diff --color -ru -x regress -x autom4te.cache -x '*.o' -x '*.lo' -x Makefile -x config.status -x configure~ -x configure.ac openssh-9.3p1/ssh_config.5 openssh-9.3p1-patched/ssh_config.5
--- openssh-9.3p1/ssh_config.5 2023-06-07 10:26:48.284590156 +0200
+++ openssh-9.3p1-patched/ssh_config.5 2023-06-07 10:26:00.623052194 +0200
@@ -378,17 +378,13 @@
causes no CNAMEs to be considered for canonicalization.
This is the default behaviour.
.It Cm CASignatureAlgorithms
+The default is handled system-wide by
+.Xr crypto-policies 7 .
+Information about defaults, how to modify the defaults and how to customize existing policies with sub-policies are present in manual page
+.Xr update-crypto-policies 8 .
+.Pp
Specifies which algorithms are allowed for signing of certificates
by certificate authorities (CAs).
-The default is:
-.Bd -literal -offset indent
-ssh-ed25519,ecdsa-sha2-nistp256,
-ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,
-sk-ssh-ed25519@openssh.com,
-sk-ecdsa-sha2-nistp256@openssh.com,
-rsa-sha2-512,rsa-sha2-256
-.Ed
-.Pp
If the specified list begins with a
.Sq +
character, then the specified algorithms will be appended to the default set
@@ -450,20 +446,25 @@
(the default),
the check will not be executed.
.It Cm Ciphers
+The default is handled system-wide by
+.Xr crypto-policies 7 .
+Information about defaults, how to modify the defaults and how to customize existing policies with sub-policies are present in manual page
+.Xr update-crypto-policies 8 .
+.Pp
Specifies the ciphers allowed and their order of preference.
Multiple ciphers must be comma-separated.
If the specified list begins with a
.Sq +
-character, then the specified ciphers will be appended to the default set
-instead of replacing them.
+character, then the specified ciphers will be appended to the built-in
+openssh default set instead of replacing them.
If the specified list begins with a
.Sq -
character, then the specified ciphers (including wildcards) will be removed
-from the default set instead of replacing them.
+from the built-in openssh default set instead of replacing them.
If the specified list begins with a
.Sq ^
character, then the specified ciphers will be placed at the head of the
-default set.
+built-in openssh default set.
.Pp
The supported ciphers are:
.Bd -literal -offset indent
@@ -479,13 +480,6 @@
chacha20-poly1305@openssh.com
.Ed
.Pp
-The default is:
-.Bd -literal -offset indent
-chacha20-poly1305@openssh.com,
-aes128-ctr,aes192-ctr,aes256-ctr,
-aes128-gcm@openssh.com,aes256-gcm@openssh.com
-.Ed
-.Pp
The list of available ciphers may also be obtained using
.Qq ssh -Q cipher .
.It Cm ClearAllForwardings
@@ -885,6 +879,11 @@
The default is
.Dq no .
.It Cm GSSAPIKexAlgorithms
+The default is handled system-wide by
+.Xr crypto-policies 7 .
+Information about defaults, how to modify the defaults and how to customize existing policies with sub-policies are present in manual page
+.Xr update-crypto-policies 8 .
+.Pp
The list of key exchange algorithms that are offered for GSSAPI
key exchange. Possible values are
.Bd -literal -offset 3n
@@ -897,10 +896,8 @@
gss-curve25519-sha256-
.Ed
.Pp
-The default is
-.Dq gss-group14-sha256-,gss-group16-sha512-,gss-nistp256-sha256-,
-gss-curve25519-sha256-,gss-group14-sha1-,gss-gex-sha1- .
This option only applies to connections using GSSAPI.
+.Pp
.It Cm HashKnownHosts
Indicates that
.Xr ssh 1
@@ -919,36 +916,25 @@
but may be manually hashed using
.Xr ssh-keygen 1 .
.It Cm HostbasedAcceptedAlgorithms
+The default is handled system-wide by
+.Xr crypto-policies 7 .
+Information about defaults, how to modify the defaults and how to customize existing policies with sub-policies are present in manual page
+.Xr update-crypto-policies 8 .
