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Check validity of signatures before using them

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This commit is contained in:
Daniel Huigens 2018-09-18 21:59:23 +02:00
parent 9614e8fc21
commit 5cf61daa19
4 changed files with 98 additions and 59 deletions
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115
src/key.js
View File

@ -261,30 +261,37 @@ Key.prototype.armor = function() {
}; };
/** /**
* Returns the signature that has the latest creation date, while ignoring signatures created in the future. * Returns the valid and non-expired signature that has the latest creation date, while ignoring signatures created in the future.
* @param {Array<module:packet.Signature>} signatures List of signatures * @param {Array<module:packet.Signature>} signatures List of signatures
* @param {Date} date Use the given date instead of the current time * @param {Date} date Use the given date instead of the current time
* @returns {module:packet.Signature} The latest signature * @returns {Promise<module:packet.Signature>} The latest valid signature
* @async
*/ */
function getLatestSignature(signatures, date=new Date()) { async function getLatestValidSignature(signatures, primaryKey, dataToVerify, date=new Date()) {
let signature = signatures[0]; let signature;
for (let i = 1; i < signatures.length; i++) { for (let i = signatures.length - 1; i >= 0; i--) {
if (signatures[i].created >= signature.created && if (
(signatures[i].created <= date || date === null)) { (!signature || signatures[i].created >= signature.created) &&
// check binding signature is not expired (ie, check for V4 expiration time)
!signatures[i].isExpired(date) &&
// check binding signature is verified
(signatures[i].verified || await signatures[i].verify(primaryKey, dataToVerify))
) {
signature = signatures[i]; signature = signatures[i];
} }
} }
return signature; return signature;
} }
function isValidSigningKeyPacket(keyPacket, signature, date=new Date()) { function isValidSigningKeyPacket(keyPacket, signature) {
if (!signature.verified || signature.revoked !== false) { // Sanity check
throw new Error('Signature not verified');
}
return keyPacket.algorithm !== enums.read(enums.publicKey, enums.publicKey.rsa_encrypt) && return keyPacket.algorithm !== enums.read(enums.publicKey, enums.publicKey.rsa_encrypt) &&
keyPacket.algorithm !== enums.read(enums.publicKey, enums.publicKey.elgamal) && keyPacket.algorithm !== enums.read(enums.publicKey, enums.publicKey.elgamal) &&
keyPacket.algorithm !== enums.read(enums.publicKey, enums.publicKey.ecdh) && keyPacket.algorithm !== enums.read(enums.publicKey, enums.publicKey.ecdh) &&
(!signature.keyFlags || (!signature.keyFlags ||
(signature.keyFlags[0] & enums.keyFlags.sign_data) !== 0) && (signature.keyFlags[0] & enums.keyFlags.sign_data) !== 0);
signature.verified && !signature.revoked && !signature.isExpired(date) &&
!isDataExpired(keyPacket, signature, date);
} }
/** /**
@ -302,8 +309,9 @@ Key.prototype.getSigningKey = async function (keyId=null, date=new Date(), userI
for (let i = 0; i < subKeys.length; i++) { for (let i = 0; i < subKeys.length; i++) {
if (!keyId || subKeys[i].getKeyId().equals(keyId)) { if (!keyId || subKeys[i].getKeyId().equals(keyId)) {
if (await subKeys[i].verify(primaryKey, date) === enums.keyStatus.valid) { if (await subKeys[i].verify(primaryKey, date) === enums.keyStatus.valid) {
const bindingSignature = getLatestSignature(subKeys[i].bindingSignatures, date); const dataToVerify = { key: primaryKey, bind: subKeys[i].keyPacket };
if (isValidSigningKeyPacket(subKeys[i].keyPacket, bindingSignature, date)) { const bindingSignature = await getLatestValidSignature(subKeys[i].bindingSignatures, primaryKey, dataToVerify, date);
