UA_StatusCode 
UA_ChannelModule_New_Context(const UA_SecurityPolicy * securityPolicy,
                             const UA_ByteString * remoteCertificate,
                             void ** channelContext) {
    if(securityPolicy == NULL || remoteCertificate == NULL || channelContext == NULL)
        return UA_STATUSCODE_BADINTERNALERROR;                                  

    Channel_Context_Basic256Sha256 *context = (Channel_Context_Basic256Sha256 *)
        UA_malloc(sizeof(Channel_Context_Basic256Sha256));
    if(context == NULL)
        return UA_STATUSCODE_BADOUTOFMEMORY;

    UA_ByteString_init(&context->localSymSigningKey);
    UA_ByteString_init(&context->localSymEncryptingKey);
    UA_ByteString_init(&context->localSymIv);
    UA_ByteString_init(&context->remoteSymSigningKey);
    UA_ByteString_init(&context->remoteSymEncryptingKey);
    UA_ByteString_init(&context->remoteSymIv);

    UA_StatusCode retval =
        UA_copyCertificate(&context->remoteCertificate, remoteCertificate);
    if(retval != UA_STATUSCODE_GOOD) {
        UA_free(context);
        return retval;
    }

    /* decode to X509 */
    context->remoteCertificateX509 = UA_OpenSSL_LoadCertificate(&context->remoteCertificate);
    if(context->remoteCertificateX509 == NULL) {
        UA_ByteString_clear(&context->remoteCertificate); 
        UA_free(context);
        return UA_STATUSCODE_BADINTERNALERROR;
    }

    context->policyContext =
        (Policy_Context_Basic256Sha256 *)securityPolicy->policyContext;
    *channelContext = context;

    UA_LOG_INFO(securityPolicy->logger, UA_LOGCATEGORY_SECURITYPOLICY, 
                "The basic256sha256 security policy channel with openssl is created.");

    return UA_STATUSCODE_GOOD;
}

/* delete the channel context */

static void 
UA_ChannelModule_Delete_Context(void * channelContext) {
    if(!channelContext)
        return;
    
    Channel_Context_Basic256Sha256 * cc = (Channel_Context_Basic256Sha256 *)channelContext;
    X509_free(cc->remoteCertificateX509);                                           
    UA_ByteString_clear(&cc->remoteCertificate); 
    UA_ByteString_clear(&cc->localSymSigningKey);
    UA_ByteString_clear(&cc->localSymEncryptingKey);
    UA_ByteString_clear(&cc->localSymIv);
    UA_ByteString_clear(&cc->remoteSymSigningKey);
    UA_ByteString_clear(&cc->remoteSymEncryptingKey);
    UA_ByteString_clear(&cc->remoteSymIv);
    
    UA_LOG_INFO(cc->policyContext->logger, UA_LOGCATEGORY_SECURITYPOLICY, 
                "The basic256sha256 security policy channel with openssl is deleted.");   
    UA_free(cc);
}

/* Verifies the signature of the message using the provided keys in the context.
 * AsymmetricSignatureAlgorithm_RSA-PKCS15-SHA2-256 */
static UA_StatusCode 
UA_AsySig_Basic256Sha256_Verify(void *channelContext, 
                                const UA_ByteString *message,
                                const UA_ByteString *signature) {
    if(message == NULL || signature == NULL || channelContext == NULL)
        return UA_STATUSCODE_BADINTERNALERROR;

    Channel_Context_Basic256Sha256 * cc =
        (Channel_Context_Basic256Sha256 *) channelContext;
    return UA_OpenSSL_RSA_PKCS1_V15_SHA256_Verify(message, cc->remoteCertificateX509,
                                                  signature);
}

/* Compares the supplied certificate with the certificate 
 * in the endpoint context 
 */

static UA_StatusCode
UA_compareCertificateThumbprint(const UA_SecurityPolicy * securityPolicy,
                                const UA_ByteString * certificateThumbprint) {
    if(securityPolicy == NULL || certificateThumbprint == NULL)
        return UA_STATUSCODE_BADINVALIDARGUMENT;
    Policy_Context_Basic256Sha256 *pc = (Policy_Context_Basic256Sha256 *)
                                        securityPolicy->policyContext;
    if(!UA_ByteString_equal(certificateThumbprint, &pc->localCertThumbprint))
        return UA_STATUSCODE_BADCERTIFICATEINVALID;
    return UA_STATUSCODE_GOOD;
}

