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) 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) 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 produced. 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 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 similar manner if their state argument is nil. An explicit conversion step is required to allow for the input to be finalized and padded. The shake_128_conv and shake_256_conv perform 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 XOFState 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 general use. Poly1305 is a one–time authenticator designed by D. J. Bernstein 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 variants 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 variants.

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; 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