ref: 1dbb193077af7ba6ff7fb70a4dd465480764382e
dir: /man/2/crypt-sha1/
.TH CRYPT-SHA1 2 .SH NAME crypt: sha1, sha224, sha256, sha384, sha512, md4, md5, hmac_sha1, hmac_md5 \- cryptographic digests .SH SYNOPSIS .EX 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; }; .ta \w'verify:\ 'u +\w'fn(\ \ \ 'u 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; .EE .SH DESCRIPTION .BR Sha1 , .BR sha224 , .BR sha256 , .BR sha384 , .BR sha512 , .B md4 and .B md5 are cryptographically secure hash functions that produce output called a message digest. Each function computes a hash of .I n bytes of the data in .IR buf , using the named algorithm, and updates the current .IR state . They can be called iteratively to form a single digest for many data blocks. The state is kept in the .B DigestState value referenced by .I state between calls. .I State should be .B nil on the first call, and a newly allocated .B DigestState will be returned for use in subsequent calls. On a call in which .I digest is not .BR nil , the hash is completed and copied into the .I digest array. .B Sha1 produces a 20-byte hash .RB ( SHA1dlen ), .B sha224 a 28-byte hash .RB ( SHA224dlen ), .B sha256 a 32-byte hash .RB ( SHA256dlen ), .B sha384 a 48-byte hash .RB ( SHA384dlen ), .B sha256 a 64-byte hash .RB ( SHA512dlen ), .B md4 and .B md5 a 16-byte one .RB ( MD4len and .BR MD5len ). .PP .B Hmac_sha1 and .B hmac_md5 are keyed versions of the hashing functions, following Internet RFC2104. The .I key must be provided in each call, but otherwise the calling conventions are those of .BR sha1 . The .I key must currently be no more than 64 bytes. .PP .B DigestState hides the state of partially completed hash functions during processing. Its .B copy operation returns a reference to a new copy of a given state. .SH EXAMPLES A program to read a file and hash it using SHA might contain the following inner loop: .IP .EX 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); .EE .SH SOURCE .B /libinterp/crypt.c .br .B /libsec/port/hmac.c .br .B /libsec/port/md4.c .br .B /libsec/port/md5.c .br .B /libsec/port/sha1.c .SH 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.