lgoldstein commented on a change in pull request #116: Add authorized_keys/verification support for OpenSSH "security key" key types URL: https://github.com/apache/mina-sshd/pull/116#discussion_r386127027
########## File path: sshd-common/src/main/java/org/apache/sshd/common/signature/AbstractSecurityKeySignature.java ########## @@ -0,0 +1,122 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, + * software distributed under the License is distributed on an + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + * KIND, either express or implied. See the License for the + * specific language governing permissions and limitations + * under the License. + */ +package org.apache.sshd.common.signature; + +import java.nio.charset.StandardCharsets; +import java.security.MessageDigest; +import java.security.PrivateKey; +import java.security.PublicKey; + +import org.apache.sshd.common.session.SessionContext; +import org.apache.sshd.common.u2f.SecurityKeyPublicKey; +import org.apache.sshd.common.util.buffer.ByteArrayBuffer; + +public abstract class AbstractSecurityKeySignature implements Signature { + + private static final int FLAG_USER_PRESENCE = 0x01; + + private final String keyType; + + private SecurityKeyPublicKey publicKey; + private MessageDigest challengeDigest; + + public AbstractSecurityKeySignature(String keyType) { + this.keyType = keyType; + } + + @Override + public String getAlgorithm() { + return "SK-ED25519"; + } + + @Override + public void initVerifier(SessionContext session, PublicKey key) throws Exception { + if (!(key instanceof SecurityKeyPublicKey)) { + throw new IllegalArgumentException("Only instances of SecurityKeyPublicKey can be used"); + } + this.publicKey = (SecurityKeyPublicKey) key; + this.challengeDigest = MessageDigest.getInstance("SHA-256"); + } + + @Override + public void update(SessionContext session, byte[] hash, int off, int len) { + if (challengeDigest == null) { + throw new IllegalStateException("initVerifier must be called before update"); + } + challengeDigest.update(hash, off, len); + } + + protected abstract String getSignatureKeyType(); + + protected abstract Signature getDelegateSignature(); + + @Override + public boolean verify(SessionContext session, byte[] sig) throws Exception { + if (challengeDigest == null) { + throw new IllegalStateException("initVerifier must be called before verify"); + } + + ByteArrayBuffer data = new ByteArrayBuffer(sig); + String keyType = data.getString(); + if (!this.keyType.equals(keyType)) { + return false; + } + byte[] rawSig = data.getBytes(); + byte flags = data.getByte(); + long counter = data.getUInt(); + + // Return false if we don't understand the flags + if ((flags & ~FLAG_USER_PRESENCE) != 0) { + return false; + } + // Check user-presence flag is present if required by the public key + if ((flags & FLAG_USER_PRESENCE) != FLAG_USER_PRESENCE && !publicKey.isNoTouchRequired()) { + return false; + } + + // Re-encode signature in a format to match the delegate + ByteArrayBuffer encoded = new ByteArrayBuffer(); + encoded.putString(getSignatureKeyType()); + encoded.putBytes(rawSig); + + MessageDigest md = MessageDigest.getInstance("SHA-256"); Review comment: Please use `SecurityUtils.getMessageDigest` ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
