---
product: Chilkat
product_version: 11.7.0
language: pascal
language_label: Lazarus Pascal
class: Dsa
license: bundle
deprecated: false
reference_html: https://www.chilkatsoft.com/refdoc/pascal_DsaRef.html
---
# Chilkat Dsa — Lazarus Pascal — v11.7.0

> Chilkat 11.7.0 · language=pascal · class=Dsa
> Other versions: replace `11.7.0` in this URL. Other languages: `https://www.chilkatsoft.com/ai-docs/v/11.7.0/<lang>/classes/Dsa.md`.
> Language-wide rules (install, unlock, error model, strings/bytes): `https://www.chilkatsoft.com/ai-docs/v/11.7.0/pascal/guide.md`.

## Purpose

**Generate, import, export, sign, and verify DSA keys and signatures.**

`Chilkat.Dsa` is the Chilkat class for DSA key generation, DSA key import/export, DSA hash signing, and DSA signature verification. It supports private and public keys in DER, PEM, encrypted PEM, XML, explicit component, and OpenSSL parameter workflows. It also exposes DSA key components as hex-encoded SSH1-format bignums and provides helpers for working with encoded hashes and signatures.

**Generate DSA keys**

Create DSA key pairs and parameters for workflows that still require DSA-based signing or verification.

**Import and export keys**

Load and save private or public DSA keys in DER, PEM, encrypted PEM, XML, component-based, and OpenSSL-compatible formats.

**Sign hashes**

Create DSA signatures over message digests using a loaded private key and the appropriate encoded hash input.

**Verify signatures**

Verify DSA signatures using a public key, encoded hash, and signature data.

**Key components**

Access DSA parameters and key components as hex-encoded SSH1-format bignums for low-level interoperability scenarios.

**Encoded data helpers**

Work with encoded hashes and signatures when applications need hex, Base64, or other textual representations of binary values.

**Common pattern:** Load or generate a DSA key, compute the message hash with the desired hash algorithm, then use `Dsa` to sign the hash with the private key or verify the signature with the public key. For new protocol designs, consider whether a more modern signature algorithm is preferred; use this class when DSA is required for compatibility.

For an extended overview, see [Dsa Class Overview](https://www.chilkatsoft.com/dsa_class_overview.asp).

## Object creation, unlocking and error handling

**Create / Free**

```pascal
uses
  Chilkat.Dsa;

var
  obj: TDsa;
begin
  obj := TDsa.Create;
  try
    if not obj.IsValid then
      raise Exception.Create('Failed to create a TDsa instance.');

    // ... use obj ...

  finally
    obj.Free;
  end;
end;
```

`constructor Create;`

Allocates the underlying CkDsa object and returns a new TDsa instance. Simply adding **Chilkat.Dsa** to the unit's `uses` clause is enough to locate and bind to the Chilkat shared library (DLL / .so / .dylib) at runtime — no separate load step is required. Check `obj.IsValid` after calling `Create`; it is `False` if the underlying library could not be found/loaded or the object could not be allocated (for example, when unlicensed).

`destructor Destroy; override;`

Every TDsa created by calling `Create` should eventually be released by calling `.Free` (inherited from `TObject`). The destructor automatically disposes the underlying CkDsa handle. A native (unmanaged) memory leak occurs if the object is never freed.

Call `Global.UnlockBundle` once at the start of the program, before using this or any other Chilkat class. Any string unlocks a fully functional 30-day trial; a purchased unlock code is used in production. See `guide.md` for the exact code in Lazarus Pascal.

