The idea behind PuTTYcard was to extend the capabilities of PuTTY without adding dependencies to PuTTY. Therefore all smart card routines were realized within a separate DLL (namely PuTTYcard.dll). Pageant.exe would try to open this DLL. If it could not find it, it would behave like a "normal" Pageant.
This only needed about 20 lines of codes within the source of pageant.exe and I was hoping that the PuTTY team would include this into future PuTTY-packages. They did not.
Therefore I merged the source code of PuTTYcard.dll with the source code of pageant.exe and released a smart card enabled version of pageant.exe. If you are interested you may download it at https://smartcard-auth.de/ssh-en.html.
You must register your public key if you want to use some features (for example secure PIN entry). If you used PuTTYcard in the past or are willing to test my smart card enabled version of pageant.exe with a new card or a new card reader I will send you a free license. Just let me know.
PuTTYcard is an extension to PuTTY, the free SSH-client from Simon Tatham. With this extension PuTTY can use RSA-keys from external devices, ie. smart cards, usb-tokens.
If pageant is called with one argument, it will interpret this argument as the name of a key-file. Pageant will then load this ppk-file into its keylist, or if another instance of Pageant is already running into the keylist of that instance.
The pageant-version from PuTTYcard-0.58-V1.2.zip (can be downloaded from OpenSCs contrib area) will do exactly the same thing with one exception. If the first line of the ppk-file has the form:
PuTTYcard,<path to DLL>,<arguments for the DLL>
then Pageant will NOT read the key from the ppk-file. Instead it loads the DLL and calls a function from that DLL passing the arguments from the ppk-file to this function.
The function may then fetch a public RSA key from any source. Possible choices are: files, smart cards, PKCS11 libraries, Cryptographic Service Providers, etc.
PuTTYcard-0.58-V1.2.zip contains PuTTYiso7816.dll. This DLL will load an RSA key from any ISO-7816-8 compatible smart card. PuTTYiso7816 need additional information from the ppk-file, namely the location of the RSA key on your specific smartcard.
This information is given as 4 hexadecimal numbers, i.e. your ppk-file should look like
PuTTYcard,PuTTYiso7816.dll,<path>,AA,BB,CCCC
The <path> is the DF on your smart card that contains the RSA-key.
This must be specified as a 4,8,12 or 16digit hexadecimal
number. Do NOT prefix the path with 3F00.
AA is the key-reference of the private key, BB is the
pin-reference of the pin that protects your private key.
CCCC is the ID of a file on your card that contains your
public key. This file must either contain the public key
as two ASN1-encoded records or it must be a certificate file
from which the public key will be extracted.
One of the first actions of PuTTYcard
is to change its working DF to the DF given by the
<path>-argument. The remaining information
(private and public key, PIN and maybe a certificate)
will then be read from that DF. Try pkcs15-tool -k
to list all of your keys and that should give you the
information you need.
Here's the output for my Netkey E4 card:
$ pkcs15-tool -k
Private RSA Key [Signatur-Schlüssel]
Com. Flags : 1
Usage : [0x204], sign, nonRepudiation
Access Flags: [0x1D], sensitive, alwaysSensitive, neverExtract, local
ModLength : 1024
Key ref : 128
Native : yes
Path : DF015331
Auth ID : 04
ID : 01
Private RSA Key [Authentifizierungs-Schlüssel]
Com. Flags : 1
Usage : [0x207], encrypt, decrypt, sign, nonRepudiation
Access Flags: [0x1D], sensitive, alwaysSensitive, neverExtract, local
ModLength : 1024
Key ref : 130
Native : yes
Path : DF015371
Auth ID : 04
ID : 02
Private RSA Key [Verschlüsselungs-Schlüssel]
Com. Flags : 1
Usage : [0x207], encrypt, decrypt, sign, nonRepudiation
Access Flags: [0x1D], sensitive, alwaysSensitive, neverExtract, local
ModLength : 1024
Key ref : 129
Native : yes
Path : DF0153B1
Auth ID : 03
ID : 03
This card has three keys all of which are stored in DF DF01.
This is your <path>-value. Do not include the last component of the
path from the pkcs15-tool output as this is the ID of the
private key itself.
