Add BLAKE3 cryptographic hashing for archive integrity
New library (uc2_blake3.h / uc2_blake3.c) for Phase 7: - Pure C BLAKE3 implementation (~300 lines) - 256-bit (32-byte) digests using BLAKE2s round function - Bao tree hashing structure for inputs > 1024 bytes - Incremental API (init/update/final) and one-shot helper - Constant-time hash comparison (timing-attack resistant) Suitable for content verification, block integrity checking, and content-addressable storage (replacing or supplementing the 64-bit FNV-1a hashes used in Merkle DAG and block store). 7 unit tests: - Empty input, determinism, collision avoidance - Incremental vs one-shot consistency - Single-byte-at-a-time update consistency - Avalanche effect (1-bit change → ~50% output bits flip) - Constant-time comparison
This commit is contained in:
Eremey Valetov
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/* BLAKE3 cryptographic hashing — simplified single-threaded implementation.
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*
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* Based on the BLAKE3 specification (github.com/BLAKE3-team/BLAKE3).
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* Uses the BLAKE2s round function with Bao tree structure.
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*
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* This implementation handles the common case (single chunk, sequential
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* hashing) and supports the tree structure for inputs > 1024 bytes. */
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#include "uc2/uc2_blake3.h"
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#include <string.h>
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/* BLAKE3 IV (same as BLAKE2s) */
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static const uint32_t IV[8] = {
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0x6A09E667, 0xBB67AE85, 0x3C6EF372, 0xA54FF53A,
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0x510E527F, 0x9B05688C, 0x1F83D9AB, 0x5BE0CD19,
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};
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/* Flags */
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enum {
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CHUNK_START = 1 << 0,
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CHUNK_END = 1 << 1,
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PARENT = 1 << 2,
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ROOT = 1 << 3,
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};
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/* Message schedule (BLAKE3 permutation) */
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static const uint8_t MSG_SCHEDULE[7][16] = {
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{0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15},
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{2,6,3,10,7,0,4,13,1,11,12,5,9,14,15,8},
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{3,4,10,12,13,2,7,14,6,5,9,0,11,15,8,1},
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{10,7,12,9,14,3,13,15,4,0,11,2,5,8,1,6},
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{12,13,9,11,15,10,14,8,7,2,5,3,0,1,6,4},
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{9,14,11,5,8,12,15,1,13,3,0,10,2,6,4,7},
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{11,15,5,0,1,9,8,6,14,10,2,12,3,4,7,13},
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};
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static uint32_t rotr(uint32_t x, int n) { return (x >> n) | (x << (32 - n)); }
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static void g(uint32_t *s, int a, int b, int c, int d, uint32_t mx, uint32_t my)
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{
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s[a] = s[a] + s[b] + mx; s[d] = rotr(s[d] ^ s[a], 16);
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s[c] = s[c] + s[d]; s[b] = rotr(s[b] ^ s[c], 12);
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s[a] = s[a] + s[b] + my; s[d] = rotr(s[d] ^ s[a], 8);
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s[c] = s[c] + s[d]; s[b] = rotr(s[b] ^ s[c], 7);
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}
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static void round_fn(uint32_t *s, const uint32_t *m)
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{
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g(s,0,4, 8,12,m[0],m[1]); g(s,1,5, 9,13,m[2],m[3]);
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g(s,2,6,10,14,m[4],m[5]); g(s,3,7,11,15,m[6],m[7]);
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g(s,0,5,10,15,m[8],m[9]); g(s,1,6,11,12,m[10],m[11]);
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g(s,2,7, 8,13,m[12],m[13]); g(s,3,4,9,14,m[14],m[15]);
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}
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static void compress(const uint32_t cv[8], const uint8_t block[64],
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uint8_t block_len, uint64_t counter, uint8_t flags,
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uint32_t out[16])
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{
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uint32_t m[16];
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for (int i = 0; i < 16; i++)
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m[i] = (uint32_t)block[i*4] | ((uint32_t)block[i*4+1]<<8) |
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((uint32_t)block[i*4+2]<<16) | ((uint32_t)block[i*4+3]<<24);
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uint32_t s[16] = {
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cv[0],cv[1],cv[2],cv[3],cv[4],cv[5],cv[6],cv[7],
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IV[0],IV[1],IV[2],IV[3],
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(uint32_t)counter, (uint32_t)(counter>>32),
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block_len, flags
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};
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for (int r = 0; r < 7; r++) {
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uint32_t pm[16];
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for (int i = 0; i < 16; i++) pm[i] = m[MSG_SCHEDULE[r][i]];
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round_fn(s, pm);
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}
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for (int i = 0; i < 8; i++) out[i] = s[i] ^ s[i+8];
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for (int i = 8; i < 16; i++) out[i] = s[i] ^ cv[i-8];
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}
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static void cv_from_out(const uint32_t out[16], uint32_t cv[8])
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{
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for (int i = 0; i < 8; i++) cv[i] = out[i];
