/*!
    \ingroup PKCS7
    
    \brief This function initializes a PKCS7 structure with a DER-formatted 
    certificate. To initialize an empty PKCS7 structure, one can pass in a NULL 
    cert and 0 for certSz. 
    
    \return 0 Returned on successfully initializing the PKCS7 structure
    \return MEMORY_E Returned if there is an error allocating memory 
    with XMALLOC
    \return ASN_PARSE_E Returned if there is an error parsing the cert header
    \return ASN_OBJECT_ID_E Returned if there is an error parsing the 
    encryption type from the cert
    \return ASN_EXPECT_0_E Returned if there is a formatting error in the 
    encryption specification of the cert file
    \return ASN_BEFORE_DATE_E Returned if the date is before the certificate 
    start date
    \return ASN_AFTER_DATE_E Returned if the date is after the certificate 
    expiration date
    \return ASN_BITSTR_E Returned if there is an error parsing a bit string 
    from the certificate
    \return ASN_NTRU_KEY_E Returned if there is an error parsing the NTRU 
    key from the certificate
    \return ECC_CURVE_OID_E Returned if there is an error parsing the ECC 
    key from the certificate
    \return ASN_UNKNOWN_OID_E Returned if the certificate is using an unknown 
    key object id
    \return ASN_VERSION_E Returned if the ALLOW_V1_EXTENSIONS option is not 
    defined and the certificate is a V1 or V2 certificate
    \return BAD_FUNC_ARG Returned if there is an error processing the 
    certificate extension
    \return ASN_CRIT_EXT_E Returned if an unfamiliar critical extension is 
    encountered in processing the certificate
    \return ASN_SIG_OID_E Returned if the signature encryption type is not 
    the same as the encryption type of the certificate in the provided file
    \return ASN_SIG_CONFIRM_E Returned if confirming the certification 
    signature fails
    \return ASN_NAME_INVALID_E Returned if the certificate’s name is not 
    permitted by the CA name constraints
    \return ASN_NO_SIGNER_E Returned if there is no CA signer to verify 
    the certificate’s authenticity

    \param pkcs7 pointer to the PKCS7 structure in which to 
    store the decoded cert
    \param cert pointer to a buffer containing a DER formatted ASN.1 
    certificate with which to initialize the PKCS7 structure
    \param certSz size of the certificate buffer
    
    _Example_
    \code
    PKCS7 pkcs7;
    byte derBuff[] = { }; // initialize with DER-encoded certificate
    if ( wc_PKCS7_InitWithCert(&pkcs7, derBuff, sizeof(derBuff)) != 0 ) {
    	// error parsing certificate into pkcs7 format
    }
    \endcode
    
    \sa wc_PKCS7_Free
*/
WOLFSSL_API int  wc_PKCS7_InitWithCert(PKCS7* pkcs7, byte* cert, word32 certSz);
/*!
    \ingroup PKCS7
    
    \brief This function releases any memory allocated by a PKCS7 initializer.
    
    \return none No returns.
    
    \param pkcs7 pointer to the PKCS7 structure to free
    
    _Example_
    \code
    PKCS7 pkcs7;
    // initialize and use PKCS7 object

    wc_PKCS7_Free(pkcs7);
    \endcode
    
    \sa wc_PKCS7_InitWithCert
*/
WOLFSSL_API void wc_PKCS7_Free(PKCS7* pkcs7);
/*!
    \ingroup PKCS7
    
    \brief This function builds the PKCS7 data content type, encoding the 
    PKCS7 structure into a buffer containing a parsable PKCS7 data packet.
    
