Question on Putty and gpg-agent

[Antony Prince]

My old key is expiring at the beginning of next month, so I've generated
a new set of keys. Dropped down to 2048 from 4096 RSA since 4096 seemed
a bit of overkill and have the master key in a single location. That's a
different discussion. Anyway, using my new Authentication key on Linux
with SSH seems to be going okay. A few issues with ssh-agent being
present, etc. All that seems to be working okay now. The issue I'm
having is using Putty and gnupg on Windows. The versions are:

OS: Windows 7 SP1 x64
Putty: 0.63

C:\Users\antony>gpg --version
gpg (GnuPG) 2.1.20
libgcrypt 1.7.6
Copyright (C) 2017 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
<https://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Home: C:/Users/antony/AppData/Roaming/gnupg
Supported algorithms:
Pubkey: RSA, ELG, DSA, ECDH, ECDSA, EDDSA
Cipher: IDEA, 3DES, CAST5, BLOWFISH, AES, AES192, AES256, TWOFISH,
        CAMELLIA128, CAMELLIA192, CAMELLIA256
Hash: SHA1, RIPEMD160, SHA256, SHA384, SHA512, SHA224
Compression: Uncompressed, ZIP, ZLIB, BZIP2

C:\Users\antony>gpg-connect-agent
> GETINFO version
D 2.1.20
OK
> bye
OK closing connection

The following options are in
"C:\Users\antony\AppData\Roaming\gnupg\gpg-agent.conf":

default-cache-ttl 300
max-cache-ttl 3000
enable-putty-support
disable-scdaemon
daemon

I have the keygrip listed in sshcontrol (the file was not created on its
own, I created it manually).

When I try to connect to the server with putty using the "Attempt
authentication using Pageant" option, I just get "Disconnected: No
supported authentication methods available. (server sent: publickey)". I
was of the understanding that gpg-agent would act as a replacement for
Pageant in this mode.

I have the public key in the ~/.ssh/authorized_keys file and can log in
successfully using ssh and gpg-agent on Linux. Before I added
"disable-scdaemon", gpg-agent would complain that it couldn't find the
key on the card (I've never had one). Since adding that option, that
error has gone away, but it still does not work and gpg-agent doesn't
provide any helpful output. The keygrip named file exists in
private-keys-v1.d, so the key is there. Any help in further
troubleshooting the issue would be greatly appreciated. I'm sorry if
this has been answered before. I looked through the archives and googled
around a bit, but couldn't find anything to point me in the right direction.

--
Regards,
Antony

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