DSA Component

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The DSA (Digital Signature Algorithm) component enables users to generate DSA hash signatures.

Syntax

TipcDSA

Remarks

The DSA (Digital Signature Algorithm) component enables users to generate DSA hash signatures.

To begin you must either specify an existing key or create a new key. Existing private keys may be specified by setting the Key* properties. To create a new key call CreateKey. Alternatively an existing certificate may be specified by setting the Certificate* properties

Signing

To sign data first set Key or Certificate. Select the input file by setting InputFile or InputMessage. Next call Sign. The Sign method will automatically compute the hash, and then sign the hash with the specified key.

Send the public key (see CreateKey for details), file, and HashSignature to the recipient.

To sign a hash without recomputing the hash simply set HashValue to the pre-computed hash value before calling Sign.

Signature Verification

To verify a signature specify the input data using InputFile or InputMessage. Set SignerKey or SignerCert. Next set HashSignature and call VerifySignature. The VerifySignature method will return True if the signature was successfully verified.

To verify a hash signature without recomputing the hash simply set HashValue to the pre-computed hash value before calling VerifySignature.

Hash Notes

The component will determine whether or not to recompute the hash based on the properties that are set. If a file is specified by InputFile or InputMessage, the hash will be recomputed when calling Sign or VerifySignature. If the HashValue property is set, the component will only sign the hash or verify the hash signature. Setting InputFile or InputMessage clears the HashValue property. Setting the HashValue property clears the input file selection.

DSA Key Notes

A DSA key is made up of a number of individual parameters. When calling CreateKey the Key* properties are populated with a new private and public key.

After calling Sign the public key must be sent to the recipient along with HashSignature so they may perform signature verification. Likewise you must obtain the public key along with HashSignature in order to perform signature verification.

The public key consists of the following parameters:

• P
• Q
• G
• Y

The component also includes the PublicKey property which holds the PEM formatted public key for ease of use. This is helpful if you are in control of both signature creation and verification process. When sending the public key to a recipient note that not all implementations will support using the PEM formatted value in PublicKey in which case the individual parameters must be sent.

The private key consists of the following parameters:

• P
• Q
• G
• Y
• X

The component also include the PrivateKey property which holds the PEM formatted private key for ease of use. This is helpful for storing the private key more easily..

Property List

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The following is the full list of the properties of the component with short descriptions. Click on the links for further details.

Method List

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The following is the full list of the methods of the component with short descriptions. Click on the links for further details.

Event List

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The following is the full list of the events fired by the component with short descriptions. Click on the links for further details.

Config Settings

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The following is a list of config settings for the component with short descriptions. Click on the links for further details.

Certificate Property (DSA Component)

The certificate used for signing.

Syntax

property Certificate: TipcCertificate read get_Certificate write set_Certificate;

Remarks

This property specifies a certificate with private key.

This may be set instead of Key. This allows a Certificate object to be used instead of a DSAKey object. This certificate is used when calling Sign. The specified certificate must have a private key.

If both this property and Key are specified, Key will be used and this property will be ignored.

Please refer to the Certificate type for a complete list of fields.

HashAlgorithm Property (DSA Component)

The hash algorithm used for hash computation.

Syntax

property HashAlgorithm: TipcDSAHashAlgorithms read get_HashAlgorithm write set_HashAlgorithm;

TipcDSAHashAlgorithms = (
  dhaSHA1,
  dhaSHA224,
  dhaSHA256,
  dhaSHA384,
  dhaSHA512,
  dhaRIPEMD160
);

Default Value

dhaSHA256

Remarks

This property specifies the hash algorithm used for hash computation. This is only applicable when calling Sign or VerifySignature and HashValue is computed. Possible values are:

HashSignature Property (DSA Component)

The hash signature.

Syntax

property HashSignature: String read get_HashSignature write set_HashSignature;
property HashSignatureB: TBytes read get_HashSignatureB write set_HashSignatureB;

Default Value

''

Remarks

This property holds the computed hash signature. This is populated after calling Sign. This must be set before calling VerifySignature.

HashValue Property (DSA Component)

The hash value of the data.

Syntax

property HashValue: String read get_HashValue write set_HashValue;
property HashValueB: TBytes read get_HashValueB write set_HashValueB;

Default Value

''

Remarks

This property holds the computed hash value for the specified data. This is populated when calling Sign or VerifySignature when an input file is specified by setting InputFile or InputMessage.