if (bindingSignature && isValidSigningKeyPacket(subKeys[i].keyPacket, bindingSignature)) {
return subKeys[i]; return subKeys[i];
} }
} }
@ -311,23 +319,24 @@ Key.prototype.getSigningKey = async function (keyId=null, date=new Date(), userI
} }
const primaryUser = await this.getPrimaryUser(date, userId); const primaryUser = await this.getPrimaryUser(date, userId);
if (primaryUser && (!keyId || primaryKey.getKeyId().equals(keyId)) && if (primaryUser && (!keyId || primaryKey.getKeyId().equals(keyId)) &&
isValidSigningKeyPacket(primaryKey, primaryUser.selfCertification, date)) { isValidSigningKeyPacket(primaryKey, primaryUser.selfCertification)) {
return this; return this;
} }
} }
return null; return null;
}; };
function isValidEncryptionKeyPacket(keyPacket, signature, date=new Date()) { function isValidEncryptionKeyPacket(keyPacket, signature) {
if (!signature.verified || signature.revoked !== false) { // Sanity check
throw new Error('Signature not verified');
}
return keyPacket.algorithm !== enums.read(enums.publicKey, enums.publicKey.dsa) && return keyPacket.algorithm !== enums.read(enums.publicKey, enums.publicKey.dsa) &&
keyPacket.algorithm !== enums.read(enums.publicKey, enums.publicKey.rsa_sign) && keyPacket.algorithm !== enums.read(enums.publicKey, enums.publicKey.rsa_sign) &&
keyPacket.algorithm !== enums.read(enums.publicKey, enums.publicKey.ecdsa) && keyPacket.algorithm !== enums.read(enums.publicKey, enums.publicKey.ecdsa) &&
keyPacket.algorithm !== enums.read(enums.publicKey, enums.publicKey.eddsa) && keyPacket.algorithm !== enums.read(enums.publicKey, enums.publicKey.eddsa) &&
(!signature.keyFlags || (!signature.keyFlags ||
(signature.keyFlags[0] & enums.keyFlags.encrypt_communication) !== 0 || (signature.keyFlags[0] & enums.keyFlags.encrypt_communication) !== 0 ||
(signature.keyFlags[0] & enums.keyFlags.encrypt_storage) !== 0) && (signature.keyFlags[0] & enums.keyFlags.encrypt_storage) !== 0);
signature.verified && !signature.revoked && !signature.isExpired(date) &&
!isDataExpired(keyPacket, signature, date);
} }
/** /**
@ -346,8 +355,9 @@ Key.prototype.getEncryptionKey = async function(keyId, date=new Date(), userId={
for (let i = 0; i < subKeys.length; i++) { for (let i = 0; i < subKeys.length; i++) {
if (!keyId || subKeys[i].getKeyId().equals(keyId)) { if (!keyId || subKeys[i].getKeyId().equals(keyId)) {
if (await subKeys[i].verify(primaryKey, date) === enums.keyStatus.valid) { if (await subKeys[i].verify(primaryKey, date) === enums.keyStatus.valid) {
const bindingSignature = getLatestSignature(subKeys[i].bindingSignatures, date); const dataToVerify = { key: primaryKey, bind: subKeys[i].keyPacket };
if (isValidEncryptionKeyPacket(subKeys[i].keyPacket, bindingSignature, date)) { const bindingSignature = await getLatestValidSignature(subKeys[i].bindingSignatures, primaryKey, dataToVerify, date);
if (bindingSignature && isValidEncryptionKeyPacket(subKeys[i].keyPacket, bindingSignature)) {
return subKeys[i]; return subKeys[i];
} }
} }
@ -356,7 +366,7 @@ Key.prototype.getEncryptionKey = async function(keyId, date=new Date(), userId={
// if no valid subkey for encryption, evaluate primary key // if no valid subkey for encryption, evaluate primary key
const primaryUser = await this.getPrimaryUser(date, userId); const primaryUser = await this.getPrimaryUser(date, userId);
if (primaryUser && (!keyId || primaryKey.getKeyId().equals(keyId)) && if (primaryUser && (!keyId || primaryKey.getKeyId().equals(keyId)) &&
isValidEncryptionKeyPacket(primaryKey, primaryUser.selfCertification, date)) { isValidEncryptionKeyPacket(primaryKey, primaryUser.selfCertification)) {
return this; return this;
} }
} }
@ -492,13 +502,13 @@ Key.prototype.getExpirationTime = async function(capabilities, keyId, userId) {