/* Generates a thumbprint for the specified certificate */

static UA_StatusCode 
UA_makeCertificateThumbprint(const UA_SecurityPolicy * securityPolicy,
                             const UA_ByteString * certificate,
                             UA_ByteString * thumbprint) {
    return UA_Openssl_X509_GetCertificateThumbprint(certificate, thumbprint, false); 
}

static UA_StatusCode 
UA_Asym_Basic256Sha256_Decrypt(void * channelContext, UA_ByteString * data) {
    if(channelContext == NULL || data == NULL)
        return UA_STATUSCODE_BADINVALIDARGUMENT;

    Channel_Context_Basic256Sha256 * cc =
        (Channel_Context_Basic256Sha256 *) channelContext;
    return UA_Openssl_RSA_Oaep_Decrypt(data, cc->policyContext->localPrivateKey);
}

static size_t
UA_Asym_Basic256Sha256_getRemoteSignatureSize(const void *channelContext) {
    if(channelContext == NULL)
        return UA_STATUSCODE_BADINTERNALERROR;

    const Channel_Context_Basic256Sha256 * cc =
        (const Channel_Context_Basic256Sha256 *) channelContext;
    UA_Int32 keyLen = 0;
    UA_Openssl_RSA_Public_GetKeyLength(cc->remoteCertificateX509, &keyLen);
    return (size_t) keyLen; 
}

static size_t 
UA_AsySig_Basic256Sha256_getLocalSignatureSize(const void *channelContext) {
    if(channelContext == NULL)
        return UA_STATUSCODE_BADINTERNALERROR;

    const Channel_Context_Basic256Sha256 *cc =
        (const Channel_Context_Basic256Sha256 *) channelContext;
    Policy_Context_Basic256Sha256 * pc = cc->policyContext;
    UA_Int32 keyLen = 0;
    UA_Openssl_RSA_Private_GetKeyLength(pc->localPrivateKey, &keyLen);
    return (size_t) keyLen; 
}

static size_t
UA_AsymEn_Basic256Sha256_getRemotePlainTextBlockSize(const void *channelContext) {
    if(channelContext == NULL)
        return UA_STATUSCODE_BADINTERNALERROR;

    const Channel_Context_Basic256Sha256 *cc =
        (const Channel_Context_Basic256Sha256 *) channelContext;
    UA_Int32 keyLen = 0;
    UA_Openssl_RSA_Public_GetKeyLength(cc->remoteCertificateX509, &keyLen);
    return (size_t) keyLen - UA_SECURITYPOLICY_BASIC256SHA256_RSAPADDING_LEN;
}

static size_t 
UA_AsymEn_Basic256Sha256_getRemoteBlockSize(const void *channelContext) {
    if(channelContext == NULL)
        return UA_STATUSCODE_BADINTERNALERROR;

    const Channel_Context_Basic256Sha256 * cc =
        (const Channel_Context_Basic256Sha256 *) channelContext;
    UA_Int32 keyLen = 0;
    UA_Openssl_RSA_Public_GetKeyLength(cc->remoteCertificateX509, &keyLen);
    return (size_t) keyLen;
}

static size_t
UA_AsymEn_Basic256Sha256_getRemoteKeyLength(const void *channelContext) {
    if(channelContext == NULL)
        return UA_STATUSCODE_BADINTERNALERROR;

    const Channel_Context_Basic256Sha256 *cc =
        (const Channel_Context_Basic256Sha256 *) channelContext;
    UA_Int32 keyLen = 0;
    UA_Openssl_RSA_Public_GetKeyLength(cc->remoteCertificateX509, &keyLen);
    return (size_t) keyLen * 8;
}

static UA_StatusCode
UA_Sym_Basic256Sha256_generateNonce(void *policyContext,
                                    UA_ByteString *out) {
    UA_Int32 rc = RAND_bytes(out->data, (int) out->length);
    if(rc != 1)
        return UA_STATUSCODE_BADUNEXPECTEDERROR;
    return UA_STATUSCODE_GOOD;                                         
}

