SECHASH(2) SECHASH(2)
NAME
md4, md5, ripemd160, sha1, sha2_224, sha2_256, sha2_384,
sha2_512, sha3_224, sha3_256, sha3_384, sha3_512,
shake_128_in, shake_128_out, shake_128_conv, shake_128,
shake_256_in, shake_256_out, shake_256_conv, shake_256,
hmac_x, hmac_md5, hmac_sha1, hmac_sha2_224, hmac_sha2_256,
hmac_sha2_384, hmac_sha2_512, blake2s_128, blake2s_256,
mac_blake2s_128, mac_blake2s_256, hmac_blake2s_256, poly1305
- cryptographically secure hashes
SYNOPSIS
#include <u.h>
#include <libc.h>
#include <mp.h>
#include <libsec.h>
#define DS DigestState /* only to abbreviate SYNOPSIS */
#define XS XOFState /* only to abbreviate SYNOPSIS */
DS* md4(uchar *data, ulong dlen, uchar *digest, DS *state)
DS* md5(uchar *data, ulong dlen, uchar *digest, DS *state)
DS* ripemd160(uchar *data, ulong dlen, uchar *digest, DS
*state)
DS* sha1(uchar *data, ulong dlen, uchar *digest, DS *state)
DS* sha2_224(uchar *data, ulong dlen, uchar *digest, DS
*state)
DS* sha2_256(uchar *data, ulong dlen, uchar *digest, DS
*state)
DS* sha2_384(uchar *data, ulong dlen, uchar *digest, DS
*state)
DS* sha2_512(uchar *data, ulong dlen, uchar *digest, DS
*state)
DS* sha3_224(uchar *data, ulong dlen, uchar *digest, DS
*state)
DS* sha3_256(uchar *data, ulong dlen, uchar *digest, DS
*state)
DS* sha3_384(uchar *data, ulong dlen, uchar *digest, DS
*state)
DS* sha3_512(uchar *data, ulong dlen, uchar *digest, DS
*state)
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SECHASH(2) SECHASH(2)
DS* shake_128_in(uchar *data, ulong dlen, DS *state)
XS* shake_128_conv(XS *out, DS *in)
void shake_128_out(uchar *out, ulong olen, XS *state)
DS* shake_128(uchar *data, ulong dlen, uchar *digest, ulong
olen)
DS* shake_256_in(uchar *data, ulong dlen, DS *state)
XS* shake_256_conv(XS *out, DS *in)
void shake_256_out(uchar *out, ulong olen, XS *state)
DS* shake_256(uchar *data, ulong dlen, uchar *digest, ulong
olen)
DS* shake_256(uchar *data, ulong dlen, uchar *digest, ulong
olen)
DS* blake2s_128(uchar *data, ulong dlen, uchar *digest, DS
*state)
DS* blake2s_256(uchar *data, ulong dlen, uchar *digest, DS
*state)
DS* hmac_x(uchar *p, ulong len, uchar *key, ulong klen,
uchar *digest, DS *s, DS*(*x)(uchar*, ulong, uchar*,
DS*), int xlen, int B)
DS* hmac_md5(uchar *data, ulong dlen, uchar *key, ulong
klen, uchar *digest, DS *state)
DS* hmac_sha1(uchar *data, ulong dlen, uchar *key, ulong
klen, uchar *digest, DS *state)
DS* hmac_sha2_224(uchar *data, ulong dlen, uchar *key,
ulong klen, uchar *digest, DS *state)
DS* hmac_sha2_256(uchar *data, ulong dlen, uchar *key,
ulong klen, uchar *digest, DS *state)
DS* hmac_sha2_384(uchar *data, ulong dlen, uchar *key,
ulong klen, uchar *digest, DS *state)
DS* hmac_sha2_512(uchar *data, ulong dlen, uchar *key,
ulong klen, uchar *digest, DS *state)
DS* hmac_sha3_224(uchar *data, ulong dlen, uchar *key,
ulong klen, uchar *digest, DS *state)
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SECHASH(2) SECHASH(2)
DS* hmac_sha3_256(uchar *data, ulong dlen, uchar *key,
ulong klen, uchar *digest, DS *state)
DS* hmac_sha3_384(uchar *data, ulong dlen, uchar *key,
ulong klen, uchar *digest, DS *state)
DS* hmac_sha3_512(uchar *data, ulong dlen, uchar *key,
ulong klen, uchar *digest, DS *state)
DS* hmac_blake2s_256(uchar *data, ulong dlen, uchar *key,
ulong klen, uchar *digest, DS *state)
DS* poly1305(uchar *p, ulong len, uchar *key, ulong klen,
uchar *digest, DS *state)
DS* mac_blake2s_128(uchar *p, ulong len, uchar *key, ulong
klen, uchar *digest, DS *state)
DS* mac_blake2s_256(uchar *p, ulong len, uchar *key, ulong
klen, uchar *digest, DS *state)
DESCRIPTION
The output of a hash is called a digest. A hash is secure
if, given the hashed data and the digest, it is difficult to
predict the change to the digest resulting from some change
to the data without rehashing the whole data. Therefore, if
a secret is part of the hashed data, the digest can be used
as an integrity check of the data by anyone possessing the
secret.