if (capabilities === 'encrypt' || capabilities === 'encrypt_sign') { if (capabilities === 'encrypt' || capabilities === 'encrypt_sign') {
const encryptKey = await this.getEncryptionKey(keyId, null, userId); const encryptKey = await this.getEncryptionKey(keyId, null, userId);
if (!encryptKey) return null; if (!encryptKey) return null;
const encryptExpiry = encryptKey.getExpirationTime(); const encryptExpiry = await encryptKey.getExpirationTime(this.keyPacket);
if (encryptExpiry < expiry) expiry = encryptExpiry; if (encryptExpiry < expiry) expiry = encryptExpiry;
} }
if (capabilities === 'sign' || capabilities === 'encrypt_sign') { if (capabilities === 'sign' || capabilities === 'encrypt_sign') {
const signKey = await this.getSigningKey(keyId, null, userId); const signKey = await this.getSigningKey(keyId, null, userId);
if (!signKey) return null; if (!signKey) return null;
const signExpiry = signKey.getExpirationTime(); const signExpiry = await signKey.getExpirationTime(this.keyPacket);
if (signExpiry < expiry) expiry = signExpiry; if (signExpiry < expiry) expiry = signExpiry;
} }
return expiry; return expiry;
@ -515,16 +525,20 @@ Key.prototype.getExpirationTime = async function(capabilities, keyId, userId) {
* @async * @async
*/ */
Key.prototype.getPrimaryUser = async function(date=new Date(), userId={}) { Key.prototype.getPrimaryUser = async function(date=new Date(), userId={}) {
const users = this.users.map(function(user, index) { const primaryKey = this.keyPacket;
const selfCertification = getLatestSignature(user.selfCertifications, date); const users = [];
return { index, user, selfCertification }; for (let i = 0; i < this.users.length; i++) {
}).filter(({ user, selfCertification }) => { const user = this.users[i];
return user.userId && selfCertification && ( if (!user.userId || !(
(userId.name === undefined || user.userId.name === userId.name) && (userId.name === undefined || user.userId.name === userId.name) &&
(userId.email === undefined || user.userId.email === userId.email) && (userId.email === undefined || user.userId.email === userId.email) &&
(userId.comment === undefined || user.userId.comment === userId.comment) (userId.comment === undefined || user.userId.comment === userId.comment)
); )) continue;
}); const dataToVerify = { userId: user.userId, key: primaryKey };
const selfCertification = await getLatestValidSignature(user.selfCertifications, primaryKey, dataToVerify, date);
if (!selfCertification) continue;
users.push({ index: i, user, selfCertification });
}
if (!users.length) { if (!users.length) {
if (userId.name !== undefined || userId.email !== undefined || if (userId.name !== undefined || userId.email !== undefined ||
userId.comment !== undefined) { userId.comment !== undefined) {
@ -539,18 +553,9 @@ Key.prototype.getPrimaryUser = async function(date=new Date(), userId={}) {
return A.isPrimaryUserID - B.isPrimaryUserID || A.created - B.created; return A.isPrimaryUserID - B.isPrimaryUserID || A.created - B.created;
}).pop(); }).pop();
const { user, selfCertification: cert } = primaryUser; const { user, selfCertification: cert } = primaryUser;
const primaryKey = this.keyPacket;
const dataToVerify = { userId: user.userId, key: primaryKey };
// skip if certificates is invalid, revoked, or expired
if (!(cert.verified || await cert.verify(primaryKey, dataToVerify))) {
return null;
}
if (cert.revoked || await user.isRevoked(primaryKey, cert, null, date)) { if (cert.revoked || await user.isRevoked(primaryKey, cert, null, date)) {
return null; return null;
} }
if (cert.isExpired(date)) {
return null;
}
return primaryUser; return primaryUser;
}; };
@ -678,12 +683,15 @@ Key.prototype.revoke = async function({
/** /**
* Get revocation certificate from a revoked key. * Get revocation certificate from a revoked key.
