/**
 *  @author   ETSI / STF481
 *  @version  $URL$
 *            $Id$
 *  @desc     Module containing functions for Security Protocol
 *
 */
module LibItsSecurity_Functions {
    
    // Libcommon
    import from LibCommon_DataStrings all;

    // LibItsCommon
    import from LibItsCommon_Functions all;
    
    // LibItsSecurity
    import from LibItsSecurity_TypesAndValues all;
    import from LibItsSecurity_Templates all;
    import from LibItsSecurity_Pixits all;
    
    group helpersFunctions {
        
        /**
         * @desc    Produces a 256-bit (32-byte) hash value
         * @param   p_toBeHashedData Data to be used to calculate the hash value
         * @return  The hash value
         */
        function f_hashWithSha256(in octetstring p_toBeHashedData) return Oct32 {
            return fx_hashWithSha256(p_toBeHashedData);
        } // End of function f_hashWithSha256
        
        /**
         * @desc    Produces a Elliptic Curve Digital Signature Algorithm (ECDSA) signaturee
         * @param   p_toBeSignedSecuredMessage    The data to be signed
         * @return  The signature value
         */
        function f_signWithEcdsaNistp256WithSha256(in Oct32 p_toBeSignedSecuredMessage) return octetstring {
            return fx_signWithEcdsaNistp256WithSha256(
                p_toBeSignedSecuredMessage,
                PX_TA_CONFIGS[PX_CERTIFICATE_CONFIG_IDX].signingPrivateKey
            );
            
        } // End of function f_signWithEcdsaNistp256WithSha256
        
        /**
         * @desc    Verify the signature of the specified data
         * @param   p_toBeVerifiedData          The data to be verified
         * @param   p_signature                 The signature
         * @param   p_ecdsaNistp256PublicKeyX   The public key (x coordinate)
         * @param   p_ecdsaNistp256PublicKeyY   The public key (y coordinate)
         * @return  true on success, false otherwise
         */
        function f_verifyWithEcdsaNistp256WithSha256(
                                                     in octetstring p_toBeVerifiedData, 
                                                     in octetstring p_signature, 
                                                     in octetstring p_ecdsaNistp256PublicKeyX, 
                                                     in octetstring p_ecdsaNistp256PublicKeyY
        ) return boolean {
            return fx_verifyWithEcdsaNistp256WithSha256(
                p_toBeVerifiedData, 
                p_signature, 
                p_ecdsaNistp256PublicKeyX, 
                p_ecdsaNistp256PublicKeyY);
        } // End of function f_verifyWithEcdsaNistp256WithSha256
        
        /**
         * @desc    Calculate digest over the certificate
         * @param   cert The certificate
         * @return  the digest
         */
        function f_calculateDigest(in Certificate cert) return HashedId8 {
            return '0000000000000000'O;
        }
        
        group hostSignatureHelpers {
            
            /**
             * @desc Build a template of a secured beacon to be used for the Test Adapter secured beaconing processing
             */
            function f_buildSecuredMessagePayloadToBeSigned()
            return ToBeSignedSecuredMessage {
                // Local variables
                var template (value) ToBeSignedSecuredMessage v_toBeSignedSecuredMessage;
                
                // Build the beacon template
                v_toBeSignedSecuredMessage := m_toBeSignedSecuredMessage(
                    c_security_profileOthers,
                    { // Field HeaderFields
                        m_header_field_signer_info(
                            m_signerInfo_certificate(
                                PX_TA_CONFIGS[PX_CERTIFICATE_CONFIG_IDX].atCertificate
                            ) // End of template m_signerInfo_certificate
                        ), // End of template m_header_field_signer_info
                        m_header_field_generation_time(oct2int('BBBBBBBB'O)),   // To be replaced by TA with current time
                        m_header_field_generation_location(
                            PX_TA_CONFIGS[PX_CERTIFICATE_CONFIG_IDX].location
                        )
                    }, // End of field HeaderFields
                    {
                        m_payload_unsecured(
                            'AAAAAAAAAA'O                                       // To be replaced by TA with real payload
                        )
                    }, // End of field HeaderFields
                    e_signature
                );
                
