RSA(8)                                                     RSA(8)

     NAME
          rsagen, rsafill, asn12rsa, rsa2pub, rsa2ssh, rsa2x509,
          rsa2csr - 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 ]

          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
          typically used), but to these utilities such attributes are
          merely comments.

     RSA(8)                                                     RSA(8)

          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 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 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 numbers 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 compatibility with exter-
          nal 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 expires
          expiretime seconds (default 3 years) later.  It contains the
          public half of the key and includes certinfo as the
          issuer/subject string (also known as a ``Distinguished

     RSA(8)                                                     RSA(8)

          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

          Generate a certificate signing request (CSR) in PEM format:

     RSA(8)                                                     RSA(8)

               auth/rsa2csr 'CN=example.com' key |
                    auth/pemencode 'CERTIFICATE REQUEST'

     SOURCE
          /sys/src/cmd/auth

     SEE ALSO
          factotum(4), pem(8),

     BUGS
          There are too many key formats.