If you know the hash value prior to using the component you may specify the pre-computed hash value here.

Hash Notes

The component will determine whether or not to recompute the hash based on the properties that are set. If a file is specified by InputFile or InputMessage, the hash will be recomputed when calling Sign or VerifySignature. If the HashValue property is set, the component will only sign the hash or verify the hash signature. Setting InputFile or InputMessage clears the HashValue property. Setting the HashValue property clears the input file selection.

InputFile Property (DSA Component)

The file to process.

Syntax

property InputFile: String read get_InputFile write set_InputFile;

Default Value

''

Remarks

This property specifies the file to be processed. Set this property to the full or relative path to the file which will be processed.

Input and Output Properties

The component will determine the source and destination of the input and output based on which properties are set.

The order in which the input properties are checked is as follows:

• SetInputStream
• InputFile
• InputMessage

When a valid source is found, the search stops. The order in which the output properties are checked is as follows:

• SetOutputStream
• OutputFile
• OutputMessage: The output data is written to this property if no other destination is specified.

When using streams, you may need to additionally set CloseInputStreamAfterProcessing or CloseOutputStreamAfterProcessing.

InputMessage Property (DSA Component)

The message to process.

Syntax

property InputMessage: String read get_InputMessage write set_InputMessage;
property InputMessageB: TBytes read get_InputMessageB write set_InputMessageB;

Default Value

''

Remarks

This property specifies the message to be processed.

Input and Output Properties

The component will determine the source and destination of the input and output based on which properties are set.

The order in which the input properties are checked is as follows:

• SetInputStream
• InputFile
• InputMessage

When a valid source is found, the search stops. The order in which the output properties are checked is as follows:

• SetOutputStream
• OutputFile
• OutputMessage: The output data is written to this property if no other destination is specified.

When using streams, you may need to additionally set CloseInputStreamAfterProcessing or CloseOutputStreamAfterProcessing.

Key Property (DSA Component)

The DSA key.

Syntax

property Key: TipcDSAKey read get_Key write set_Key;

Remarks

This property specifies the DSA key used to create a signature. This property must be set before calling Sign. Alternatively, a certificate may be specified by setting Certificate

DSA Key Notes

A DSA key is made up of a number of individual parameters. When calling CreateKey the Key* properties are populated with a new private and public key.

After calling Sign the public key must be sent to the recipient along with HashSignature so they may perform signature verification. Likewise you must obtain the public key along with HashSignature in order to perform signature verification.

The public key consists of the following parameters:

• P
• Q
• G
• Y

The component also includes the PublicKey property which holds the PEM formatted public key for ease of use. This is helpful if you are in control of both signature creation and verification process. When sending the public key to a recipient note that not all implementations will support using the PEM formatted value in PublicKey in which case the individual parameters must be sent.

The private key consists of the following parameters:

• P
• Q
• G
• Y
• X

The component also include the PrivateKey property which holds the PEM formatted private key for ease of use. This is helpful for storing the private key more easily.

Please refer to the DSAKey type for a complete list of fields.

SignerCert Property (DSA Component)

The certificate used for signature verification.

Syntax

property SignerCert: TipcCertificate read get_SignerCert write set_SignerCert;

Remarks

This property specifies a certificate for signature verification.

This may be set instead of SignerKey. This allows a Certificate object to be used instead of a DSAKey object. This certificate is used when calling VerifySignature.

If both this property and SignerKey are specified, SignerKey will be used and this property will be ignored.

Please refer to the Certificate type for a complete list of fields.

SignerKey Property (DSA Component)

The public key used to verify the signature.

Syntax

property SignerKey: TipcDSAKey read get_SignerKey write set_SignerKey;

Remarks

This property specifies the public key used to verify the signature. This public key corresponds to the private key used when creating the signature. This must be set before calling VerifySignature. Alternatively, a certificate may be specified by setting SignerCert

DSA Key Notes

A DSA key is made up of a number of individual parameters. When calling CreateKey the Key* properties are populated with a new private and public key.

After calling Sign the public key must be sent to the recipient along with HashSignature so they may perform signature verification. Likewise you must obtain the public key along with HashSignature in order to perform signature verification.

The public key consists of the following parameters:

• P
• Q
• G
• Y

The component also includes the PublicKey property which holds the PEM formatted public key for ease of use. This is helpful if you are in control of both signature creation and verification process. When sending the public key to a recipient note that not all implementations will support using the PEM formatted value in PublicKey in which case the individual parameters must be sent.

The private key consists of the following parameters:

• P
• Q
• G
• Y
• X

The component also include the PrivateKey property which holds the PEM formatted private key for ease of use. This is helpful for storing the private key more easily.

Please refer to the DSAKey type for a complete list of fields.

UseHex Property (DSA Component)

Whether HashValue and HashSignature are hex encoded.

Syntax

property UseHex: Boolean read get_UseHex write set_UseHex;

Default Value

false

Remarks

This property specifies whether HashValue and HashSignature are hex encoded.

If set to True, when Sign is called the component will compute the hash for the specified file and populate HashValue with the hex encoded hash value. It will then create the hash signature and populate HashSignature with the hex encoded hash signature value. If HashValue is specified directly, it must be a hex encoded value.

If set to True, when VerifySignature is called the component will compute the hash value for the specified file and populate HashValue with the hex encoded hash value. It will then hex decode HashSignature and verify the signature. HashSignature must hold a hex encoded value. If HashValue is specified directly, it must be a hex encoded value.

Config Method (DSA Component)

This method sets or retrieves a configuration setting.

Syntax

function Config(ConfigurationString: String): String;

Remarks

Config is a generic method available in every component. It is used to set and retrieve configuration settings for the component.

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the component, access to these internal properties is provided through the Config method.

To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).

To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.

CreateKey Method (DSA Component)

Creates a new key.

Syntax

procedure CreateKey();

Remarks

This method creates a new public and private key.

DSA Key Notes

A DSA key is made up of a number of individual parameters. When calling CreateKey the Key* properties are populated with a new private and public key.

After calling Sign the public key must be sent to the recipient along with HashSignature so they may perform signature verification. Likewise you must obtain the public key along with HashSignature in order to perform signature verification.

The public key consists of the following parameters:

• P
• Q
• G
• Y

The component also includes the PublicKey property which holds the PEM formatted public key for ease of use. This is helpful if you are in control of both signature creation and verification process. When sending the public key to a recipient note that not all implementations will support using the PEM formatted value in PublicKey in which case the individual parameters must be sent.

The private key consists of the following parameters:

• P
• Q
• G
• Y
• X

The component also include the PrivateKey property which holds the PEM formatted private key for ease of use. This is helpful for storing the private key more easily.

Reset Method (DSA Component)

Resets the component.

Syntax

procedure Reset();

Remarks

When called, the component will reset all of its properties to their default values.

SetInputStream Method (DSA Component)

Sets the stream from which the component will read data to encrypt or decrypt.

Syntax

procedure SetInputStream(InputStream: TStream);

Remarks

This method sets the stream from which the component will read data to encrypt or decrypt.

Input and Output Properties

The component will determine the source and destination of the input and output based on which properties are set.

The order in which the input properties are checked is as follows:

• SetInputStream
• InputFile
• InputMessage

When a valid source is found, the search stops. The order in which the output properties are checked is as follows:

• SetOutputStream
• OutputFile
• OutputMessage: The output data is written to this property if no other destination is specified.

When using streams, you may need to additionally set CloseInputStreamAfterProcessing or CloseOutputStreamAfterProcessing.

Sign Method (DSA Component)

Creates a hash signature.

Syntax

procedure Sign();

Remarks

This method will create a hash signature.

Before calling this method specify the input file by setting InputFile or InputMessage.

A key is required to create the hash signature. You may create a new key by calling CreateKey, or specify an existing key pair in Key. Alternatively, a certificate may be specified by setting Certificate. When this method is called the component will compute the hash for the specified file and populate HashValue. It will then create the hash signature using the specified Key and populate HashSignature.

To create the hash signature without first computing the hash simply specify HashValue before calling this method.

The Progress event will fire with updates for the hash computation progress only. The hash signature creation process is quick and does not require progress updates.

VerifySignature Method (DSA Component)

Verifies the signature for the specified data.

Syntax

function VerifySignature(): Boolean;

Remarks

This method will verify a hash signature.

Before calling this method specify the input file by setting InputFile or InputMessage.

A public key and the hash signature are required to perform the signature verification. Specify the public key in SignerKey. Alternatively, a certificate may be specified by setting SignerCert. Specify the hash signature in HashSignature.

