3 ms·

Great article! Love the focus on implementing. Fingers crossed he will explain PQ signatures like SPHINCS+ as a follow up.

by er4hn 3y ago

coppsilgold 3y ago
SPHINCS+ is an elaborate scheme building up on very simple blocks. It's all down to cryptographic hashes, there is no other security assumption involved. There is a good talk given out by a NIST guy that starts from the simplest one time hash signature construction and builds up to XMSS/SPHINCS: <https://www.youtube.com/watch?v=jiU0ICoiPI0 https://www.youtube.com/watch?v=jiU0ICoiPI0> TLDR; SPHINCS+ is a hypertree of Merkle trees where leafs of Merkle trees are used to sign Merkle roots of other Merkle trees. Leafs of the hypertree (final layer of Merkle trees) are used to sign messages. Paths through the hypertree need only be constructed on demand through the use of a PRF - computing paths through the hypertree requires computing entire Merkle trees. The private key is just a secret key to a PRF. A hypertree can be as big as you want it. Merkle roots are parts of the public key and public signatures and can only be determined through computation, if the Merkle tree is too big you will not compute the root in reasonable time.
- bluegate010 3y ago
  Another talk about LMS / SPHINCS+: https://www.youtube.com/watch?v=lZ1PnJml1CY https://www.youtube.com/watch?v=lZ1PnJml1CY
- loxias 3y ago
  > SPHINCS+ is a hypertree of Merkle trees where leafs of Merkle trees are used to sign Merkle roots of other Merkle trees. Leafs of the hypertree (final layer of Merkle trees) are used to sign messages. > Paths through the hypertree need only be constructed on demand through the use of a PRF - computing paths through the hypertree requires computing entire Merkle trees. The private key is just a secret key to a PRF. Wow, thank you so much. Such a perfect match between exactly what I didn't know described in terms I do. "Cool. Now I could write a high performant SPHINCS+ c++ impl, if i ever wanted to or thought it was cool" :D Edit: I love it when stuff like that happens, it's the reason I still bother to read the comments on this website. I/we've all got our own unique decades of experience and collection of earned wisdom, and sometimes substantial technological progress happens when the right people get the right "holes in understanding" filled at the right time.

Great article! Love the focus on implementing. Fingers crossed he will explain PQ signatures like SPHINCS+ as a follow up.

by er4hn 3y ago

Great article! Love the focus on implementing. Fingers crossed he will explain PQ signatures like SPHINCS+ as a follow up.

coppsilgold 3y ago

SPHINCS+ is an elaborate scheme building up on very simple blocks. It's all down to cryptographic hashes, there is no other security assumption involved. There is a good talk given out by a NIST guy that starts from the simplest one time hash signature construction and builds up to XMSS/SPHINCS: <https://www.youtube.com/watch?v=jiU0ICoiPI0 https://www.youtube.com/watch?v=jiU0ICoiPI0> TLDR; SPHINCS+ is a hypertree of Merkle trees where leafs of Merkle trees are used to sign Merkle roots of other Merkle trees. Leafs of the hypertree (final layer of Merkle trees) are used to sign messages. Paths through the hypertree need only be constructed on demand through the use of a PRF - computing paths through the hypertree requires computing entire Merkle trees. The private key is just a secret key to a PRF. A hypertree can be as big as you want it. Merkle roots are parts of the public key and public signatures and can only be determined through computation, if the Merkle tree is too big you will not compute the root in reasonable time.

bluegate010 3y ago
Another talk about LMS / SPHINCS+: https://www.youtube.com/watch?v=lZ1PnJml1CY https://www.youtube.com/watch?v=lZ1PnJml1CY
loxias 3y ago
> SPHINCS+ is a hypertree of Merkle trees where leafs of Merkle trees are used to sign Merkle roots of other Merkle trees. Leafs of the hypertree (final layer of Merkle trees) are used to sign messages. > Paths through the hypertree need only be constructed on demand through the use of a PRF - computing paths through the hypertree requires computing entire Merkle trees. The private key is just a secret key to a PRF. Wow, thank you so much. Such a perfect match between exactly what I didn't know described in terms I do. "Cool. Now I could write a high performant SPHINCS+ c++ impl, if i ever wanted to or thought it was cool" :D Edit: I love it when stuff like that happens, it's the reason I still bother to read the comments on this website. I/we've all got our own unique decades of experience and collection of earned wisdom, and sometimes substantial technological progress happens when the right people get the right "holes in understanding" filled at the right time.