    \return Success On successfully encoding the PKCS7 data into the buffer, 
    returns the index parsed up to in the PKCS7 structure. This index also 
    corresponds to the bytes written to the output buffer.
    \return BUFFER_E Returned if the given buffer is not large enough to hold 
    the encoded certificate
    
    \param pkcs7 pointer to the PKCS7 structure to encode
    \param output pointer to the buffer in which to store the encoded 
    certificate
    \param outputSz size available in the output buffer
    
    _Example_
    \code
    PKCS7 pkcs7;
    int ret;

    byte derBuff[] = { }; // initialize with DER-encoded certificate
    byte pkcs7Buff[FOURK_BUF];

    wc_PKCS7_InitWithCert(&pkcs7, derBuff, sizeof(derBuff));
    // update message and data to encode
    pkcs7.privateKey = key;
    pkcs7.privateKeySz = keySz;
    pkcs7.content = data;
    pkcs7.contentSz = dataSz;
    ... etc.

    ret = wc_PKCS7_EnocodeData(&pkcs7, pkcs7Buff, sizeof(pkcs7Buff));
    if ( ret != 0 ) {
	    // error encoding into output buffer
    }
    \endcode
    
    \sa wc_PKCS7_InitWithCert
*/
WOLFSSL_API int  wc_PKCS7_EncodeData(PKCS7* pkcs7, byte* output,
                                       word32 outputSz);
/*!
    \ingroup PKCS7
    
    \brief This function builds the PKCS7 signed data content type, encoding 
    the PKCS7 structure into a buffer containing a parsable PKCS7 
    signed data packet.
    
    \return Success On successfully encoding the PKCS7 data into the buffer, 
    returns the index parsed up to in the PKCS7 structure. This index also 
    corresponds to the bytes written to the output buffer.
    \return BAD_FUNC_ARG Returned if the PKCS7 structure is missing one or 
    more required elements to generate a signed data packet
    \return MEMORY_E Returned if there is an error allocating memory
    \return PUBLIC_KEY_E Returned if there is an error parsing the public key
    \return RSA_BUFFER_E Returned if buffer error, output too small or input 
    too large
    \return BUFFER_E Returned if the given buffer is not large enough to hold 
    the encoded certificate
    \return MP_INIT_E may be returned if there is an error generating 
    the signature
    \return MP_READ_E may be returned if there is an error generating 
    the signature
    \return MP_CMP_E may be returned if there is an error generating 
    the signature
    \return MP_INVMOD_E may be returned if there is an error generating 
    the signature
    \return MP_EXPTMOD_E may be returned if there is an error generating 
    the signature
    \return MP_MOD_E may be returned if there is an error generating 
    the signature
    \return MP_MUL_E may be returned if there is an error generating 
    the signature
    \return MP_ADD_E may be returned if there is an error generating 
    the signature
    \return MP_MULMOD_E may be returned if there is an error generating 
    the signature
    \return MP_TO_E may be returned if there is an error generating 
    the signature
    \return MP_MEM may be returned if there is an error generating the signature
    
    \param pkcs7 pointer to the PKCS7 structure to encode
    \param output pointer to the buffer in which to store the 
    encoded certificate
    \param outputSz size available in the output buffer

    _Example_
    \code
    PKCS7 pkcs7;
    int ret;

    byte derBuff[] = { }; // initialize with DER-encoded certificate
    byte pkcs7Buff[FOURK_BUF];

    wc_PKCS7_InitWithCert(&pkcs7, derBuff, sizeof(derBuff));
    // update message and data to encode
    pkcs7.privateKey = key;
    pkcs7.privateKeySz = keySz;
    pkcs7.content = data;
    pkcs7.contentSz = dataSz;
    ... etc.

    ret = wc_PKCS7_EnocodeSignedData(&pkcs7, pkcs7Buff, sizeof(pkcs7Buff));
    if ( ret != 0 ) {
    	// error encoding into output buffer
    }
    \endcode
    
    \sa wc_PKCS7_InitWithCert
    \sa wc_PKCS7_VerifySignedData
*/
WOLFSSL_API int  wc_PKCS7_EncodeSignedData(PKCS7* pkcs7,
                                       byte* output, word32 outputSz);
/*!
    \ingroup PKCS7
    
    \brief This function takes in a transmitted PKCS7 signed data message, 
    extracts the certificate list and certificate revocation list, and then 
    verifies the signature. It stores the extracted content in the given 
    PKCS7 structure.
    
