KEYRING-SHA1(2) KEYRING-SHA1(2)
NAME
keyring: sha1, md4, md5, hmac_sha1, hmac_md5, sign, verify -
cryptographic digests and digital signatures
SYNOPSIS
include "keyring.m";
keyring := load Keyring Keyring->PATH;
sha1: fn(buf: array of byte, n: int, digest: array of byte,
state: ref DigestState): ref DigestState;
md4: fn(buf: array of byte, n: int, digest: array of byte,
state: ref DigestState): ref DigestState;
md5: fn(buf: array of byte, n: int, digest: array of byte,
state: ref DigestState): ref DigestState;
hmac_sha1: fn(buf: array of byte, n: int, key: array of byte, digest: array of byte,
state: ref DigestState): ref DigestState;
hmac_md5: fn(buf: array of byte, n: int, key: array of byte, digest: array of byte,
state: ref DigestState): ref DigestState;
sign: fn(sk: ref SK, exp: int, state: ref DigestState,
ha: string): ref Certificate;
verify: fn(pk: ref PK, cert: ref Certificate,
state: ref DigestState): int;
DESCRIPTION
Sha1, md4 and md5 are cryptographically secure hash func-
tions that produce output called a message digest. Each
function computes a hash of n bytes of the data in buf, and
updates the current state. They can be called iteratively to
form a single digest for many data blocks. The state is
kept in the DigestState value referenced by state between
calls. State should be nil on the first call, and a newly
allocated DigestState will be returned for use in subsequent
calls. On a call in which digest is not nil, the hash is
completed and copied into the digest array. Sha1 produces a
20-byte hash (SHA1dlen), md4 and md5 a 16-byte one (MD4len
and MD5len).
Hmac_sha1 and hmac_md5 are keyed versions of the hashing
functions, following Internet RFC2104. The key must be pro-
vided in each call, but otherwise the calling conventions
are those of sha1. The key must currently be no more than
64 bytes.
Sign creates a digital signature of a digest from the con-
catenation of: a message, the name of the signer, and an
expiration time. State is the digest state after running
sha1, md4 or md5 over the message. Ha is a string specify-
ing the hash algorithm to use: "sha", "sha1", "md4" or
"md5". Sign extends the digest to cover the signer's name
(taken from the private key, sk) and the expiration time.
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KEYRING-SHA1(2) KEYRING-SHA1(2)
It returns a certificate containing the digital signature of
the digest, signer name, hash algorithm and signature algo-
rithm. If any parameter is invalid, sign returns nil. The
signature algorithm is implied by the type of the private
key.
Verify uses public key pk to verify a certificate. It
returns non-zero (true) if the certificate is valid; zero
(false) otherwise. State is the digest state after running
the chosen digest algorithm over the message.
EXAMPLES
A program to read a file and hash it using SHA might contain
the following inner loop:
state: ref DigestState = nil;
while((n := sys->read(fd, buf, len buf)) > 0)
state = kr->sha1(buf, n, nil, state);
digest := array[kr->SHA1dlen] of byte;
kr->sha1(buf, 0, digest, state);
SOURCE
/libinterp/keyring.c
/libcrypt/hmac.c
/libcrypt/md4.c
/libcrypt/md5.c
/libcrypt/sha1.c
BUGS
The MD4 algorithm is included only to allow communication
with software that might still use it; it should not other-
wise be used now, because it is easily broken.
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