## Members common to every Chilkat class

Documented once per language in `common-members.md`; listed here so this page is self-contained.

| Property | Signature | Access | Meaning |
|---|---|---|---|
| `DebugLogFilePath` | `property DebugLogFilePath: string read GetDebugLogFilePath write SetDebugLogFilePath;` | read/write | If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. |
| `LastErrorHtml` | `property LastErrorHtml: string read GetLastErrorHtml;` | read-only | Provides HTML-formatted information about the last called method or property. |
| `LastErrorText` | `property LastErrorText: string read GetLastErrorText;` | read-only | Provides plain text information about the last called method or property. |
| `LastErrorXml` | `property LastErrorXml: string read GetLastErrorXml;` | read-only | Provides XML-formatted information about the last called method or property. |
| `LastMethodSuccess` | `property LastMethodSuccess: Boolean read GetLastMethodSuccess write SetLastMethodSuccess;` | read/write | Indicates the success or failure of the most recent method call: `True` means success, `False` means failure. |
| `VerboseLogging` | `property VerboseLogging: Boolean read GetVerboseLogging write SetVerboseLogging;` | read/write | If set to `True`, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. |
| `Version` | `property Version: string read GetVersion;` | read-only | Version of the component/library, such as "10.1.0" |

## Member index

| Member | Kind | Signature |
|---|---|---|
| `GroupSize` | property, read/write | `property GroupSize: Integer read GetGroupSize write SetGroupSize;` |
| `HexG` | property, read-only | `property HexG: string read GetHexG;` |
| `HexP` | property, read-only | `property HexP: string read GetHexP;` |
| `HexQ` | property, read-only | `property HexQ: string read GetHexQ;` |
| `HexX` | property, read-only | `property HexX: string read GetHexX;` |
| `HexY` | property, read-only | `property HexY: string read GetHexY;` |
| `UncommonOptions` | property, read/write | `property UncommonOptions: string read GetUncommonOptions write SetUncommonOptions;` |
| `FromDerBd` | method | `// bd is a TBinData object. function FromDerBd(bd: TChilkatBase): Boolean;` |
| `FromDerFile` | method | `function FromDerFile(const path: string): Boolean;` |
| `FromEncryptedPem` | method | `function FromEncryptedPem(const password: string;     const pemData: string): Boolean;` |
| `FromPem` | method | `function FromPem(const pemData: string): Boolean;` |
| `FromPublicDerBd` | method | `// bd is a TBinData object. function FromPublicDerBd(bd: TChilkatBase): Boolean;` |
| `FromPublicDerFile` | method | `function FromPublicDerFile(const path: string): Boolean;` |
| `FromPublicPem` | method | `function FromPublicPem(const pemData: string): Boolean;` |
| `FromXml` | method | `function FromXml(const xmlKey: string): Boolean;` |
| `GenKey` | method | `function GenKey(numBits: Integer): Boolean;` |
| `GenKey2` | method | `function GenKey2(keyLenBits: Integer;     modLenBits: Integer): Boolean;` |
| `GenKeyFromParamsDerBd` | method | `// bd is a TBinData object. function GenKeyFromParamsDerBd(bd: TChilkatBase): Boolean;` |
| `GenKeyFromParamsDerFile` | method | `function GenKeyFromParamsDerFile(const path: string): Boolean;` |
| `GenKeyFromParamsPem` | method | `function GenKeyFromParamsPem(const pem: string): Boolean;` |
| `GenKeyFromParamsPemFile` | method | `function GenKeyFromParamsPemFile(const path: string): Boolean;` |
| `GenKeyFromPQG` | method | `function GenKeyFromPQG(const pHex: string;     const qHex: string;     const gHex: string): Boolean;` |
| `GetEncodedHash` | method | `function GetEncodedHash(const encoding: string): string;` |
| `GetEncodedSignature` | method | `function GetEncodedSignature(const encoding: string): string;` |
| `LoadText` | method | `function LoadText(const path: string): string;` |
| `SaveText` | method | `function SaveText(const strToSave: string;     const path: string): Boolean;` |
| `SetEncodedHash` | method | `function SetEncodedHash(const encoding: string;     const encodedHash: string): Boolean;` |
| `SetEncodedSignature` | method | `function SetEncodedSignature(const encoding: string;     const encodedSig: string): Boolean;` |
| `SetEncodedSignatureRS` | method | `function SetEncodedSignatureRS(const encoding: string;     const encodedR: string;     const encodedS: string): Boolean;` |
| `SetKeyExplicit` | method | `function SetKeyExplicit(groupSizeInBytes: Integer;     const pHex: string;     const qHex: string;     const gHex: string;     const xHex: string): Boolean;` |
| `SetPubKeyExplicit` | method | `function SetPubKeyExplicit(groupSizeInBytes: Integer;     const pHex: string;     const qHex: string;     const gHex: string;     const yHex: string): Boolean;` |
| `SignHash` | method | `function SignHash: Boolean;` |
| `ToDerBd` | method | `// bd is a TBinData object. function ToDerBd(bd: TChilkatBase): Boolean;` |
| `ToDerFile` | method | `function ToDerFile(const path: string): Boolean;` |
| `ToEncryptedPem` | method | `function ToEncryptedPem(const password: string): string;` |
| `ToPem` | method | `function ToPem: string;` |
| `ToPublicDerFile` | method | `function ToPublicDerFile(const path: string): Boolean;` |
| `ToPublicPem` | method | `function ToPublicPem: string;` |
| `ToXml` | method | `function ToXml(bPublicOnly: Boolean): string;` |
| `Verify` | method | `function Verify: Boolean;` |
| `VerifyKey` | method | `function VerifyKey: Boolean;` |

