strongSwan

h1. Bimodal Lattice Signature Scheme (BLISS)

BLISS is a post-quantum signature scheme based on the CRYPTO 2013 paper "Lattice Signatures and Bimodal Gaussians":https://eprint.iacr.org/2013/383 by Léo Ducas, Alain Durmus, Tancrède Lepoint, and Vadim Lyubashevsky. Starting with the strongSwan [[5.2.2]] release we offer BLISS as an IKEv2 public key authentication method and added full BLISS key and certificate generation support to the strongSwan [[IpsecPki|pki]] tool.

h2. BLISS Private Key Generation

strongSwan currently supports the BLISS-I, BLISS-III, and BLISS-IV schemes with a cryptographic strength of 128 bits, 160 bits and 192 bits, respectively. Using the [[IpsecPki|pki]] tool a private BLISS key can be generated as follows:

<pre>

pki --gen --type bliss --size 1 --debug 2 > key1.der

mgf1 based on sha1 is seeded with 20 octets

mgf1 generated 240 octets

mgf1 based on sha1 is seeded with 20 octets

mgf1 generated 240 octets

l2 norm of s1||s2: 771, Nk(S): 47150 (46479 max)

mgf1 based on sha1 is seeded with 20 octets

mgf1 generated 220 octets

mgf1 based on sha1 is seeded with 20 octets

mgf1 generated 240 octets

l2 norm of s1||s2: 771, Nk(S): 43332 (46479 max)

secret key generation succeeded after 2 trials

</pre>

When generating the private key consisting of the two polynomials *s1* and *s2*, the _Nk(S)_ metric must be fulfilled. This means that often several trials are needed in order to obtain a valid BLISS private key.

With the command

<pre>

pki --print --type bliss-priv --in key1.der

private key with:

pubkey:    BLISS 128 bits strength

keyid:     d1:a3:fb:04:8d:1b:86:4f:fa:a7:d8:45:ec:e3:e3:ec:ef:7b:85:ca

subjkey:   e3:fc:6b:59:9a:ee:81:d5:10:3a:58:9f:e2:99:f7:7f:5c:3b:1c:96

</pre>

information on the BLISS private key is displayed.

Let's now generate a BLISS-IV key with 192 bit cryptographic strength in base64-encoded PEM format

<pre>

pki --gen --type bliss --size 4 --outform pem  > key4.pem

secret key generation succeeded after 4 trials

</pre>

The PEM key format is printable

<pre>

 cat key4.pem

-----BEGIN BLISS PRIVATE KEY-----

MIIFGgYLKwYBBAGCoCoFAgQDggOBACUkEElEU1wx3rTZLRp7ejCQl7beNwsiFfMs

WWtH2EbLR1KxExmkc07Wp6GwEgQQVh5iHQaq0cX8aRSWUpne27elaBgfnv2lKIIY

YRBechxMh7YGYVQl/8se1EeCZqqZiR7hEHyYCFogDiCM7aW8RTw0ZtbJBK37UkTR

ZDoNjk9kyYEhZdoEsjGo0h5DBFLcxExk6Git+9e8xsJL4rdjLImGezgBOczbhTow

migPmqQx4bi441BAIC65oIoSdQwdMmLnaHi6CAT314jGS8UG6hcTL6qO5iaoaKFA

AVSX9EPRCtIxVq/IgqBKybK+bO9LWqQ1Pcn5u2KitXioNYg10YPcko0XNitUik/v

VSQPW1EJ6ZJ9v/bTZZFi7QjTtKq8GoIld0Vhh1TFnfEOblOCSsi7B+TxJHAf5BkR

ia1oxEN8iDA9xNL2ohzUJurdO/wCsCAstVC9HOKooqAR7EiFP7CEQwxXpxuw8Kv9

2/0L8jy4Sq0thxlrSbtSdZGq1/gNYLqNII7oZJH0HfhpC6oMnq0t6GILZIME3Pti

9Kj9WMxZMCxOTC6Fl5IvzsCV1vHgNoB4MgUaJy6MUJyU+LdAhYmjso9rNdBah0Ku

drJh1o1uS7ERUohYkJtlzky9XuS2pjwTELxpAsrPz6VM6ZXiZAZCuqF00crUoy2K

yjiOpS5/4nKKEYyGez3QepLjTYzMapC7TXw7sD80H0S8BuSW+HJMFy4BWMXP5bps

Chw7tFsWMa5i1oiXPUDoYlW740Zj5YwIY6e2oeBiEceU/5TkNXcbBJ4gojaKxwdz

oOExefSthX91OcHhq2W0GSyZ9I+aUngseEdcYjKk2IL76kxWrdwoM95feDGY925r

sRV0tpqiSKh04K1gV0wSRzT7w82lVwPwQlY9Hw1nVfVU99bzujoHSfiEFVUURFlQ

jWAMBq32hwdfeghOEkLBLQYqRjWOyWSi7I1GWMJ/P7CaBiKiM096NCJiYJyUuj6l

yM0gJJ0iiNNSF6oqQIQcwFOP9HTQk9DNE3AplGqrJptROtN8lvFlpnhQt6YQBHQX

qAUCx47EsrN8W+m+XQKrdMOKhz3JxB+tcJOoQSsoZ1AT9eUaM5VxLoRGY3GMmG3e

J3SETcNggvZlP25VgapsCInEWbnAJmPQ7ydTov8yF0EQdiiZYUQlHXvktTPpHgFP

Vcc6A9TFA4HBAAQOAeOAdsAACDxyADyADyPwAOAR+CSuBxzweASQCBwRwQgCBxx+

QAQSAMAAeDwQAfyOTiST+AASOODuBx/wACQiOAASQeOACQB/9yAgOASDjyDwCQfw

N+AeOAOOACPwQBwsAPwPzwMcCCCQADwSACCBx+DwQAPwASABwOOgBvwQCQDwPwAQ

SBwFwOESSAef+QCT+ACPwAAeRyBsfwAAQAABgPwUAQOehweRwN+eNwDx/yDiOFyQ

AOOABwEQAOBwAQOBwQDngAH9DAcg/hHoAlAE8AAfckfrgYkccA/IgAcEgY/gEIfk

cHgEEEHjkgcfkjgDgYfj4AEAAAkAAgFcf8Dj/hEggADEBADjjjAgnjADogDj8/8f

kjgAcAAAAEAcAA/gf/gg8cAALjkAcAEEgEYjk8AEDgcj8EAH/kEEcA7ggAADkcA8

AEkAkgAk/AAAEngEAgAAD8HkA8kEAjgA8A8YFcjoAAgD//jA8c/8cf/j8cAngAAc

AHgHgkBE/nj8kcDgIAE=

-----END BLISS PRIVATE KEY-----

</pre>