+.Pp
Specifies the signature algorithms that will be used for hostbased
authentication as a comma-separated list of patterns.
Alternately if the specified list begins with a
.Sq +
character, then the specified signature algorithms will be appended
-to the default set instead of replacing them.
+to the built-in openssh default set instead of replacing them.
If the specified list begins with a
.Sq -
character, then the specified signature algorithms (including wildcards)
-will be removed from the default set instead of replacing them.
+will be removed from the built-in openssh default set instead of replacing them.
If the specified list begins with a
.Sq ^
character, then the specified signature algorithms will be placed
-at the head of the default set.
-The default for this option is:
-.Bd -literal -offset 3n
-ssh-ed25519-cert-v01@openssh.com,
-ecdsa-sha2-nistp256-cert-v01@openssh.com,
-ecdsa-sha2-nistp384-cert-v01@openssh.com,
-ecdsa-sha2-nistp521-cert-v01@openssh.com,
-sk-ssh-ed25519-cert-v01@openssh.com,
-sk-ecdsa-sha2-nistp256-cert-v01@openssh.com,
-rsa-sha2-512-cert-v01@openssh.com,
-rsa-sha2-256-cert-v01@openssh.com,
-ssh-ed25519,
-ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,
-sk-ssh-ed25519@openssh.com,
-sk-ecdsa-sha2-nistp256@openssh.com,
-rsa-sha2-512,rsa-sha2-256
-.Ed
+at the head of the built-in openssh default set.
.Pp
The
.Fl Q
@@ -1001,6 +987,17 @@
.Pp
The list of available signature algorithms may also be obtained using
.Qq ssh -Q HostKeyAlgorithms .
+.Pp
+The proposed
+.Cm HostKeyAlgorithms
+during KEX are limited to the set of algorithms that is defined in
+.Cm PubkeyAcceptedAlgorithms
+and therefore they are indirectly affected by system-wide
+.Xr crypto_policies 7 .
+.Xr crypto_policies 7 can not handle the list of host key algorithms directly as doing so
+would break the order given by the
+.Pa known_hosts
+file.
.It Cm HostKeyAlias
Specifies an alias that should be used instead of the
real host name when looking up or saving the host key
@@ -1232,30 +1229,25 @@
and
.Cm pam .
.It Cm KexAlgorithms
+The default is handled system-wide by
+.Xr crypto-policies 7 .
+Information about defaults, how to modify the defaults and how to customize existing policies with sub-policies are present in manual page
+.Xr update-crypto-policies 8 .
+.Pp
Specifies the available KEX (Key Exchange) algorithms.
Multiple algorithms must be comma-separated.
If the specified list begins with a
.Sq +
-character, then the specified algorithms will be appended to the default set
-instead of replacing them.
+character, then the specified methods will be appended to the built-in
+openssh default set instead of replacing them.
If the specified list begins with a
.Sq -
character, then the specified algorithms (including wildcards) will be removed
-from the default set instead of replacing them.
+from the built-in openssh default set instead of replacing them.
If the specified list begins with a
.Sq ^
character, then the specified algorithms will be placed at the head of the
-default set.
-The default is:
-.Bd -literal -offset indent
-sntrup761x25519-sha512@openssh.com,
-curve25519-sha256,curve25519-sha256@libssh.org,
-ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,
-diffie-hellman-group-exchange-sha256,
-diffie-hellman-group16-sha512,
-diffie-hellman-group18-sha512,
-diffie-hellman-group14-sha256
-.Ed
+built-in openssh default set.
.Pp
The list of available key exchange algorithms may also be obtained using
.Qq ssh -Q kex .
@@ -1365,37 +1357,33 @@
file.
This option is intended for debugging and no overrides are enabled by default.
.It Cm MACs
+The default is handled system-wide by
+.Xr crypto-policies 7 .
+Information about defaults, how to modify the defaults and how to customize existing policies with sub-policies are present in manual page
+.Xr update-crypto-policies 8 .
+.Pp
Specifies the MAC (message authentication code) algorithms
in order of preference.
The MAC algorithm is used for data integrity protection.