## Properties

### Dsa.GroupSize

`Chilkat 11.7.0 · pascal · Dsa · GroupSize · property · read/write`

```pascal
property GroupSize: Integer read GetGroupSize write SetGroupSize;
```

Specifies the size, in bits, of the DSA subgroup parameter `Q` used by the legacy `GenKey` method. The default is `160`. This also determines the natural size of the DSA signature components `r` and `s`.

Applications should normally leave this property at its default. When an explicit standards-era `(L, N)` parameter pair is required, use `GenKey2`, where `L` is the bit length of `P` and `N` is the bit length of `Q`.

**Legacy algorithm:** NIST FIPS 186-5 no longer approves DSA for generating new digital signatures. Retain DSA generation and signing only for interoperability with systems or data formats that specifically require it; DSA verification remains useful for legacy signatures.

### Dsa.HexG

`Chilkat 11.7.0 · pascal · Dsa · HexG · property · read-only`

```pascal
property HexG: string read GetHexG;
```

Returns the DSA domain parameter `G`, the generator of the subgroup of order `Q` modulo `P`.

The returned text is a hexadecimal encoding of Chilkat's SSH1-format bignum representation, which includes a two-byte bit-length prefix followed by the unsigned integer bytes.

### Dsa.HexP

`Chilkat 11.7.0 · pascal · Dsa · HexP · property · read-only`

```pascal
property HexP: string read GetHexP;
```

Returns the DSA domain parameter `P`, the large prime modulus.

The returned text is a hexadecimal encoding of Chilkat's SSH1-format bignum representation, which includes a two-byte bit-length prefix followed by the unsigned integer bytes.

### Dsa.HexQ

`Chilkat 11.7.0 · pascal · Dsa · HexQ · property · read-only`

```pascal
property HexQ: string read GetHexQ;
```

Returns the DSA domain parameter `Q`, a prime divisor of `P - 1`. The bit length of `Q` is commonly written as `N` and determines the range of the private value `X` and signature components `r` and `s`.

The returned text is a hexadecimal encoding of Chilkat's SSH1-format bignum representation, which includes a two-byte bit-length prefix followed by the unsigned integer bytes.

### Dsa.HexX

`Chilkat 11.7.0 · pascal · Dsa · HexX · property · read-only`

```pascal
property HexX: string read GetHexX;
```

Returns the DSA private value `X`. It is present only when the object contains a private key and satisfies `0 < X < Q`.

The returned text is a hexadecimal encoding of Chilkat's SSH1-format bignum representation, which includes a two-byte bit-length prefix followed by the unsigned integer bytes.

**Sensitive value:** Anyone who obtains `X` can create signatures as the key owner. Do not log, transmit, or persist this value unless it is protected as private-key material.

