``` SECHASH(2) SECHASH(2) NAME md4, md5, ripemd160, sha1, sha2_224, sha2_256, sha2_384, sha2_512, 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 #include #include #include #define DS DigestState /* 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(uchar *data, ulong dlen, uchar *digest, ulong olen, DS *state) DS* shake_256(uchar *data, ulong dlen, uchar *digest, ulong olen, DS *state) 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 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 and shake_256 are extensible output functions that use the SHA3 keccak block. For these functions the olen argument specifies how many bytes to write out to the dig- est. 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; 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); SOURCE /sys/src/libsec SEE ALSO blowfish(2), des(2), elgamal(2), rc4(2), rsa(2) /lib/rfc/rfc2104 HMAC specification ```