The original SSH RFC 4253 explicitly disallows padding. This applies to
ssh-rsa signatures.
The updated SSH RFC 8332 which defines the SHA2 RSA signature variants
explicitly calls out the existence of signers who produce short
signatures and specifies that verifiers may allow this behavior.
In practice, PuTTY 0.81 and prior versions, as well as SSH.NET prior to
2024.1.0 always generated short signatures. Furthermore, PuTTY is
embedded in other software like WinSCP and FileZilla, which are updated
on their own schedules as well. This leads to occasional unexplained
login errors, when using RSA keys.
OpenSSH server allows these short signatures for all RSA algorithms.
Fixesgolang/go#68286
Change-Id: Ia60ece21bf9c111c490fac0c066443ed5ff7dd29
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/598534
Reviewed-by: Nicola Murino <nicola.murino@gmail.com>
Reviewed-by: Roland Shoemaker <roland@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Nicola Murino <nicola.murino@gmail.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
This is a follow-up to CL 317169, which dropped go1.12 compatibility,
and made the golang.org/x/crypto/ed25519 package an alias / wrapper for
crypto/ed25519 in stdlib.
This patch updates uses within this repository to use stdlib instead of
depending on the wrapper. With this patch applied, the only remaining
use of the wrapper is in ed25519_test, which appears to be in place to
verify compatibility of the wrapper itself.
Change-Id: I0195396102a75ae20bdd82ca8ab59855c0eb5cea
GitHub-Last-Rev: 24dbec563cbd84bc47bdc7736b0245fc83dd3353
GitHub-Pull-Request: golang/crypto#238
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/448238
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Nicola Murino <nicola.murino@gmail.com>
Reviewed-by: Nicola Murino <nicola.murino@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Joedian Reid <joedian@golang.org>
Reviewed-by: Roland Shoemaker <roland@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
The server implementation looks at the HostKeys to advertise and
negotiate host key signature algorithms. A fundamental issue of the
Signer and AlgorithmSigner interfaces is that they don't expose the
supported signature algorithms, so really the server has to guess.
Currently, it would guess exclusively based on the PublicKey.Type,
regardless of whether the host key implemented AlgorithmSigner. This
means that a legacy Signer that only supports ssh-rsa still led the
server to negotiate rsa-sha2 algorithms. The server would then fail to
find a suitable host key to make the signature and crash.
This won't happen if only Signers from this package are used, but if a
custom Signer that doesn't support SignWithAlgorithm() but returns
"ssh-rsa" from PublicKey().Type() is used as a HostKey, the server is
vulnerable to DoS.
The only workable rules to determine what to advertise seems to be:
1. a pure Signer will always Sign with the PublicKey.Type
2. an AlgorithmSigner supports all algorithms associated with the
PublicKey.Type
Rule number two means that we can't add new supported algorithms in the
future, which is not great, but it's too late to fix that.
rsaSigner was breaking rule number one, and although it would have been
fine where it's used, I didn't want to break our own interface contract.
It's unclear why we had separate test key entries for rsa-sha2
algorithms, since we can use the ssh-rsa key for those. The only test
that used them, TestCertTypes, seemed broken: the init was actually
failing at making the corresponding signers rsaSigners, and indeed the
test for the SHA-256 signer expected and checked a SHA-512 signature.
Pending CVE
For golang/go#49952
Change-Id: Ie658eefcadd87906e63fc7faae8249376aa96c79
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/392355
Trust: Filippo Valsorda <filippo@golang.org>
Run-TryBot: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Roland Shoemaker <roland@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
RFC 8332, Section 2 sets up two overlapping namespaces: public key
formats and public key algorithms.
* The formats are what we currently have KeyAlgo constants for, and they
appear in PublicKey.Type.
* The algorithms are the set of both KeyAlgo and SigAlgo constants, and
they appear in Signature.Format (amongst other places).
This is incoherent, because that means Signature.Format can be both a
KeyAlgo (like KeyAlgoECDSA256) or a SigAlgo (like SigAlgoRSASHA2256).
One solution would be to duplicate all the KeyAlgo constants into the
SigAlgo namespace, but that would be confusing because applications are
currently using KeyAlgos where they'd be supposed to use the new
SigAlgos (while we can't deprecate the KeyAlgos because they are still
necessary for the PublicKey.Type namespace).
Instead, drop the separate namespaces, and use KeyAlgos throughout.
There are simply some KeyAlgos that can't be a PublicKey.Type.
Take the opportunity to fix the stuttering SHA22565/SHA2512 names. It's
totally ok to call those hashes SHA-256 and SHA-512 without the family
infix.
For golang/go#49952
Change-Id: Ia1fce3912a7e60aa70a88f75ed311be331fd19d5
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/392354
Trust: Filippo Valsorda <filippo@golang.org>
Run-TryBot: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Roland Shoemaker <roland@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
This change adds support for RSA SHA-2 based signatures for host keys and certificates. It also switches the default certificate signature algorithm for RSA to use SHA-512. This is implemented by treating ssh.Signer specially when the key type is `ssh-rsa` by also allowing SHA-256 and SHA-512 signatures.