* (To get a revocation certificate for an unrevoked key, call revoke() first.) * (To get a revocation certificate for an unrevoked key, call revoke() first.)
* @returns {String} armored revocation certificate * @returns {Promise<String>} armored revocation certificate
* @async
*/ */
Key.prototype.getRevocationCertificate = function() { Key.prototype.getRevocationCertificate = async function() {
if (this.revocationSignatures.length) { const dataToVerify = { key: this.keyPacket };
const revocationSignature = await getLatestValidSignature(this.revocationSignatures, this.keyPacket, dataToVerify);
if (revocationSignature) {
const packetlist = new packet.List(); const packetlist = new packet.List();
packetlist.push(getLatestSignature(this.revocationSignatures)); packetlist.push(revocationSignature);
return armor.encode(enums.armor.public_key, packetlist.write(), null, null, 'This is a revocation certificate'); return armor.encode(enums.armor.public_key, packetlist.write(), null, null, 'This is a revocation certificate');
} }
}; };
@ -1090,17 +1098,17 @@ SubKey.prototype.verify = async function(primaryKey, date=new Date()) {
const that = this; const that = this;
const dataToVerify = { key: primaryKey, bind: this.keyPacket }; const dataToVerify = { key: primaryKey, bind: this.keyPacket };
// check subkey binding signatures // check subkey binding signatures
const bindingSignature = getLatestSignature(this.bindingSignatures, date); const bindingSignature = await getLatestValidSignature(this.bindingSignatures, primaryKey, dataToVerify, date);
// check binding signature is verified // check binding signature is verified
if (!(bindingSignature.verified || await bindingSignature.verify(primaryKey, dataToVerify))) { if (!bindingSignature) {
return enums.keyStatus.invalid; return enums.keyStatus.invalid;
} }
// check binding signature is not revoked // check binding signature is not revoked
if (bindingSignature.revoked || await that.isRevoked(primaryKey, bindingSignature, null, date)) { if (bindingSignature.revoked || await that.isRevoked(primaryKey, bindingSignature, null, date)) {
return enums.keyStatus.revoked; return enums.keyStatus.revoked;
} }
// check binding signature is not expired (ie, check for V4 expiration time) // check for expiration time
if (bindingSignature.isExpired(date)) { if (isDataExpired(this.keyPacket, bindingSignature, date)) {
return enums.keyStatus.expired; return enums.keyStatus.expired;
} }
return enums.keyStatus.valid; // binding signature passed all checks return enums.keyStatus.valid; // binding signature passed all checks
@ -1108,11 +1116,16 @@ SubKey.prototype.verify = async function(primaryKey, date=new Date()) {
/** /**
* Returns the expiration time of the subkey or Infinity if key does not expire * Returns the expiration time of the subkey or Infinity if key does not expire
* @param {module:packet.SecretKey|
* module:packet.PublicKey} primaryKey The primary key packet
* @param {Date} date Use the given date instead of the current time * @param {Date} date Use the given date instead of the current time
* @returns {Date} * @returns {Promise<Date>}
* @async
*/ */
SubKey.prototype.getExpirationTime = function(date=new Date()) { SubKey.prototype.getExpirationTime = async function(primaryKey, date=new Date()) {
const bindingSignature = getLatestSignature(this.bindingSignatures, date); const dataToVerify = { key: primaryKey, bind: this.keyPacket };
const bindingSignature = await getLatestValidSignature(this.bindingSignatures, primaryKey, dataToVerify, date);
if (!bindingSignature) return null;
const keyExpiry = getExpirationTime(this.keyPacket, bindingSignature); const keyExpiry = getExpirationTime(this.keyPacket, bindingSignature);