Multiple algorithms must be comma-separated.
If the specified list begins with a
.Sq +
-character, then the specified algorithms will be appended to the default set
-instead of replacing them.
+character, then the specified algorithms will be appended to the built-in
+openssh default set instead of replacing them.
If the specified list begins with a
.Sq -
character, then the specified algorithms (including wildcards) will be removed
-from the default set instead of replacing them.
+from the built-in openssh default set instead of replacing them.
If the specified list begins with a
.Sq ^
character, then the specified algorithms will be placed at the head of the
-default set.
+built-in openssh default set.
.Pp
The algorithms that contain
.Qq -etm
calculate the MAC after encryption (encrypt-then-mac).
These are considered safer and their use recommended.
.Pp
-The default is:
-.Bd -literal -offset indent
-umac-64-etm@openssh.com,umac-128-etm@openssh.com,
-hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,
-hmac-sha1-etm@openssh.com,
-umac-64@openssh.com,umac-128@openssh.com,
-hmac-sha2-256,hmac-sha2-512,hmac-sha1
-.Ed
-.Pp
The list of available MAC algorithms may also be obtained using
.Qq ssh -Q mac .
.It Cm NoHostAuthenticationForLocalhost
@@ -1567,39 +1555,31 @@
The default is
.Cm no .
.It Cm PubkeyAcceptedAlgorithms
+The default is handled system-wide by
+.Xr crypto-policies 7 .
+Information about defaults, how to modify the defaults and how to customize existing policies with sub-policies are present in manual page
+.Xr update-crypto-policies 8 .
+.Pp
Specifies the signature algorithms that will be used for public key
authentication as a comma-separated list of patterns.
If the specified list begins with a
.Sq +
-character, then the algorithms after it will be appended to the default
-instead of replacing it.
+character, then the algorithms after it will be appended to the built-in
+openssh default instead of replacing it.
If the specified list begins with a
.Sq -
character, then the specified algorithms (including wildcards) will be removed
-from the default set instead of replacing them.
+from the built-in openssh default set instead of replacing them.
If the specified list begins with a
.Sq ^
character, then the specified algorithms will be placed at the head of the
-default set.
-The default for this option is:
-.Bd -literal -offset 3n
-ssh-ed25519-cert-v01@openssh.com,
-ecdsa-sha2-nistp256-cert-v01@openssh.com,
-ecdsa-sha2-nistp384-cert-v01@openssh.com,
-ecdsa-sha2-nistp521-cert-v01@openssh.com,
-sk-ssh-ed25519-cert-v01@openssh.com,
-sk-ecdsa-sha2-nistp256-cert-v01@openssh.com,
-rsa-sha2-512-cert-v01@openssh.com,
-rsa-sha2-256-cert-v01@openssh.com,
-ssh-ed25519,
-ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,
-sk-ssh-ed25519@openssh.com,
-sk-ecdsa-sha2-nistp256@openssh.com,
-rsa-sha2-512,rsa-sha2-256
-.Ed
+built-in openssh default set.
.Pp
The list of available signature algorithms may also be obtained using
.Qq ssh -Q PubkeyAcceptedAlgorithms .
+.Pp
+This option affects also
+.Cm HostKeyAlgorithms
.It Cm PubkeyAuthentication
Specifies whether to try public key authentication.
The argument to this keyword must be
@@ -2265,7 +2245,9 @@
This file must be world-readable.
.El
.Sh SEE ALSO
-.Xr ssh 1
+.Xr ssh 1 ,
+.Xr crypto-policies 7 ,
+.Xr update-crypto-policies 8
.Sh AUTHORS
.An -nosplit
OpenSSH is a derivative of the original and free
diff --color -ru -x regress -x autom4te.cache -x '*.o' -x '*.lo' -x Makefile -x config.status -x configure~ -x configure.ac openssh-9.3p1/sshd_config.5 openssh-9.3p1-patched/sshd_config.5
--- openssh-9.3p1/sshd_config.5 2023-06-07 10:26:48.277590077 +0200
+++ openssh-9.3p1-patched/sshd_config.5 2023-06-07 10:26:00.592051845 +0200
@@ -379,17 +379,13 @@
then no banner is displayed.
