term% cat index.txt RSA(8) System Manager's Manual RSA(8)
NAME
rsagen, rsafill, asn12rsa, rsa2pub, rsa2ssh, rsa2x509 - generate and
format rsa keys
SYNOPSIS
rsagen [ -b nbits ] [ -t tag ]
rsafill [ file ]
asn12rsa [ -t tag ] [ file ]
rsa2pub [ file ]
rsa2ssh [ -2 ] [ -c comment ] [ file ]
rsa2x509 [ -e expiretime ] certinfo [ file ]
DESCRIPTION
Plan 9 represents an RSA key as an attribute-value pair list prefixed
with the string key; this is the generic key format used by facto‐
tum(4). A full RSA private key has the following attributes:
proto must be rsa
size the number of significant bits in n
ek the encryption exponent
n the product of !p and !q
!dk the decryption exponent
!p a large prime
!q another large prime
!kp, !kq, !c2
parameters derived from the other attributes, cached to speed
decryption
All the numbers are in hexadecimal except size , which is decimal. An
RSA public key omits the attributes beginning with A key may have other
attributes as well (for example, a service attribute identifying how
this key is typically used), but to these utilities such attributes are
merely comments.
For example, a very small (and thus insecure) private key and corre‐
sponding public key might be:
key proto=rsa size=8 ek=7 n=8F !dk=67 !p=B !q=D !kp=3 !kq=7 !c2=6
key proto=rsa size=8 ek=7 n=8F
Note that the order of the attributes does not matter.
Rsagen prints a randomly generated RSA private key whose n has exactly
nbits (default 1024) significant bits. If tag is specified, it is
printed between key and proto=rsa; typically, tag is a sequence of at‐
tribute-value comments describing the key.
Rsafill reads a private key, recomputes the !kp, !kq, and !c2 at‐
tributes if they are missing, and prints a full key.
Asn12rsa reads an RSA private key stored as ASN.1 encoded in the binary
Distinguished Encoding Rules (DER) and prints a Plan 9 RSA key, insert‐
ing tag exactly as rsagen does. ASN.1/DER is a popular key format on
Unix and Windows; it is often encoded in text form using the Privacy
Enhanced Mail (PEM) format in a section labeled as an ``RSA PRIVATE
KEY.'' The command:
auth/pemdecode 'RSA PRIVATE KEY' | auth/asn12rsa
extracts the key section from a textual ASN.1/DER/PEM key into binary
ASN.1/DER format and then converts it to a Plan 9 RSA key.
Rsa2pub reads a Plan 9 RSA public or private key, removes the private
attributes, and prints the resulting public key. Comment attributes
are preserved.
Rsa2ssh reads a Plan 9 RSA public or private key and prints the public
portion in the format used by SSH: three space-separated decimal num‐
bers size, ek, and n. The -2 option will change the output to SSH2 RSA
public key format. The -c option will set the comment. For compatibil‐
ity with external SSH implementations, the public keys in
/sys/lib/ssh/keyring and $home/lib/keyring are stored in this format.
Rsa2x509 reads a Plan 9 RSA private key and writes a self-signed X.509
certificate encoded in ASN.1/DER format to standard output. (Note that
ASN.1/DER X.509 certificates are different from ASN.1/DER private
keys). The certificate uses the current time as its start time and ex‐
pires expiretime seconds (default 3 years) later. It contains the pub‐
lic half of the key and includes certinfo as the issuer/subject string
(also known as a ``Distinguished Name''). This info is typically in
the form:
C=US ST=NJ L=07974 O=Lucent OU='Bell Labs' CN=G.R.Emlin
The X.509 ASN.1/DER format is often encoded in text using a PEM section
labeled as a ``CERTIFICATE.'' The command:
auth/rsa2x509 'C=US OU=''Bell Labs''' file |
auth/pemencode CERTIFICATE
generates such a textual certificate. Applications that serve TLS-en‐
crypted sessions (for example, httpd(8), pop3(8), and tlssrv(8)) expect
certificates in ASN.1/DER/PEM format.
The Plan 9 RSA private key needs to be loaded into factotum for TLS
server applications. It is recommended to put the key into secstore(1),
avoiding it being stored unencrypted on the filesystem.
EXAMPLES
Generate a fresh key and use it to start a TLS-enabled web server:
auth/rsagen -t 'service=tls owner=*' >key
auth/rsa2x509 'C=US CN=*.cs.bell-labs.com' key |
auth/pemencode CERTIFICATE >cert
cat key >/mnt/factotum/ctl
ip/httpd/httpd -c cert
Generate a fresh key and configure a remote Unix system to allow use of
that key for logins:
auth/rsagen -t 'service=ssh' >key
auth/rsa2ssh key | ssh unix 'cat >>.ssh/authorized_keys'
cat key >/mnt/factotum/ctl
ssh unix
SOURCE
/sys/src/cmd/auth
SEE ALSO
factotum(4), pem(8), ssh(1)
BUGS
There are too many key formats.
RSA(8)