CRYPT-INTRO(2) CRYPT-INTRO(2)
NAME
Crypt intro - introduction to the Crypt cryptography module
SYNOPSIS
include "ipints.m";
ipints := load IPints IPints->PATH;
IPint: import ipints;
include "crypt.m";
crypt := load Crypt Crypt->PATH;
DESCRIPTION
Crypt contains a mixed set of functions that variously:
+o form cryptographically secure digests; see crypt-
sha1(2)
+o generate public/private key pairs; see crypt-gensk(2)
+o encrypt data, using AES, DES, or IDEA; see crypt-
crypt(2)
+o create and verify cryptographic signatures using the
public keys; see crypt-sign(2)
Public Key Cryptography
Public key cryptography has many uses. Inferno relies on it
only for digital signatures. The private key may be used to
digitally sign data, the public one to verify the signature.
Inferno provides three data types to represent the different
components of the public key signature scheme. The PK adt
contains the data necessary to construct a public key; the
SK adt contains the data necessary to construct a secret
key. A key contains the public or secret parameters for the
signature algorithm specified by the adt's pick tag. Owner-
ship of a key is not recorded in the key value itself but in
a separate certificate. Finally, the PKsig adt contains one
or more values representing a given form of digital signa-
ture.
Certificates and indeed signature representations are var-
ied, and implemented by other modules.
Large Precision Arithmetic
Many Crypt operations require integers much larger than int
or big. It therefore uses the multiple-precision package
ipints(2). That module's IPint adt stands for infinite pre-
cision integer, though, for space considerations, our imple-
mentation limits the maximum integer to 28192-1.
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CRYPT-INTRO(2) CRYPT-INTRO(2)
An IPint can be converted into two external formats. The
first is an array of bytes in which the first byte is the
highest order byte of the integer. This format is useful
when communicating with the ssl(3) device. The second is
similar but represents the array of bytes as text, using
either base 16 or a MIME base 64 format, allowing IPints to
be stored in files or transmitted across networks in a human
readable form.
SOURCE
/libinterp/crypt.c
/libinterp/ipint.c
/libmp
/libsec
SEE ALSO
security-intro(2)
B. Schneier, Applied Cryptography, 1996, J. Wiley & Sons,
Inc.
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