commit 01503b01abb2d8c0a89d0207b51080a2303647dd
Author: finwo <finwo@pm.me>
Date: Wed, 7 Oct 2026 00:03:30 +0200
Project init, pseudocode idea
Diffstat:
| A | README.md | | | 87 | +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ |
1 file changed, 87 insertions(+), 0 deletions(-)
diff --git a/README.md b/README.md
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+sphincs+ inspired data signing library
+
+Rough idea:
+
+ 4 bits of the original hash per tree layer
+ original hash = tree path
+
+ pre-image input = <N-seed><layer><masked-org-hash>
+ pre-image source = shake256, get 32*32=1024 bytes
+
+ each layer = cat( h(pre-image[i], current[i]) )
+ pubkey of leaf = h(cat(h(pre-image[i], 256)))
+
+ next layer = sign(cat(pubkeys of all leafs)) // 16 leafs per layer -- 4 bits
+
+Pseudocode:
+
+```c
+
+char *seed = "supersecret";
+char *org = h(message);
+char *current = org;
+
+char ** pre_img( char *seed, int mask, char *org_hash ) {
+ char * pre_input = concat( seed, mask/4, cidr(org_hash, mask) );
+ char * pre_source = shake_init(pre_input);
+
+ char *output[32];
+ for(int i=0; i<32; i++) {
+ output[i] = hash(pre_source.shake(32));
+ }
+
+ return output;
+}
+
+char ** sign( char **pre_image, char *current_hash ) {
+ char *output[32];
+ for(int n=0; n<32; n++) {
+ output[i] = hash(pre_image[i], current_hash[i]);
+ }
+ return output;
+}
+
+char * pubkey_for( char **pre_image ) {
+ char *output[32] = calloc(1, 32*32);
+ memcpy(output, pre_image, 32*32);
+ for(int n=0; n<32; n++) {
+ for(int i=0; i<256; i++) {
+ output[n] = hash(output[n]);
+ }
+ }
+ return hash(concat(output));
+}
+
+// The full signing cycle
+char *org = hash(message);
+char *current = org;
+char *msg;
+
+for ( int mask=256; mask>=0; mask-=4 ) {
+
+ // Provide pre-image proof of current leaf
+ char **pre = pre_img( seed, mask, org );
+ char **proof = sign(pre, current);
+ append_preimage(out, proof);
+
+ // Provide neighbours if not root
+ if ( mask > 0 ) {
+ int self = bitbuffer_get_i4(current, mask-4);
+ char *base = cidr(current, mask-4);
+
+ msg = "";
+
+ for(int i=0 ; i<16; i++) {
+ bitbuffer_put_i4( org, mask-4, i);
+ char *pub_neighbour = pubkey_for(pre_img( seed, mask, org ))
+ append_pubkey(msg, pub_neighbour);
+ if (i == self) continue;
+ append_pubkey(out, pub_neighbour);
+ }
+
+ current = hash(msg);
+ }
+
+}
+```
+
