putty/doc/pgpkeys.but

\A{pgpkeys} PuTTY download keys and signatures

\cfg{winhelp-topic}{pgpfingerprints}

\I{verifying new versions}We create \i{GPG signatures} for all the PuTTY
files distributed from our web site, so that users can be confident
that the files have not been tampered with. Here we identify
our public keys, and explain our signature policy so you can have an
accurate idea of what each signature guarantees.
This description is provided as both a web page on the PuTTY site, and
an appendix in the PuTTY manual.

As of release 0.58, all of the PuTTY executables contain fingerprint
material (usually accessed via the \i\c{-pgpfp} command-line
option), such that if you have an executable you trust, you can use
it to establish a trust path, for instance to a newer version
downloaded from the Internet.

(Note that none of the keys, signatures, etc mentioned here have
anything to do with keys used with SSH - they are purely for verifying
the origin of files distributed by the PuTTY team.)

\H{pgpkeys-pubkey} Public keys

We maintain multiple keys, stored with different levels of security
due to being used in different ways. See \k{pgpkeys-security} below
for details.

The keys we provide are:

\dt Snapshot Key

\dd Used to sign routine development builds of PuTTY: nightly
snapshots, pre-releases, and sometimes also custom diagnostic builds
we send to particular users.

\dt Release Key

\dd Used to sign manually released versions of PuTTY.

\dt Secure Contact Key

\dd An encryption-capable key suitable for people to send confidential
messages to the PuTTY team, e.g. reports of vulnerabilities.

\dt Master Key

\dd Used to tie all the above keys into the GPG web of trust. The
Master Key signs all the other keys, and other GPG users have signed
it in turn.

The current issue of those keys are available for download from the
PuTTY website, and are also available on PGP keyservers using the key
IDs listed below.

\dt \W{http://www.chiark.greenend.org.uk/~sgtatham/putty/keys/master-2015.asc}{\s{Master Key}}

\dd RSA, 4096-bit. Key ID: \cw{4096R/04676F7C} (long version:
\cw{4096R/AB585DC604676F7C}). Fingerprint:
\cw{440D\_E3B5\_B7A1\_CA85\_B3CC\_\_1718\_AB58\_5DC6\_0467\_6F7C}

\dt \W{http://www.chiark.greenend.org.uk/~sgtatham/putty/keys/release-2015.asc}{\s{Release Key}}

\dd RSA, 2048-bit. Key ID: \cw{2048R/B43434E4} (long version:
\cw{2048R/9DFE2648B43434E4}). Fingerprint:
\cw{0054\_DDAA\_8ADA\_15D2\_768A\_\_6DE7\_9DFE\_2648\_B434\_34E4}

\dt \W{http://www.chiark.greenend.org.uk/~sgtatham/putty/keys/contact-2016.asc}{\s{Secure Contact Key}}

\dd RSA, 2048-bit. Main key ID: \cw{2048R/8A0AF00B} (long version:
\cw{2048R/C4FCAAD08A0AF00B}). Encryption subkey ID:
\cw{2048R/50C2CF5C} (long version: \cw{2048R/9EB39CC150C2CF5C}).
Fingerprint:
\cw{8A26\_250E\_763F\_E359\_75F3\_\_118F\_C4FC\_AAD0\_8A0A\_F00B}

\dt \W{http://www.chiark.greenend.org.uk/~sgtatham/putty/keys/snapshot-2015.asc}{\s{Snapshot Key}}

\dd RSA, 2048-bit. Key ID: \cw{2048R/D15F7E8A} (long version:
\cw{2048R/EEF20295D15F7E8A}). Fingerprint:
\cw{0A3B\_0048\_FE49\_9B67\_A234\_\_FEB6\_EEF2\_0295\_D15F\_7E8A}

\H{pgpkeys-security} Security details

The various keys have various different security levels. This
section explains what those security levels are, and how far you can
expect to trust each key.

\S{pgpkeys-snapshot} The Development Snapshots key

The Development Snapshots private key is stored \e{without a
passphrase}. This is necessary, because the snapshots are generated
every night without human intervention, so nobody would be able to
type a passphrase.

The snapshots are built and signed on a team member's home computers,
before being uploaded to the web server from which you download them.

Therefore, a signature from the Development Snapshots key \e{DOES}
protect you against:

\b People tampering with the PuTTY binaries between the PuTTY web site
and you.

\b The maintainers of our web server attempting to abuse their root
privilege to tamper with the binaries.

But it \e{DOES NOT} protect you against:

\b People tampering with the binaries before they are uploaded to our
download servers.

\b People tampering with the build machines so that the next set of
binaries they build will be malicious in some way.

\b People stealing the unencrypted private key from the build machine
it lives on.

Of course, we take all reasonable precautions to guard the build
machines. But when you see a signature, you should always be certain
of precisely what it guarantees and precisely what it does not.