static size_t 
UA_SymEn_Basic256Sha256_getLocalKeyLength(const void *channelContext) {
    /* 32 bytes 256 bits */
    return UA_SECURITYPOLICY_BASIC256SHA256_SYM_ENCRYPTION_KEY_LENGTH; 
}

static size_t 
UA_SymSig_Basic256Sha256_getLocalKeyLength(const void *channelContext) {
    /* 32 bytes 256 bits */                                                
    return UA_SECURITYPOLICY_BASIC256SHA256_SYM_SIGNING_KEY_LENGTH; 
}

static UA_StatusCode
UA_Sym_Basic256Sha256_generateKey(void *policyContext,
                                  const UA_ByteString *secret,
                                  const UA_ByteString *seed,
                                  UA_ByteString *out) {
    return UA_Openssl_Random_Key_PSHA256_Derive(secret, seed, out);
}

static UA_StatusCode
UA_ChannelModule_Basic256Sha256_setLocalSymSigningKey(void * channelContext,
                                                      const UA_ByteString * key) {
    if(key == NULL || channelContext == NULL)
        return UA_STATUSCODE_BADINTERNALERROR;
    Channel_Context_Basic256Sha256 * cc = (Channel_Context_Basic256Sha256 *) channelContext;
    UA_ByteString_clear(&cc->localSymSigningKey);
    return UA_ByteString_copy(key, &cc->localSymSigningKey);
}

static UA_StatusCode
UA_ChannelM_Basic256Sha256_setLocalSymEncryptingKey(void * channelContext,
                                                    const UA_ByteString * key) {
    if(key == NULL || channelContext == NULL)
        return UA_STATUSCODE_BADINTERNALERROR;
    Channel_Context_Basic256Sha256 * cc = (Channel_Context_Basic256Sha256 *) channelContext;
    UA_ByteString_clear(&cc->localSymEncryptingKey);
    return UA_ByteString_copy(key, &cc->localSymEncryptingKey);
}

static UA_StatusCode
UA_ChannelM_Basic256Sha256_setLocalSymIv(void * channelContext,
                                         const UA_ByteString * iv) {
    if(iv == NULL || channelContext == NULL)
        return UA_STATUSCODE_BADINTERNALERROR;
    Channel_Context_Basic256Sha256 * cc = (Channel_Context_Basic256Sha256 *) channelContext;
    UA_ByteString_clear(&cc->localSymIv);
    return UA_ByteString_copy(iv, &cc->localSymIv);
}

static size_t
UA_SymEn_Basic256Sha256_getRemoteKeyLength(const void * channelContext) {
    /* 32 bytes 256 bits */
    return UA_SECURITYPOLICY_BASIC256SHA256_SYM_ENCRYPTION_KEY_LENGTH; 
}

static size_t
UA_SymEn_Basic256Sha256_getBlockSize(const void *channelContext) {
    return UA_SECURITYPOLICY_BASIC256SHA256_SYM_ENCRYPTION_BLOCK_SIZE;
}

static size_t
UA_SymSig_Basic256Sha256_getRemoteKeyLength(const void * channelContext) {
    /* 32 bytes 256 bits */                                                
    return UA_SECURITYPOLICY_BASIC256SHA256_SYM_SIGNING_KEY_LENGTH;
}

static UA_StatusCode
UA_ChannelM_Basic256Sha256_setRemoteSymSigningKey(void *channelContext,
                                                  const UA_ByteString * key) {
    if(key == NULL || channelContext == NULL)
        return UA_STATUSCODE_BADINTERNALERROR;
    Channel_Context_Basic256Sha256 * cc = (Channel_Context_Basic256Sha256 *) channelContext;
    UA_ByteString_clear(&cc->remoteSymSigningKey);
    return UA_ByteString_copy(key, &cc->remoteSymSigningKey);
}

static UA_StatusCode
UA_ChannelM_Basic256Sha256_setRemoteSymEncryptingKey(void *channelContext,
                                                     const UA_ByteString * key) {
    if(key == NULL || channelContext == NULL)
        return UA_STATUSCODE_BADINTERNALERROR;
    Channel_Context_Basic256Sha256 * cc = (Channel_Context_Basic256Sha256 *) channelContext;
    UA_ByteString_clear(&cc->remoteSymEncryptingKey);
    return UA_ByteString_copy(key, &cc->remoteSymEncryptingKey);
}

