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/*
* Copyright (C) 2022, Workday Inc.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0 which is available at
* https://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package org.eclipse.jgit.transport;
import static java.nio.charset.StandardCharsets.UTF_8;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.time.Instant;
import java.time.OffsetDateTime;
import java.time.ZoneOffset;
import java.time.format.DateTimeFormatter;
import java.util.HashMap;
import java.util.Map;
import java.util.stream.Collectors;
import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import org.eclipse.jgit.internal.JGitText;
import org.eclipse.jgit.util.Hex;
import org.eclipse.jgit.util.HttpSupport;
/**
* Utility class for signing requests to AWS service endpoints using the V4
* signing protocol.
*
* Reference implementation: <a href=
* "https://docs.aws.amazon.com/AmazonS3/latest/API/samples/AWSS3SigV4JavaSamples.zip">AWSS3SigV4JavaSamples.zip</a>
*
* @see <a href=
* "https://docs.aws.amazon.com/general/latest/gr/signature-version-4.html">AWS
* Signature Version 4</a>
*
* @since 5.13.1
*/
public final class AwsRequestSignerV4 {
/** AWS version 4 signing algorithm (for authorization header). **/
private static final String ALGORITHM = "HMAC-SHA256"; //$NON-NLS-1$
/** Java Message Authentication Code (MAC) algorithm name. **/
private static final String MAC_ALGORITHM = "HmacSHA256"; //$NON-NLS-1$
/** AWS version 4 signing scheme. **/
private static final String SCHEME = "AWS4"; //$NON-NLS-1$
/** AWS version 4 terminator string. **/
private static final String TERMINATOR = "aws4_request"; //$NON-NLS-1$
/** SHA-256 hash of an empty request body. **/
private static final String EMPTY_BODY_SHA256 = "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"; //$NON-NLS-1$
/** Date format for the 'x-amz-date' header. **/
private static final DateTimeFormatter AMZ_DATE_FORMAT = DateTimeFormatter
.ofPattern("yyyyMMdd'T'HHmmss'Z'"); //$NON-NLS-1$
/** Date format for the string-to-sign's scope. **/
private static final DateTimeFormatter SCOPE_DATE_FORMAT = DateTimeFormatter
.ofPattern("yyyyMMdd"); //$NON-NLS-1$
private AwsRequestSignerV4() {
// Don't instantiate utility class
}
/**
* Sign the provided request with an AWS4 signature as the 'Authorization'
* header.
*
* @param httpURLConnection
* The request to sign.
* @param queryParameters
* The query parameters being sent in the request.
* @param contentLength
* The content length of the data being sent in the request
* @param bodyHash
* Hex-encoded SHA-256 hash of the data being sent in the request
* @param serviceName
* The signing name of the AWS service (e.g. "s3").
* @param regionName
* The name of the AWS region that will handle the request (e.g.
* "us-east-1").
* @param awsAccessKey
* The user's AWS Access Key.
* @param awsSecretKey
* The user's AWS Secret Key.
*/
public static void sign(HttpURLConnection httpURLConnection,
Map<String, String> queryParameters, long contentLength,
String bodyHash, String serviceName, String regionName,
String awsAccessKey, char[] awsSecretKey) {
// get request headers
Map<String, String> headers = new HashMap<>();
httpURLConnection.getRequestProperties()
.forEach((headerName, headerValues) -> headers.put(headerName,
String.join(",", headerValues))); //$NON-NLS-1$
// add required content headers
if (contentLength > 0) {
headers.put(HttpSupport.HDR_CONTENT_LENGTH,
String.valueOf(contentLength));
} else {
bodyHash = EMPTY_BODY_SHA256;
}
headers.put("x-amz-content-sha256", bodyHash); //$NON-NLS-1$
// add the 'x-amz-date' header
OffsetDateTime now = Instant.now().atOffset(ZoneOffset.UTC);
String amzDate = now.format(AMZ_DATE_FORMAT);
headers.put("x-amz-date", amzDate); //$NON-NLS-1$
// add the 'host' header
URL endpointUrl = httpURLConnection.getURL();
int port = endpointUrl.getPort();
String hostHeader = (port > -1)
? endpointUrl.getHost().concat(":" + port) //$NON-NLS-1$
: endpointUrl.getHost();
headers.put("Host", hostHeader); //$NON-NLS-1$
// construct the canonicalized request
String canonicalizedHeaderNames = getCanonicalizeHeaderNames(headers);
String canonicalizedHeaders = getCanonicalizedHeaderString(headers);
String canonicalizedQueryParameters = getCanonicalizedQueryString(
queryParameters);
String httpMethod = httpURLConnection.getRequestMethod();
String canonicalRequest = httpMethod + '\n'
+ getCanonicalizedResourcePath(endpointUrl) + '\n'
+ canonicalizedQueryParameters + '\n' + canonicalizedHeaders
+ '\n' + canonicalizedHeaderNames + '\n' + bodyHash;
// construct the string-to-sign
String scopeDate = now.format(SCOPE_DATE_FORMAT);
String scope = scopeDate + '/' + regionName + '/' + serviceName + '/'
+ TERMINATOR;
String stringToSign = SCHEME + '-' + ALGORITHM + '\n' + amzDate + '\n'
+ scope + '\n' + Hex.toHexString(hash(
canonicalRequest.getBytes(StandardCharsets.UTF_8)));
// compute the signing key
byte[] secretKey = (SCHEME + new String(awsSecretKey)).getBytes(UTF_8);
byte[] dateKey = signStringWithKey(scopeDate, secretKey);
byte[] regionKey = signStringWithKey(regionName, dateKey);
byte[] serviceKey = signStringWithKey(serviceName, regionKey);
byte[] signingKey = signStringWithKey(TERMINATOR, serviceKey);
byte[] signature = signStringWithKey(stringToSign, signingKey);
// construct the authorization header
String credentialsAuthorizationHeader = "Credential=" + awsAccessKey //$NON-NLS-1$
+ '/' + scope;
String signedHeadersAuthorizationHeader = "SignedHeaders=" //$NON-NLS-1$
+ canonicalizedHeaderNames;
String signatureAuthorizationHeader = "Signature=" //$NON-NLS-1$
+ Hex.toHexString(signature);
String authorizationHeader = SCHEME + '-' + ALGORITHM + ' '
+ credentialsAuthorizationHeader + ", " //$NON-NLS-1$
+ signedHeadersAuthorizationHeader + ", " //$NON-NLS-1$
+ signatureAuthorizationHeader;
// Copy back the updated request headers
headers.forEach(httpURLConnection::setRequestProperty);
// Add the 'authorization' header
httpURLConnection.setRequestProperty(HttpSupport.HDR_AUTHORIZATION,
authorizationHeader);
}
/**
* Calculates the hex-encoded SHA-256 hash of the provided byte array.