By default, no banner is displayed.
.It Cm CASignatureAlgorithms
+The default is handled system-wide by
+.Xr crypto-policies 7 .
+Information about defaults, how to modify the defaults and how to customize existing policies with sub-policies are present in manual page
+.Xr update-crypto-policies 8 .
+.Pp
Specifies which algorithms are allowed for signing of certificates
by certificate authorities (CAs).
-The default is:
-.Bd -literal -offset indent
-ssh-ed25519,ecdsa-sha2-nistp256,
-ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,
-sk-ssh-ed25519@openssh.com,
-sk-ecdsa-sha2-nistp256@openssh.com,
-rsa-sha2-512,rsa-sha2-256
-.Ed
-.Pp
If the specified list begins with a
.Sq +
character, then the specified algorithms will be appended to the default set
@@ -525,20 +521,25 @@
indicating not to
.Xr chroot 2 .
.It Cm Ciphers
+The default is handled system-wide by
+.Xr crypto-policies 7 .
+Information about defaults, how to modify the defaults and how to customize existing policies with sub-policies are present in manual page
+.Xr update-crypto-policies 8 .
+.Pp
Specifies the ciphers allowed.
Multiple ciphers must be comma-separated.
If the specified list begins with a
.Sq +
-character, then the specified ciphers will be appended to the default set
-instead of replacing them.
+character, then the specified ciphers will be appended to the built-in
+openssh default set instead of replacing them.
If the specified list begins with a
.Sq -
character, then the specified ciphers (including wildcards) will be removed
-from the default set instead of replacing them.
+from the built-in openssh default set instead of replacing them.
If the specified list begins with a
.Sq ^
character, then the specified ciphers will be placed at the head of the
-default set.
+built-in openssh default set.
.Pp
The supported ciphers are:
.Pp
@@ -565,13 +566,6 @@
chacha20-poly1305@openssh.com
.El
.Pp
-The default is:
-.Bd -literal -offset indent
-chacha20-poly1305@openssh.com,
-aes128-ctr,aes192-ctr,aes256-ctr,
-aes128-gcm@openssh.com,aes256-gcm@openssh.com
-.Ed
-.Pp
The list of available ciphers may also be obtained using
.Qq ssh -Q cipher .
.It Cm ClientAliveCountMax
@@ -766,53 +760,43 @@
.Cm GSSAPIKeyExchange
needs to be enabled in the server and also used by the client.
.It Cm GSSAPIKexAlgorithms
+The default is handled system-wide by
+.Xr crypto-policies 7 .
+Information about defaults, how to modify the defaults and how to customize existing policies with sub-policies are present in manual page
+.Xr update-crypto-policies 8 .
+.Pp
The list of key exchange algorithms that are accepted by GSSAPI
key exchange. Possible values are
.Bd -literal -offset 3n
-gss-gex-sha1-,
-gss-group1-sha1-,
-gss-group14-sha1-,
-gss-group14-sha256-,
-gss-group16-sha512-,
-gss-nistp256-sha256-,
+gss-gex-sha1-
+gss-group1-sha1-
+gss-group14-sha1-
+gss-group14-sha256-
+gss-group16-sha512-
+gss-nistp256-sha256-
gss-curve25519-sha256-
.Ed
-.Pp
-The default is
-.Dq gss-group14-sha256-,gss-group16-sha512-,gss-nistp256-sha256-,
-gss-curve25519-sha256-,gss-group14-sha1-,gss-gex-sha1- .
This option only applies to connections using GSSAPI.
.It Cm HostbasedAcceptedAlgorithms
+The default is handled system-wide by
+.Xr crypto-policies 7 .
+Information about defaults, how to modify the defaults and how to customize existing policies with sub-policies are present in manual page
+.Xr update-crypto-policies 8 .
+.Pp
Specifies the signature algorithms that will be accepted for hostbased
authentication as a list of comma-separated patterns.
Alternately if the specified list begins with a
.Sq +
character, then the specified signature algorithms will be appended to
-the default set instead of replacing them.
+the built-in openssh default set instead of replacing them.
