NAME

crypt: sha1, sha224, sha256, sha384, sha512, md4, md5, hmac_sha1, hmac_md5 - cryptographic digests

SYNOPSIS

include "ipints.m";
ipints := load IPints IPints->PATH;
IPint: import ipints;

include "crypt.m";
crypt := load Crypt Crypt->PATH;

DigestState: adt
{
    # hidden state
    copy:   fn(d: self ref DigestState): ref DigestState;
};

sha1:	fn(buf: array of byte, n: int, digest: array of byte,
		state: ref DigestState): ref DigestState;
sha224:	fn(buf: array of byte, n: int, digest: array of byte,
		state: ref DigestState): ref DigestState;
sha256:	fn(buf: array of byte, n: int, digest: array of byte,
		state: ref DigestState): ref DigestState;
sha384:	fn(buf: array of byte, n: int, digest: array of byte,
		state: ref DigestState): ref DigestState;
sha512:	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;

SHA1dlen, SHA224dlen, SHA256dlen, SHA384dlen, SHA512dlen, MD4dlen, MD5dlen: con ...;

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;

DESCRIPTION

Sha1, sha224, sha256, sha384, sha512, md4 and md5 are cryptographically secure hash functions that produce output called a message digest. Each function computes a hash of n bytes of the data in buf, using the named algorithm, 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), sha224 a 28-byte hash (SHA224dlen), sha256 a 32-byte hash (SHA256dlen), sha384 a 48-byte hash (SHA384dlen), sha256 a 64-byte hash (SHA512dlen), 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 provided in each call, but otherwise the calling conventions are those of sha1. The key must currently be no more than 64 bytes.

DigestState hides the state of partially completed hash functions during processing. Its copy operation returns a reference to a new copy of a given state.

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/crypt.c
/libsec/port/hmac.c
/libsec/port/md4.c
/libsec/port/md5.c
/libsec/port/sha1.c

BUGS

The MD4 algorithm is included only to allow communication with software that might still use it; it should not otherwise be used now, because it is easily broken.

CRYPT-SHA1(2 )

Rev:  Tue Mar 31 02:42:39 GMT 2015