const sigExpiry = bindingSignature.getExpirationTime(); const sigExpiry = bindingSignature.getExpirationTime();
return keyExpiry < sigExpiry ? keyExpiry : sigExpiry; return keyExpiry < sigExpiry ? keyExpiry : sigExpiry;
@ -1556,7 +1569,7 @@ async function isDataRevoked(primaryKey, dataToVerify, revocations, signature, k
// TODO further verify that this is the signature that should be revoked // TODO further verify that this is the signature that should be revoked
if (signature) { if (signature) {
signature.revoked = revocationKeyIds.some(keyId => keyId.equals(signature.issuerKeyId)) ? true : signature.revoked = revocationKeyIds.some(keyId => keyId.equals(signature.issuerKeyId)) ? true :
signature.revoked; signature.revoked || false;
return signature.revoked; return signature.revoked;
} }
return revocationKeyIds.length > 0; return revocationKeyIds.length > 0;

6
src/openpgp.js
View File

@ -124,7 +124,7 @@ export function generateKey({ userIds=[], passphrase="", numBits=2048, keyExpira
} }
return generate(options).then(async key => { return generate(options).then(async key => {
const revocationCertificate = key.getRevocationCertificate(); const revocationCertificate = await key.getRevocationCertificate();
key.revocationSignatures = []; key.revocationSignatures = [];
return convertStreams({ return convertStreams({
@ -159,8 +159,8 @@ export function reformatKey({privateKey, userIds=[], passphrase="", keyExpiratio
options.revoked = options.revocationCertificate; options.revoked = options.revocationCertificate;
return reformat(options).then(key => { return reformat(options).then(async key => {
const revocationCertificate = key.getRevocationCertificate(); const revocationCertificate = await key.getRevocationCertificate();
key.revocationSignatures = []; key.revocationSignatures = [];
return { return {

6
src/packet/signature.js
View File

@ -201,6 +201,12 @@ Signature.prototype.sign = async function (key, data) {
this.signature = stream.fromAsync(async () => crypto.signature.sign( this.signature = stream.fromAsync(async () => crypto.signature.sign(
publicKeyAlgorithm, hashAlgorithm, params, toHash, await stream.readToEnd(hash) publicKeyAlgorithm, hashAlgorithm, params, toHash, await stream.readToEnd(hash)
)); ));
// Store the fact that this signature is valid, e.g. for when we call `await
// getLatestValidSignature(this.revocationSignatures, key, data)` later. Note
// that this only holds up if the key and data passed to verify are the same
// as the ones passed to sign.
this.verified = true;
return true; return true;
}; };

30
test/general/key.js
View File

@ -1389,7 +1389,7 @@ function versionSpecificTests() {
const actual_delta = (new Date(expiration) - new Date()) / 1000; const actual_delta = (new Date(expiration) - new Date()) / 1000;
expect(Math.abs(actual_delta - expect_delta)).to.be.below(60); expect(Math.abs(actual_delta - expect_delta)).to.be.below(60);
const subKeyExpiration = await key.subKeys[0].getExpirationTime(); const subKeyExpiration = await key.subKeys[0].getExpirationTime(key.primaryKey);
expect(subKeyExpiration).to.exist; expect(subKeyExpiration).to.exist;
const actual_subKeyDelta = (new Date(subKeyExpiration) - new Date()) / 1000; const actual_subKeyDelta = (new Date(subKeyExpiration) - new Date()) / 1000;
@ -1799,7 +1799,7 @@ describe('Key', function() {
const pubKey = (await openpgp.key.readArmored(twoKeys)).keys[1]; const pubKey = (await openpgp.key.readArmored(twoKeys)).keys[1];
expect(pubKey).to.exist; expect(pubKey).to.exist;
expect(pubKey).to.be.an.instanceof(openpgp.key.Key); expect(pubKey).to.be.an.instanceof(openpgp.key.Key);
