return hex.EncodeToString(sumHMAC(signingKey, []byte(stringToSign)))
}

// Check to see if Policy is signed correctly.
func doesPolicySignatureMatch(formValues http.Header) (auth.Credentials, APIErrorCode) {
	// For SignV2 - Signature field will be valid
	if _, ok := formValues[xhttp.AmzSignatureV2]; ok {
		return doesPolicySignatureV2Match(formValues)
	}

	// Save signature finally.
	req.URL.RawQuery += "&Signature=" + url.QueryEscape(signature)
	return nil
}

// Sign given request using Signature V2.
func signRequestV2(req *http.Request, accessKey, secretKey string) error {
	signer.SignV2(*req, accessKey, secretKey, false)
	return nil
}

// Sign given request using Signature V4.
func signRequestV4(req *http.Request, accessKey, secretKey string) error {

// POSIX specifies a sum of the unsigned byte values, but the Sun tar used
// signed byte values.
// We compute and return both.
func (b *block) computeChecksum() (unsigned, signed int64) {
	for i, c := range b {
		if 148 <= i && i < 156 {
			c = ' ' // Treat the checksum field itself as all spaces.
		}
		unsigned += int64(c)
		signed += int64(int8(c))
	}
	return unsigned, signed
}

			partNumberMarker: "",
			maxParts:         "",
			expectedErr:      noSuchUploadErr,
		},
	}

	// string to represent V2 signed HTTP request.
	reqV2Str := "V2 Signed HTTP request"
	// string to represent V4 signed HTTP request.
	reqV4Str := "V4 Signed HTTP request"
	// Collection of HTTP request and ResponseRecorder and request type string.
	type inputReqRec struct {
		req     *http.Request

  "token_type": "Bearer",
  "expires_in": 3600
}
```

### 4. JWT Claims

The id_token received is a signed JSON Web Token (JWT). Use a JWT decoder to decode the id_token to access the payload of the token that includes following JWT claims:

	instructions["JGE"] = x86.AJGE  /* greater than or equal (signed) (SF = OF) */
	instructions["JGT"] = x86.AJGT  /* greater than (signed) (ZF = 0 && SF = OF) */
	instructions["JHI"] = x86.AJHI  /* higher (unsigned) (CF = 0 && ZF = 0) */
	instructions["JHS"] = x86.AJCC  /* alternate */
	instructions["JL"] = x86.AJLT   /* alternate */
	instructions["JLE"] = x86.AJLE  /* less than or equal (signed) (ZF = 1 || SF != OF) */

  (the latter if this is not a complete fix) to this comment
+ If referring to a repo other than `golang/go` you can use the
  `owner/repo#issue_number` syntax: `Fixes golang/tools#1234`
+ We do not use Signed-off-by lines in Go. Please don't add them.
  Our Gerrit server & GitHub bots enforce CLA compliance instead.

***NOTE***: Only original source code from you and other people that have signed the CLA can be accepted into the main repository.

### Contributing code

If you have improvements to TensorFlow, send us your pull requests! For those
just getting started, GitHub has a
[how-to](https://help.github.com/articles/using-pull-requests/).

TensorFlow team members will be assigned to review your pull requests. Once the

<!--- Link to relevant issues or forum discussions here -->

### Contributor Checklist
- [ ] [Review Contribution Guidelines](https://github.com/gradle/gradle/blob/master/CONTRIBUTING.md).
- [ ] Make sure that all commits are [signed off](https://git-scm.com/docs/git-commit#Documentation/git-commit.txt---signoff) to indicate that you agree to the terms of [Developer Certificate of Origin](https://developercertificate.org/).

However, further setup is required to run tests or programs directly on a device.

First make sure you have a valid developer certificate and have setup your device properly
to run apps signed by your developer certificate. Then install the libimobiledevice and
ideviceinstaller tools from https://www.libimobiledevice.org/. Use the HEAD versions from