| RSA(1) | RSA(1)

NAME

| dsagen, rsagen, rsafill, asn12dsa, asn12rsa, dsa2pub, rsa2csr, rsa2pub, dsa2ssh, rsa2ssh, rsa2x509 – generate and format dsa and rsa keys

SYNOPSIS

`dsagen` [ `−t` tag ]

`rsagen` [ `−b` nbits ] [ `−t` tag ]

`rsafill` [ file ]

`asn12dsa` [ `−t` tag ] [ file ]

`asn12rsa` [ `−t` tag ] [ file ]

`dsa2pub` [ file ]

`rsa2pub` [ file ]

`dsa2ssh` [ file ]

`rsa2ssh` [ `−2` ] [ file ]

`rsa2x509` [ `−e` expiretime ] certinfo [ file ]

`rsa2csr` certinfo [ file ]

DESCRIPTION

Plan 9 represents DSA and RSA keys as attribute-value pair lists prefixed with the string `key`; this is the generic key format used by factotum(4). A full DSA private key has the following attributes:
`proto`must be `dsa
p` prime public modulus
`q` prime group order; divides `p`-1
`alpha`group generator
`key alpha`^`!secret` mod `p
!secret
`

the secret exponent

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 in both keys are in hexadecimal except RSA’s size , which is decimal. A 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 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.

Dsagen prints a randomly generated DSA private key using the NIST-recommended algorithm. If tag is specified, it is printed between `key` and `proto=dsa`; typically, tag is a sequence of attribute-value comments describing the key.

Rsagen prints a randomly generated RSA private key whose `n` has exactly nbits (default 1024) significant bits.

Rsafill reads a private key, recomputes the `!kp`, `!kq`, and `!c2` attributes if they are missing, and prints a full key.

Asn12dsa reads an DSA private key stored as ASN.1 encoded in the binary Distinguished Encoding Rules (DER) and prints a Plan 9 DSA key, inserting tag exactly as dsagen 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 “`DSA PRIVATE KEY`.” The command:

`pemdecode 'DSA PRIVATE KEY' | asn12dsa

`

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 DSA key.

Asn12rsa is similar but operates on RSA keys.

Dsa2pub reads a Plan 9 DSA public or private key, removes the private attributes, and prints the resulting public key. Comment attribtes are preserved.

Rsa2pub is similar but operates on RSA keys.

Dsa2ssh reads a Plan 9 DSA public or private key and prints the public portion in the format used by SSH version 2 (version 1 did not support DSA). If the key has a `comment` attribute, that comment is appended to the key.

Rsa2ssh is similar but operates on RSA keys. It decides whether to print in version 1 or version 2 format by inspecting the `service` attribute.

Dsa2ssh and rsa2ssh are useful for generating SSH’s `authorized_keys` file.

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 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:

`rsa2x509 'C=US OU=''Bell Labs''' file |
pemencode CERTIFICATE

`

generates such a textual certificate. Applications that serve TLS-encrypted sessions typically expect certificates in ASN.1/DER/PEM format.

Rsa2csr is like rsa2x509 but writes an X.509 certificate request.

EXAMPLES

Generate a fresh key and use it to start the Plan 9 TLS-enabled web server:

`rsagen −t 'service=tls owner=*' >key
rsa2x509 'C=US CN=*.cs.bell−labs.com' key |

| pemencode CERTIFICATE >cert

cat key >/mnt/factotum/ctl
ip/httpd/httpd −c cert

`

Generate a fresh set of SSH keys (only one is necessary), load them into factotum, and configure a remote Unix system to allow those keys for logins:

`rsagen −t 'service=ssh role=decrypt' >rsa1
rsagen −t 'service=ssh−rsa role=sign' >rsa2
dsagen −t 'service=ssh−dss role=sign' >dsa2

`

Convert existing Unix SSH version 2 keys instead of generating new ones:

`cd $HOME/.ssh
pemdecode 'DSA PRIVATE KEY' id_dsa | asn12dsa >dsa2
pemdecode 'RSA PRIVATE KEY' id_rsa | asn12rsa >rsa2

`

Load those keys into factotum:

| `cat rsa1 rsa2 dsa2 | 9p write −l factotum/ctl` Allow use of those keys for logins on other systems: `rsa2ssh rsa1 >auth.keys rsa2ssh rsa2 >>auth.keys dsa2ssh dsa2 >>auth.keys scp auth.keys unix:.ssh/authorized_keys`

SOURCE

| `/usr/local/plan9/src/cmd/auth`

SEE ALSO

| factotum(4), pem(1), ssh(1)

BUGS

There are too many key formats.

There is no program to convert SSH version 1 RSA private keys.