RFC 9941

Secure Shell (SSH) Key Exchange Method Using Hybrid Streamlined NTRU Prime sntrup761 and X25519 with SHA-512: sntrup761x25519-sha512

📅 published April 2026, from ietf

Secure Shell (SSH) Key Exchange Method Using Hybrid Streamlined NTRU Prime sntrup761 and X25519 with SHA-512: sntrup761x25519-sha512 💖

Okay bestie, here's the title block rundown 🎀:

  • RFC number: 9941
  • Authors: M. Friedl (OpenSSH), J. Mojzis (TinySSH), S. Josefsson
  • Category: Informational 🌸
  • ISSN: 2070-1721
  • Date: April 2026
  • Obsoletes / Updates: this title block doesn't list any, so nothing is obsoleted or updated 🧚

Abstract ✨

So the TL;DR is that this doc describes a hybrid key exchange method for SSH, the secure remote login protocol, which mixes Streamlined NTRU Prime sntrup761 with X25519 and SHA-512. It's already widely deployed, which is so real 🔥.

Status of This Memo 📜

Quick vibe check: this is not an Internet Standards Track spec. It's published for informational purposes 💅.

It's still an IETF product 🦋 and it reflects the consensus of the IETF community. It went through public review and was approved for publication by the Internet Engineering Steering Group (IESG). Not every IESG-approved doc is a candidate for any level of Internet Standard, so check Section 2 of RFC 7841 if you want the deets 🙈.

For the current status, any errata, and how to send feedback, go to https://www.rfc-editor.org/info/rfc9941 🍓.

Copyright (c) 2026 IETF Trust and the persons identified as the document authors. All rights reserved 🌈.

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) as they're in effect on the date of publication. Please read these carefully, because they spell out your rights and restrictions for this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions, and they're provided without warranty as described in the Revised BSD License 💜.

Table of Contents 🗂️

1.  Introduction
2.  Requirements Language
3.  Key Exchange Method: sntrup761x25519-sha512
4.  Security Considerations
5.  IANA Considerations
6.  References
  6.1.  Normative References
  6.2.  Informative References
Appendix A.  Test Vectors
Acknowledgements
Authors' Addresses

1. Introduction ✨

Okay so Secure Shell (SSH) [RFC4251] is a secure remote login protocol, the one everyone trusts 🔐. The key exchange protocol in [RFC4253] supports an extensible set of methods, which is so iconic of it 👑. [RFC5656] defines how elliptic curves plug into that extensible SSH framework, and [RFC8731] adds curve25519-sha256 to support the pre-quantum Elliptic Curve Diffie-Hellman (ECDH) X25519 function [RFC7748] 🦋.

Streamlined NTRU Prime [NTRUPrimePQCS] [NTRUPrime] [NTRUPrimeWeb] gives you post-quantum small lattice-based key-encapsulation mechanisms 🧚. The sntrup761 instance has been implemented widely, so it's not some obscure thing 💅.

This document specifies a hybrid construction that uses both sntrup761 and X25519. The intention is that the hybrid stays secure if either algorithm is secure 🫶.

This document also describes how to implement key exchange based on a hybrid of Streamlined NTRU Prime sntrup761 and X25519 with SHA-512 [RFC6234] in SSH 🎀.

This document was derived from SSH KEX Using Curve25519 and Curve448 [RFC8731] 🍓.

2. Requirements Language 📏

Here's the key words bit. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here 💖.

3. Key Exchange Method: sntrup761x25519-sha512 🔥

The key agreement is done by the X25519 Diffie-Hellman protocol as described in Section 3 ("Key Exchange Methods") of [RFC8731], and by the key encapsulation method described in [NTRUPrimePQCS] 🌸.

The key exchange procedure reuses the ECDH key exchange defined in Sections 4 ("ECDH Key Exchange") and 7.1 ("ECDH Message Numbers") of [RFC5656] ✨.

The protocol flow and the SSH_MSG_KEX_ECDH_INIT and SSH_MSG_KEX_ECDH_REPLY messages are identical, except that we use different ephemeral public values Q_C and Q_S and shared secret K, as described below 🧚.

