Skip to content

crypto: warn on invalid authentication tag length #17566

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
tniessen wants to merge 6 commits into from
Closed

crypto: warn on invalid authentication tag length #17566

Show file tree
Hide file tree
Changes from 1 commit
Commits
Show all changes
6 commits
Select commit Hold shift + click to select a range
c5d0372
test: use valid authentication tag length
tniessen Dec 9, 2017
fc6c652
crypto: warn on invalid authentication tag length
tniessen Dec 9, 2017
54d49c1
[squash] remove GCM check
tniessen Dec 10, 2017
bbf356e
[squash] fix FIPS failure
tniessen Dec 10, 2017
0b5c90f
[squash] fix FIPS (again)
tniessen Dec 10, 2017
e694393
[squash] add dot
tniessen Dec 11, 2017
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
Prev Previous commit
Next Next commit
crypto: warn on invalid authentication tag length 
Refs: #17523
  • Loading branch information
@tniessen
tniessen committed Dec 9, 2017
commit fc6c652b251e3c30dc82e02de23c6e4bc8f14ac0
13 changes: 11 additions & 2 deletions src/node_crypto.cc
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3767,9 +3767,18 @@ void CipherBase::SetAuthTag(const FunctionCallbackInfo<Value>& args) {
return args.GetReturnValue().Set(false);
}

// FIXME(bnoordhuis) Throw when buffer length is not a valid tag size.
unsigned int tag_len = Buffer::Length(args[0]);
if (EVP_CIPHER_CTX_mode(cipher->ctx_) == EVP_CIPH_GCM_MODE) {
Copy link
Copy Markdown
Member

@bnoordhuis bnoordhuis Dec 9, 2017

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Superfluous, always true because of the cipher->IsAuthenticatedMode() check above.

Copy link
Copy Markdown
Member Author

@tniessen tniessen Dec 9, 2017

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

If we ever add support for other authenticated modes, IsAuthenticatedMode will be true even if the cipher mode is not GCM, and other modes might have different restrictions on the tag size. I can remove the check if you would like.

Copy link
Copy Markdown
Member

@bnoordhuis bnoordhuis Dec 9, 2017

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

We'd audit all IsAuthenticatedMode() call sites anyway in that case so that's not a problem.

if (tag_len > 16 || (tag_len < 12 && tag_len != 8 && tag_len != 4)) {
ProcessEmitWarning(cipher->env(),
"Permitting authentication tag lengths of %u bytes is deprecated. "
"Valid GCM tag lengths are 4, 8, 12, 13, 14, 15, 16.",
tag_len);
}
}

// Note: we don't use std::max() here to work around a header conflict.
cipher->auth_tag_len_ = Buffer::Length(args[0]);
cipher->auth_tag_len_ = tag_len;
if (cipher->auth_tag_len_ > sizeof(cipher->auth_tag_))
cipher->auth_tag_len_ = sizeof(cipher->auth_tag_);

Expand Down
19 changes: 19 additions & 0 deletions test/parallel/test-crypto-authenticated.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -335,6 +335,14 @@ const errMessages = {

const ciphers = crypto.getCiphers();

common.expectWarning('Warning', [
'Use Cipheriv for counter mode of aes-192-gcm'
].concat(
[0, 1, 2, 6, 9, 10, 11, 17]
.map((i) => `Permitting authentication tag lengths of ${i} bytes is ` +
'deprecated. Valid GCM tag lengths are 4, 8, 12, 13, 14, 15, 16.')
));

for (const i in TEST_CASES) {
const test = TEST_CASES[i];

Expand Down Expand Up @@ -476,3 +484,14 @@ for (const i in TEST_CASES) {
assert.throws(() => encrypt.setAAD(Buffer.from('123', 'ascii')),
errMessages.state);
}

// GCM only supports specific authentication tag lengths, invalid lengths should
// produce warnings.
{
for (const length of [0, 1, 2, 4, 6, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]) {
const decrypt = crypto.createDecipheriv('aes-256-gcm',
'FxLKsqdmv0E9xrQhp0b1ZgI0K7JFZJM8',
'qkuZpJWCewa6Szih');
decrypt.setAuthTag(Buffer.from('1'.repeat(length)));
}
}