                return v_toBeSignedSecuredMessage;
            }
            
            /**
             * @desc This function build and sign the SecureMessage part covered by the signature process
             * @param p_securedMessage      The signed  SecureMessage part
             * @param p_unsecuredPayload    The unsigned payload (e.g. a beacon)
             * @param p_threeDLocation      The ThreeDLocation value
             * @param p_headerFields        Additional HeaderFields
             * @return true on success, false otherwise
             * @verdict Unchanged
             */
            function f_buildGnSecuredCam(
                                         out template (value) SecuredMessage p_securedMessage, 
                                         in octetstring p_unsecuredPayload, 
                                         in ThreeDLocation p_threeDLocation, 
                                         in template (omit) HeaderFields p_headerFields := omit
            ) return boolean {
                
                // Local variables
                var octetstring v_secPayload, v_signature;
                var Oct32 v_hash;
                var template (value) ToBeSignedSecuredMessage v_toBeSignedSecuredMessage;
                 
                // Create SecuredMessage payload to be signed
                v_toBeSignedSecuredMessage := m_toBeSignedSecuredMessage(
                    c_security_profileOthers,
                    { // Field HeaderFields
                        m_header_field_signer_info(
                            m_signerInfo_certificate(
                                PX_TA_CONFIGS[PX_CERTIFICATE_CONFIG_IDX].atCertificate
                            ) // End of template m_signerInfo_certificate
                        ), // End of template m_header_field_signer_info
                        m_header_field_generation_time(f_getCurrentTime()),
                        m_header_field_generation_location(
                            p_threeDLocation
                        ),
                        m_header_field_message_type(c_messageType_CAM)
                    }, // End of field HeaderFields
                    {
                        m_payload_unsecured(
                            p_unsecuredPayload
                        )
                    }, // End of field HeaderFields
                    e_signature
                );
                // Add additional header fields if any
                if (ispresent(p_headerFields) == true) {
                    var integer v_addItemIndex := lengthof(v_toBeSignedSecuredMessage.header_fields);
                    var integer v_counter;
                    
                    for (v_counter := 0; v_counter < lengthof(p_headerFields); v_counter := v_counter + 1) {
                        v_toBeSignedSecuredMessage.header_fields[v_addItemIndex] := p_headerFields[v_counter];
                        v_addItemIndex := v_addItemIndex + 1;
                    } // End of 'for' statement
                }
                
                v_secPayload := bit2oct(encvalue(v_toBeSignedSecuredMessage));
                
                // Calculate the hash of the SecuredMessage payload to be signed
                v_hash := f_hashWithSha256(v_secPayload);
                
                // Signed payload
                v_signature := f_signWithEcdsaNistp256WithSha256(
                    v_hash
                );
                
                p_securedMessage := m_securedMessage_profileOther( // See Clause 7.3   Generic security profile for other signed messages
                    v_toBeSignedSecuredMessage.header_fields,
                    v_toBeSignedSecuredMessage.payload_fields,
                    {
                        m_trailer_field_signature(
                            m_signature(
                                m_ecdsaSignature(
                                    m_eccPointecdsa_nistp256_with_sha256_y_coordinate_only(
                                        substr(v_signature, 2, 32)
                                    ),
                                    substr(v_signature, 34, 32)
                                )
                            )
                        )
                    }
                ); // End of template m_securedMessageBeacon
                
                return true;
            }
            
            /**
             * @desc This function build and sign the SecureMessage part covered by the signature process
             * @param p_securedMessage      The signed  SecureMessage part
             * @param p_unsecuredPayload    The unsigned payload (e.g. a beacon)
             * @param p_threeDLocation      The ThreeDLocation value
             * @param p_headerFields        Additional HeaderFields
             * @return true on success, false otherwise
             * @verdict Unchanged
             */
            function f_buildGnSecuredDenm(
                                          out template (value) SecuredMessage p_securedMessage, 
                                          in octetstring p_unsecuredPayload, 
                                          in ThreeDLocation p_threeDLocation, 
                                          in template (omit) HeaderFields p_headerFields := omit
            ) return boolean {
                