const expirationTime = await pubKey.subKeys[0].getExpirationTime(); const expirationTime = await pubKey.subKeys[0].getExpirationTime(pubKey.primaryKey);
expect(expirationTime.toISOString()).to.be.equal('2018-11-26T10:58:29.000Z'); expect(expirationTime.toISOString()).to.be.equal('2018-11-26T10:58:29.000Z');
}); });
@ -1990,7 +1990,7 @@ describe('Key', function() {
it('getRevocationCertificate() should produce the same revocation certificate as GnuPG', async function() { it('getRevocationCertificate() should produce the same revocation certificate as GnuPG', async function() {
const revKey = (await openpgp.key.readArmored(revoked_key_arm4)).keys[0]; const revKey = (await openpgp.key.readArmored(revoked_key_arm4)).keys[0];
const revocationCertificate = revKey.getRevocationCertificate(); const revocationCertificate = await revKey.getRevocationCertificate();
const input = await openpgp.armor.decode(revocation_certificate_arm4); const input = await openpgp.armor.decode(revocation_certificate_arm4);
const packetlist = new openpgp.packet.List(); const packetlist = new openpgp.packet.List();
@ -2002,7 +2002,7 @@ describe('Key', function() {
it('getRevocationCertificate() should have an appropriate comment', async function() { it('getRevocationCertificate() should have an appropriate comment', async function() {
const revKey = (await openpgp.key.readArmored(revoked_key_arm4)).keys[0]; const revKey = (await openpgp.key.readArmored(revoked_key_arm4)).keys[0];
const revocationCertificate = revKey.getRevocationCertificate(); const revocationCertificate = await revKey.getRevocationCertificate();
expect(revocationCertificate).to.match(/Comment: This is a revocation certificate/); expect(revocationCertificate).to.match(/Comment: This is a revocation certificate/);
expect(revKey.armor()).not.to.match(/Comment: This is a revocation certificate/); expect(revKey.armor()).not.to.match(/Comment: This is a revocation certificate/);
@ -2170,7 +2170,27 @@ VYGdb3eNlV8CfoEC
it('Selects the most recent subkey binding signature', async function() { it('Selects the most recent subkey binding signature', async function() {
const key = (await openpgp.key.readArmored(multipleBindingSignatures)).keys[0]; const key = (await openpgp.key.readArmored(multipleBindingSignatures)).keys[0];
expect(key.subKeys[0].getExpirationTime().toISOString()).to.equal('2015-10-18T07:41:30.000Z'); expect((await key.subKeys[0].getExpirationTime(key.primaryKey)).toISOString()).to.equal('2015-10-18T07:41:30.000Z');
});
it('Selects the most recent non-expired subkey binding signature', async function() {
const key = (await openpgp.key.readArmored(multipleBindingSignatures)).keys[0];
key.subKeys[0].bindingSignatures[1].signatureNeverExpires = false;
key.subKeys[0].bindingSignatures[1].signatureExpirationTime = 0;
expect((await key.subKeys[0].getExpirationTime(key.primaryKey)).toISOString()).to.equal('2018-09-07T06:03:37.000Z');
});
it('Selects the most recent valid subkey binding signature', async function() {
const key = (await openpgp.key.readArmored(multipleBindingSignatures)).keys[0];
key.subKeys[0].bindingSignatures[1].signatureData[0]++;
expect((await key.subKeys[0].getExpirationTime(key.primaryKey)).toISOString()).to.equal('2018-09-07T06:03:37.000Z');
});
it('Handles a key with no valid subkey binding signatures gracefully', async function() {
const key = (await openpgp.key.readArmored(multipleBindingSignatures)).keys[0];
key.subKeys[0].bindingSignatures[0].signatureData[0]++;
key.subKeys[0].bindingSignatures[1].signatureData[0]++;
expect(await key.subKeys[0].getExpirationTime(key.primaryKey)).to.be.null;
}); });
it('Reject encryption with revoked subkey', async function() { it('Reject encryption with revoked subkey', async function() {