RSA(8) RSA(8)
NAME
rsagen, rsafill, asn12rsa, rsa2asn1, rsa2pub, rsa2ssh,
rsa2x509, rsa2csr - generate and format rsa keys
SYNOPSIS
rsagen [ -b nbits ] [ -t tag ]
rsafill [ file ]
asn12rsa [ -t tag ] [ file ]
rsa2asn1 [ -a ] [ file ]
rsa2pub [ file ]
rsa2ssh [ -c comment ] [ file ]
rsa2x509 [ -e expiretime ] certinfo [ file ]
rsa2csr subject [ 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 factotum(4). A full RSA private key has the follow-
ing 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
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RSA(8) RSA(8)
typically used), but to these utilities such attributes are
merely comments.
For example, a very small (and thus insecure) private key
and corresponding 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 2048) significant bits. If tag
is specified, it is printed between key and proto=rsa; typi-
cally, tag is a sequence of attribute-value comments
describing the key.
Rsafill reads a private key, recomputes the !kp, !kq, and
!c2 attributes if they are missing, and prints a full key.
Asn12rsa reads an RSA private or public key stored as ASN.1
encoded in the binary Distinguished Encoding Rules (DER) and
prints a Plan 9 RSA key, inserting tag exactly as rsagen
does. ASN.1/DER is a popular key format on Unix and Win-
dows; 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.
Rsa2asn1 is like rsa2pub but outputs the public key in
ASN.1/DER format. With the -a flag a private key is read
and encoded in ANS.1/DER format.
Rsa2ssh reads a Plan 9 RSA public or private key and prints
the public portion in the format used by SSH2. The -c option
will set the comment.
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 expires
expiretime seconds (default 3 years) later. It contains the
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RSA(8) RSA(8)
public 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
One can append further Distinguished Names, DNS Names and
E-Mail addresses as a ``Subject Alternative Name'' separated
with a comma after the main subject.
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-encrypted 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.
Rsa2csr takes the subject and a RSA private key and outputs
a signing request in ASN.1 format.
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
Convert a private key in PEM format (as generated by
OpenSSL) and load it into factotum:
auth/pemdecode 'PRIVATE KEY' key.pem |
auth/asn12rsa -t 'service=tls' >/mnt/factotum/ctl
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RSA(8) RSA(8)
Generate a certificate signing request (CSR) in PEM format:
auth/rsa2csr 'CN=example.com' key |
auth/pemencode 'CERTIFICATE REQUEST'
Generate a tinc host key:
auth/rsagen -t 'service=tinc role=client host=myhost' > myhost.key
auth/rsa2pub < myhost.key |
auth/rsa2asn1 | auth/pemencode 'RSA PUBLIC KEY' > hosts/myhost
SOURCE
/sys/src/cmd/auth
SEE ALSO
factotum(4), pem(8),
BUGS
There are too many key formats.
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