### Dsa.HexY

`Chilkat 11.7.0 · pascal · Dsa · HexY · property · read-only`

```pascal
property HexY: string read GetHexY;
```

Returns the DSA public value `Y`, where `Y = GX mod P`. It is available when either a public or private DSA key is loaded.

The returned text is a hexadecimal encoding of Chilkat's SSH1-format bignum representation, which includes a two-byte bit-length prefix followed by the unsigned integer bytes.

### Dsa.UncommonOptions

`Chilkat 11.7.0 · pascal · Dsa · UncommonOptions · property · read/write · since 9.5.0.90`

```pascal
property UncommonOptions: string read GetUncommonOptions write SetUncommonOptions;
```

Reserved for uncommon or compatibility-specific options. The default is the empty string, and applications should normally leave this property unchanged unless Chilkat documentation or support identifies a specific keyword required for the target system.

## Methods

### Dsa.FromDerBd

`Chilkat 11.7.0 · pascal · Dsa · FromDerBd · method · since 11.0.0`

```pascal
// bd is a TBinData object.

function  FromDerBd(bd: TChilkatBase): Boolean;
```

Loads a DSA private key from the DER bytes contained in the `BinData` object passed in `bd`. Returns `True` on successful decoding.

**Private-key handling:** The `BinData` content contains secret key material and should be cleared or released when no longer needed.

Returns True for success, False for failure.

### Dsa.FromDerFile

`Chilkat 11.7.0 · pascal · Dsa · FromDerFile · method`

```pascal
function  FromDerFile(const path: string): Boolean;
```

Loads a DSA private key from the DER-encoded file specified by `path`. Returns `True` when the file is read and decoded successfully; otherwise returns `False`.

**Private-key handling:** Restrict access to the file because it contains secret key material. Check `LastErrorText` when loading fails.

Returns True for success, False for failure.

### Dsa.FromEncryptedPem

`Chilkat 11.7.0 · pascal · Dsa · FromEncryptedPem · method`

```pascal
function  FromEncryptedPem(const password: string;
    const pemData: string): Boolean;
```

Loads a DSA private key from the PEM text in `pemData`. `password` supplies the password when the PEM is encrypted. If the PEM is unencrypted, the password is ignored and the key is loaded normally.

Returns `True` on success and `False` if the PEM cannot be decoded, the password is incorrect, or the contained key is not a supported DSA private key.

**Security:** Do not embed production passwords in source code or log the PEM text. Prefer protected secret storage and encrypted private-key files where practical.

Returns True for success, False for failure.

### Dsa.FromPem

`Chilkat 11.7.0 · pascal · Dsa · FromPem · method`

```pascal
function  FromPem(const pemData: string): Boolean;
```

Loads an unencrypted DSA private key from the PEM text in `pemData`. On success, the object contains the private key and its corresponding public components.

**Unencrypted private key:** PEM armor is only a text encoding; it does not protect the private key. Treat the string as highly sensitive and use `FromEncryptedPem` when password-protected PEM is available.

Returns True for success, False for failure.

### Dsa.FromPublicDerBd

`Chilkat 11.7.0 · pascal · Dsa · FromPublicDerBd · method · since 11.0.0`

```pascal
// bd is a TBinData object.

function  FromPublicDerBd(bd: TChilkatBase): Boolean;
```

Loads a DSA public key from the DER bytes contained in the `BinData` object passed in `bd`. The resulting key can verify signatures but cannot sign.

Returns True for success, False for failure.

### Dsa.FromPublicDerFile

`Chilkat 11.7.0 · pascal · Dsa · FromPublicDerFile · method`

```pascal
function  FromPublicDerFile(const path: string): Boolean;
```

Loads a DSA public key from the DER-encoded file specified by `path`. Returns `True` when the file is read and decoded successfully; otherwise returns `False`.

Returns True for success, False for failure.