    \return 0 Returned on successfully extracting the information 
    from the message
    \return BAD_FUNC_ARG Returned if one of the input parameters is invalid
    \return ASN_PARSE_E Returned if there is an error parsing from the 
    given pkiMsg
    \return PKCS7_OID_E Returned if the given pkiMsg is not a signed data type
    \return ASN_VERSION_E Returned if the PKCS7 signer info is not version 1
    \return MEMORY_E Returned if there is an error allocating memory
    \return PUBLIC_KEY_E Returned if there is an error parsing the public key
    \return RSA_BUFFER_E Returned if buffer error, output too small or 
    input too large
    \return BUFFER_E Returned if the given buffer is not large enough to 
    hold the encoded certificate
    \return MP_INIT_E may be returned if there is an error generating 
    the signature
    \return MP_READ_E may be returned if there is an error generating 
    the signature
    \return MP_CMP_E may be returned if there is an error generating 
    the signature
    \return MP_INVMOD_E may be returned if there is an error generating 
    the signature
    \return MP_EXPTMOD_E may be returned if there is an error generating 
    the signature
    \return MP_MOD_E may be returned if there is an error generating 
    the signature
    \return MP_MUL_E may be returned if there is an error generating 
    the signature
    \return MP_ADD_E may be returned if there is an error generating 
    the signature
    \return MP_MULMOD_E may be returned if there is an error generating 
    the signature
    \return MP_TO_E may be returned if there is an error generating 
    the signature
    \return MP_MEM may be returned if there is an error generating the signature
    
    \param pkcs7 pointer to the PKCS7 structure in which to store the parsed 
    certificates
    \param pkiMsg pointer to the buffer containing the signed message to verify 
    and decode
    \param pkiMsgSz size of the signed message
    
    _Example_
    \code
    PKCS7 pkcs7;
    int ret;

    byte derBuff[] = { }; // initialize with DER-encoded certificate
    byte pkcs7Buff[FOURK_BUF];

    wc_PKCS7_InitWithCert(&pkcs7, derBuff, sizeof(derBuff));
    // update message and data to encode
    pkcs7.privateKey = key;
    pkcs7.privateKeySz = keySz;
    pkcs7.content = data;
    pkcs7.contentSz = dataSz;
    ... etc.

    ret = wc_PKCS7_EnocodeSignedData(&pkcs7, pkcs7Buff, sizeof(pkcs7Buff));
    if ( ret != 0 ) {
    	// error encoding into output buffer
    }
    \endcode
    
    \sa wc_PKCS7_InitWithCert
    \sa wc_PKCS7_EncodeSignedData
*/
WOLFSSL_API int  wc_PKCS7_VerifySignedData(PKCS7* pkcs7,
                                       byte* pkiMsg, word32 pkiMsgSz);
/*!
    \ingroup PKCS7
    
    \brief This function builds the PKCS7 enveloped data content type, encoding 
    the PKCS7 structure into a buffer containing a parsable PKCS7 enveloped 
    data packet.
    
    \return Success Returned on successfully encoding the message in enveloped 
    data format, returns the size written to the output buffer
    \return BAD_FUNC_ARG: Returned if one of the input parameters is invalid, 
    or if the PKCS7 structure is missing required elements
    \return ALGO_ID_E Returned if the PKCS7 structure is using an unsupported 
    algorithm type. Currently, only DESb and DES3b are supported 
    \return BUFFER_E Returned if the given output buffer is too small to store 
    the output data
    \return MEMORY_E Returned if there is an error allocating memory
    \return RNG_FAILURE_E Returned if there is an error initializing the random 
    number generator for encryption
    \return DRBG_FAILED Returned if there is an error generating numbers with 
    the random number generator used for encryption
    
    \param pkcs7 pointer to the PKCS7 structure to encode
    \param output pointer to the buffer in which to store the encoded 
    certificate
    \param outputSz size available in the output buffer
    
