ssh-keygen and openssl gives two different public keys - encryption

Is it possible that ssh-keygen & openssl can generate two different public keys from same private key? Command ssh-keygen -y -f ./my.key gives (contents after ssh-rsa in the same line) different public key to the one generated (contents between -----BEGIN PUBLIC KEY----- and -----END PUBLIC KEY-----) with command openssl rsa -in my.key -pubout .

It's the same key but different representations. OpenSSL uses X.509 SubjectPublicKeyInfo in ASN.1, usually (including here) wrapped in PEM; OpenSSH (except 'rsa1' keys for SSHv1 which is broken and you shouldn't use) uses the XDR-like SSH wire format, in base64.
Dupe or neardupe:
Convert pem key to ssh-rsa format
RSA Public Key format
Convert RSA public key to RSA DER
Converting an OpenSSL generated RSA public key to OpenSSH format (PHP)
How to convert RSA key to ssh-rsa
How to store/retrieve RSA public/private key (buried in the middle)
and less obvious cross-stack https://security.stackexchange.com/questions/42268/how-do-i-get-the-rsa-bit-length-with-the-pubkey-and-openssl

Related

Convert OpenSSH ED25519 Private Key Format to PEM format

I have generated a an ED25519 SSH key pair using
ssh-keygen -t ed25519
The output of the id_ed25519 file is in OpenSSH format:
-----BEGIN OPENSSH PRIVATE KEY-----
...
-----END OPENSSH PRIVATE KEY-----
I would like to convert it to a PEM file format. If it were an RSA key pair, there would be no need for that as an RSA id_rsa key is already in a PEM file format but the ED25519 key pair is an OpenSSH format.
How can I convert this to a PEM file format?
Use
ssh-keygen -p -f path/to/your/key -m pem
to convert your key file to PEM, but be sure to make a backup of the file first.
Taking from https://github.com/pickware/github-action-ssh-agent
I think this would work:
openssl pkey -in ed25519.pem -out ed25519.pub -pubout
It does for a private key generated this way:
openssl genpkey -algorithm ed25519 > ed25519.pem
I haven't tested ssh-keygen's private key format explicitly but I would assume that it is using OpenSSL under the hood. If the private key's base64 starts with "MC", then I would say it probably would be compatible.

How to check the algorithm used in key generation using openssl genrsa output

I have create a keypair using
openssl genrsa -out test1.key
I want to verify how the key is encrypted, by looking at openssl genrsa --help ,
-des encrypt the generated key with DES in cbc mode
-des3 encrypt the generated key with DES in ede cbc mode (168 bit key)
--idea encrypt the generated key with IDEA in cbc mode
I used openssl rsa -in test1.key -text but it is not showing any information
about those.
Please if there is anyway to check that?
You're expecting an encrypted key, but it isn't by default. The genrsa man page clearly states (emphasis mine):
-aes128|-aes192|-aes256|-aria128|-aria192|-aria256|-camellia128|-camellia192|-camellia256|-des|-des3|-idea
These options encrypt the private key with specified cipher before
outputting it. If none of these options is specified no encryption
is used. If encryption is used a pass phrase is prompted for if it
is not supplied via the -passout argument.
This can also be seen from the generated PEM file which has no information other than the key itself:
$ openssl genrsa -out test-plain.key
Generating RSA private key, 2048 bit long modulus (2 primes)
...........................................................................................+++++
..........................+++++
e is 65537 (0x010001)
$ head -n 2 test-plain.key
-----BEGIN RSA PRIVATE KEY-----
MIIEpAIBAAKCAQEA5RCtTAg3fuspy1VdZpHqrFz4Lt9p5MnZkjH0FZ9wAk9vpvRF
On the other hand, if we specify an encryption algorithm to apply to the key, two things happen:
I am prompted for a password (unless specified through -passout)
the algorithm and block cipher mode is shown in the PEM output
$ openssl genrsa -out test-aes.key -aes128
Generating RSA private key, 2048 bit long modulus (2 primes)
............................................................+++++
................................+++++
e is 65537 (0x010001)
Enter pass phrase for test-aes.key: foobar
Verifying - Enter pass phrase for test-aes.key: foobar
$ head -n 3 test-aes.key
-----BEGIN RSA PRIVATE KEY-----
Proc-Type: 4,ENCRYPTED
DEK-Info: AES-128-CBC,ED364325F65A0F212D07BC9E643D6424
We can clearly see that AES-128-CBC is being used with the indicated IV.

Get private key from .pk file

I have a .pk file that should contain a private key. I can not find any information about this file format. Is it similar to .pkcs12?
How can I retrieve the private key from this kind of file?
According to fileinfo.com .pk is not a known certificate store file extension. Maybe you could ask from the source of the file why they named it like that.
Check if it's pkcs12 file by trying to output info about the file:
openssl pkcs12 -info -in yourfile.pk
If it's pkcs12 then you can export the private key from it with the following command:
openssl pkcs12 -in yourfile.pk -nocerts -nodes privatekey.pem
Obviously, your file is in PEM format. You can check the file in text editor for -----BEGIN texts to see what's inside. Cand you see BEGIN ENCRYPTED PRIVATE KEY or BEGIN RSA PRIVATE KEY or BEGIN PRIVATE KEY text in the file? Are there also certificate(s) in the same file, i.e. can you see BEGIN RSA PUBLIC KEY or BEGIN PUBLIC KEY once or multiple times?
You can remove a passphrase from RSA private key like this:
openssl rsa -in yourfile.pk -out privatekey.pem