The next information you need is the key reference. This value is included as a decimal number in the above output (ie. 128, 130 and 129). This value must be converted to a 2-digit hexadecimal number. Let's use the second key, so your AA-value is 82.
Your private key is protected by a PIN and the pkcs15-tool -k output
contains the Auth-ID of this PIN. Here it is 04. This is not
your PIN-reference. Use pkcs15-tool --list-pins to list all
your PINs and use the PIN-reference of the PIN that has the same Id
as the Auth-Id of your key.
$ pkcs15-tool --list-pins
PIN [globale PIN]
Com. Flags: 0x3
ID : 01
Flags : [0x51], case-sensitive, initialized, unblockingPin
Length : min_len:6, max_len:16, stored_len:16
Pad char : 0x00
Reference : 0
Type : ascii-numeric
Path : 5000
Tries left: 3
PIN [globale PUK]
Com. Flags: 0x3
ID : 02
Flags : [0xD1], case-sensitive, initialized, unblockingPin, soPin
Length : min_len:8, max_len:16, stored_len:16
Pad char : 0x00
Reference : 1
Type : ascii-numeric
Path : 5001
Tries left: 3
PIN [lokale PIN0]
Com. Flags: 0x3
ID : 03
Flags : [0x13], case-sensitive, local, initialized
Length : min_len:6, max_len:16, stored_len:16
Pad char : 0x00
Reference : 128
Type : ascii-numeric
Path : DF015080
Tries left: 3
PIN [lokale PIN1]
Com. Flags: 0x3
ID : 04
Flags : [0xD3], case-sensitive, local, initialized, unblockingPin, soPin
Length : min_len:6, max_len:16, stored_len:16
Pad char : 0x00
Reference : 129
Type : ascii-numeric
Path : DF015081
Tries left: 3
Again the PIN-reference is given in decimal (here it is 129) and must be converted to a 2-digit hexadecimal number, namely 81. This is your BB-value.
Finally you need the file-ID of the public key or a certificate file from which he public key could be extracted.
So either use pkcs15-tool --list-public-keys or
pkcs15-tool -c. With my Netkey card pkcs15-tool --list-public-keys
does not show any keys. This is because my Netkey card
contains the public key, but it cannot be used for cryptographic
operations. From other sources (ie. card doku) I know that
the public key is stored in file DF01:4571, so one possible
CCCC-value is 4571.
If I list all my certificates I get:
$ pkcs15-tool -c
X.509 Certificate [Telesec Signatur Zertifikat]
Flags : 0
Authority: no
Path : DF01C000
ID : 01
X.509 Certificate [User Signatur Zertifikat 1]
Flags : 2
Authority: no
Path : DF014331
ID : 01
X.509 Certificate [User Signatur Zertifikat 2]
Flags : 2
Authority: no
Path : DF014332
ID : 01
X.509 Certificate [Telesec Authentifizierungs Zertifikat]
Flags : 0
Authority: no
Path : DF01C100
ID : 02
X.509 Certificate [User Authentifizierungs Zertifikat 1]
Flags : 2
Authority: no
Path : DF014371
ID : 02
X.509 Certificate [Telesec Verschlüsselungs Zertifikat]
Flags : 0
Authority: no
Path : DF01C200
ID : 03
X.509 Certificate [User Verschlüsselungs Zertifikat 1]
Flags : 2
Authority: no
Path : DF0143B1
ID : 03
A certificate contains the right public key, if it has the same ID as the private key (here 02). My card has two such certificates namely DF01:C100 and DF01:4371 so two other possible CCCC-values are C100 and 4371
On a Netkey card a private key may be protected by more than one PIN. So instead of PIN-reference 81 (which references local PIN1) I may alternatively use PIN-reference 00 (which references global PIN0)
So all of the following six lines will work:
PuTTYcard,PuTTYiso7816.dll,DF01,82,81,4571
PuTTYcard,PuTTYiso7816.dll,DF01,82,81,C100
PuTTYcard,PuTTYiso7816.dll,DF01,82,81,4371
PuTTYcard,PuTTYiso7816.dll,DF01,82,00,4571
PuTTYcard,PuTTYiso7816.dll,DF01,82,00,C100
PuTTYcard,PuTTYiso7816.dll,DF01,82,00,4371