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age -d -i does not support aes256-cbc encrypted ed25519 private keys #100

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martinseener opened this issue Feb 12, 2020 · 3 comments · Fixed by #111
Closed

age -d -i does not support aes256-cbc encrypted ed25519 private keys #100

martinseener opened this issue Feb 12, 2020 · 3 comments · Fixed by #111

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@martinseener
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martinseener commented Feb 12, 2020 •
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Environment

  • OS: Linux Mint 19.3
  • age version: 9fdb125

What were you trying to do

I have encrypted a file using age -r "ssh-ed25519 AAAA..." -o testfile.age testfile and then wanted to decrypt it using age -d -i ~/.ssh/id_ed25519 testfile.age

What happened

age errored that it does not support aes-cbc mode:

Enter passphrase for "/home/myusername/.ssh/id_ed25519": 
Error: failed to decrypt SSH key file: ssh: unknown cipher "aes256-cbc", only supports "aes256-ctr"

I created my key some years ago with ssh-keygen -t ed25519
I expect age to support decrypting aes-cbc as well (128/256bits)

Interesting side note: My RSA private key is encrypted using aes-128-cbc but using it with age works at this point. Not sure why though.
@martinseener martinseener changed the title age -d -i does not support aes256-cbc encrypted private keys age -d -i does not support aes256-cbc encrypted ed25519 private keys Feb 12, 2020
@str4d
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str4d commented Feb 12, 2020 •
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Looks like the default cipher that ssh-keygen uses to encrypt keys was switched from aes256-cbc to aes256-ctr (issue) in OpenSSH 7.6, released 2017-10-03.

AFAICT those are the only two ciphers that have ever been default for ssh-keygen (for the OpenSSH privkey format, which was introduced in OpenSSH 6.5, released 2014-01-30), so if we support both of those, that will cover basically all encrypted OpenSSH keys.

@RKinsey
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RKinsey commented Mar 18, 2020

Unfortunately, this isn't really fixable from here. x/crypto/ssh explicitly checks for the "aes256-ctr" string and fails otherwise when using passphrase-protected keys. I'll open an issue to see if excluding CBC was intentional.

@RKinsey RKinsey mentioned this issue Mar 19, 2020
Closed
str4d added a commit to str4d/rage that referenced this issue Mar 21, 2020
@str4d
Add support for OpenSSH keys encrypted with "aes256-cbc"
a58456b 
When OpenSSH introduced its current encrypted-key format, ssh-keygen
defaulted to "aes256-cbc" for the cipher. This was changed in OpenSSH 7.6
(released 2017-10-03) to "aes256-ctr", and is the same to this day.

Adding support for "aes256-cbc" ensures compatibility with all encrypted
keys generated by ssh-keygen since OpenSSH 6.5 (released 2014-01-30).

See also FiloSottile/age#100
@str4d str4d mentioned this issue Mar 21, 2020
Merged
@RKinsey
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RKinsey commented Mar 23, 2020

I submitted a change to fix this to x/crypto, so it's closable once the commit is merged

str4d added a commit to str4d/rage that referenced this issue Mar 23, 2020
@str4d
Add support for OpenSSH keys encrypted with "aes256-cbc"
985276c 
When OpenSSH introduced its current encrypted-key format, ssh-keygen
defaulted to "aes256-cbc" for the cipher. This was changed in OpenSSH 7.6
(released 2017-10-03) to "aes256-ctr", and is the same to this day.

Adding support for "aes256-cbc" ensures compatibility with all encrypted
keys generated by ssh-keygen in this format since it was introduced in
OpenSSH 6.5 (released 2014-01-30).

See also FiloSottile/age#100
str4d added a commit to str4d/rage that referenced this issue Mar 23, 2020
@str4d
Add support for OpenSSH keys encrypted with "aes256-cbc"
0170250 
When OpenSSH introduced its current encrypted-key format, ssh-keygen
defaulted to "aes256-cbc" for the cipher. This was changed in OpenSSH 7.6
(released 2017-10-03) to "aes256-ctr", and is the same to this day.

Adding support for "aes256-cbc" ensures compatibility with all encrypted
keys generated by ssh-keygen in this format since it was introduced in
OpenSSH 6.5 (released 2014-01-30).

See also FiloSottile/age#100
@RKinsey RKinsey mentioned this issue Mar 24, 2020
Merged
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Updated go.mod for aes256-cbc fix RKinsey/age
3 participants
@martinseener @str4d @RKinsey