### Dsa.FromPublicPem

`Chilkat 11.7.0 · pascal · Dsa · FromPublicPem · method`

```pascal
function  FromPublicPem(const pemData: string): Boolean;
```

Loads a DSA public key from the PEM text in `pemData`. Returns `True` when the PEM contains a supported DSA public key and is decoded successfully.

Returns True for success, False for failure.

### Dsa.FromXml

`Chilkat 11.7.0 · pascal · Dsa · FromXml · method`

```pascal
function  FromXml(const xmlKey: string): Boolean;
```

Loads a DSA public or private key from the XML text in `xmlKey`. The XML content determines whether the resulting object contains public components only or also includes the private value `X`.

**Security:** XML is only a representation format. If the XML contains `X`, it contains the complete private key and must be protected accordingly.

Returns True for success, False for failure.

### Dsa.GenKey

`Chilkat 11.7.0 · pascal · Dsa · GenKey · method`

```pascal
function  GenKey(numBits: Integer): Boolean;
```

Generates a new DSA key pair with a `P` size of `numBits` bits. `numBits` must be at least 1024 and a multiple of 64. This legacy method uses the subgroup size selected by `GroupSize`, whose default is 160 bits.

For explicit standard parameter pairs such as `(2048, 224)` or `(3072, 256)`, use `GenKey2`.

**Legacy algorithm:** DSA signature generation is no longer approved by FIPS 186-5. Generate new DSA keys only when required for compatibility with an existing protocol, key store, or signature format.

Returns True for success, False for failure.

### Dsa.GenKey2

`Chilkat 11.7.0 · pascal · Dsa · GenKey2 · method · since 9.5.0.90`

```pascal
function  GenKey2(keyLenBits: Integer;
    modLenBits: Integer): Boolean;
```

Generates a new DSA key pair using an explicit `(L, N)` parameter-size combination. `keyLenBits` is `L`, the bit length of the prime modulus `P`. `modLenBits` is `N`, the bit length of the subgroup prime `Q`.

| L | N | Historical FIPS 186-4 combination |
| :--- | :--- | :--- |
| `1024` | `160` | Legacy |
| `2048` | `224` or `256` | Supported parameter pairs |
| `3072` | `256` | Largest listed pair |

**Current standards status:** These combinations come from the superseded FIPS 186-4 DSA specification. FIPS 186-5 no longer approves DSA signature generation; use this method only for compatibility.

Returns True for success, False for failure.

### Dsa.GenKeyFromParamsDerBd

`Chilkat 11.7.0 · pascal · Dsa · GenKeyFromParamsDerBd · method · since 11.0.0`

```pascal
// bd is a TBinData object.

function  GenKeyFromParamsDerBd(bd: TChilkatBase): Boolean;
```

Generates a new DSA key pair from OpenSSL-style DSA parameters stored as DER bytes in the `BinData` object passed in `bd`.

The supplied data contains DSA domain parameters `P`, `Q`, and `G`, not an existing private key. Chilkat validates or imports those parameters and generates a fresh private value `X` and corresponding public value `Y`.

Returns True for success, False for failure.

### Dsa.GenKeyFromParamsDerFile

`Chilkat 11.7.0 · pascal · Dsa · GenKeyFromParamsDerFile · method`

```pascal
function  GenKeyFromParamsDerFile(const path: string): Boolean;
```

Generates a new DSA key pair from the OpenSSL-style DER DSA-parameters file specified by `path`.

The supplied data contains DSA domain parameters `P`, `Q`, and `G`, not an existing private key. Chilkat validates or imports those parameters and generates a fresh private value `X` and corresponding public value `Y`.

Returns `True` when the parameters are loaded and a key pair is generated successfully.

Returns True for success, False for failure.

### Dsa.GenKeyFromParamsPem

`Chilkat 11.7.0 · pascal · Dsa · GenKeyFromParamsPem · method`

```pascal
function  GenKeyFromParamsPem(const pem: string): Boolean;
```

Generates a new DSA key pair from OpenSSL-style DSA parameters supplied as PEM text in `pem`.