                // Local variables
                var octetstring v_secPayload, v_signature;
                var Oct32 v_hash;
                var template (value) ToBeSignedSecuredMessage v_toBeSignedSecuredMessage;
                 
                // Create SecuredMessage payload to be signed
                v_toBeSignedSecuredMessage := m_toBeSignedSecuredMessage(
                    c_security_profileOthers,
                    { // Field HeaderFields
                        m_header_field_signer_info(
                            m_signerInfo_certificate(
                                PX_TA_CONFIGS[PX_CERTIFICATE_CONFIG_IDX].atCertificate
                            ) // End of template m_signerInfo_certificate
                        ), // End of template m_header_field_signer_info
                        m_header_field_generation_time(f_getCurrentTime()),
                        m_header_field_generation_location(
                            p_threeDLocation
                        ),
                        m_header_field_message_type(c_messageType_DENM)
                    }, // End of field HeaderFields
                    {
                        m_payload_unsecured(
                            p_unsecuredPayload
                        )
                    }, // End of field HeaderFields
                    e_signature
                );
                // Add additional header fields if any
                if (ispresent(p_headerFields) == true) {
                    var integer v_addItemIndex := lengthof(v_toBeSignedSecuredMessage.header_fields);
                    var integer v_counter;
                    
                    for (v_counter := 0; v_counter < lengthof(p_headerFields); v_counter := v_counter + 1) {
                        v_toBeSignedSecuredMessage.header_fields[v_addItemIndex] := p_headerFields[v_counter];
                        v_addItemIndex := v_addItemIndex + 1;
                    } // End of 'for' statement
                }
                 
                v_secPayload := bit2oct(encvalue(v_toBeSignedSecuredMessage));
                
                // Calculate the hash of the SecuredMessage payload to be signed
                v_hash := f_hashWithSha256(v_secPayload);
                
                // Signed payload
                v_signature := f_signWithEcdsaNistp256WithSha256(
                    v_hash
                );
                
                p_securedMessage := m_securedMessage_profileOther( // See Clause 7.3   Generic security profile for other signed messages
                    v_toBeSignedSecuredMessage.header_fields,
                    v_toBeSignedSecuredMessage.payload_fields,
                    {
                        m_trailer_field_signature(
                            m_signature(
                                m_ecdsaSignature(
                                    m_eccPointecdsa_nistp256_with_sha256_y_coordinate_only(
                                        substr(v_signature, 2, 32)
                                    ),
                                    substr(v_signature, 34, 32)
                                )
                            )
                        )
                    }
                ); // End of template m_securedMessageBeacon
                
                return true;
            } // End of function f_buildGnSecuredDenm
            
            /**
             * @desc This function build and sign the SecureMessage part covered by the signature process
             * @param p_securedMessage      The signed  SecureMessage part
             * @param p_unsecuredPayload    The unsigned payload (e.g. a beacon)
             * @param p_threeDLocation      The ThreeDLocation value
             * @param p_headerFields        Additional HeaderFields
             * @return true on success, false otherwise
             * @verdict Unchanged
             */
            function f_buildGnSecuredOtherMessage(
                                                  out template (value) SecuredMessage p_securedMessage, 
                                                  in octetstring p_unsecuredPayload, 
                                                  in ThreeDLocation p_threeDLocation, 
                                                  in template (omit) HeaderFields p_headerFields := omit
            ) return boolean {
                
                // Local variables
                var octetstring v_secPayload, v_signature;
                var Oct32 v_hash;
                var template (value) ToBeSignedSecuredMessage v_toBeSignedSecuredMessage;
                 