\S{pgpkeys-release} The Releases key

The Releases key is more secure: because it is only used at release
time, to sign each release by hand, we can store it encrypted.

The Releases private key is kept encrypted on the developers' own
local machines. So an attacker wanting to steal it would have to also
steal the passphrase.

\S{pgpkeys-contact} The Secure Contact Key

The Secure Contact Key is stored with a similar level of security to
the Release Key: it is stored with a passphrase, and no automated
script has access to it.

\S{pgpkeys-master} The Master Keys

The Master Key signs almost nothing. Its purpose is to bind the other
keys together and certify that they are all owned by the same people
and part of the same integrated setup. The only signatures produced by
the Master Key, \e{ever}, should be the signatures on the other keys.

The Master Key is especially long, and its private key and passphrase
are stored with special care.

We have collected some third-party signatures on the Master Key, in
order to increase the chances that you can find a suitable trust path
to them.

We have uploaded our various keys to public keyservers, so that
even if you don't know any of the people who have signed our
keys, you can still be reasonably confident that an attacker would
find it hard to substitute fake keys on all the public keyservers at
once.

\H{pgpkeys-rollover} Key rollover

Our current keys were generated in September 2015, except for the
Secure Contact Key which was generated in February 2016 (we didn't
think of it until later).

Prior to that, we had a much older set of keys generated in 2000. For
each of the key types above (other than the Secure Contact Key), we
provided both an RSA key \e{and} a DSA key (because at the time we
generated them, RSA was not in practice available to everyone, due to
export restrictions).

The new Master Key is signed with both of the old ones, to show that
it really is owned by the same people and not substituted by an
attacker. Also, we have retrospectively signed the old Release Keys
with the new Master Key, in case you're trying to verify the
signatures on a release prior to the rollover and can find a chain of
trust to those keys from any of the people who have signed our new
Master Key.

Future releases will be signed with the up-to-date keys shown above.
Releases prior to the rollover are signed with the old Release Keys.

For completeness, those old keys are given here:

\dt \W{http://www.chiark.greenend.org.uk/~sgtatham/putty/keys/master-rsa.asc}{\s{Master Key} (original RSA)}

\dd RSA, 1024-bit. Key ID: \cw{1024R/1E34AC41} (long version:
\cw{1024R/9D5877BF1E34AC41}). Fingerprint:
\cw{8F\_15\_97\_DA\_25\_30\_AB\_0D\_\_88\_D1\_92\_54\_11\_CF\_0C\_4C}

\dt \W{http://www.chiark.greenend.org.uk/~sgtatham/putty/keys/master-dsa.asc}{\s{Master Key} (original DSA)}

\dd DSA, 1024-bit. Key ID: \cw{1024D/6A93B34E} (long version:
\cw{1024D/4F5E6DF56A93B34E}). Fingerprint:
\cw{313C\_3E76\_4B74\_C2C5\_F2AE\_\_83A8\_4F5E\_6DF5\_6A93\_B34E}

\dt \W{http://www.chiark.greenend.org.uk/~sgtatham/putty/keys/release-rsa.asc}{\s{Release Key} (original RSA)}

\dd RSA, 1024-bit. Key ID: \cw{1024R/B41CAE29} (long version:
\cw{1024R/EF39CCC0B41CAE29}). Fingerprint:
\cw{AE\_65\_D3\_F7\_85\_D3\_18\_E0\_\_3B\_0C\_9B\_02\_FF\_3A\_81\_FE}

\dt \W{http://www.chiark.greenend.org.uk/~sgtatham/putty/keys/release-dsa.asc}{\s{Release Key} (original DSA)}

\dd DSA, 1024-bit. Key ID: \cw{1024D/08B0A90B} (long version:
\cw{1024D/FECD6F3F08B0A90B}). Fingerprint:
\cw{00B1\_1009\_38E6\_9800\_6518\_\_F0AB\_FECD\_6F3F\_08B0\_A90B}

\dt \W{http://www.chiark.greenend.org.uk/~sgtatham/putty/keys/snapshot-rsa.asc}{\s{Snapshot Key} (original RSA)}

\dd RSA, 1024-bit. Key ID: \cw{1024R/32B903A9} (long version:
\cw{1024R/FAAED21532B903A9}). Fingerprint:
\cw{86\_8B\_1F\_79\_9C\_F4\_7F\_BD\_\_8B\_1B\_D7\_8E\_C6\_4E\_4C\_03}

\dt \W{http://www.chiark.greenend.org.uk/~sgtatham/putty/keys/snapshot-dsa.asc}{\s{Snapshot Key} (original DSA)}

\dd DSA, 1024-bit. Key ID: \cw{1024D/7D3E4A00} (long version:
\cw{1024D/165E56F77D3E4A00}). Fingerprint:
\cw{63DD\_8EF8\_32F5\_D777\_9FF0\_\_2947\_165E\_56F7\_7D3E\_4A00}