The supplied data contains DSA domain parameters `P`, `Q`, and `G`, not an existing private key. Chilkat validates or imports those parameters and generates a fresh private value `X` and corresponding public value `Y`.

Returns True for success, False for failure.

### Dsa.GenKeyFromParamsPemFile

`Chilkat 11.7.0 · pascal · Dsa · GenKeyFromParamsPemFile · method`

```pascal
function  GenKeyFromParamsPemFile(const path: string): Boolean;
```

Generates a new DSA key pair from the OpenSSL-style PEM DSA-parameters file specified by `path`.

The supplied data contains DSA domain parameters `P`, `Q`, and `G`, not an existing private key. Chilkat validates or imports those parameters and generates a fresh private value `X` and corresponding public value `Y`.

A typical parameter file is PEM-armored with a `BEGIN DSA PARAMETERS` header. The newly generated private key can be exported with the applicable `To*` methods.

Returns True for success, False for failure.

### Dsa.GenKeyFromPQG

`Chilkat 11.7.0 · pascal · Dsa · GenKeyFromPQG · method · since 9.5.0.90`

```pascal
function  GenKeyFromPQG(const pHex: string;
    const qHex: string;
    const gHex: string): Boolean;
```

Generates a new DSA private/public key pair using the preselected domain parameters `P`, `Q`, and `G` supplied in `pHex`, `qHex`, and `gHex`.

Each argument is hexadecimal text in Chilkat's SSH1-format bignum representation. Chilkat generates a fresh private value `X` and derives `Y`; the supplied values are domain parameters, not an existing key pair.

**Parameter provenance:** Only use DSA parameters obtained from a trusted, validated source. Malformed or maliciously chosen domain parameters can undermine signature security.

Returns True for success, False for failure.

### Dsa.GetEncodedHash

`Chilkat 11.7.0 · pascal · Dsa · GetEncodedHash · method`

```pascal
function  GetEncodedHash(const encoding: string): string;
```

Returns the current `Hash` bytes encoded according to `encoding`. Use `hex` or `base64`.

This method does not compute a hash; it only converts the bytes already stored in the `Hash` property to text.

Returns True for success, False for failure.

### Dsa.GetEncodedSignature

`Chilkat 11.7.0 · pascal · Dsa · GetEncodedSignature · method`

```pascal
function  GetEncodedSignature(const encoding: string): string;
```

Returns the current `Signature` bytes encoded according to `encoding`. Use `hex` or `base64`.

After a successful `SignHash` call, the returned bytes are the ASN.1 DER-encoded DSA signature containing the integers `r` and `s`.

Returns True for success, False for failure.

### Dsa.LoadText

`Chilkat 11.7.0 · pascal · Dsa · LoadText · method`

```pascal
function  LoadText(const path: string): string;
```

Loads the entire file specified by `path` and returns its contents as text using the legacy ANSI character encoding.

**Encoding note:** This convenience method is suitable for ASCII-compatible PEM and similar legacy text. It is not a general Unicode file reader; use an API with an explicit character encoding when UTF-8 or other Unicode text must be preserved.

Returns True for success, False for failure.

### Dsa.SaveText

`Chilkat 11.7.0 · pascal · Dsa · SaveText · method`

```pascal
function  SaveText(const strToSave: string;
    const path: string): Boolean;
```

Writes `strToSave` to the file specified by `path` using the legacy ANSI character encoding. Returns `True` on success.

**Encoding note:** This convenience method is appropriate for ASCII-compatible PEM text. It can lose characters that are not representable in the active ANSI encoding, so use an explicitly encoded text-writing API for general Unicode content.

Returns True for success, False for failure.

### Dsa.SetEncodedHash

`Chilkat 11.7.0 · pascal · Dsa · SetEncodedHash · method`

```pascal
function  SetEncodedHash(const encoding: string;
    const encodedHash: string): Boolean;
```

Decodes `encodedHash` using the encoding named by `encoding` and stores the resulting bytes in the `Hash` property. Use `hex` or `base64`.

