mail_crypt_global_private_key: Couldn't parse private key: Unknown/invalid PEM key type

[Antti Antinoja]

Version: Dovecot 2.3.13 (89f716dc2)

Issue: Dovecot states it can't parse the private key

= Background =

== Creating private EC key ==

* Curve: secp521r1
* Encryption: aes-256-ctr
* Format: pkey
* Enacapsulation: Base64

  # openssl ecparam -name secp521r1 -genkey | openssl pkey |\
    openssl ec -aes-256-ctr | base64 -w0 > test_keys_remove/private_key_encrypted.pem

== Extract public key ==

  # cat test_keys_remove/private_key_encrypted.pem | base64 -d |\
    openssl ec -pubout | base64 -w0 > test_keys_remove/public_key.pem

== Checking keys ==

* 592 Feb 20 07:27 private_key_encrypted.pem:
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

* 360 Feb 20 07:28 public_key.pem:
LS0tLS1CRUdJTiBQVUJMSUMgS0VZLS0tLS0KTUlHYk1CQUdCeXFHU000OUFnRUdCU3VCQkFBakE0R0dBQVFBK2w2M0ZIckpuT0dPZ1lDTG5PRVpOaHpSdW5YWgpoMHd5dTNPS1VzSEozUDJPVWxNWmxKOFFjZTF0SExUTWFxMWxkOTIwbkdJQmo1TGNYUklVdWRweElTd0I2Tld0Ck1TWncrZFBEUVRjc0hQMFRqWUh5Njl4d25BZHV4ZHZYdnh0Uk5TRzZGNlJPUnR0L2t2ekk3bWRPM0NpQ1FyMTQKTjZWalZyYWVpaXZkR2dPQ250bz0KLS0tLS1FTkQgUFVCTElDIEtFWS0tLS0tCg==

== Notes ==

* The keys are then saved in database and fetched to userdb by Dovecot via passdb lookup (Details in the logs)
* mail-crypt settings:

    mail_plugins = $mail_plugins mail_crypt
    plugin {
        mail_crypt_curve = secp521r1
        mail_crypt_save_version = 0
    }

* Note: User record on database has mail_crypt_save_version = 2 as can be seen from the log extract below.

= Dovecot log on client IMAP message retrieval =

Feb 20 07:45:01 pf1 dovecot[19612]: auth: Debug: sql(test1 at g1.fi,x.x.x.x,<wFzVEb67CMQKZgkb>): Performing passdb lookup
Feb 20 07:45:02 pf1 dovecot[19612]: auth: Debug: sql(test1 at g1.fi,x.x.x.x,<wFzVEb67CMQKZgkb>): Finished passdb lookup
Feb 20 07:45:02 pf1 dovecot[19612]: auth: Debug: auth(test1 at g1.fi,x.x.x.x,<wFzVEb67CMQKZgkb>): Auth request finished
Feb 20 07:45:02 pf1 dovecot[19612]: auth: Debug: client passdb out: OK  1       user=test1 at g1.fi        
Feb 20 07:45:02 pf1 dovecot[19612]: auth: Debug: sql(test1 at g1.fi,x.x.x.x,<wFzVEb67CMQKZgkb>): Performing userdb lookup
Feb 20 07:45:02 pf1 dovecot[19612]: auth: Debug: sql(test1 at g1.fi,x.x.x.x,<wFzVEb67CMQKZgkb>): Finished userdb lookup
Feb 20 07:45:02 pf1 dovecot[19612]: auth: Debug: master userdb out: USER        1609957377      test1 at g1.fi     mail_crypt_global_private_password=key_pass_we_know_this_is_correct mail_crypt_global_private_key=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  mail_crypt_global_public_key=LS0tLS1CRUdJTiBQVUJMSUMgS0VZLS0tLS0KTUlHYk1CQUdCeXFHU000OUFnRUdCU3VCQkFBakE0R0dBQVFBK2w2M0ZIckpuT0dPZ1lDTG5PRVpOaHpSdW5YWgpoMHd5dTNPS1VzSEozUDJPVWxNWmxKOFFjZTF0SExUTWFxMWxkOTIwbkdJQmo1TGNYUklVdWRweElTd0I2Tld0Ck1TWncrZFBEUVRjc0hQMFRqWUh5Njl4d25BZHV4ZHZYdnh0Uk5TRzZGNlJPUnR0L2t2ekk3bWRPM0NpQ1FyMTQKTjZWalZyYWVpaXZkR2dPQ250bz0KLS0tLS1FTkQgUFVCTElDIEtFWS0tLS0tCg==   mail_crypt_save_version=2       quota_rule=*:bytes=0    home=/var/vmail/g1.fi/test1     uid=10000       gid=10000       auth_mech=PLAIN auth_token=66d2d0f66bcce2758235fb53dbfe821804c6e79c
Feb 20 07:45:02 pf1 dovecot[19612]: imap-login: Login: user=<test1 at g1.fi>, method=PLAIN, rip=x.x.x.x, lip=y.y,y,y, mpid=19618, TLS, session=<wFzVEb67CMQKZgkb>
Feb 20 07:45:02 pf1 dovecot[19612]: imap(test1 at g1.fi)<19618><wFzVEb67CMQKZgkb>: Debug: Added userdb setting: plugin/mail_crypt_global_private_key=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
Feb 20 07:45:02 pf1 dovecot[19612]: imap(test1 at g1.fi)<19618><wFzVEb67CMQKZgkb>: Debug: Added userdb setting: plugin/mail_crypt_global_private_password=<hidden>
Feb 20 07:45:02 pf1 dovecot[19612]: imap(test1 at g1.fi)<19618><wFzVEb67CMQKZgkb>: Debug: Added userdb setting: plugin/mail_crypt_global_public_key=LS0tLS1CRUdJTiBQVUJMSUMgS0VZLS0tLS0KTUlHYk1CQUdCeXFHU000OUFnRUdCU3VCQkFBakE0R0dBQVFBK2w2M0ZIckpuT0dPZ1lDTG5PRVpOaHpSdW5YWgpoMHd5dTNPS1VzSEozUDJPVWxNWmxKOFFjZTF0SExUTWFxMWxkOTIwbkdJQmo1TGNYUklVdWRweElTd0I2Tld0Ck1TWncrZFBEUVRjc0hQMFRqWUh5Njl4d25BZHV4ZHZYdnh0Uk5TRzZGNlJPUnR0L2t2ekk3bWRPM0NpQ1FyMTQKTjZWalZyYWVpaXZkR2dPQ250bz0KLS0tLS1FTkQgUFVCTElDIEtFWS0tLS0tCg==
Feb 20 07:45:02 pf1 dovecot[19612]: imap(test1 at g1.fi)<19618><wFzVEb67CMQKZgkb>: Debug: Added userdb setting: plugin/=2
Feb 20 07:45:02 pf1 dovecot[19612]: imap(test1 at g1.fi)<19618><wFzVEb67CMQKZgkb>: Debug: Added userdb setting: plugin/quota_rule=*:bytes=0
Feb 20 07:45:02 pf1 dovecot[19612]: imap(test1 at g1.fi)<19618><wFzVEb67CMQKZgkb>: Error: mail_crypt_plugin: mail_crypt_global_private_key: Couldn't parse private key: Unknown/invalid PEM key type

== Question ==

Any idea why Dovecot can't parse the private key?

I tested this with several keys. Even with some without encryption -> Always same error.

According to the debug messages the private key is correctly loaded (and indeed matches the one created on command line).

Thank you for your time.

Cheers,
Antti

-- 
Antti Antinoja <reader at fennosys.fi>