If the specified list begins with a
.Sq -
character, then the specified signature algorithms (including wildcards)
-will be removed from the default set instead of replacing them.
+will be removed from the built-in openssh default set instead of replacing them.
If the specified list begins with a
.Sq ^
character, then the specified signature algorithms will be placed at
-the head of the default set.
-The default for this option is:
-.Bd -literal -offset 3n
-ssh-ed25519-cert-v01@openssh.com,
-ecdsa-sha2-nistp256-cert-v01@openssh.com,
-ecdsa-sha2-nistp384-cert-v01@openssh.com,
-ecdsa-sha2-nistp521-cert-v01@openssh.com,
-sk-ssh-ed25519-cert-v01@openssh.com,
-sk-ecdsa-sha2-nistp256-cert-v01@openssh.com,
-rsa-sha2-512-cert-v01@openssh.com,
-rsa-sha2-256-cert-v01@openssh.com,
-ssh-ed25519,
-ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,
-sk-ssh-ed25519@openssh.com,
-sk-ecdsa-sha2-nistp256@openssh.com,
-rsa-sha2-512,rsa-sha2-256
-.Ed
+the head of the built-in openssh default set.
.Pp
The list of available signature algorithms may also be obtained using
.Qq ssh -Q HostbasedAcceptedAlgorithms .
@@ -879,25 +863,14 @@
.Ev SSH_AUTH_SOCK
environment variable.
.It Cm HostKeyAlgorithms
+The default is handled system-wide by
+.Xr crypto-policies 7 .
+Information about defaults, how to modify the defaults and how to customize existing policies with sub-policies are present in manual page
+.Xr update-crypto-policies 8 .
+.Pp
Specifies the host key signature algorithms
that the server offers.
The default for this option is:
-.Bd -literal -offset 3n
-ssh-ed25519-cert-v01@openssh.com,
-ecdsa-sha2-nistp256-cert-v01@openssh.com,
-ecdsa-sha2-nistp384-cert-v01@openssh.com,
-ecdsa-sha2-nistp521-cert-v01@openssh.com,
-sk-ssh-ed25519-cert-v01@openssh.com,
-sk-ecdsa-sha2-nistp256-cert-v01@openssh.com,
-rsa-sha2-512-cert-v01@openssh.com,
-rsa-sha2-256-cert-v01@openssh.com,
-ssh-ed25519,
-ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,
-sk-ssh-ed25519@openssh.com,
-sk-ecdsa-sha2-nistp256@openssh.com,
-rsa-sha2-512,rsa-sha2-256
-.Ed
-.Pp
The list of available signature algorithms may also be obtained using
.Qq ssh -Q HostKeyAlgorithms .
.It Cm IgnoreRhosts
@@ -1044,20 +1017,25 @@
The default is
.Cm yes .
.It Cm KexAlgorithms
+The default is handled system-wide by
+.Xr crypto-policies 7 .
+Information about defaults, how to modify the defaults and how to customize existing policies with sub-policies are present in manual page
+.Xr update-crypto-policies 8 .
+.Pp
Specifies the available KEX (Key Exchange) algorithms.
Multiple algorithms must be comma-separated.
Alternately if the specified list begins with a
.Sq +
-character, then the specified algorithms will be appended to the default set
-instead of replacing them.
+character, then the specified methods will be appended to the built-in
+openssh default set instead of replacing them.
If the specified list begins with a
.Sq -
character, then the specified algorithms (including wildcards) will be removed
-from the default set instead of replacing them.
+from the built-in openssh default set instead of replacing them.
If the specified list begins with a
.Sq ^
character, then the specified algorithms will be placed at the head of the
-default set.
+built-in openssh default set.
The supported algorithms are:
.Pp
.Bl -item -compact -offset indent
@@ -1089,16 +1067,6 @@
sntrup761x25519-sha512@openssh.com
.El
.Pp
-The default is:
-.Bd -literal -offset indent
-sntrup761x25519-sha512@openssh.com,
-curve25519-sha256,curve25519-sha256@libssh.org,
-ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,
-diffie-hellman-group-exchange-sha256,
-diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,
-diffie-hellman-group14-sha256
-.Ed
-.Pp
The list of available key exchange algorithms may also be obtained using
.Qq ssh -Q KexAlgorithms .