static UA_StatusCode
UA_ChannelM_Basic256Sha256_setRemoteSymIv(void *channelContext,
                                          const UA_ByteString * key) {
    if(key == NULL || channelContext == NULL)
        return UA_STATUSCODE_BADINTERNALERROR;
    Channel_Context_Basic256Sha256 * cc = (Channel_Context_Basic256Sha256 *) channelContext;
    UA_ByteString_clear(&cc->remoteSymIv);
    return UA_ByteString_copy(key, &cc->remoteSymIv);
}

static UA_StatusCode
UA_AsySig_Basic256Sha256_sign(void *channelContext, const UA_ByteString * message,
                              UA_ByteString *signature) {
    if(channelContext == NULL || message == NULL || signature == NULL)
        return UA_STATUSCODE_BADINTERNALERROR; 
    Channel_Context_Basic256Sha256 *cc = (Channel_Context_Basic256Sha256 *) channelContext;
    Policy_Context_Basic256Sha256 *pc = cc->policyContext;
    return UA_Openssl_RSA_PKCS1_V15_SHA256_Sign(message, pc->localPrivateKey, signature);
}

static UA_StatusCode
UA_AsymEn_Basic256Sha256_encrypt(void *channelContext, UA_ByteString *data) {
    if(channelContext == NULL || data == NULL)
        return UA_STATUSCODE_BADINTERNALERROR; 
    Channel_Context_Basic256Sha256 * cc =
        (Channel_Context_Basic256Sha256 *) channelContext;    
    return UA_Openssl_RSA_OAEP_Encrypt(data, UA_SECURITYPOLICY_BASIC256SHA256_RSAPADDING_LEN,
                                       cc->remoteCertificateX509);
}

static size_t
UA_SymSig_Basic256Sha256_getRemoteSignatureSize(const void *channelContext) {
    return UA_SHA256_LENGTH;
}

static UA_StatusCode
UA_SymSig_Basic256Sha256_verify(void *channelContext, const UA_ByteString *message,
                                const UA_ByteString *signature) {
    if(channelContext == NULL || message == NULL || signature == NULL)
        return UA_STATUSCODE_BADINTERNALERROR;
    
    Channel_Context_Basic256Sha256 * cc = (Channel_Context_Basic256Sha256 *) channelContext;
    return UA_OpenSSL_HMAC_SHA256_Verify(message, &cc->remoteSymSigningKey, signature);   
}

static UA_StatusCode 
UA_SymSig_Basic256Sha256_sign(void *channelContext, const UA_ByteString *message,
                              UA_ByteString *signature) {
    if(channelContext == NULL || message == NULL || signature == NULL)
        return UA_STATUSCODE_BADINTERNALERROR;
    
    Channel_Context_Basic256Sha256 * cc = (Channel_Context_Basic256Sha256 *) channelContext;
    return UA_OpenSSL_HMAC_SHA256_Sign(message, &cc->localSymSigningKey, signature);
}

static size_t
UA_SymSig_Basic256Sha256_getLocalSignatureSize(const void * channelContext) {
    return UA_SHA256_LENGTH;
}

static UA_StatusCode
UA_SymEn_Basic256Sha256_decrypt(void *channelContext, UA_ByteString *data) {
    if(channelContext == NULL || data == NULL)
        return UA_STATUSCODE_BADINTERNALERROR;
    Channel_Context_Basic256Sha256 * cc = (Channel_Context_Basic256Sha256 *) channelContext;
    return UA_OpenSSL_AES_256_CBC_Decrypt(&cc->remoteSymIv,
                                          &cc->remoteSymEncryptingKey, data);
}

static UA_StatusCode
UA_SymEn_Basic256Sha256_encrypt(void *channelContext, UA_ByteString *data) {
    if(channelContext == NULL || data == NULL)
        return UA_STATUSCODE_BADINTERNALERROR;
    