                // Create SecuredMessage payload to be signed
                v_toBeSignedSecuredMessage := m_toBeSignedSecuredMessage(
                    c_security_profileOthers,
                    { // Field HeaderFields
                        m_header_field_signer_info(
                            m_signerInfo_certificate(
                                PX_TA_CONFIGS[PX_CERTIFICATE_CONFIG_IDX].atCertificate
                            ) // End of template m_signerInfo_certificate
                        ), // End of template m_header_field_signer_info
                        m_header_field_generation_time(f_getCurrentTime()),
                        m_header_field_generation_location(
                            p_threeDLocation
                        )
                    }, // End of field HeaderFields
                    {
                        m_payload_unsecured(
                            p_unsecuredPayload
                        )
                    }, // End of field HeaderFields
                    e_signature
                );
                // Add additional header fields if any
                if (ispresent(p_headerFields) == true) {
                    var integer v_addItemIndex := lengthof(v_toBeSignedSecuredMessage.header_fields);
                    var integer v_counter;
                    
                    for (v_counter := 0; v_counter < lengthof(p_headerFields); v_counter := v_counter + 1) {
                        v_toBeSignedSecuredMessage.header_fields[v_addItemIndex] := p_headerFields[v_counter];
                        v_addItemIndex := v_addItemIndex + 1;
                    } // End of 'for' statement
                }
                log("v_toBeSignedSecuredMessage= ", v_toBeSignedSecuredMessage);
                
                v_secPayload := bit2oct(encvalue(v_toBeSignedSecuredMessage));
                
                // Calculate the hash of the SecuredMessage payload to be signed
                v_hash := f_hashWithSha256(v_secPayload);
                
                // Signed payload
                v_signature := f_signWithEcdsaNistp256WithSha256(
                    v_hash
                );
                
                p_securedMessage := m_securedMessage_profileOther( // See Clause 7.3   Generic security profile for other signed messages
                    v_toBeSignedSecuredMessage.header_fields,
                    v_toBeSignedSecuredMessage.payload_fields,
                    {
                        m_trailer_field_signature(
                            m_signature(
                                m_ecdsaSignature(
                                    m_eccPointecdsa_nistp256_with_sha256_y_coordinate_only(
                                        substr(v_signature, 2, 32)
                                    ),
                                    substr(v_signature, 34, 32)
                                )
                            )
                        )
                    }
                ); // End of template m_securedMessageBeacon
                
                return true;
            } // End of function f_buildGnSecuredOtherMessage
            
        } // End of group hostSignatureHelpers
        
        group deviceSignatureHelpers {
             
            /**
             * @desc Verify the signature of the provided secured message
             * @param p_aaCertifcate    Enrolment Credential certificate
             * @param p_atCertificate   Authorization Ticket certificate
             * @return true on success, false otherwise
             * @verdict 
             */
            function f_verifyCertificateSignatureWithIssuingCertificate(
                                                                        in template (value) Certificate p_aaCertifcate,
                                                                        in template (value) Certificate p_atCertificate 
            ) return boolean {
                
                // Local variables
                var octetstring v_secPayload;
                var octetstring v_signedData;
                var Oct32 v_hash;
                var boolean v_result := false;
                var template (value) ToBeSignedCertificate v_toBeSignedCertificate;
                
                // Create Certificate payload to be signed
                v_toBeSignedCertificate := m_toBeSignedCertificate(p_atCertificate);
                
                v_secPayload := bit2oct(encvalue(v_toBeSignedCertificate));
                
                // Calculate the hash of the SecuredMessage payload to be signed
                v_hash := fx_hashWithSha256(v_secPayload);
                
                // Verify payload
                v_signedData := 
                    '0000'O & 
                    p_atCertificate.signature_.signature_.ecdsa_signature.r.x & 
                    p_atCertificate.signature_.signature_.ecdsa_signature.s;
                v_result := f_verifyWithEcdsaNistp256WithSha256(
                    v_hash,
                    v_signedData,
                    p_aaCertifcate.subject_attributes[0].attribute.key.public_key.eccPoint.x,
                    p_aaCertifcate.subject_attributes[0].attribute.key.public_key.eccPoint.y.y
                );
                
                return v_result;
            } // End of function f_verifyGnSecuredOtherMessage
            
        } // End of group hostSignatureHelpers
        
        group deviceSignatureHelpers {
             
            /**
             * @desc Verify the signature of the provided certificate
             * @param p_cert  Certificate to be verified
             * @param p_key   Public key to verify
             * @return true on success, false otherwise
             * @verdict 
             */
            function f_verifyCertificateSignatureWithPublicKey(
                                                  in template (value) Certificate p_cert,
                                                  in template (value) PublicKey key 
            ) return boolean {
                // TODO To be implemented
                return false;
            }