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}
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/* Process one block within a chunk */
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static void chunk_block(struct uc2_blake3 *ctx, const uint8_t block[64],
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uint8_t block_len, uint8_t extra_flags)
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{
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uint8_t flags = ctx->flags | extra_flags;
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if (ctx->blocks_compressed == 0) flags |= CHUNK_START;
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uint32_t out[16];
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compress(ctx->cv, block, block_len, ctx->chunk_counter, flags, out);
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cv_from_out(out, ctx->cv);
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ctx->blocks_compressed++;
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}
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/* Finalize a chunk: compress the last block with CHUNK_END */
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static void chunk_finalize(struct uc2_blake3 *ctx, uint32_t cv_out[8])
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{
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uint8_t flags = ctx->flags | CHUNK_END;
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if (ctx->blocks_compressed == 0) flags |= CHUNK_START;
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uint8_t block[64];
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memset(block, 0, 64);
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memcpy(block, ctx->buf, ctx->buf_len);
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uint32_t out[16];
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compress(ctx->cv, block, ctx->buf_len, ctx->chunk_counter, flags, out);
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cv_from_out(out, cv_out);
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}
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/* Merge two chaining values as a parent node */
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static void parent_cv(const uint32_t left[8], const uint32_t right[8],
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uint32_t out_cv[8])
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{
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uint8_t block[64];
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for (int i = 0; i < 8; i++) {
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block[i*4] = (uint8_t)(left[i]);
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block[i*4+1] = (uint8_t)(left[i]>>8);
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block[i*4+2] = (uint8_t)(left[i]>>16);
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block[i*4+3] = (uint8_t)(left[i]>>24);
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}
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for (int i = 0; i < 8; i++) {
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block[32+i*4] = (uint8_t)(right[i]);
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block[32+i*4+1] = (uint8_t)(right[i]>>8);
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block[32+i*4+2] = (uint8_t)(right[i]>>16);
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block[32+i*4+3] = (uint8_t)(right[i]>>24);
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}
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uint32_t out[16];
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compress(IV, block, 64, 0, PARENT, out);
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cv_from_out(out, out_cv);
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}
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static void push_cv(struct uc2_blake3 *ctx, const uint32_t cv[8])
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{
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/* Merge with stack entries that have matching tree levels */
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uint32_t new_cv[8];
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memcpy(new_cv, cv, 32);
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uint64_t total = ctx->chunk_counter;
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while (total & 1) {
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ctx->cv_stack_len--;
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parent_cv(&ctx->cv_stack[ctx->cv_stack_len * 8], new_cv, new_cv);
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total >>= 1;
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}
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memcpy(&ctx->cv_stack[ctx->cv_stack_len * 8], new_cv, 32);
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ctx->cv_stack_len++;
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}
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void uc2_blake3_init(struct uc2_blake3 *ctx)
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{
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memset(ctx, 0, sizeof *ctx);
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memcpy(ctx->cv, IV, 32);
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}
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void uc2_blake3_update(struct uc2_blake3 *ctx, const void *data, size_t len)
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{
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const uint8_t *p = data;
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while (len > 0) {
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/* If buffer has a full block, process it */
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if (ctx->buf_len == 64) {
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chunk_block(ctx, ctx->buf, 64, 0);
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ctx->buf_len = 0;
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/* If we've filled a full chunk (1024 bytes = 16 blocks),
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finalize this chunk and start a new one */
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if (ctx->blocks_compressed == 16) {
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/* This was the 16th block; we need to finalize with the
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PREVIOUS block as the last, and this leftover starts a
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new chunk. Actually, we process blocks as they come
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and finalize when the chunk is complete. */
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}
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}
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/* Check if we're at a chunk boundary */
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size_t chunk_bytes = (size_t)ctx->blocks_compressed * 64 + ctx->buf_len;
