// Get signature.
	newSignature := getSignature(signingKey, formValues.Get("Policy"))

	// Verify signature.
	if !compareSignatureV4(newSignature, formValues.Get(xhttp.AmzSignature)) {
		return cred, ErrSignatureDoesNotMatch
	}

	// Success.
	return cred, ErrNone
}

// doesPresignedSignatureMatch - Verify query headers with presigned signature

	signature := calculateSignatureV2(stringToSign, cred.SecretKey)
	return signature
}

// compareSignatureV2 returns true if and only if both signatures
// are equal. The signatures are expected to be base64 encoded strings
// according to the AWS S3 signature V2 spec.
func compareSignatureV2(sig1, sig2 string) bool {
	// Decode signature string to binary byte-sequence representation is required

			},
			expected: ErrInvalidAccessKeyID,
		},
		// (2) It should fail with a bad signature.
		{
			form: http.Header{
				"X-Amz-Credential": []string{fmt.Sprintf(credentialTemplate, accessKey, now.Format(yyyymmdd), globalMinioDefaultRegion)},
				"X-Amz-Date":       []string{now.Format(iso8601Format)},
				"X-Amz-Signature":  []string{"invalidsignature"},
				"Policy":           []string{"policy"},
			},

			return n, cr.err
		}
	}

	// Now, we read the signature of the following payload and expect:
	//   chunk-signature=" + <signature-as-hex> + "\r\n"
	//
	// The signature is 64 bytes long (hex-encoded SHA256 hash) and
	// starts with a 16 byte header: len("chunk-signature=") + 64 == 80.
	var signature [80]byte
	_, err = io.ReadFull(cr.reader, signature[:])
	if err == io.EOF {
		err = io.ErrUnexpectedEOF
	}

			// validating the extraction/parsing of signature field.
			if !compareSignatureV4(testCase.expectedAuthField.Signature, parsedAuthField.Signature) {
				t.Errorf("Test %d: Parsed Signature field mismatch: Expected \"%s\", got \"%s\"", i+1, testCase.expectedAuthField.Signature, parsedAuthField.Signature)
			}

			// validating the extracted signed headers.

		{"X-Amz-Content-Sha256", unsignedPayload, "X-Amz-Credential", "", true},

		// Test case - 4.
		// Enabling PreSigned Signature v4, but X-Amz-Content-Sha256 not set has to be skipped.
		{"", "", "X-Amz-Credential", "", true},

		// Test case - 5.
		// Enabling PreSigned Signature v4, but X-Amz-Content-Sha256 set and its not UNSIGNED-PAYLOAD, we shouldn't skip.

    path_param_names = get_path_param_names(path)
    endpoint_signature = get_typed_signature(call)
    signature_params = endpoint_signature.parameters
    dependant = Dependant(
        call=call,
        name=name,
        path=path,
        security_scopes=security_scopes,
        use_cache=use_cache,
    )
    for param_name, param in signature_params.items():
        is_path_param = param_name in path_param_names

          issuerUniqueID = null,
          subjectUniqueID = null,
          extensions = extensions(),
        )

      // Signature.
      val signature =
        Signature.getInstance(tbsCertificate.signatureAlgorithmName).run {
          initSign(issuerKeyPair.private)
          update(CertificateAdapters.tbsCertificate.toDer(tbsCertificate).toByteArray())
          sign().toByteString()

	}
}

// postPresignSignatureV4 - presigned signature for PostPolicy requests.
func postPresignSignatureV4(policyBase64 string, t time.Time, secretAccessKey, location string) string {
	// Get signining key.
	signingkey := getSigningKey(secretAccessKey, t, location, "s3")
	// Calculate signature.
	signature := getSignature(signingkey, policyBase64)
	return signature
}

      .isEqualTo(javaCertificate.signature.toByteString())

    assertThat(okHttpCertificate).isEqualTo(
      Certificate(
        tbsCertificate =
          TbsCertificate(
            // v3.
            version = 2L,
            serialNumber = BigInteger("1372799044"),
            signature =
              AlgorithmIdentifier(