            /**
             * @desc Verify the signature of the provided secured message
             * @param p_cert    Certificate to be verified
             * @param p_verify  Certificate to be used to verify
             * @return true on success, false otherwise
             * @verdict 
             */
            function f_verifyCertificateSignatureWithIssuingCertificate(
                                                  in template (value) Certificate p_cert,
                                                  in template (value) Certificate p_verify 
            ) return boolean {
                return f_verifyCertificateSignatureWithPublicKey(p_cert, 
                            p_verify.subject_attributes[0].attribute.key); 
            }
            
            /**
             * @desc Verify the signature of the provided secured message
             * @param p_securedMessage  The message to be verified
             * @param p_publicKey       The ECDSA public key to verify a signature 
             * @param p_certificate     Certificate to be used to verify the message
             * @return true on success, false otherwise
             * @verdict 
             */
             function f_verifyCertificateSignatureWithPublicKey(
                                                               in template (value) SecuredMessage p_securedMessage,
                                                               in template (value) PublicKey p_publicKey 
            ) return boolean {
                
                // Local variables
                var octetstring v_secPayload;
                var octetstring v_signedData;
                var Oct32 v_hash;
                var integer v_counter;
                var boolean v_result := false;
                var template (value) ToBeSignedSecuredMessage v_toBeSignedSecuredMessage;
                
                // Create SecuredMessage payload to be signed
                v_toBeSignedSecuredMessage := m_toBeSignedSecuredMessage(
                    p_securedMessage.security_profile,
                    p_securedMessage.header_fields, 
                    p_securedMessage.payload_fields, 
                    e_signature
                );
                 
                v_secPayload := bit2oct(encvalue(v_toBeSignedSecuredMessage));
                
                // Calculate the hash of the SecuredMessage payload to be signed
                v_hash := fx_hashWithSha256(v_secPayload);
                
                // Verify payload
                for (v_counter := 0; v_counter < lengthof(p_securedMessage.trailer_fields); v_counter := v_counter + 1) {
                    if (
                        (p_securedMessage.trailer_fields[v_counter].type_ == e_signature) and 
                        (p_securedMessage.trailer_fields[v_counter].trailerField.signature_.algorithm == e_ecdsa_nistp256_with_sha256)
                    ) {
                        v_signedData := 
                            '0000'O & 
                            p_securedMessage.trailer_fields[v_counter].trailerField.signature_.signature_.ecdsa_signature.r.x & 
                            p_securedMessage.trailer_fields[v_counter].trailerField.signature_.signature_.ecdsa_signature.s;
                        v_result := f_verifyWithEcdsaNistp256WithSha256(
                            v_hash,
                            v_signedData,
                            p_publicKey.public_key.eccPoint.x,
                            p_publicKey.public_key.eccPoint.y.y
                        );
                    }
                } // End of 'for' statement
                
                return v_result;
            } // End of function f_verifyCertificateSignatureWithPublicKey
            
            /**
             * @desc Verify the signature of the provided secured message
             * @param p_securedMessage
             * @param p_certificate     Certificate to be used to verify the message
             * @return true on success, false otherwise
             * @verdict 
             */
            function f_verifyGnSecuredMessageWithDeviceCertificate(
                                                                   in template (value) SecuredMessage p_securedMessage,
                                                                   in template (value) Certificate p_certificate 
            ) return boolean {
                return f_verifyGnSecuredMessageWithPublicKey(p_securedMessage,
                            p_certificate.subject_attributes[0].attribute.key);
            } // End of function f_verifyGnSecuredOtherMessageWithDeviceCertificate 
            