Implementations MAY use the name SSH_MSG_KEX_HYBRID_INIT where SSH_MSG_KEX_ECDH_INIT is used, and the name SSH_MSG_KEX_HYBRID_REPLY where SSH_MSG_KEX_ECDH_REPLY is used, as long as the encoding on the wire is identical. These symbolic names don't show up on the wire. They're just used in specs to refer to particular byte values. For consistency with [RFC5656], which defines the packet syntax, we use those names in the rest of this document 💅.

The SSH_MSG_KEX_ECDH_INIT value Q_C, which holds the client's ephemeral public key, MUST be built by concatenating the 1158-byte public key output from the sntrup761 key generator with the 32-byte K_A = X25519(a, 9), as described in [NTRUPrimePQCS] and [RFC8731]. So Q_C ends up being 1190 bytes 🎀.

The SSH_MSG_KEX_ECDH_REPLY value Q_S, which holds the server's ephemeral public key, MUST be built by concatenating the 1039-byte ciphertext output from the sntrup761 key encapsulation mechanism with the 32-byte K_B = X25519(b, 9), as described in [NTRUPrimePQCS] and [RFC8731]. So Q_S ends up being 1071 bytes 🌈.

Clients and servers MUST abort if the length of the received public keys Q_C or Q_S is not the expected length. An abort here is defined as a disconnect (SSH_MSG_DISCONNECT) of the session, and it SHOULD use the SSH_DISCONNECT_KEY_EXCHANGE_FAILED reason for the message. See Section 11.1 ("Disconnection Message") of [RFC4253]. No further validation is required beyond what's described in [RFC7748], [RFC8731], and [NTRUPrimePQCS] 🚨.

The SSH_MSG_KEX_ECDH_REPLY signature value is computed as described in ECC for SSH [RFC5656], with the following changes. Instead of encoding the shared secret K as "mpint", it MUST be encoded as "string". The shared secret K value MUST be the 64-byte octet string output of the SHA-512 hash, computed over the 32-byte octet string key output from the sntrup761 key encapsulation mechanism concatenated with the 32-byte octet string of X25519(a, X25519(b, 9)) = X25519(b, X25519(a, 9)) 🔐.

Some earlier implementations may only implement this protocol through the name sntrup761x25519-sha512@openssh.com. Because of that, it is RECOMMENDED to announce and accept that name as an alias of this protocol, to increase the chances of successfully negotiating the protocol 🫶💜.

6.2. Informative References ✨

okay so these are the informative ones, meaning the stuff that's good to know about but isn't required reading to build the thing 💅

Appendix A. Test Vectors 🧪

okay this is the part where we get to see the real bytes 🤓 these are test vectors, so you can check your own implementation against known-good values. the labels go right above each dump, and the hex is the actual data, so it's giving precision 💖

Starting with the first message, SSH2_MSG_KEX_ECDH_INIT 🌸:

SSH2_MSG_KEX_ECDH_INIT

client public key sntrup761:
0000: 5d b3 a9 d3 93 30 31 76 0e 8a f5 87 f7 b2 8c 4f
0016: 97 a1 74 0e 6b 6f cf 1a d9 d9 99 8a 32 a5 61 e5
0032: 9e 4d 93 67 e2 66 18 f0 0a f5 54 f4 48 65 0c 60
0048: d1 12 92 c2 aa a9 e4 7c ea 32 a3 f5 86 cb c4 c3
0064: d5 c2 6f 34 5e 7f d3 57 51 d3 e3 d9 cc 1c e4 49
0080: bb ea 3e 2e 58 5e ac ba 0a b8 22 00 7c 77 a4 e0
0096: bd 16 5c 3a f7 b3 25 08 c1 81 fd 0d 9f 99 a3 be
0112: ae e3 38 84 13 ff f0 b4 0f cb ab 76 1e 95 3e 1e
0128: 7c 74 1e 58 46 f6 81 f0 f2 f2 56 5b f3 be ce c9
0144: c8 99 9f 03 88 81 db 17 75 1d fb f5 b1 e2 f3 5d
0160: 32 ce 19 75 49 e7 e1 17 bf 35 0d 97 7c ac 0a cf
0176: 6c 8a 0f fc 07 4b a7 8b c5 93 f7 47 7c b6 d5 bf
0192: 02 f0 96 80 e8 dc f3 87 c9 f0 b2 91 e7 37 70 82
0208: 3e 47 b7 18 72 be 5a da b1 85 d3 6e 56 5d 8a a3
0224: 62 fa 3e d0 ea 6e b9 fa 69 ec 96 86 94 81 2e 88
0240: 2b ba e5 af 70 1e ae ba 5f cb ea 82 e5 ba 67 0e
0256: 4d f6 2a ec 13 a9 19 b4 08 9c b7 32 bb 40 de c3
0272: e9 33 e1 c4 0d 5b 72 00 06 c4 3b 7f 57 d4 85 76
0288: 4c 4c 3d ab 8e 1b 00 00 ac d9 8c 05 b3 18 24 85
0304: 77 28 74 71 0d 68 8b 02 2c 59 55 a7 4d a4 6e 37
0320: 85 6c 77 68 f5 b7 a7 52 61 af 37 b4 09 07 34 68
0336: b6 83 ca f2 03 25 47 f9 09 e6 da bd 82 07 7e d1
0352: 78 16 74 1a a5 4c 5b ac 78 d8 0f 1a 44 08 44 a7
0368: ef 85 00 43 19 c3 3e b4 54 e6 3f f1 ac 83 03 ce
0384: 7c bd ef 3c fd eb 47 6f f7 f9 e0 1f 13 9f cb 77
0400: 52 40 9d 3a d7 8b ad bf cc f1 06 ec 93 32 48 be
0416: 0a 53 99 5c dd 9e 96 3b 84 21 8f b2 b4 fd b8 97
0432: 8b 7a 8f 71 aa e6 af 4e 22 53 18 f0 a2 30 a0 53
0448: 30 c9 d8 a9 d7 67 08 a5 ad 81 64 7b 3a 02 ae ff
0464: e7 fa 41 68 d0 54 e3 42 86 da f7 f0 98 31 38 e5
0480: 8c fa 86 5c 5c f9 82 f8 a2 09 91 91 96 72 12 e5
0496: 8f 8b 8e 9b e8 5d bd 66 4b 6e ec a3 b3 03 c5 4e
0512: 0f 7e a5 15 ef ab 01 8c 6d 02 52 77 bc 9a 02 f2
0528: 2e bf 03 40 fe 5a 80 5a c0 78 1e 95 21 10 9d dd
0544: 37 87 00 ae 13 c5 9d 9c 81 87 37 3e 7d e0 40 bc
0560: 83 76 69 4f 9f c4 08 fd aa a1 7e aa 88 0e 4c 56