The routines md4, md5, ripemd160, sha1, sha2_224, sha2_256,
sha2_384, sha2_512, sha3_224, sha3_256, sha3_384, sha3_512,
blake2s_128, blake2s_256, differ only in the length of the
resulting digest and in the security of the hash. Sha2_*
and hmac_sha2_* are the SHA-2 functions; the number after
the final underscore is the number of bits in the resulting
digest. Usage for each is the same. The first call to the
routine should have nil as the state parameter. This call
returns a state which can be used to chain subsequent calls.
The last call should have digest non-`nil'. Digest must
point to a buffer of at least the size of the digest pro-
duced. This last call will free the state and copy the
result into digest.
The constants MD4dlen, MD5dlen, RIPEMD160dlen, SHA1dlen,
SHA2_224dlen, SHA2_256dlen, SHA2_384dlen, SHA2_512dlen,
SHA3_224dlen, SHA3_256dlen, SHA3_384dlen, SHA3_512dlen,
BLAKE2S_128dlen, BLAKE2S_256dlen and Poly1305dlen define the
lengths of the digests.
Shake_128_in, shake_128_out, shake_128_conv, shake_256_in,
shake_256_out, and shake_256_conv are functions which
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SECHASH(2) SECHASH(2)
implement the SHAKE extensible output hashes. They provide
an incremental interface for both the input and output sides
of the hash. The shake_128_in and shake_256_in functions
provide the incremental input, mirroring the non extensible
hash functions. They will allocate a DigestState in a simi-
lar manner if their state argument is nil. An explicit con-
version step is required to allow for the input to be final-
ized and padded. The shake_128_conv and shake_256_conv per-
form that conversion, finalizing the DigestState supplied in
ds and storing the result in xs. The supplied DigestState
is freed if it was malloced via a previous call, and a newly
allocated XOFState is returned if the xs argument is nil.
The shake_128_out and shake_256_out functions take a XOFS-
tate and fill the supplied out buffer with olen bytes. A
final call with an output buffer of nil is used to free an
allocated XOFState. Shake_128, and shake_256 provide non
incremental interfaces, hashing the input and filling olen
bytes of digest.
Hmac_md5, hmac_sha1, hmac_sha2_224, hmac_sha2_256,
hmac_sha2_384, hmac_sha2_512, hmac_blake2s_256 and poly1305
are used slightly differently. These hash algorithms are
keyed and require a key to be specified on every call. The
digest lengths for these hashes are the obvious ones from
the above list of length constants. The hmac_* routines all
call hmac_x internally, but hmac_x is not intended for gen-
eral use.
Poly1305 is a one-time authenticator designed by D. J. Bern-
stein is documented in RFC8439. It takes a 32-byte one-time
key and a message and produces a 16-byte tag.
Mac_blake2s_128 and mac_blake2s_256 provide the keyed vari-
ants of their respective blake2s functions. Unlike their
hmac variants, the key may only be specified on the first
call. Subsequent calls are free to use the non keyed vari-
ants.
EXAMPLES
To hash a single buffer using md5:
uchar digest[MD5dlen];
md5(data, len, digest, nil);
To chain a number of buffers together, bounded on each end
by some secret:
char buf[256];
uchar digest[MD5dlen];
DigestState *s;
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SECHASH(2) SECHASH(2)
s = md5("my password", 11, nil, nil);
while((n = read(fd, buf, 256)) > 0)
md5(buf, n, nil, s);
md5("drowssap ym", 11, digest, s);
To give incremental input and take incremental output from
shake128:
uchar buf[256];
uchar output[1024];
DigestState *ds;
XOFState *xs;
for(ds = nil; (n = read(fd, buf, 256)) > 0;)
ds = shake_128_in(buf, n, ds);
xs = shake_128_conv(nil, ds);
shake_128_out(output, 512, xs);
shake_128_out(output + 512, 512, xs);
shake_128_out(nil, 0, xs);
SOURCE
/sys/src/libsec
SEE ALSO
blowfish(2), des(2), elgamal(2), rc4(2), rsa(2)
/lib/rfc/rfc2104 HMAC specification
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