*
* @param data
* Byte array to hash
*
* @return Hex-encoded SHA-256 hash of the provided byte array.
*/
public static String calculateBodyHash(final byte[] data) {
return (data == null || data.length < 1) ? EMPTY_BODY_SHA256
: Hex.toHexString(hash(data));
}
/**
* Construct a string listing all request headers in sorted case-insensitive
* order, separated by a ';'.
*
* @param headers
* Map containing all request headers.
*
* @return String that lists all request headers in sorted case-insensitive
* order, separated by a ';'.
*/
private static String getCanonicalizeHeaderNames(
Map<String, String> headers) {
return headers.keySet().stream().map(String::toLowerCase).sorted()
.collect(Collectors.joining(";")); //$NON-NLS-1$
}
/**
* Constructs the canonical header string for a request.
*
* @param headers
* Map containing all request headers.
*
* @return The canonical headers with values for the request.
*/
private static String getCanonicalizedHeaderString(
Map<String, String> headers) {
if (headers == null || headers.isEmpty()) {
return ""; //$NON-NLS-1$
}
StringBuilder sb = new StringBuilder();
headers.keySet().stream().sorted(String.CASE_INSENSITIVE_ORDER)
.forEach(key -> {
String header = key.toLowerCase().replaceAll("\\s+", " "); //$NON-NLS-1$ //$NON-NLS-2$
String value = headers.get(key).replaceAll("\\s+", " "); //$NON-NLS-1$ //$NON-NLS-2$
sb.append(header).append(':').append(value).append('\n');
});
return sb.toString();
}
/**
* Constructs the canonicalized resource path for an AWS service endpoint.
*
* @param url
* The AWS service endpoint URL, including the path to any
* resource.
*
* @return The canonicalized resource path for the AWS service endpoint.
*/
private static String getCanonicalizedResourcePath(URL url) {
if (url == null) {
return "/"; //$NON-NLS-1$
}
String path = url.getPath();
if (path == null || path.isEmpty()) {
return "/"; //$NON-NLS-1$
}
String encodedPath = HttpSupport.urlEncode(path, true);
if (encodedPath.startsWith("/")) { //$NON-NLS-1$
return encodedPath;
}
return "/".concat(encodedPath); //$NON-NLS-1$
}
/**
* Constructs the canonicalized query string for a request.
*
* @param queryParameters
* The query parameters in the request.
*
* @return The canonicalized query string for the request.
*/
public static String getCanonicalizedQueryString(
Map<String, String> queryParameters) {
if (queryParameters == null || queryParameters.isEmpty()) {
return ""; //$NON-NLS-1$
}
return queryParameters
.keySet().stream().sorted().map(
key -> HttpSupport.urlEncode(key, false) + '='
+ HttpSupport.urlEncode(
queryParameters.get(key), false))
.collect(Collectors.joining("&")); //$NON-NLS-1$
}
/**
* Hashes the provided byte array using the SHA-256 algorithm.
*
* @param data
* The byte array to hash.
*
* @return Hashed string contents of the provided byte array.
*/
public static byte[] hash(byte[] data) {
try {
MessageDigest md = MessageDigest.getInstance("SHA-256"); //$NON-NLS-1$
md.update(data);
return md.digest();
} catch (Exception e) {
throw new RuntimeException(
JGitText.get().couldNotHashByteArrayWithSha256, e);
}
}
/**
* Signs the provided string data using the specified key.
*
* @param stringToSign
* The string data to sign.
* @param key
* The key material of the secret key.
*
* @return Signed string data.
*/
private static byte[] signStringWithKey(String stringToSign, byte[] key) {
try {
byte[] data = stringToSign.getBytes(StandardCharsets.UTF_8);
Mac mac = Mac.getInstance(MAC_ALGORITHM);
mac.init(new SecretKeySpec(key, MAC_ALGORITHM));
return mac.doFinal(data);
} catch (Exception e) {
throw new RuntimeException(JGitText.get().couldNotSignStringWithKey,
e);
}
}
}
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