0576: a0 47 c5 d6 94 fb 52 67 f3 36 de b2 7e bf d1 33
0592: 41 fd 05 20 66 60 f4 91 96 5f 19 33 2d 17 ec e0
0608: 3e 93 7a 66 3b b0 de f4 ad 51 90 a4 a1 94 f3 37
0624: 9a 77 11 02 67 45 6d 4d 19 80 33 58 56 2c b8 11
0640: 51 7b bc ec 43 fe 3d 96 ac f7 f0 8b 8d c6 2c 02
0656: 2f c0 67 21 56 49 ee bf 07 17 48 f9 30 0b 18 2c
0672: fa 7b 57 93 be f7 12 99 57 be 98 e7 55 84 da ed
0688: 5c 94 71 fa 48 0f ed 97 ab e4 a5 d6 b6 26 3a e4
0704: cb fe f9 ed 07 4b 42 bf e5 a1 d1 34 4d 7b 67 b9
0720: b7 06 7b d2 c7 ae 57 15 21 58 55 70 70 93 f1 87
0736: 31 bf 85 74 fe 36 0d 08 c8 07 a2 14 fc d5 96 8b
0752: 59 62 97 30 43 75 c2 a9 4f ec f9 e9 33 a9 38 cb
0768: ae ee 63 34 8c 65 54 e7 9d d4 23 a2 4f b9 00 ed
0784: b4 be 0b 1c df d4 97 c0 89 ab dd 5f 75 13 ce 37
0800: f3 d2 26 55 72 39 61 f0 d2 11 e8 e7 5f 93 5b 79
0816: e5 6c 28 f3 0a f9 5e 99 b8 a0 e6 4a 22 88 e5 28
0832: 82 0c 6f 72 1d dd 80 84 57 04 72 f4 26 56 71 f3
0848: 92 23 ff 9e a9 fd 05 0b 51 99 72 32 98 a5 02 87
0864: fe bb 99 18 5a b3 ec ab f9 26 7b 97 79 da 5f 19
0880: 4e e7 7d a5 2d 53 40 2a 1f 1b 62 df 3b 11 82 e6
0896: 90 7f 0f 56 0c 75 14 03 e7 6f aa f0 0e 0a 17 13
0912: 54 f5 ea d7 21 31 2c 7a c5 7f a3 ae 14 f3 05 42
0928: e9 c9 6c 6d d1 0a cb 19 35 7f 01 8a 8c e2 a1 09
0944: b5 c6 e5 e8 2b 4f 1e a2 e9 ce 5b e4 76 f7 53 4f
0960: 52 d4 75 22 4b aa 1e cd 42 0e be d7 dc 76 6f 94
0976: 0a 37 47 ca 44 bd e6 9e c1 2a 0d 57 f3 c2 47 40
0992: 23 db a8 45 c7 9b 4a 96 13 6a 73 ad 6a a2 a8 e4
1008: df 92 34 76 f9 47 8d b9 21 63 46 c2 d7 f2 64 e6
1024: 17 27 9f cf f3 ae cd 3a 7d ed 5e 46 7c 33 71 f6
1040: 71 c8 92 dc ae e6 a0 c8 05 0c e0 37 fb ea 15 ed
1056: b0 78 a5 bf b1 48 8b 46 64 1e c8 81 00 55 82 89
1072: 25 f8 b1 8b 1c e4 96 54 f8 be 97 b1 d3 20 f3 a0
1088: b5 c1 dd d5 27 d0 61 d9 96 2a 74 76 a8 33 10 78
1104: ff b2 86 ee 4f 0b 78 73 dd 7f 7c b5 02 e9 12 35
1120: d3 9e ab 81 cd 9b 61 fb 2b 33 72 ee c6 bb 8a bc
1136: bd 4f e5 9b c2 55 8f a0 b1 e7 1a 6a c1 e3 f1 5c
1152: 83 8f f0 9c 5b 04

