---
product: Chilkat
product_version: 11.7.0
language: c
language_label: C
class: AuthAws
license: bundle
deprecated: false
reference_html: https://www.chilkatsoft.com/refdoc/c_CkAuthAwsRef.html
---
# Chilkat AuthAws — C — v11.7.0

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

## Purpose

**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](https://www.chilkatsoft.com/authaws_class_overview.asp).

## Object creation, unlocking and error handling

**Create/Dispose**

```c
HCkAuthAws instance = CkAuthAws_Create();
// ...
CkAuthAws_Dispose(instance);
```

`HCkAuthAws CkAuthAws_Create(void);`

Creates an instance of the HCkAuthAws object and returns a handle ("void \*" pointer). The handle is passed in the 1st argument for the functions listed on this page.

`void CkAuthAws_Dispose(HCkAuthAws handle);`

Objects created by calling CkAuthAws_Create must be freed by calling this method. A memory leak occurs if a handle is not disposed by calling this function. Also, any handle returned by a Chilkat "C" function must also be freed by the application by calling the appropriate Dispose method, such as CkAuthAws_Dispose.

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 C.

## 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` | `void CkAuthAws_getDebugLogFilePath(HCkAuthAws cHandle, HCkString retval); void CkAuthAws_putDebugLogFilePath(HCkAuthAws cHandle, const char *newVal); const char *CkAuthAws_debugLogFilePath(HCkAuthAws cHandle);` | 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` | `void CkAuthAws_getLastErrorHtml(HCkAuthAws cHandle, HCkString retval); const char *CkAuthAws_lastErrorHtml(HCkAuthAws cHandle);` | read-only | Provides HTML-formatted information about the last called method or property. |
| `LastErrorText` | `void CkAuthAws_getLastErrorText(HCkAuthAws cHandle, HCkString retval); const char *CkAuthAws_lastErrorText(HCkAuthAws cHandle);` | read-only | Provides plain text information about the last called method or property. |
| `LastErrorXml` | `void CkAuthAws_getLastErrorXml(HCkAuthAws cHandle, HCkString retval); const char *CkAuthAws_lastErrorXml(HCkAuthAws cHandle);` | read-only | Provides XML-formatted information about the last called method or property. |
| `LastMethodSuccess` | `BOOL CkAuthAws_getLastMethodSuccess(HCkAuthAws cHandle); void CkAuthAws_putLastMethodSuccess(HCkAuthAws cHandle, BOOL newVal);` | read/write | Indicates the success or failure of the most recent method call: `TRUE` means success, `FALSE` means failure. |
| `Utf8` | `BOOL CkAuthAws_getUtf8(HCkAuthAws cHandle); void CkAuthAws_putUtf8(HCkAuthAws cHandle, BOOL newVal);` | read/write | When set to `TRUE`, all `const char *` arguments and return values are interpreted as UTF-8 strings. |
| `VerboseLogging` | `BOOL CkAuthAws_getVerboseLogging(HCkAuthAws cHandle); void CkAuthAws_putVerboseLogging(HCkAuthAws cHandle, BOOL newVal);` | read/write | If set to `TRUE`, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. |
| `Version` | `void CkAuthAws_getVersion(HCkAuthAws cHandle, HCkString retval); const char *CkAuthAws_version(HCkAuthAws cHandle);` | read-only | Version of the component/library, such as "10.1.0" |

## Member index

| Member | Kind | Signature |
|---|---|---|
| `AccessKey` | property, read/write | `void CkAuthAws_getAccessKey(HCkAuthAws cHandle, HCkString retval); void CkAuthAws_putAccessKey(HCkAuthAws cHandle, const char *newVal); const char *CkAuthAws_accessKey(HCkAuthAws cHandle);` |
| `CanonicalizedResourceV2` | property, read/write | `void CkAuthAws_getCanonicalizedResourceV2(HCkAuthAws cHandle, HCkString retval); void CkAuthAws_putCanonicalizedResourceV2(HCkAuthAws cHandle, const char *newVal); const char *CkAuthAws_canonicalizedResourceV2(HCkAuthAws cHandle);` |
| `EnableSecrets` | property, read/write | `BOOL CkAuthAws_getEnableSecrets(HCkAuthAws cHandle); void CkAuthAws_putEnableSecrets(HCkAuthAws cHandle, BOOL newVal);` |
| `PrecomputedMd5` | property, read/write | `void CkAuthAws_getPrecomputedMd5(HCkAuthAws cHandle, HCkString retval); void CkAuthAws_putPrecomputedMd5(HCkAuthAws cHandle, const char *newVal); const char *CkAuthAws_precomputedMd5(HCkAuthAws cHandle);` |
| `PrecomputedSha256` | property, read/write | `void CkAuthAws_getPrecomputedSha256(HCkAuthAws cHandle, HCkString retval); void CkAuthAws_putPrecomputedSha256(HCkAuthAws cHandle, const char *newVal); const char *CkAuthAws_precomputedSha256(HCkAuthAws cHandle);` |
| `Region` | property, read/write | `void CkAuthAws_getRegion(HCkAuthAws cHandle, HCkString retval); void CkAuthAws_putRegion(HCkAuthAws cHandle, const char *newVal); const char *CkAuthAws_region(HCkAuthAws cHandle);` |
| `SecretKey` | property, read/write | `void CkAuthAws_getSecretKey(HCkAuthAws cHandle, HCkString retval); void CkAuthAws_putSecretKey(HCkAuthAws cHandle, const char *newVal); const char *CkAuthAws_secretKey(HCkAuthAws cHandle);` |
| `ServiceName` | property, read/write | `void CkAuthAws_getServiceName(HCkAuthAws cHandle, HCkString retval); void CkAuthAws_putServiceName(HCkAuthAws cHandle, const char *newVal); const char *CkAuthAws_serviceName(HCkAuthAws cHandle);` |
| `SignatureVersion` | property, read/write | `int CkAuthAws_getSignatureVersion(HCkAuthAws cHandle); void CkAuthAws_putSignatureVersion(HCkAuthAws cHandle, int newVal);` |
| `GenPresignedUrl` | method | `BOOL CkAuthAws_GenPresignedUrl(HCkAuthAws cHandle, const char *httpVerb, BOOL useHttps, const char *domain, const char *path, int numSecondsValid, const char *awsService, HCkString outStr); const char *CkAuthAws_genPresignedUrl(HCkAuthAws cHandle, const char *httpVerb, BOOL useHttps, const char *domain, const char *path, int numSecondsValid, const char *awsService);` |

