AuthAws Lazarus Pascal Reference Documentation

AuthAws

Current Version: 11.6.0
Requires Chilkat Bundle License

Chilkat.AuthAws

Configure AWS request signing for REST calls and temporary pre-signed URLs.

Chilkat.AuthAws holds the AWS authentication settings used by Chilkat.Rest when sending signed AWS requests. It supports AWS Signature Version 4 by default, can optionally use the older Signature Version 2 where applicable, accepts direct credential values or secure secret specifiers, and can generate temporary Signature V4 pre-signed URLs for AWS services.

REST authentication object

Provide AWS signing settings to Chilkat.Rest so outgoing requests are authenticated according to AWS requirements.

Signature Version 4

Sign requests using AWS Signature Version 4, including service, region, credentials, headers, and request payload details.

Credentials and secrets

Use access keys and secret keys directly, or use secret specifiers when credentials should be resolved from a secure credential source.

Region and service targeting

Configure the AWS region and service name so signatures are generated for the correct AWS endpoint.

Temporary credentials

Include session tokens when signing requests with temporary AWS credentials from STS, IAM roles, or similar credential flows.

Pre-signed URLs

Generate temporary Signature V4 pre-signed URLs when a client needs limited-time access without sending AWS credentials.

Common pattern: Create and configure an AuthAws object with the AWS access key, secret key or secret specifier, region, service name, and optional session token, then pass it to Chilkat.Rest before sending the request. Use AuthAws for AWS request signing; use service-specific Chilkat classes or Chilkat.Http/Chilkat.Rest for constructing and sending the actual API request.

For an extended overview, see AuthAws Class Overview.

Create / Free

uses
  Chilkat.AuthAws;

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

    // ... use obj ...

  finally
    obj.Free;
  end;
end;
constructor Create;

Allocates the underlying CkAuthAws object and returns a new TAuthAws instance. Simply adding Chilkat.AuthAws 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 TAuthAws created by calling Create should eventually be released by calling .Free (inherited from TObject). The destructor automatically disposes the underlying CkAuthAws handle. A native (unmanaged) memory leak occurs if the object is never freed.

Properties

AccessKey
property AccessKey: string read GetAccessKey write SetAccessKey;
Introduced in version 9.5.0.58

The AWS access key.

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CanonicalizedResourceV2
property CanonicalizedResourceV2: string read GetCanonicalizedResourceV2 write SetCanonicalizedResourceV2;
Introduced in version 9.5.0.58

If AWS Signature Version V2 is used, then this property must be set. The rules for setting the canonicalized resource for the V2 signature method is described here: Constructing the CanonicalizedResource Element.

More Information and Examples
(using AWS Signature Version 2) Streaming Download to File
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DebugLogFilePath
property DebugLogFilePath: string read GetDebugLogFilePath write SetDebugLogFilePath;

If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. This logging helps identify the context and history of Chilkat calls leading up to any crash or hang, aiding in debugging.

Enabling the VerboseLogging property provides more detailed information. This property is mainly used for debugging rare instances where a Chilkat method call causes a hang or crash, which should generally not happen.

Possible causes of hangs include:

  • A timeout property set to 0, indicating an infinite timeout.
  • A hang occurring within an event callback in the application code.
  • An internal bug in the Chilkat code causing the hang.

More Information and Examples
Example showing how to use DebugLogFilePath.
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EnableSecrets
property EnableSecrets: Boolean read GetEnableSecrets write SetEnableSecrets;
Introduced in version 11.5.0

If True a secret specifier of the format "!!part1|part2|.." can be provided instead of the actual value for the AccessKey and SecretKey properties.

The default value is False.

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LastErrorHtml
property LastErrorHtml: string read GetLastErrorHtml;

Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

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LastErrorText
property LastErrorText: string read GetLastErrorText;

Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

More Information and Examples
Concept of LastErrorTextLastErrorText Standard Information
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LastErrorXml
property LastErrorXml: string read GetLastErrorXml;

Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

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LastMethodSuccess
property LastMethodSuccess: Boolean read GetLastMethodSuccess write SetLastMethodSuccess;

Indicates the success or failure of the most recent method call: True means success, False means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages. Note: This property does not apply to methods that return integer values or to boolean-returning methods where the boolean does not indicate success or failure.