When this method is called the component will compute the hash for the specified file and populate HashValue. It will verify the signature using the specified SignerKey and HashSignature.

To verify the hash signature without first computing the hash simply specify HashValue before calling this method.

The Progress event will fire with updates for the hash computation progress only. The hash signature verification process is quick and does not require progress updates.

Error Event (DSA Component)

This event is fired for information about errors during data delivery.

Syntax

type TErrorEvent = procedure (
  Sender: TObject;
  const ErrorCode: Integer;
  const Description: String
) of Object;

property OnError: TErrorEvent read FOnError write FOnError;

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally the component raises an exception.

ErrorCode contains an error code and Description contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Error Codes section.

Progress Event (DSA Component)

Fired as progress is made.

Syntax

type TProgressEvent = procedure (
  Sender: TObject;
  const BytesProcessed: Int64;
  const PercentProcessed: Integer
) of Object;

property OnProgress: TProgressEvent read FOnProgress write FOnProgress;

Remarks

This event is fired automatically as data is processed by the component.

The PercentProcessed parameter indicates the current status of the operation.

The BytesProcessed parameter holds the total number of bytes processed so far.

Certificate Type

This is the digital certificate being used.

Remarks

This type describes the current digital certificate. The certificate may be a public or private key. The fields are used to identify or select certificates.

Fields

Constructors

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constructor Create();

Creates a Certificate instance whose properties can be set. This is useful for use with CERTMGR when generating new certificates.

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constructor Create(valEncoded: TBytes);

Parses Encoded as an X509 public key.

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constructor Create(valStoreType: TipcCertStoreTypes; valStore: String; valStorePassword: String; valSubject: String);

CertStoreType identifies the type of certificate store to use. See StoreType for descriptions of the different certificate stores. Store is a file containing the certificate store. StorePassword is the password used to protect the store. After the store has been successfully opened, the component will attempt to find the certificate identified by Subject . This can be either a complete or a substring match of the X509 certificate's subject Distinguished Name (DN). The Subject parameter can also take an MD5, SHA1, or SHA256 thumbprint of the certificate to load in a "Thumbprint=value" format.

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constructor Create(valStoreType: TipcCertStoreTypes; valStore: TBytes; valStorePassword: String; valSubject: String);

CertStoreType identifies the type of certificate store to use. See StoreType for descriptions of the different certificate stores. Store is a string (binary- or base64-encoded) containing the certificate data. StorePassword is the password used to protect the store. After the store has been successfully opened, the component will attempt to find the certificate identified by Subject . This can be either a complete or a substring match of the X509 certificate's subject Distinguished Name (DN). The Subject parameter can also take an MD5, SHA1, or SHA256 thumbprint of the certificate to load in a "Thumbprint=value" format.

DSAKey Type

Contains the parameters for the DSA algorithm.

Remarks

This type is made up of fields that represent the private and public key parameters used by the DSA algorithm.

DSA Key Notes

A DSA key is made up of a number of individual parameters. When calling CreateKey the Key* properties are populated with a new private and public key.

After calling Sign the public key must be sent to the recipient along with HashSignature so they may perform signature verification. Likewise you must obtain the public key along with HashSignature in order to perform signature verification.

The public key consists of the following parameters:

• P
• Q
• G
• Y

The component also includes the PublicKey property which holds the PEM formatted public key for ease of use. This is helpful if you are in control of both signature creation and verification process. When sending the public key to a recipient note that not all implementations will support using the PEM formatted value in PublicKey in which case the individual parameters must be sent.

The private key consists of the following parameters:

• P
• Q
• G
• Y
• X

The component also include the PrivateKey property which holds the PEM formatted private key for ease of use. This is helpful for storing the private key more easily.

Fields

Constructors

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constructor Create();

The default constructor creates a new DSAKey instance but does not assign a public or private key.

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constructor Create(valP: TBytes; valQ: TBytes; valG: TBytes; valY: TBytes);

The public key constructor assigns an existing public key.

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constructor Create(valP: TBytes; valQ: TBytes; valG: TBytes; valY: TBytes; valX: TBytes);

The private key constructor assigns an existing private key.

Config Settings (DSA Component)

The component accepts one or more of the following configuration settings. Configuration settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the component, access to these internal properties is provided through the Config method.

DSA Config Settings

Base Config Settings

Trappable Errors (DSA Component)

DSA Errors