## Properties

### AuthAws.AccessKey

`Chilkat 11.7.0 · c · AuthAws · AccessKey · property · read/write · since 9.5.0.58`

```c
void CkAuthAws_getAccessKey(HCkAuthAws cHandle, HCkString retval);
void CkAuthAws_putAccessKey(HCkAuthAws cHandle, const char *newVal);
const char *CkAuthAws_accessKey(HCkAuthAws cHandle);
```

The AWS access key.

### AuthAws.CanonicalizedResourceV2

`Chilkat 11.7.0 · c · AuthAws · CanonicalizedResourceV2 · property · read/write · since 9.5.0.58`

```c
void CkAuthAws_getCanonicalizedResourceV2(HCkAuthAws cHandle, HCkString retval);
void CkAuthAws_putCanonicalizedResourceV2(HCkAuthAws cHandle, const char *newVal);
const char *CkAuthAws_canonicalizedResourceV2(HCkAuthAws cHandle);
```

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](http://docs.aws.amazon.com/AmazonS3/latest/dev/RESTAuthentication.html#ConstructingTheCanonicalizedResourceElement).

### AuthAws.EnableSecrets

`Chilkat 11.7.0 · c · AuthAws · EnableSecrets · property · read/write · since 11.5.0`

```c
BOOL CkAuthAws_getEnableSecrets(HCkAuthAws cHandle);
void CkAuthAws_putEnableSecrets(HCkAuthAws cHandle, BOOL newVal);
```

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`.

### AuthAws.PrecomputedMd5

`Chilkat 11.7.0 · c · AuthAws · PrecomputedMd5 · property · read/write · since 9.5.0.58`

```c
void CkAuthAws_getPrecomputedMd5(HCkAuthAws cHandle, HCkString retval);
void CkAuthAws_putPrecomputedMd5(HCkAuthAws cHandle, const char *newVal);
const char *CkAuthAws_precomputedMd5(HCkAuthAws cHandle);
```

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.

### AuthAws.PrecomputedSha256

`Chilkat 11.7.0 · c · AuthAws · PrecomputedSha256 · property · read/write · since 9.5.0.58`

```c
void CkAuthAws_getPrecomputedSha256(HCkAuthAws cHandle, HCkString retval);
void CkAuthAws_putPrecomputedSha256(HCkAuthAws cHandle, const char *newVal);
const char *CkAuthAws_precomputedSha256(HCkAuthAws cHandle);
```

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)

### AuthAws.Region

`Chilkat 11.7.0 · c · AuthAws · Region · property · read/write · since 9.5.0.58`

```c
void CkAuthAws_getRegion(HCkAuthAws cHandle, HCkString retval);
void CkAuthAws_putRegion(HCkAuthAws cHandle, const char *newVal);
const char *CkAuthAws_region(HCkAuthAws cHandle);
```

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.

### AuthAws.SecretKey

`Chilkat 11.7.0 · c · AuthAws · SecretKey · property · read/write · since 9.5.0.58`

```c
void CkAuthAws_getSecretKey(HCkAuthAws cHandle, HCkString retval);
void CkAuthAws_putSecretKey(HCkAuthAws cHandle, const char *newVal);
const char *CkAuthAws_secretKey(HCkAuthAws cHandle);
```

The AWS secret key.

### AuthAws.ServiceName

`Chilkat 11.7.0 · c · AuthAws · ServiceName · property · read/write · since 9.5.0.58`

```c
void CkAuthAws_getServiceName(HCkAuthAws cHandle, HCkString retval);
void CkAuthAws_putServiceName(HCkAuthAws cHandle, const char *newVal);
const char *CkAuthAws_serviceName(HCkAuthAws cHandle);
```

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.

### AuthAws.SignatureVersion

`Chilkat 11.7.0 · c · AuthAws · SignatureVersion · property · read/write · since 9.5.0.58`

```c
int CkAuthAws_getSignatureVersion(HCkAuthAws cHandle);
void CkAuthAws_putSignatureVersion(HCkAuthAws cHandle, int newVal);
```

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.

## Methods

### AuthAws.GenPresignedUrl

`Chilkat 11.7.0 · c · AuthAws · GenPresignedUrl · method · since 9.5.0.85`

```c
BOOL CkAuthAws_GenPresignedUrl(HCkAuthAws cHandle, const char *httpVerb, BOOL useHttps, const char *domain, const char *path, int numSecondsValid, const char *awsService, HCkString outStr);
const char *CkAuthAws_genPresignedUrl(HCkAuthAws cHandle, const char *httpVerb, BOOL useHttps, const char *domain, const char *path, int numSecondsValid, const char *awsService);
```

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)](https://www.chilkatsoft.com/aws_pre_signed_urls_for_post_operations.asp)

Returns TRUE for success, FALSE for failure.