The decoded value must be the already-computed message digest that will be signed by `SignHash` or checked by `Verify`.

Returns True for success, False for failure.

### Dsa.SetEncodedSignature

`Chilkat 11.7.0 · pascal · Dsa · SetEncodedSignature · method`

```pascal
function  SetEncodedSignature(const encoding: string;
    const encodedSig: string): Boolean;
```

Decodes the signature text in `encodedSig` using the encoding named by `encoding` and stores the resulting bytes in the `Signature` property. Use `hex` or `base64`.

The decoded bytes are expected to contain the ASN.1 DER-encoded DSA signature. Set the corresponding `Hash` and public key before calling `Verify`.

Returns True for success, False for failure.

### Dsa.SetEncodedSignatureRS

`Chilkat 11.7.0 · pascal · Dsa · SetEncodedSignatureRS · method`

```pascal
function  SetEncodedSignatureRS(const encoding: string;
    const encodedR: string;
    const encodedS: string): Boolean;
```

Builds the DSA signature from separately encoded `r` and `s` integer values. `encoding` identifies the encoding used by both `encodedR` and `encodedS`; use `hex` or `base64`.

On success, `Signature` contains the ASN.1 DER `SEQUENCE` of the two integers and is ready for use with `Verify`.

Returns True for success, False for failure.

### Dsa.SetKeyExplicit

`Chilkat 11.7.0 · pascal · Dsa · SetKeyExplicit · method`

```pascal
function  SetKeyExplicit(groupSizeInBytes: Integer;
    const pHex: string;
    const qHex: string;
    const gHex: string;
    const xHex: string): Boolean;
```

Loads a DSA private key from explicitly supplied components. `groupSizeInBytes` is the size of `Q` in bytes. `pHex`, `qHex`, `gHex`, and `xHex` provide `P`, `Q`, `G`, and the private value `X`, respectively.

The corresponding public value `Y = GX mod P` is derived from the private key.

**SSH1 bignums:** Each component string is hexadecimal text representing an SSH1-format bignum: a two-byte bit-length prefix followed by the unsigned integer bytes.

**Sensitive value:** `xHex` contains the private key. Do not expose it in logs or transmit it over an unprotected channel.

Returns True for success, False for failure.

### Dsa.SetPubKeyExplicit

`Chilkat 11.7.0 · pascal · Dsa · SetPubKeyExplicit · method`

```pascal
function  SetPubKeyExplicit(groupSizeInBytes: Integer;
    const pHex: string;
    const qHex: string;
    const gHex: string;
    const yHex: string): Boolean;
```

Loads a DSA public key from explicitly supplied components. `groupSizeInBytes` is the size of `Q` in bytes. `pHex`, `qHex`, `gHex`, and `yHex` provide `P`, `Q`, `G`, and the public value `Y`, respectively.

The resulting object can verify DSA signatures but cannot create them.

**SSH1 bignums:** Each component string is hexadecimal text representing an SSH1-format bignum: a two-byte bit-length prefix followed by the unsigned integer bytes.

Returns True for success, False for failure.

### Dsa.SignHash

`Chilkat 11.7.0 · pascal · Dsa · SignHash · method`

```pascal
function  SignHash: Boolean;
```

Creates a DSA signature over the digest currently stored in `Hash`. A DSA private key must be loaded, and the digest must be set directly or with `SetEncodedHash` before this method is called.

On success, `Signature` contains an ASN.1 DER-encoded sequence of the DSA values `r` and `s`. Retrieve it with `GetEncodedSignature` or read the `Signature` property.

**Security-critical nonce:** Each DSA signature requires a secret per-signature value. Reuse or poor generation of that value can reveal the private key. Chilkat performs this generation internally; applications should not attempt to reuse signature state.

**Standards status:** FIPS 186-5 no longer approves DSA for generating new signatures. Use this method only for required legacy interoperability.

Returns True for success, False for failure.