client public key c25519:
0000: be f9 23 79 d7 fd 4e 8a 10 55 9b dc e5 3e 62 13
0016: eb 9b 6a 6f ca de ed 90 04 db b1 30 f6 ff ef 4f

Next up is SSH2_MSG_KEX_ECDH_REPLY 💫 the server's answer, and it's a whole vibe 🫶

SSH2_MSG_KEX_ECDH_REPLY

server cipher text:
0000: 71 67 00 55 f8 ac 87 1a af 7c ef cf 1c b4 7d b9
0016: 4f b6 22 5e 4d 77 81 73 4f 1d b9 82 79 ff e9 34
0032: 26 9f d2 2e 4e c6 a3 5f 79 9c 26 68 99 3a 0f 40
0048: 33 2a 7d dd fa 7a e7 6b 1e e7 9d 50 b7 48 0f aa
0064: aa 97 ff e7 8c 6c ac 5d 10 df 2b e3 cc 93 ea dc
0080: 18 17 b3 34 42 70 7a 27 85 58 2a ae c2 e6 b9 26
0096: 93 fd 23 a9 ae ac 4a 35 8b 57 c1 5c 95 cb 23 fb
0112: e5 93 0f 7c f5 63 6b 5b a1 53 b5 55 d0 75 16 21
0128: 8a db 95 ff c8 58 ac f4 7e 46 69 0a 4c a9 c8 cc
0144: eb e8 66 7c c4 fb fd 98 2c 0c 7f 41 8c 34 89 49
0160: a0 25 59 eb 63 a1 e6 8f 37 bf bc b3 ce 0a da 53
0176: 54 7f c2 41 52 eb 6c 9e 6e d0 ea af 6a 82 5d 17
0192: 6f 17 8d 06 8a 86 55 60 28 31 12 4a 0c de 6b be
0208: eb fd 38 13 6c 56 69 ad 0e 72 c8 bd b4 69 9d 32
0224: b4 1c 8e 6f f4 25 e1 9b c5 6f 8b 02 77 52 ae 72
0240: eb 9b 03 c8 9f de 15 bd f6 5a e8 9d 83 81 7b 48
0256: 7a 69 9a d0 91 41 aa 07 5a fa ad d6 e8 55 39 d9
0272: d1 0f d2 18 dc a0 9d 1c f1 e4 1c 0d f8 88 85 6b
0288: 6d 11 24 3e 61 de 48 95 5f 2a d1 c9 ad 3f b8 41
0304: 49 6d 9f 7c 3c bf 20 fe 37 7f 8c 8c 8f 72 ca f4
0320: 19 e4 cc a1 d8 08 cb 69 ec da 2b 88 e8 98 e9 1e
0336: 29 af 86 6f 19 a8 67 56 ef b4 33 e4 2b b8 fe 61
0352: ad 36 4c 42 f8 ec 04 38 09 62 02 66 b5 54 fc 69
0368: 46 29 05 27 d8 32 fd 37 4c d4 62 55 e1 ae e9 62
0384: 66 a0 f4 cb 4b 01 af 6b ea 09 80 00 a2 2b ff 0e
0400: 85 2c 92 b2 5c f9 f3 eb 44 a3 9a e8 55 bb e3 2f
0416: 2d 20 5a 77 67 97 57 90 7f 4b b3 08 92 41 1a c0
0432: f6 1b e9 a4 06 29 ea 31 eb 81 f0 94 96 aa 26 95
0448: 06 ed 4b f0 d3 9f aa 73 89 fa 6e f7 8f 4b f5 fa
0464: e4 5f 7c b6 08 e9 b2 18 77 99 9c ac 7b fb ec 41
0480: 41 1e 29 c2 d0 a5 de bc 59 2f 14 45 6d af b1 e0
0496: 9c 77 73 0e ac 52 23 73 11 35 27 17 8c a3 ff 0e
0512: 52 5d b7 c8 06 c5 05 43 15 53 e8 fc 83 64 df 10
0528: 8b 9c 74 5c 0e d9 54 5e 9a 49 cf 13 e4 1d 86 35
0544: 24 a3 27 75 d3 d6 b4 95 78 8f 0d 81 3b 80 6b 26
0560: 25 9f 14 b1 65 73 e8 ce fa 95 6d b1 15 0c 76 3c
0576: b1 75 a9 96 78 c8 4b 91 06 a9 94 bc ec fa 44 eb
0592: 39 77 4d ee df ae eb 0e 90 61 eb ab 6a 17 1b 24
0608: 3c 3a 6e c4 bb 6f 72 46 3d 9a b8 8c 6a e7 45 c7
0624: 0f 81 db 19 6e ce 65 74 ca db 73 ec 1e ce 5f d7
0640: 43 6b fe ff c0 e1 61 26 aa b7 6f e0 dc 7f d1 de
0656: 95 f0 28 fd 24 9c 73 1c cf ef 3e fe 21 a1 e5 4e
0672: 77 da db 12 01 7a e4 2c b5 f3 9d 30 e6 49 99 d6
0688: 21 58 cc 5b 5b d5 ff ca ea df 9a fd d6 73 be cd
0704: ae 7c 0d ea 78 e4 dd 74 f9 93 53 21 70 b7 cd 16
0720: ea c7 e9 5d 01 e0 e3 e6 53 46 7f fa a0 48 3e 5b
0736: af 64 46 ff 0f 0c b5 c9 92 48 e8 20 35 1d c8 ae
0752: d8 c4 38 31 aa 2c b5 91 6b eb 86 ac 2b fa 86 f2
0768: d1 bd 7d 51 4c be f3 bf 4b d0 f0 78 0e 20 d3 30
0784: fc f8 00 53 2a 6a 9b d9 e4 0e 08 d1 ad 52 7a ca
0800: f3 8b 0e a8 fb 45 3c 66 03 66 b4 54 a5 3d 8e df
0816: 4a 8f 66 f0 16 44 3b a9 f1 b3 db bb 7e d6 38 e5
0832: 5f 62 27 bb ba 34 0a 6f 9b 78 dd ae 54 ab 54 53
0848: 3a e1 d2 f1 d8 1e 8b 31 61 cd 69 8a 63 fb 7c 24
0864: 75 5f e6 6d 64 3d e4 12 cb 2d b3 6f 0f 5a 19 28
0880: 1f d6 f6 9c ee 44 11 1a c5 84 d6 e3 a2 05 5d d4
0896: 85 db f1 8f e4 17 df bc 4c 78 98 d1 70 3b 63 d6
0912: a4 91 db f1 9e 16 23 fa e0 54 f6 64 d1 0b d0 d6
0928: a6 fd f1 66 72 8c 65 d8 17 af c9 33 49 c8 e9 4d
0944: 1c 0a 77 2b 96 86 f2 16 55 3a e3 f6 00 bb b6 5a
0960: 86 f6 fc 3f d6 f9 a4 1d fd 29 1d 5b 65 dc b3 14
0976: 96 10 3e c1 9a 90 23 e8 88 81 24 42 68 7a aa 25
0992: ba f3 50 bd b9 ae be dc b3 ff 39 81 44 89 00 9d
1008: 4e 26 d6 ef df 7c e0 53 d3 ed 34 07 3d f2 1e 42
1024: 28 af 1d 12 ce 98 c7 b0 7b 90 81 b5 ea f3 2c