    _Example_
    \code
    PKCS7 pkcs7;
    int ret;

    byte derBuff[] = { }; // initialize with DER-encoded certificate
    byte pkcs7Buff[FOURK_BUF];

    wc_PKCS7_InitWithCert(&pkcs7, derBuff, sizeof(derBuff));
    // update message and data to encode
    pkcs7.privateKey = key;
    pkcs7.privateKeySz = keySz;
    pkcs7.content = data;
    pkcs7.contentSz = dataSz;
    ... etc.

    ret = wc_PKCS7_EncodeEnvelopedData(&pkcs7, pkcs7Buff, sizeof(pkcs7Buff));
    if ( ret != 0 ) {
    	// error encoding into output buffer
    }
    \endcode
    
    \sa wc_PKCS7_InitWithCert
    \sa wc_PKCS7_DecodeEnvelopedData
*/
WOLFSSL_API int  wc_PKCS7_EncodeEnvelopedData(PKCS7* pkcs7,
                                          byte* output, word32 outputSz);
/*!
    \ingroup PKCS7
    
    \brief This function unwraps and decrypts a PKCS7 enveloped data content 
    type, decoding the message into output. It uses the private key of the 
    PKCS7 object passed in to decrypt the message.
    
    \return On successfully extracting the information from the message, 
    returns the bytes written to output
    \return BAD_FUNC_ARG Returned if one of the input parameters is invalid
    \return ASN_PARSE_E Returned if there is an error parsing from the 
    given pkiMsg
    \return PKCS7_OID_E Returned if the given pkiMsg is not an enveloped 
    data type
    \return ASN_VERSION_E Returned if the PKCS7 signer info is not version 0
    \return MEMORY_E Returned if there is an error allocating memory
    \return ALGO_ID_E Returned if the PKCS7 structure is using an unsupported 
    algorithm type. Currently, only DESb and DES3b are supported for 
    encryption, with RSAk for signature generation
    \return PKCS7_RECIP_E Returned if there is no recipient found in the 
    enveloped data that matches the recipient provided
    \return RSA_BUFFER_E Returned if there is an error during RSA signature 
    verification due to buffer error, output too small or input too large.
    \return MP_INIT_E may be returned if there is an error during signature 
    verification
    \return MP_READ_E may be returned if there is an error during signature 
    verification
    \return MP_CMP_E may be returned if there is an error during signature 
    verification
    \return MP_INVMOD_E may be returned if there is an error during signature 
    verification
    \return MP_EXPTMOD_E may be returned if there is an error during signature 
    verification
    \return MP_MOD_E may be returned if there is an error during signature 
    verification
    \return MP_MUL_E may be returned if there is an error during signature 
    verification
    \return MP_ADD_E may be returned if there is an error during signature 
    verification
    \return MP_MULMOD_E may be returned if there is an error during signature 
    verification
    \return MP_TO_E may be returned if there is an error during signature 
    verification
    \return MP_MEM may be returned if there is an error during signature 
    verification
    
    \param pkcs7 pointer to the PKCS7 structure containing the private key with 
    which to decode the enveloped data package
    \param pkiMsg pointer to the buffer containing the enveloped data package
    \param pkiMsgSz size of the enveloped data package
    \param output pointer to the buffer in which to store the decoded message
    \param outputSz size available in the output buffer

    _Example_
    \code
    PKCS7 pkcs7;
    byte received[] = { }; // initialize with received enveloped message
    byte decoded[FOURK_BUF];
    int decodedSz;

    // initialize pkcs7 with certificate
    // update key
    pkcs7.privateKey = key;
    pkcs7.privateKeySz = keySz;

    decodedSz = wc_PKCS7_DecodeEnvelopedData(&pkcs7, received, 
    sizeof(received),decoded, sizeof(decoded));
    if ( decodedSz != 0 ) {
    	// error decoding message
    }
    \endcode
    
    \sa wc_PKCS7_InitWithCert
    \sa wc_PKCS7_EncodeEnvelopedData
*/
WOLFSSL_API int  wc_PKCS7_DecodeEnvelopedData(PKCS7* pkcs7, byte* pkiMsg,
                                          word32 pkiMsgSz, byte* output,
                                          word32 outputSz);
