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c11730490a
function old new delta hmac_blocks - 88 +88 static.PBKDF2_SHA256 176 213 +37 yescrypt_kdf32_body 1046 1052 +6 static.smix 759 762 +3 hmac_block 88 64 -24 HMAC_SHA256_Final 53 - -53 HMAC_SHA256_Buf 58 - -58 HMAC_SHA256_Init 159 - -159 ------------------------------------------------------------------------------ (add/remove: 1/3 grow/shrink: 3/1 up/down: 134/-294) Total: -160 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
107 lines
3.2 KiB
C
107 lines
3.2 KiB
C
/*
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* Copyright (C) 2025 Denys Vlasenko
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*
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* Licensed under GPLv2, see file LICENSE in this source tree.
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*/
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//kbuild:lib-$(CONFIG_TLS) += hash_hmac.o
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//kbuild:lib-$(CONFIG_USE_BB_CRYPT_YES) += hash_hmac.o
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#include "libbb.h"
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// RFC 2104:
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// HMAC(key, text) based on a hash H (say, sha256) is:
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// ipad = [0x36 x INSIZE]
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// opad = [0x5c x INSIZE]
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// HMAC(key, text) = H((key XOR opad) + H((key XOR ipad) + text))
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//
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// H(key XOR opad) and H(key XOR ipad) can be precomputed
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// if we often need HMAC hmac with the same key.
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//
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// text is often given in disjoint pieces.
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void FAST_FUNC hmac_begin(hmac_ctx_t *ctx, const uint8_t *key, unsigned key_size, md5sha_begin_func *begin)
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{
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#if HMAC_ONLY_SHA256
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#define begin sha256_begin
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#endif
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uint8_t key_xor_ipad[SHA2_INSIZE];
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uint8_t key_xor_opad[SHA2_INSIZE];
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unsigned i;
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// "The authentication key can be of any length up to INSIZE, the
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// block length of the hash function. Applications that use keys longer
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// than INSIZE bytes will first hash the key using H and then use the
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// resultant OUTSIZE byte string as the actual key to HMAC."
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if (key_size > SHA2_INSIZE) {
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uint8_t tempkey[SHA1_OUTSIZE < SHA256_OUTSIZE ? SHA256_OUTSIZE : SHA1_OUTSIZE];
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/* use ctx->hashed_key_xor_ipad as scratch ctx */
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begin(&ctx->hashed_key_xor_ipad);
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md5sha_hash(&ctx->hashed_key_xor_ipad, key, key_size);
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key_size = sha_end(&ctx->hashed_key_xor_ipad, tempkey);
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key = tempkey;
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}
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for (i = 0; i < key_size; i++) {
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key_xor_ipad[i] = key[i] ^ 0x36;
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key_xor_opad[i] = key[i] ^ 0x5c;
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}
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for (; i < SHA2_INSIZE; i++) {
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key_xor_ipad[i] = 0x36;
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key_xor_opad[i] = 0x5c;
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}
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begin(&ctx->hashed_key_xor_ipad);
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begin(&ctx->hashed_key_xor_opad);
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md5sha_hash(&ctx->hashed_key_xor_ipad, key_xor_ipad, SHA2_INSIZE);
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md5sha_hash(&ctx->hashed_key_xor_opad, key_xor_opad, SHA2_INSIZE);
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}
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#undef begin
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unsigned FAST_FUNC hmac_end(hmac_ctx_t *ctx, uint8_t *out)
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{
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unsigned len = sha_end(&ctx->hashed_key_xor_ipad, out);
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/* out = H((key XOR opad) + out) */
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md5sha_hash(&ctx->hashed_key_xor_opad, out, len);
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return sha_end(&ctx->hashed_key_xor_opad, out);
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}
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unsigned FAST_FUNC hmac_block(const uint8_t *key, unsigned key_size, md5sha_begin_func *begin, const void *in, unsigned sz, uint8_t *out)
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{
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hmac_ctx_t ctx;
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hmac_begin(&ctx, key, key_size, begin);
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hmac_hash(&ctx, in, sz);
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return hmac_end(&ctx, out);
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}
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/* TLS helpers */
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void FAST_FUNC hmac_hash_v(
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hmac_ctx_t *ctx,
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va_list va)
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{
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uint8_t *in;
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/* ctx->hashed_key_xor_ipad contains unclosed "H((key XOR ipad) +" state */
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/* ctx->hashed_key_xor_opad contains unclosed "H((key XOR opad) +" state */
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/* calculate out = H((key XOR ipad) + text) */
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while ((in = va_arg(va, uint8_t*)) != NULL) {
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unsigned size = va_arg(va, unsigned);
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md5sha_hash(&ctx->hashed_key_xor_ipad, in, size);
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}
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}
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/* Using HMAC state, make a copy of it (IOW: without affecting this state!)
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* hash in the list of (ptr,size) blocks, and finish the HMAC to out[] buffer.
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* This function is useful for TLS PRF.
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*/
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unsigned FAST_FUNC hmac_peek_hash(hmac_ctx_t *ctx, uint8_t *out, ...)
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{
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hmac_ctx_t tmpctx = *ctx; /* struct copy */
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va_list va;
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va_start(va, out);
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hmac_hash_v(&tmpctx, va);
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va_end(va);
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return hmac_end(&tmpctx, out);
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}
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