fv:   defaultFormVals.Clone().Set(xhttp.AmzSignature, "my-signature"),
		},
		{
			name: "XIgnoreFoo does not have to appear in policy",
			fv:   defaultFormVals.Clone().Set("X-Ignore-Foo", "my-foo-value"),
		},
		{
			name: "File does not have to appear in policy",
			fv:   defaultFormVals.Clone().Set("File", "file-value"),
		},
		{
			name: "Signature does not have to appear in policy",

	return strings.HasPrefix(r.Header.Get(xhttp.Authorization), jwtAlgorithm)
}

// Verify if request has AWS Signature Version '4'.
func isRequestSignatureV4(r *http.Request) bool {
	return strings.HasPrefix(r.Header.Get(xhttp.Authorization), signV4Algorithm)
}

// Verify if request has AWS Signature Version '2'.
func isRequestSignatureV2(r *http.Request) bool {

If you want to play with JWT tokens and see how they work, check <a href="https://jwt.io/" class="external-link" target="_blank">https://jwt.io</a>.

## Install `PyJWT` { #install-pyjwt }

	// Dummy putBucketACL
	AmzACL = "x-amz-acl"

	// Signature V4 related constants.
	AmzContentSha256        = "X-Amz-Content-Sha256"
	AmzDate                 = "X-Amz-Date"
	AmzAlgorithm            = "X-Amz-Algorithm"
	AmzExpires              = "X-Amz-Expires"
	AmzSignedHeaders        = "X-Amz-SignedHeaders"
	AmzSignature            = "X-Amz-Signature"
	AmzCredential           = "X-Amz-Credential"

      }
      return builder.build();
    }
  }

  private static final class Signature {
    private final String name;
    private final ImmutableList<Class<?>> parameterTypes;

    Signature(Method method) {
      this(method.getName(), ImmutableList.copyOf(method.getParameterTypes()));
    }

    Signature(String name, ImmutableList<Class<?>> parameterTypes) {
      this.name = name;

        // Assert
        assertTrue(result, "Verify should return true for valid signature");
        verify(signingDigest, times(1)).verify(testData, offset, length, extraPad, message);
    }

    @Test
    @DisplayName("Test verify method returns false for invalid signature")
    void testVerifyReturnsFalse() {
        // Arrange
        int offset = 0;
        int length = testData.length;

xlHeaderVersion version == 1:

```
//msgp:tuple xlMetaV2VersionHeader
type xlMetaV2VersionHeader struct {
 VersionID [16]byte  // Version UUID, raw.
 ModTime   int64     // Unix nanoseconds.
 Signature [4]byte   // Signature of metadata.
 Type      uint8     // Type if the version
 Flags     uint8
}
```

The following flags are defined:

```
const (
 FreeVersion = 1 << 0
 UsesDataDir = 1 << 1

	if err != nil {
		t.Fatal(err)
	}

  if (TF_GetCode(status) != TF_OK) return;

  tensorflow::GradientDef gdef;
  gdef.set_function_name(func->record->fdef().signature().name());
  gdef.set_gradient_func(grad->record->fdef().signature().name());
  status->status = g->graph.AddGradientDef(std::move(gdef));
}

int TF_GraphNumFunctions(TF_Graph* g) {
  tensorflow::mutex_lock l(g->mu);

                    12:8b
        X509v3 extensions:
            X509v3 Key Usage: critical
                Digital Signature
            X509v3 Extended Key Usage: 
                TLS Web Client Authentication
            X509v3 Basic Constraints: critical
                CA:FALSE
    Signature Algorithm: ED25519
         7e:aa:be:ed:47:4d:b9:2f:fc:ed:7f:5a:fc:6b:c0:05:5b:f5: