I'm having trouble decrypting a file originally encrypted using an SSH identity

[voltagex]

This is likely to be user error - I haven't used age in... ages.

A file was created with age -R ~/.ssh/id_age.pub < file (with v1.0.0) on Linux

/root/.ssh/id_age.pub: OpenSSH ED25519 public key

I'm trying to decrypt the file on Windows - don't I need to hand it the private key?

PS C:\temp> age --version
v1.1.0-rc.1
PS C:\temp> age --decrypt -i C:\keys\id_age_backups .\file
age: error: reading "C:\\keys\\id_age_backups": malformed SSH identity in "C:\\keys\\id_age_backups": unsupported SSH identity type: ed25519.PrivateKey
age: report unexpected or unhelpful errors at https://filippo.io/age/report

[FiloSottile]

It's not user error, but a surprising issue in golang.org/x/crypto/ssh that we don't work around yet. age is failing to use Ed25519 SSH keys that are encoded as PKCS#8. See golang/go#51974. I'll get a fix out ASAP, in the meantime you can convert it to the default OpenSSH format, which should work. Sorry about this!

ssh-keygen -i -f C:\keys\id_age_backups -o C:\keys\id_age_backups_new

[voltagex]

Oh wow, this is not the first time I've been bitten by OpenSSH key formats - thank you!

[voltagex]

I wasn't able to get your command line working (ssh-keygen says "too many arguments"). Will investigate via that issue you linked.

[FiloSottile]

Yeah... actually, I am a bit confused as to how you generated that key, because I can't get ssh-keygen to generate or even read PKCS8 Ed25519 keys. Could you tell me the header line and the length of the key? Is it -----BEGIN PRIVATE KEY----- and 64 characters of Base64? (Obviously, don't post the whole key :))

[voltagex]

A bit of an adventure - I forgot I'd generated the key using 1Password's new SSH key support.

https://www.reddit.com/r/1Password/comments/u68spy/exported_ssh_ed25519_private_keys_have_invalid/ says that private keys via the copy (to clipboard) button are in a different format than keys saved out of the password manager via the download button

Copy: starts with -----BEGIN PRIVATE KEY-----, ends with -----END PRIVATE KEY-----, key length 117 bytes (?), looks like base64

Download: OpenSSH format, starts with -----BEGIN OPENSSH PRIVATE KEY----- ends with -----END OPENSSH PRIVATE KEY----- key is 316 bytes.

[FiloSottile]

Yeah, -----BEGIN PRIVATE KEY----- is presumably in PKCS#8, which OpenSSH just doesn't support, which is why we never ran into this before. 117 bytes is a weird length for an Ed25519 PKCS#8 encoding but who knows, maybe it encodes the public key too or something.

If you use the OpenSSH format you should be set. Might be worth reporting this to 1Password, even if the age bug is fixed.

[arunsathiya]

I see that a fix was pushed in #429 to support decrypting files using Ed25519 SSH private key that starts in "BEGIN PRIVATE KEY" but that fails well. Here's what I am seeing:

➜  ~ op item get vwcxwek3pnefua2xrys3rdtvqu --fields private_key --format json | jq .value -r | age -d -i - ~/Downloads/001.zip-001.age > ~/Downloads/001-age-out.zip
age: error: reading "-": malformed SSH identity in "-": unsupported SSH identity type: ed25519.PrivateKey
age: report unexpected or unhelpful errors at https://filippo.io/age/report

Could you advise, @FiloSottile? Thank you!

[arunsathiya]

Just noticed I am on age 1.0.0 which was released on 8th of Sep 2021, while f31a8ad is from July 2022. I'll update to https://github.com/FiloSottile/age/releases/tag/v1.1.0-rc.1 and try again. 👀

[arunsathiya]

Works great at HEAD, thank you for de7c1fb!