Fixesgolang/go#37278
Change-Id: I2ee1ac4ae4c9c1de441a2d6cf1e806357ef18910
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/220037
Trust: Jason A. Donenfeld <Jason@zx2c4.com>
Run-TryBot: Jason A. Donenfeld <Jason@zx2c4.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Roland Shoemaker <roland@golang.org>
The existing code for decrypting OpenSSH-format keys only allows aes256-ctr, the current ssh-keygen default.
However, the default encryption scheme was aes256-cbc until relatively recently, and some of these keys are still in use.
Support for aes256-cbc has been added.
Fixesgolang/go#37939
Change-Id: I3730347109c5dd18e4cbe61b48bbca9566ad61d2
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/224817
Reviewed-by: Filippo Valsorda <filippo@golang.org>
An attacker can craft an ssh-ed25519 or sk-ssh-ed25519@openssh.com
public key, such that the library will panic when trying to verify a
signature with it. Clients can deliver such a public key and signature
to any golang.org/x/crypto/ssh server with a PublicKeyCallback, and
servers can deliver them to any golang.org/x/crypto/ssh client.
This issue was discovered and reported by Alex Gaynor, Fish in a Barrel,
and is tracked as CVE-2020-9283.
Change-Id: Ie25b78a0b0181fbbc8cc7de4f4e27d908777529c
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/220357
Run-TryBot: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Katie Hockman <katie@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
The behavior of ParsePrivateKeyWithPassphrase when the key is
unencrypted is unspecified. Currently, it just parses them like
ParsePrivateKey, which is unlikely to be what anyone wants: for us to
ignore a passphrase that they explicitly passed. It also makes the
implementation of encrypted OpenSSH keys in the next CL more confused.
Instead, make ParsePrivateKey return a PassphraseNeededError, so the
application logic can be ParsePrivateKey -> detect encrypted key ->
obtain passphrase -> ParsePrivateKeyWithPassphrase. That error will also
let us return the public key for OpenSSH keys.
Change-Id: Ife4fb2499ae538bef36e353adf9bc8e902662386
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/207599
Run-TryBot: Filippo Valsorda <filippo@golang.org>
Run-TryBot: Han-Wen Nienhuys <hanwen@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Han-Wen Nienhuys <hanwen@google.com>
This commit implements two new features. To preserve backwards
compatibility the new methods are added to an `ExtendedAgent` interface
which extends `Agent`. The client code implements `ExtendedAgent`
(which extends Agent) so you can call these additional methods against
SSH agents such as the OpenSSH agent. The ServeAgent method still
accepts Agent but will attempt to upcast the agent to `ExtendedAgent`
as needed, so if you supply an ExtendedAgent implementation you can
implement these additional methods (which keyring does).
The first feature is supporting the standard flags that can be passed to
SSH Sign requests, requesting that RSA signatures use SHA-256 or
SHA-512. See section 4.5.1 of the SSH agent protocol draft:
https://tools.ietf.org/html/draft-miller-ssh-agent-02
The second feature is supporting calling custom extensions from clients
and implementing custom extensions from servers. See section 4.7 of the
SSH agent protocol draft:
https://tools.ietf.org/html/draft-miller-ssh-agent-02
Change-Id: I0f74feb893762c27e921ec37604d3a46434ee6ef
GitHub-Last-Rev: 2e23fd01c0e95b664e8507682f0bd5bd61d4c146
GitHub-Pull-Request: golang/crypto#53
Reviewed-on: https://go-review.googlesource.com/c/123955
Reviewed-by: Han-Wen Nienhuys <hanwen@google.com>
Run-TryBot: Han-Wen Nienhuys <hanwen@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
None are "wrong" per se, but there are a lot of good suggestions and
in one case a docstring that was not present in godoc due to the
presence of an extra newline.
Changed "Id" in struct properties to "ID" in some non-exported
structs. Removed a trailing period from some error messages; I believe
the exact contents of error strings are not covered by the Go
compatibility promise.
Change-Id: I7c620582dc247396f72c52d38c909ccc0ec87b83
Reviewed-on: https://go-review.googlesource.com/80145
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
When implemented by ssh.PublicKey types, the new CryptoPublicKey
interface exposes the public key in the the crypto.PublicKey form via a
CryptoPublicKey() method.
This is useful for example in a custom ServerConfig.PublicKeyCallback
function to check or record additional details about the underlying
crypto.PublicKey
Change-Id: I4429df42c6fc5119f7c0023a539aaa9c59648bba
Reviewed-on: https://go-review.googlesource.com/23974
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
RSA and DSA keys if encrypted have the
phrase ENCRYPTED in their Proc-Type block
header according to RFC 1421 Section 4.6.1.1.
This CL checks for that phrase and errors out
if we encounter it, since we don't yet have
decryption of encrypted private keys.