    Channel_Context_Basic256Sha256 * cc = (Channel_Context_Basic256Sha256 *) channelContext;
    return UA_OpenSSL_AES_256_CBC_Encrypt(&cc->localSymIv, &cc->localSymEncryptingKey, data);
}

static UA_StatusCode
UA_ChannelM_Basic256Sha256_compareCertificate(const void *channelContext,
                                              const UA_ByteString *certificate) {
    if(channelContext == NULL || certificate == NULL)
        return UA_STATUSCODE_BADINTERNALERROR;
    
    const Channel_Context_Basic256Sha256 * cc =
        (const Channel_Context_Basic256Sha256 *) channelContext;
    return UA_OpenSSL_X509_compare(certificate, cc->remoteCertificateX509);
}

static size_t 
UA_AsymEn_Basic256Sha256_getLocalKeyLength(const void *channelContext) {
    if(channelContext == NULL)
        return UA_STATUSCODE_BADINTERNALERROR;

    const Channel_Context_Basic256Sha256 * cc =
        (const Channel_Context_Basic256Sha256 *) channelContext;
    Policy_Context_Basic256Sha256 *pc = cc->policyContext;
    UA_Int32 keyLen = 0;
    UA_Openssl_RSA_Private_GetKeyLength(pc->localPrivateKey, &keyLen);
    return (size_t) keyLen * 8; 
}

/* the main entry of Basic256Sha256 */

UA_StatusCode
UA_SecurityPolicy_Basic256Sha256(UA_SecurityPolicy *policy,
                                 const UA_ByteString localCertificate,
                                 const UA_ByteString localPrivateKey, 
                                 const UA_Logger *logger) {
    UA_SecurityPolicyAsymmetricModule *asymmetricModule = &policy->asymmetricModule;
    UA_SecurityPolicySymmetricModule *symmetricModule = &policy->symmetricModule;
    UA_SecurityPolicyChannelModule *channelModule = &policy->channelModule; 
    UA_LOG_INFO(logger, UA_LOGCATEGORY_SECURITYPOLICY, 
                "The basic256sha256 security policy with openssl is added.");

    UA_Openssl_Init();
    memset(policy, 0, sizeof(UA_SecurityPolicy));
    policy->logger = logger;
    policy->policyUri =
        UA_STRING("http://opcfoundation.org/UA/SecurityPolicy#Basic256Sha256\0");

    /* Set ChannelModule context  */
    channelModule->newContext = UA_ChannelModule_New_Context;
    channelModule->deleteContext = UA_ChannelModule_Delete_Context;
    channelModule->setLocalSymSigningKey =
        UA_ChannelModule_Basic256Sha256_setLocalSymSigningKey;
    channelModule->setLocalSymEncryptingKey =
        UA_ChannelM_Basic256Sha256_setLocalSymEncryptingKey;
    channelModule->setLocalSymIv = UA_ChannelM_Basic256Sha256_setLocalSymIv;
    channelModule->setRemoteSymSigningKey =
        UA_ChannelM_Basic256Sha256_setRemoteSymSigningKey;
    channelModule->setRemoteSymEncryptingKey =
        UA_ChannelM_Basic256Sha256_setRemoteSymEncryptingKey;
    channelModule->setRemoteSymIv = UA_ChannelM_Basic256Sha256_setRemoteSymIv;
    channelModule->compareCertificate = UA_ChannelM_Basic256Sha256_compareCertificate;
    UA_StatusCode retval =
        UA_OpenSSL_LoadLocalCertificate(&localCertificate, &policy->localCertificate);
    if(retval != UA_STATUSCODE_GOOD)
        return retval;

    /* AsymmetricModule - signature algorithm */
    UA_SecurityPolicySignatureAlgorithm *asySigAlgorithm =
        &asymmetricModule->cryptoModule.signatureAlgorithm;
    asySigAlgorithm->uri = UA_STRING("http://www.w3.org/2001/04/xmldsig-more#rsa-sha256\0");
    asySigAlgorithm->verify = UA_AsySig_Basic256Sha256_Verify;
    asySigAlgorithm->sign = UA_AsySig_Basic256Sha256_sign;
    asySigAlgorithm->getLocalSignatureSize = UA_AsySig_Basic256Sha256_getLocalSignatureSize;
    asySigAlgorithm->getRemoteSignatureSize = UA_Asym_Basic256Sha256_getRemoteSignatureSize;
    asySigAlgorithm->getLocalKeyLength = NULL;
    asySigAlgorithm->getRemoteKeyLength = NULL;