"No DEK-Info header in block" when attempting to read encrypted private key

I'm trying to read an encrypted PKCS8 private key file. I generated the keys like this:
openssl genrsa -out file.pem -passout pass:file -aes256 1024
openssl pkcs8 -topk8 -inform pem -in file.pem -outform pem -out filePKCS8.pem
And I try reading it in Go this way:
block, _ := pem.Decode(key)
return x509.DecryptPEMBlock(block, password)
But I get an error saying:
x509: no DEK-Info header in block
However, I can't figure out what's going wrong. Am I generating the key wrong or am I using the wrong library? I see libraries specifically for reading unencrypted PKCS8 files but none for encrypted PKCS8 files specifically.
Does anyone have any idea?
Go don't have function to decrypt PKCS8 keys in standard library.
You can this package:
https://github.com/youmark/pkcs8/blob/master/pkcs8.go#L103
A longer explaination for anyone with the same problem.
What would work
Your first command
openssl genrsa -out file.pem -passout pass:file -aes256 1024
generates a PKCS#1 private key file (file.pem):
-----BEGIN RSA PRIVATE KEY-----
Proc-Type: 4,ENCRYPTED
DEK-Info: AES-256-CBC,1DA219DB746F88C6DDA0D852A0FD3232
AEf09rGkgGEJ79GgO4dEVsArwv4IbbODlxy95uHhfkdGYmuk6OlTpiCUE0GT68wn
KFJfBcHr8Z3VqiHGsXxM5QlKhgnfptxfbrdKErgBD5LQcrvnqmf43KeD4lGQcpiy
...
...
mAKMCwiU/GKZz8ZwQ4qGkBlVVCOFfgwmfbqguJF2l8yzM8lYI9MZ9NEwKkvEbc
-----END RSA PRIVATE KEY-----
This private key file can be parsed and decrypted by x509.DecryptPEMBlock() alright.
What would not work and why
Your second command
openssl pkcs8 -topk8 -inform pem -in file.pem -outform pem -out filePKCS8.pem
converts that file into PKCS#8 format (filePKCS8.pem).
The subcommmand genpkey would directly produce a similar result:
openssl genpkey -algorithm RSA -aes256 \
-pkeyopt rsa_keygen_bits:1024 -out filePKCS8.pem
The generated filePKCS8.pem (either way) would look similar to this:
-----BEGIN ENCRYPTED PRIVATE KEY-----
MIISrTBXBgkqhkiG9w0BBQ0wSjKpBgkqhkiG9w0BBQwwHAQIKL+ordsVfqsCAggB
MAwGCCqGSIb3DQIJCQAwHQYJYIZIWAUDBAEqBBCipOAAxWkC0/zkNLNYTSMgBIIS
...
...
zfdxjZ0XmPiwED2azsLMnRrWnRj2UqMtnv9zO/ucik9za
-----END ENCRYPTED PRIVATE KEY-----
x509.DecryptPEMBlock() does not support this format. And as specified in #8860, the Go's core library has no real plan to support pkcs#8 in the near future.
As mentioned by Gregory, if you want to work with it, you'll have better luck with 3rd party library like github.com/youmark/pkcs8 (Documentation).

Signing and Encrypting file via GnuPG encryption

I'm trying to sign and encrypt a text file via GnuPG encryption from a command line, but I'm getting the following error:
sign+encrypt failed: No secret key
I know very little about GnuPG. Our client gave me two OpenPGP keys with .asc file extensions. He said file 1 is to sign the file and file 2 is to encrypt it.
File1.asc (to sign the file) looked something like this:
-----BEGIN PGP PRIVATE KEY BLOCK-----
Version: PGP 7.0.1
(key code here)
-----END PGP PRIVATE KEY BLOCK-----
-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: PGP 7.0.1
(key code here)
-----END PGP PUBLIC KEY BLOCK-----
File2.asc (to encrypt) looked like this:
-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: PGP for Personal Privacy 5.0
(key code here)
-----END PGP PUBLIC KEY BLOCK-----
I then tried running GnuPG via command line with something like the following:
gpg -r [file ame of encryption key] -s -u [password client gave for signing] -o DirectoryWhereToOutputFile\sample.pgp -e DirectoryOfSampleFile\SampleFile
What do I need to change to get this to successfully sign and encrypt a file?
GnuPG does not use keys as files, you have to import them before and use their key IDs.
gpg --import [private-key]
gpg --import [public-key]
Then, use the key ID of the public key (the one to encrypt for):
gpg -r [key-id] -s -o [output-file] -e [input-file]
If you don't know the IDs, use gpg --list-keys to obtain a list of all known keys. gpg --list-secret-keys will only show those you have the private key for, thus the one you can use for signing.
In GnuPG, we generate keypair gpg --gen-key
Encrypt using shared/imported public key - gpg --recipient bob --encrypt filename
Decrypt using private key - gpg --decrypt sharedMessage.asc
Refer https://linux.101hacks.com/unix/gpg-command-examples/

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