        } // End of group deviceSignatureHelpers
        
        group messageGetters {
            
            /**
             * @desc    return SecuredMessage header field of given type or null if none 
             * @param   p_msg the SecuredMessage
             * @param   p_type header field type
             * @return  HeaderField of given type if any or null
             */
            function f_getMsgHeaderField(
                                         in SecuredMessage p_securedMessage, 
                                         in HeaderFieldType p_headerFieldType
            ) return HeaderField {
                var HeaderField v_return;
                var integer v_length := lengthof(p_securedMessage.header_fields);
                var integer v_index;
                
                for (v_index := 0; v_index < v_length; v_index := v_index + 1) {
                    if (p_securedMessage.header_fields[v_index].type_ == p_headerFieldType) {
                        v_return := p_securedMessage.header_fields[v_index]; 
                        break;
                    }
                }
                
                return v_return;
            }
            
            /**
             * @desc    return SignerInfo SecuredMessage field
             */
            function f_getMsgSignerInfo(
                                        in SecuredMessage p_securedMessage
            ) return SignerInfo {
                var HeaderField v_hf := f_getMsgHeaderField(p_securedMessage, e_signer_info);
                
                if (isbound(v_hf)) {
                    return v_hf.headerField.signer;
                }
                
                return null;
            }
            
        }// End of group messageGetters
        
        group certificateGetters {
            
            function f_getCertificateValidityRestriction(
                                                         in Certificate p_cert, 
                                                         in ValidityRestrictionType p_type
            ) return ValidityRestriction {
                var ValidityRestriction v_return;
                var integer v_length := lengthof(p_cert.validity_restrictions);
                var integer v_index;
                
                for (v_index := 0; v_index < v_length; v_index := v_index + 1) {
                    if( p_cert.validity_restrictions[v_index].type_ == p_type ) {
                        v_return := p_cert.validity_restrictions[v_index];
                        break;
                    }
                }
                return v_return;
            }
            
            function f_getCertificateSignerInfo (in Certificate p_cert)
            return SignerInfo {
                var SignerInfo ret;
                if (lengthof(p_cert.signer_infos) > 0) {
                    ret := p_cert.signer_infos[0];
                }
                return ret;
            }
            
        }// End of group certificateGetters
        
        group CertRequests{
            
            function f_askForCertificate (in HashedId3 p_digest) {
                
            }
            
        } // End of group CertRequests 
    
    } // End of group helpersFunctions

    group externalFunctions {
        
        /**
         * @desc    Produces a 256-bit (32-byte) hash value
         * @param   p_toBeHashedData Data to be used to calculate the hash value
         * @return  The hash value
         */
        external function fx_hashWithSha256(in octetstring p_toBeHashedData) return Oct32;
        
        /**
         * @desc    Produces a Elliptic Curve Digital Signature Algorithm (ECDSA) signaturee
         * @param   p_toBeSignedSecuredMessage    The data to be signed
         * @param   p_privateKey        The private key
         * @return  The signature value
         */
        external function fx_signWithEcdsaNistp256WithSha256(in octetstring p_toBeSignedSecuredMessage, in octetstring/*UInt64*/ p_privateKey) return octetstring;
        
        /**
         * @desc    Verify the signature of the specified data
         * @param   p_toBeVerifiedData          The data to be verified
         * @param   p_signature                 The signature
         * @param   p_ecdsaNistp256PublicKeyX   The public key (x coordinate)
         * @param   p_ecdsaNistp256PublicKeyY   The public key (y coordinate)
         * @return  true on success, false otherwise
         */
        external function fx_verifyWithEcdsaNistp256WithSha256(in octetstring p_toBeVerifiedData, in octetstring p_signature, in octetstring p_ecdsaNistp256PublicKeyX, in octetstring p_ecdsaNistp256PublicKeyY) return boolean;
        
        /**
         * @desc    Produce a new public/private key pair based on Elliptic Curve Digital Signature Algorithm (ECDSA) algorithm.
         *          This function should not be used by the ATS
         * @param   p_privateKey    The new private key value
         * @param   p_publicKeyX    The new public key value (x coordinate)
         * @param   p_publicKeyX    The new public key value (y coordinate)
         * @return  true on success, false otherwise
         */
        external function fx_generateKeyPair(out octetstring/*UInt64*/ p_privateKey, out octetstring p_publicKeyX, out octetstring p_publicKeyY) return boolean;
        
    } // End of group externalFunctions
    
} // End of module LibItsSecurity_Functions