### Dsa.ToDerBd

`Chilkat 11.7.0 · pascal · Dsa · ToDerBd · method · since 11.0.0`

```pascal
// bd is a TBinData object.

function  ToDerBd(bd: TChilkatBase): Boolean;
```

Writes the DER-encoded DSA private key to the `BinData` object passed in `bd`. Returns `True` on success.

**Sensitive output:** The destination contains unencrypted private-key bytes after a successful call. Protect and clear it appropriately.

Returns True for success, False for failure.

### Dsa.ToDerFile

`Chilkat 11.7.0 · pascal · Dsa · ToDerFile · method`

```pascal
function  ToDerFile(const path: string): Boolean;
```

Writes the loaded DSA private key to the DER file specified by `path`. Returns `True` on success.

**Sensitive output:** The file contains unencrypted private-key material. Apply restrictive filesystem permissions and avoid writing it to shared or temporary locations.

Returns True for success, False for failure.

### Dsa.ToEncryptedPem

`Chilkat 11.7.0 · pascal · Dsa · ToEncryptedPem · method`

```pascal
function  ToEncryptedPem(const password: string): string;
```

Returns the loaded DSA private key as password-encrypted PEM text using `password` as the password.

**Password protection:** Use a strong password and protect it separately from the PEM. Encrypted PEM reduces exposure at rest but does not make it safe to log or transmit indiscriminately.

Returns True for success, False for failure.

### Dsa.ToPem

`Chilkat 11.7.0 · pascal · Dsa · ToPem · method`

```pascal
function  ToPem: string;
```

Returns the loaded DSA private key as unencrypted PEM text.

**Unencrypted private key:** PEM armor is not encryption. Anyone who obtains this text can use the private key, so prefer `ToEncryptedPem` when password protection is required.

Returns True for success, False for failure.

### Dsa.ToPublicDerFile

`Chilkat 11.7.0 · pascal · Dsa · ToPublicDerFile · method`

```pascal
function  ToPublicDerFile(const path: string): Boolean;
```

Writes the public portion of the loaded DSA key to the DER file specified by `path`. Returns `True` on success.

Returns True for success, False for failure.

### Dsa.ToPublicPem

`Chilkat 11.7.0 · pascal · Dsa · ToPublicPem · method`

```pascal
function  ToPublicPem: string;
```

Returns the public portion of the loaded DSA key as PEM text. Public-key PEM may be distributed to parties that need to verify signatures; it does not contain the private value `X`.

Returns True for success, False for failure.

### Dsa.ToXml

`Chilkat 11.7.0 · pascal · Dsa · ToXml · method`

```pascal
function  ToXml(bPublicOnly: Boolean): string;
```

Returns the loaded DSA key as XML. Set `bPublicOnly` to `True` to export public components only. Set it to `False` to include the private component when a private key is loaded.

**Security:** When `bPublicOnly` is `False`, the XML can contain the private value `X`. Protect it as private-key material.

Returns True for success, False for failure.

### Dsa.Verify

`Chilkat 11.7.0 · pascal · Dsa · Verify · method`

```pascal
function  Verify: Boolean;
```

Verifies the DSA signature currently stored in `Signature` against the digest stored in `Hash`, using the loaded public key. Both values must be set before calling this method.

Returns `True` only when the signature is valid. A `False` result can indicate an invalid signature, malformed input, an incompatible key, or another operational error; inspect `LastErrorText` when the reason matters.

Returns True for success, False for failure.

### Dsa.VerifyKey

`Chilkat 11.7.0 · pascal · Dsa · VerifyKey · method`

```pascal
function  VerifyKey: Boolean;
```

Checks the mathematical validity and internal consistency of the DSA public or private key currently loaded in the object. Returns `True` when the key parameters and available key components pass validation.

This does not establish who owns the key, whether the key came from a trusted source, or whether it is suitable for a particular protocol.

## Related classes

[`BinData`](https://www.chilkatsoft.com/ai-docs/v/11.7.0/pascal/classes/BinData.md)