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PrecomputedMd5
property PrecomputedMd5: string read GetPrecomputedMd5 write SetPrecomputedMd5;
Introduced in version 9.5.0.58

This property can optionally be set for AWS requests that have a non-empty request body. This should be the base64 encoding of the 16 bytes of the MD5 hash. The most common need for this is if doing an S3 upload from a stream. (If the pre-computed MD5 is not provided, then Chilkat is forced to stream the entire file into memory so that it can calculate the MD5 for authentication.)

Note: AWS Signature Version 2 uses the MD5, whereas Signature Version 4 uses SHA256.

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PrecomputedSha256
property PrecomputedSha256: string read GetPrecomputedSha256 write SetPrecomputedSha256;
Introduced in version 9.5.0.58

This property can optionally be set for AWS requests that have a non-empty request body. This should be the lowercase hex encoding of the 32-bytes of the SHA256 hash. The most common need for this is if doing an S3 upload from a stream. (If the pre-computed SHA-256 is not provided, then Chilkat is forced to stream the entire file into memory so that it can calculate the SHA-256 for authentication.)

Note: AWS Signature Version 4 uses the SHA256 hash. (AWS Signature Version 2 uses MD5)

More Information and Examples
AWS S3 File Streaming Upload
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Region
property Region: string read GetRegion write SetRegion;
Introduced in version 9.5.0.58

The AWS region, such as us-east-1, us-west-2, eu-west-1, eu-central-1, etc. The default is us-east-1. It is only used when the SignatureVersion property is set to 4. This property is unused when the SignatureVersion property is set to 2.

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SecretKey
property SecretKey: string read GetSecretKey write SetSecretKey;
Introduced in version 9.5.0.58

The AWS secret key.

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ServiceName
property ServiceName: string read GetServiceName write SetServiceName;
Introduced in version 9.5.0.58

The AWS service namespace, such as s3, ses, etc. See http://docs.aws.amazon.com/general/latest/gr/aws-arns-and-namespaces.html#genref-aws-service-namespaces

This property is unused when the SignatureVersion property is set to 2.

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SignatureVersion
property SignatureVersion: Integer read GetSignatureVersion write SetSignatureVersion;
Introduced in version 9.5.0.58

The AWS Signature Version to be used in authentication. The default value is 4. This can optionally be set to the value 2 to use the older V2 signature version.

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VerboseLogging
property VerboseLogging: Boolean read GetVerboseLogging write SetVerboseLogging;

If set to True, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is False. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.

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Version
property Version: string read GetVersion;

Version of the component/library, such as "10.1.0"

More Information and Examples
How to get the Chilkat version at runtime.
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Methods

GenPresignedUrl
function GenPresignedUrl(const httpVerb: string;
    useHttps: Boolean;
    const domain: string;
    const path: string;
    numSecondsValid: Integer;
    const awsService: string): string;
Introduced in version 9.5.0.85

Generates a temporary pre-signed URL for an Amazon AWS service using AWS Signature V4. Requires that the SecretKey, AccessKey, and Region properties be set to valid values prior to calling this method.

The URL that is generated has this format: 

https://<domain>/<path>
?X-Amz-Algorithm=AWS4-HMAC-SHA256
&X-Amz-Credential=<AccessKey>/<currentDate>/<Region>/<awsService>/aws4_request
&X-Amz-Date=<currentDateTime>
&X-Amz-Expires=<numSecondsValid>
&X-Amz-SignedHeaders=host
&X-Amz-Signature=<signature-value>

The httpVerb is the HTTP verb such as GET, PUT, POST, DELETE, etc. The awsService is a string naming the AWS service, such as s3, execute-api, etc. If useHttps is True, then the returned URL begins with https://, otherwise it begins with http://.

Note: It is generally not feasible to use pre-signed URLs for POST operations for any AWS service except for S3. See AWS Pre-Signed URLs for POST Operations (non-S3)

Returns True for success, False for failure.

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