.It Cm ListenAddress
@@ -1184,21 +1152,26 @@
file.
This option is intended for debugging and no overrides are enabled by default.
.It Cm MACs
+The default is handled system-wide by
+.Xr crypto-policies 7 .
+Information about defaults, how to modify the defaults and how to customize existing policies with sub-policies are present in manual page
+.Xr update-crypto-policies 8 .
+.Pp
Specifies the available MAC (message authentication code) algorithms.
The MAC algorithm is used for data integrity protection.
Multiple algorithms must be comma-separated.
If the specified list begins with a
.Sq +
-character, then the specified algorithms will be appended to the default set
-instead of replacing them.
+character, then the specified algorithms will be appended to the built-in
+openssh default set instead of replacing them.
If the specified list begins with a
.Sq -
character, then the specified algorithms (including wildcards) will be removed
-from the default set instead of replacing them.
+from the built-in openssh default set instead of replacing them.
If the specified list begins with a
.Sq ^
character, then the specified algorithms will be placed at the head of the
-default set.
+built-in openssh default set.
.Pp
The algorithms that contain
.Qq -etm
@@ -1241,15 +1214,6 @@
umac-128-etm@openssh.com
.El
.Pp
-The default is:
-.Bd -literal -offset indent
-umac-64-etm@openssh.com,umac-128-etm@openssh.com,
-hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,
-hmac-sha1-etm@openssh.com,
-umac-64@openssh.com,umac-128@openssh.com,
-hmac-sha2-256,hmac-sha2-512,hmac-sha1
-.Ed
-.Pp
The list of available MAC algorithms may also be obtained using
.Qq ssh -Q mac .
.It Cm Match
@@ -1633,36 +1597,25 @@
The default is
.Cm yes .
.It Cm PubkeyAcceptedAlgorithms
+The default is handled system-wide by
+.Xr crypto-policies 7 .
+Information about defaults, how to modify the defaults and how to customize existing policies with sub-policies are present in manual page
+.Xr update-crypto-policies 8 .
+.Pp
Specifies the signature algorithms that will be accepted for public key
authentication as a list of comma-separated patterns.
Alternately if the specified list begins with a
.Sq +
-character, then the specified algorithms will be appended to the default set
-instead of replacing them.
+character, then the specified algorithms will be appended to the built-in
+openssh default set instead of replacing them.
If the specified list begins with a
.Sq -
character, then the specified algorithms (including wildcards) will be removed
-from the default set instead of replacing them.
+from the built-in openssh default set instead of replacing them.
If the specified list begins with a
.Sq ^
character, then the specified algorithms will be placed at the head of the
-default set.
-The default for this option is:
-.Bd -literal -offset 3n
-ssh-ed25519-cert-v01@openssh.com,
-ecdsa-sha2-nistp256-cert-v01@openssh.com,
-ecdsa-sha2-nistp384-cert-v01@openssh.com,
-ecdsa-sha2-nistp521-cert-v01@openssh.com,
-sk-ssh-ed25519-cert-v01@openssh.com,
-sk-ecdsa-sha2-nistp256-cert-v01@openssh.com,
-rsa-sha2-512-cert-v01@openssh.com,
-rsa-sha2-256-cert-v01@openssh.com,
-ssh-ed25519,
-ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,
-sk-ssh-ed25519@openssh.com,
-sk-ecdsa-sha2-nistp256@openssh.com,
-rsa-sha2-512,rsa-sha2-256
-.Ed
+built-in openssh default set.
.Pp
The list of available signature algorithms may also be obtained using
.Qq ssh -Q PubkeyAcceptedAlgorithms .
@@ -2131,7 +2084,9 @@
.El
.Sh SEE ALSO
.Xr sftp-server 8 ,
-.Xr sshd 8
+.Xr sshd 8 ,
+.Xr crypto-policies 7 ,
+.Xr update-crypto-policies 8
.Sh AUTHORS
.An -nosplit
OpenSSH is a derivative of the original and free