ninja.Aws4HashCalculator Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of s3ninja Show documentation
S3 ninja emulates the S3 API for development and testing purposes.
There is a newer version: 2.7
/*
 * Made with all the love in the world
 * by scireum in Remshalden, Germany
 *
 * Copyright by scireum GmbH
 * http://www.scireum.de - [email protected]
 */

package ninja;

import sirius.kernel.commons.Strings;
import sirius.kernel.di.std.Part;
import sirius.kernel.di.std.Register;
import sirius.web.http.WebContext;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.util.regex.MatchResult;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import static com.google.common.base.Charsets.UTF_8;
import static com.google.common.hash.Hashing.sha256;
import static com.google.common.io.BaseEncoding.base16;

/**
 * Hash calculator for AWS
 * signature v4 calculation
 */
@Register(classes = Aws4HashCalculator.class)
public class Aws4HashCalculator {
    protected static final Pattern AWS_AUTH4_PATTERN =
            Pattern.compile("AWS4-HMAC-SHA256 Credential=([^/]+)/([^/]+)/([^/]+)/s3/aws4_request, SignedHeaders=([^,"
                            + "]+), Signature=(.+)");

    @Part
    private Storage storage;

    /**
     * Determines if the given request contains an AWS4 auth token.
     *
     * @param ctx the request to check
     * @return true if the request contains an AWS4 auth token, false  otherwise.
     */
    public boolean supports(final WebContext ctx) {
        final Matcher aws4Header = buildMatcher(ctx);
        return aws4Header.matches();
    }

    private Matcher initializedMatcher(final WebContext ctx) {
        Matcher matcher = buildMatcher(ctx);
        return matcher.matches() ? matcher : null;
    }

    private Matcher buildMatcher(final WebContext ctx) {
        return AWS_AUTH4_PATTERN.matcher(ctx.getHeaderValue("Authorization").asString(""));
    }

    /**
     * Computes the authentication hash as specified by the AWS SDK for verification purposes.
     *
     * @param ctx the current request to fetch parameters from
     * @return the computes hash value
     * @throws Exception in case of an unexpected error
     */
    public String computeHash(WebContext ctx) throws Exception {
        final MatchResult aws4Header = initializedMatcher(ctx);

        byte[] dateKey = hmacSHA256(("AWS4" + storage.getAwsSecretKey()).getBytes(UTF_8), aws4Header.group(2));
        byte[] dateRegionKey = hmacSHA256(dateKey, aws4Header.group(3));
        byte[] dateRegionServiceKey = hmacSHA256(dateRegionKey, "s3");
        byte[] signingKey = hmacSHA256(dateRegionServiceKey, "aws4_request");

        byte[] signedData = hmacSHA256(signingKey, buildStringToSign(ctx));
        return base16().lowerCase().encode(signedData);
    }

    private String buildStringToSign(final WebContext ctx) {
        final StringBuilder canonicalRequest = buildCanonicalRequest(ctx);
        final MatchResult aws4Header = initializedMatcher(ctx);
        return "AWS4-HMAC-SHA256\n"
               + getAmazonDateHeader(ctx)
               + "\n"
               + getAmazonDateHeader(ctx).substring(0, 8)
               + "/"
               + aws4Header.group(3)
               + "/s3/aws4_request\n"
               + hashedCanonicalRequest(canonicalRequest);
    }

    private String getAmazonDateHeader(final WebContext ctx) {
        return ctx.getHeaderValue("x-amz-date").asString();
    }

    private StringBuilder buildCanonicalRequest(final WebContext ctx) {
        final MatchResult aws4Header = initializedMatcher(ctx);
        StringBuilder canonicalRequest = new StringBuilder(ctx.getRequest().getMethod().name());
        canonicalRequest.append("\n");
        canonicalRequest.append(ctx.getRequestedURI());
        canonicalRequest.append("\n");
        canonicalRequest.append(ctx.getQueryString());
        canonicalRequest.append("\n");

        for (String name : aws4Header.group(4).split(";")) {
            canonicalRequest.append(name.trim());
            canonicalRequest.append(":");
            canonicalRequest.append(Strings.join(ctx.getRequest().headers().getAll(name), ",").trim());
            canonicalRequest.append("\n");
        }
        canonicalRequest.append("\n");
        canonicalRequest.append(aws4Header.group(4));
        canonicalRequest.append("\n");
        canonicalRequest.append(ctx.getHeader("x-amz-content-sha256"));
        return canonicalRequest;
    }

    private String hashedCanonicalRequest(final StringBuilder canonicalRequest) {
        return sha256().hashString(canonicalRequest, UTF_8).toString();
    }

    private byte[] hmacSHA256(byte[] key, String value) throws Exception {
        SecretKeySpec keySpec = new SecretKeySpec(key, "HmacSHA256");
        Mac mac = Mac.getInstance("HmacSHA256");
        mac.init(keySpec);
        return mac.doFinal(value.getBytes(UTF_8));
    }
}