    /* AsymmetricModule encryption algorithm */
    UA_SecurityPolicyEncryptionAlgorithm *asymEncryAlg =
        &asymmetricModule->cryptoModule.encryptionAlgorithm;
    asymEncryAlg->uri = UA_STRING("http://www.w3.org/2001/04/xmlenc#rsa-oaep\0");
    asymEncryAlg->encrypt = UA_AsymEn_Basic256Sha256_encrypt;
    asymEncryAlg->decrypt = UA_Asym_Basic256Sha256_Decrypt;
    asymEncryAlg->getLocalKeyLength = UA_AsymEn_Basic256Sha256_getLocalKeyLength;
    asymEncryAlg->getRemoteKeyLength = UA_AsymEn_Basic256Sha256_getRemoteKeyLength;
    asymEncryAlg->getRemoteBlockSize = UA_AsymEn_Basic256Sha256_getRemoteBlockSize;
    asymEncryAlg->getRemotePlainTextBlockSize = 
            UA_AsymEn_Basic256Sha256_getRemotePlainTextBlockSize;

    /* AsymmetricModule */
    asymmetricModule->compareCertificateThumbprint = UA_compareCertificateThumbprint;
    asymmetricModule->makeCertificateThumbprint = UA_makeCertificateThumbprint;

    /* SymmetricModule */
    symmetricModule->secureChannelNonceLength = 32;
    symmetricModule->generateNonce = UA_Sym_Basic256Sha256_generateNonce;
    symmetricModule->generateKey = UA_Sym_Basic256Sha256_generateKey;

    /* Symmetric encryption Algorithm */
    UA_SecurityPolicyEncryptionAlgorithm *symEncryptionAlgorithm =
        &symmetricModule->cryptoModule.encryptionAlgorithm;
    symEncryptionAlgorithm->uri =
        UA_STRING("http://www.w3.org/2001/04/xmlenc#aes256-cbc\0");        
    symEncryptionAlgorithm->encrypt = UA_SymEn_Basic256Sha256_encrypt;
    symEncryptionAlgorithm->decrypt = UA_SymEn_Basic256Sha256_decrypt;
    symEncryptionAlgorithm->getLocalKeyLength = UA_SymEn_Basic256Sha256_getLocalKeyLength;
    symEncryptionAlgorithm->getRemoteKeyLength = UA_SymEn_Basic256Sha256_getRemoteKeyLength;
    symEncryptionAlgorithm->getRemoteBlockSize = UA_SymEn_Basic256Sha256_getBlockSize;
    symEncryptionAlgorithm->getRemotePlainTextBlockSize = UA_SymEn_Basic256Sha256_getBlockSize;

    /* Symmetric signature Algorithm */
    UA_SecurityPolicySignatureAlgorithm *symSignatureAlgorithm =
        &symmetricModule->cryptoModule.signatureAlgorithm;
    symSignatureAlgorithm->uri =
        UA_STRING("http://www.w3.org/2000/09/xmldsig#hmac-sha2-256\0");
    symSignatureAlgorithm->verify = UA_SymSig_Basic256Sha256_verify;
    symSignatureAlgorithm->sign = UA_SymSig_Basic256Sha256_sign;
    symSignatureAlgorithm->getLocalSignatureSize =
        UA_SymSig_Basic256Sha256_getLocalSignatureSize;
    symSignatureAlgorithm->getRemoteSignatureSize = 
        UA_SymSig_Basic256Sha256_getRemoteSignatureSize;
    symSignatureAlgorithm->getLocalKeyLength =
        UA_SymSig_Basic256Sha256_getLocalKeyLength;
    symSignatureAlgorithm->getRemoteKeyLength =
        UA_SymSig_Basic256Sha256_getRemoteKeyLength;

    policy->clear = UA_Policy_Clear_Context;
    retval = UA_Policy_New_Context(policy, localPrivateKey, logger);
    if(retval != UA_STATUSCODE_GOOD) {
        UA_ByteString_clear(&policy->localCertificate);
        return retval;
    }

    /* Use the same signature algorithm as the asymmetric component for
     * certificate signing (see standard) */
    policy->certificateSigningAlgorithm =
        policy->asymmetricModule.cryptoModule.signatureAlgorithm;

    return UA_STATUSCODE_GOOD;
}

#endif