server public key c25519:
0000: 18 6c 55 03 db 1c 38 e3 40 d7 09 24 77 46 14 b8
0016: 5e e4 7f 19 98 04 9b 90 1f f6 b9 7f b0 70 9e 32

Now the secrets 🔑 these are the shared values both sides end up with:

shared secret
0000: 9b 73 7d 41 d6 cf bb 12 56 c5 8c ad 0a 6a e2 c9
0016: bf 84 a9 0a 72 91 eb 52 e4 c1 81 c8 d2 44 7b 56

client kem key:
0000: 2c 0c 5a 36 e6 77 70 b4 d8 ab 38 9a 92 96 3a cd
0016: 10 82 38 36 40 be 2d 66 08 02 b8 17 cf eb b9 be

concatenation of KEM key and ECDH shared key:
0000: 2c 0c 5a 36 e6 77 70 b4 d8 ab 38 9a 92 96 3a cd
0016: 10 82 38 36 40 be 2d 66 08 02 b8 17 cf eb b9 be
0032: 9b 73 7d 41 d6 cf bb 12 56 c5 8c ad 0a 6a e2 c9
0048: bf 84 a9 0a 72 91 eb 52 e4 c1 81 c8 d2 44 7b 56

encoded shared secret:
0000: 00 00 00 40 42 54 58 44 6f 22 75 63 04 de d7 5a
0016: 1f 23 fe f9 b1 8b 36 eb e0 e6 e2 60 c3 00 12 63
0032: b0 18 3f 42 49 07 e6 d8 22 b3 b7 6c 6c 38 37 b5
0048: b4 1f b0 d0 76 35 c7 57 e6 5e fb ef cb 5b c3 8a
0064: 1a 15 a9 6d

Figure 1 🎀

Acknowledgements 🌈

okay the credits, and they're so deserved 🥹

Jan Mojzis added "sntrup4591761x25519-sha512@tinyssh.org" to TinySSH [TinySSH] in 2018, and Markus Friedl implemented it for OpenSSH [OpenSSH] in 2019. In 2020, Damien Miller replaced sntrup4591761 with sntrup761 in OpenSSH to create "sntrup761x25519-sha512@openssh.com". TinySSH added support for it in 2021. It became the default key exchange algorithm in OpenSSH in 2022. That is identical to the "sntrup761x25519-sha512" mechanism described in this document. 👑

Thanks to the following people for review and comments: Roman Danyliw, Loganaden Velvindron, Panos Kampanakis, Mark Baushke, Theo de Raadt, Tero Kivinen, Deb Cooley, Paul Wouters, Damien Miller, Mike Bishop, Éric Vyncke, D. J. Bernstein, and Gorry Fairhurst. 🫶 the whole review crew, iconic

Authors' Addresses 📮

  • Markus Friedl OpenSSH Email: markus@openbsd.org
  • Jan Mojzis TinySSH Email: jan.mojzis@gmail.com
  • Simon Josefsson Email: simon@josefsson.org URI: https://blog.josefsson.org/
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