keytext - textual form of Inferno public/private keys Keyring-certtostr (2) defines a set of functions that convert between textual forms of the elements of the Inferno public-key authentication system and their internal data types. The textual form is used for key storage and as the transport format for the authentication protocol auth (6). In storage and transport each encoded value is encapsulated by the record-oriented encoding defined in keyring-getmsg (2). The format represents public and private keys, and signer's certificates. In this context a certificate is a time-limited cryptographically signed hash of some other value (usually a public key) and contains neither that value nor the signer's key, which is assumed to be available elsewhere.

All values are represented by a sequence of newline-separated text fields. The type of any given value is determined by its context. Each type of value has a common prefix that includes an algorithm identifier, followed by a sequence of algorithm-dependent fields:

.EX "authinfo" " ::= " "signer-public-key certificate !private-key big-alpha big-p"

certificate " ::= " "sigalg hashalg signer-name exp-time *-sig"

sigalg " ::= " "rsa" " | " "dsa" " | " "elgamal"

hashalg " ::= " sha1 " | " md5

"*-key" " ::= " "sigalg owner-name ..." "rsa-public-key" " ::= " rsa owner-name "big-n big-ek"

"rsa-private-key" " ::= " rsa owner-name "big-n big-ek"

" !big-dk !big-p !big-q !big-kp !big-kq !big-c2"

"dsa-public-key" " ::= " dsa owner-name "big-p big-q big-alpha big-key"

"dsa-private-key" " ::= " dsa owner-name "big-p big-q big-alpha big-key !big-secret" rsa-sig " ::= " "big-val"

dsa-sig " ::= " "big-r big-s"

elgamal-sig " ::= " "big-r big-s"

Each value labelled as ` big- ' is an unsigned multiple-precision integer from keyring-ipint (2), represented as a sequence of bytes with in big-endian order, as produced by IPint->iptobytes with an extra leading zero byte added if the top bit of the first byte is set, and then encoded in base-64 (as by encoding (2)). Each value labelled ` -name ' is utf (6) text not containing a newline; it is interpreted by an application and need not be a name. The expiry time exp-time is represented in decimal as seconds from the Epoch (1 January 1970 00:00 GMT); if it is zero, no expiry time is set. A label prefixed by ` ! ' marks a value that should be considered secret.

The hash of a key is computed over its textual encoding according to the syntax above. A certificate's signature value is produced by digitally signing using sigalg the hash (using hashalg ) of the concatenation of the value to be authenticated, the signer-name in utf (6), a single space, and the exp-time in decimal (with no leading zeroes). When checking a signature, comparisons are done with values in internal multiple-precision form (ie, as IPint s), not in base-64 form.

keyring-certtostr (2), keyring-getmsg (2), factotum (4), keys (6), getauthinfo (8) The byte-array encoding of IPint should not require the leading zero; it does so for compatibility with old keys.