Fixesgolang/go#6650
Change-Id: I5b157716a2f93557d289af5f62994234a2e7a0ed
Reviewed-on: https://go-review.googlesource.com/29676
Reviewed-by: Han-Wen Nienhuys <hanwen@google.com>
Run-TryBot: Han-Wen Nienhuys <hanwen@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Added support for parsing the "new" openssh private key format.
(ed25519 keys only in this format for now)
Signing and verifying functions now work with ed25519 keys.
ed25519 can now be accepted by the server to authenticate a client.
ed25519 can now be accepted by a client as a server host key.
Related documentation used:
https://www.ietf.org/archive/id/draft-bjh21-ssh-ed25519-02.txt
Change-Id: I84385f24d666fea08de21f980f78623f7bff8007
Reviewed-on: https://go-review.googlesource.com/22512
Reviewed-by: Han-Wen Nienhuys <hanwen@google.com>
Run-TryBot: Han-Wen Nienhuys <hanwen@google.com>
This allows the golang ssh-agent to support the full suite of keys
the library accepts.
Currently constraints are ignored.
Change-Id: I7d48c78e9a355582eb54788571a483a736c3d3ef
Reviewed-on: https://go-review.googlesource.com/21536
Reviewed-by: Han-Wen Nienhuys <hanwen@google.com>
Run-TryBot: Han-Wen Nienhuys <hanwen@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This adds a NewSignerFromSigner to crypto/ssh which takes a
crypto.Signer and turns it into an ssh.Signer, helpful if, e.g., your
crypto.Signer is backed by some sort of hardware device.
The interfaces are very similar - the biggest differences are that a
crypto.Signer accepts hashed data, while an ssh.Signer does not, and
some differences in encoding for DSA and ECDSA signatures.
This also adjusts NewSignerFromKey to use NewSignerFromSigner where
possible, dropping the rsaPrivateKey and ecdsaPrivateKey types in
favor of wrappedSigner. (However, because *dsa.PrivateKey is not a
crypto.Signer, we still have to keep dsaPrivateKey)
Change-Id: Ia2e20ece9c9d3844b4e5a64c1a7d997178ec8781
Reviewed-on: https://go-review.googlesource.com/10953
Reviewed-by: Adam Langley <agl@golang.org>
Change parseECDSA() to unmarshal the key's contents into a struct
representing the wire format, consistent with the parseRSA() and
parseDSA(), to make the code more readable and its intent clearer.
Change-Id: Iea85630107ac0b3e681807d2278390c8c50ce141
Reviewed-on: https://go-review.googlesource.com/13663
Reviewed-by: Han-Wen Nienhuys <hanwenn@gmail.com>
Reviewed-by: Adam Langley <agl@golang.org>
The change to add the PublicKey interface accidentally caused certificate handling to expect an extra copy of the private key algorithm name in the binary representation. This change adapts a suitable parsing API and adds a test to ensure that cert handling isn't easily broken in the future.
R=agl, hanwen, jmpittman
CC=golang-dev
https://golang.org/cl/13272055
Simplify MarshalAuthorizedKey by using the algoName func.
Make the algoName func be very specific about supported key types in openssh certs.
Generalize some of the commentary that previously mentioned specific key types.
R=agl, dave
CC=golang-dev
https://golang.org/cl/6938067
Export key and certificate algorithm names.
Switch from string literals over to using the constants for any key/cert algorithm references.
Make URL references visible in the godoc web display.
Standardize url reference names with surrounding [].
R=dave, agl, jonathan.mark.pittman
CC=golang-dev
https://golang.org/cl/6944047
This allows easy import/export of public keys in the format
expected by OpenSSH for authorized_keys files, as well as
allowing comparisons with ServerConfig's PublickeyCallback.
Fixesgolang/go#3908.
R=agl, dave, golang-dev, bradfitz
CC=agl, golang-dev
https://golang.org/cl/6855107
These are the cosmetic cleanups from the bits of code that I
rereviewed.
1) stringLength now takes a int; the length of the string. Too many
callers were allocating with stringLength([]byte(s)) and
stringLength only needs to call len().
2) agent.go now has sendAndReceive to remove logic that was
duplicated.
3) We now reject negative DH values
4) We now reject empty packets rather than crashing.
R=dave, jonathan.mark.pittman
CC=golang-dev
https://golang.org/cl/6061052
Ilia Mirkin
Mariano Cano
Nicola Murino
Sebastiaan van Stijn
Anmol Sethi
cui fliter
Filippo Valsorda
Hans Nielsen
Ross Kinsey
Mariano Cano
Filippo Valsorda
Sebastian Kinne
Ian Haken
Adam Langley
Noel Georgi
Han-Wen Nienhuys
Kevin Burke
Yasuhiro Matsumoto
Paul Querna
Ryuzo Yamamoto
Dmitry Savintsev
Martin Garton
Emmanuel Odeke
Martin Hamrle
Peter Moody
Peter Moody
Evan Broder
Matt Bostock
Jonathan Pittman
JP Sugarbroad
Shawn Ledbetter