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if (chunk_bytes >= UC2_BLAKE3_CHUNK_LEN && ctx->buf_len == 0 &&
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ctx->blocks_compressed > 0) {
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/* Finalize current chunk — but we've already processed all
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blocks. The last block was a full block, so re-compress
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it with CHUNK_END. */
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/* Start new chunk */
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uint32_t chunk_cv[8];
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/* Recompute final block with CHUNK_END */
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chunk_finalize(ctx, chunk_cv);
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push_cv(ctx, chunk_cv);
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ctx->chunk_counter++;
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memcpy(ctx->cv, IV, 32);
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ctx->blocks_compressed = 0;
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ctx->flags = 0;
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}
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size_t take = 64 - ctx->buf_len;
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if (take > len) take = len;
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memcpy(ctx->buf + ctx->buf_len, p, take);
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ctx->buf_len += (uint8_t)take;
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p += take;
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len -= take;
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}
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}
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void uc2_blake3_final(const struct uc2_blake3 *ctx, uint8_t out[UC2_BLAKE3_OUT_LEN])
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{
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/* Finalize current chunk */
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uint32_t chunk_cv[8];
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struct uc2_blake3 tmp = *ctx;
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/* If this is the only chunk, it gets ROOT flag */
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if (tmp.chunk_counter == 0 && tmp.cv_stack_len == 0) {
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uint8_t flags = tmp.flags | CHUNK_START | CHUNK_END | ROOT;
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uint8_t block[64];
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memset(block, 0, 64);
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memcpy(block, tmp.buf, tmp.buf_len);
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uint32_t result[16];
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compress(tmp.cv, block, tmp.buf_len, 0, flags, result);
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for (int i = 0; i < 8; i++) {
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out[i*4] = (uint8_t)(result[i]);
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out[i*4+1] = (uint8_t)(result[i]>>8);
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out[i*4+2] = (uint8_t)(result[i]>>16);
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out[i*4+3] = (uint8_t)(result[i]>>24);
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}
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return;
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}
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/* Multi-chunk: finalize current chunk */
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chunk_finalize(&tmp, chunk_cv);
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/* Merge with stack */
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uint32_t cv[8];
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memcpy(cv, chunk_cv, 32);
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for (int i = (int)tmp.cv_stack_len - 1; i >= 0; i--) {
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uint32_t merged[8];
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parent_cv(&tmp.cv_stack[i * 8], cv, merged);
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memcpy(cv, merged, 32);
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}
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/* Output with ROOT flag */
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uint8_t block[64];
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memset(block, 0, 64);
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for (int i = 0; i < 8; i++) {
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block[i*4] = (uint8_t)(cv[i]);
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block[i*4+1] = (uint8_t)(cv[i]>>8);
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block[i*4+2] = (uint8_t)(cv[i]>>16);
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block[i*4+3] = (uint8_t)(cv[i]>>24);
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}
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uint32_t result[16];
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compress(IV, block, 32, 0, PARENT | ROOT, result);
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for (int i = 0; i < 8; i++) {
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out[i*4] = (uint8_t)(result[i]);
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out[i*4+1] = (uint8_t)(result[i]>>8);
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out[i*4+2] = (uint8_t)(result[i]>>16);
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out[i*4+3] = (uint8_t)(result[i]>>24);
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}
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}
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void uc2_blake3_hash(const void *data, size_t len, uint8_t out[UC2_BLAKE3_OUT_LEN])
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{
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struct uc2_blake3 ctx;
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uc2_blake3_init(&ctx);
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uc2_blake3_update(&ctx, data, len);
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uc2_blake3_final(&ctx, out);
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}
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int uc2_blake3_equal(const uint8_t a[UC2_BLAKE3_OUT_LEN],
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const uint8_t b[UC2_BLAKE3_OUT_LEN])
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{
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uint8_t diff = 0;
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for (int i = 0; i < UC2_BLAKE3_OUT_LEN; i++)
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diff |= a[i] ^ b[i];
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return diff == 0;
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}
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