I'm looking to secure the software update procedure for a little device I'm maintaining that runs Linux. I want to generate an md5sum of the update package's contents and then encrypt that hash with a private key before sending it out to the customer. When they load the update, the device should then decrypt the hash, verify it, and proceed with installation of the package.
I'm trying to do this with OpenSSL and RSA. I found this thread, and was discouraged. I then found this thread and wondered how Perl gets around the purported impossibility of it all. I'm doing this in C, so perhaps there's a parallel function in an SSL library somewhere?
So my question really is: can I force command line Linux to take a public key as the decryption input, or perhaps use C to circumvent that limitation?
Thanks in advance, all.
Let's assume you have generated a public and private RSA key using openssl genrsa:
$ openssl genrsa -out mykey
Generating RSA private key, 512 bit long modulus
...++++++++++++
..........++++++++++++
e is 65537 (0x10001)
$ openssl rsa -in mykey -pubout -out mykey.pub
writing RSA key
You can sign something with the private key like this:
$ md5sum myfile | openssl rsautl -inkey mykey -sign > checksum.signed
You can verify this data using the public key:
$ openssl rsautl -inkey mykey.pub -pubin -in checksum.signed
df713741d8e92b15977ccd6e019730a5 myfile
Is this what you're looking for?
NOTE: I recommend you use the sign and verify routines instead of trying to implement them yourself with the underlying RSA encrypt and decrypt routines.
Nonetheless, Openssl CLI can achieve "decrypting with the public key" via the rsautl subcommand like so:
openssl rsautl -verify -inkey public_key.pem -pubin -in data.sig -raw -hexdump
Related
I am encrypting a file with this openssl command -
openssl smime -encrypt -aes256 -in <input-file> -binary -outform DEM publicKey.pem
Although the command uses public key but it does not uses RSA as the input file is certainly larger in size.
The same file can be decrypted by -
cat encrypted | openssl smime -decrypt -binary -inform DEM -inkey publickey.pem
My question is, what method openssl uses here to encrypt using public key and how to achieve this command line functionality in code using node.js / ruby ?
Which programme or command do you use to extract the public key from a p12 protected with a password? I am trying with the command hydrabut i think it only works along networks
You can use openssl to check, convert etc. a p12 file.
E.g.:
openssl pkcs12 -info -in example.p12
or
openssl pkcs12 -in example.p12 -out example.pem -nodes
etc.
You can make openssl read the password from a file or stdin. E.g.:
openssl [...] -pass stdin
See man page for openssl for more ideas.
I am new with Openssl i have generated a private key myprivatekey.pem and a publickey mypublickey.pem with :
openssl ecparam -genkey -name secp160k1 -noout -out myprivatekey.pem
and my public key with :
openssl -ec -in myprivatekey.pem -pubout -out mypublickey.pem
What i want to do next is to encrypte my ecdsa with a passphrase private key and make a certification request for my public key and thank you for your help.
It would seem that ecparam doesn't have a built-in option for encrypting the generated key. Instead, you can simply do the following:
openssl ec -in myprivatekey.pem -out myprivatekey_encrypted.pem -aes256
Compared to genrsa, an extra step is required, but this basically does the same thing.
Now as far as the certificate request, the command is pretty much the same regardless of the type of private key used:
openssl req -new -sha256 -key myprivatekey.pem -out mycertrequest.pem
You can then take the resulting mycertrequest.pem and send it to a CA for signing.
Edit:
If you have concerns about writing the unencrypted private key to disk, you can do both the generation and encryption of the key in one step like so:
openssl ecparam -genkey -name secp256k1 | openssl ec -aes256 -out privatekey.pem
This generates a P-256 key, then prompts you for a passphrase. The key is then encrypted using AES256 and saved into privatekey.pem.
While ecparam doesn't have an option to encrypt the generated key, genpkey can generate ECC private keys and does have such an option:
openssl genpkey -algorithm ec -pkeyopt ec_paramgen_curve:secp160k1 -aes-256-cbc -out myprivatekey_encrypted.pem
The -aes-256-cbc option specifies to encrypt it (with aes-256-cbc; other options are available for different types of encryption).
You can pass -passin pass:password or -passin file:mypassword.pass to specify the password on the commandline.
Is there any (easy) way to create a signature for a file using the command and the openssl rsautl command while the necessary key is stored in a TPM?
I just want to do the following with "key.pem" being a TPM-stored key.
openssl rsautl -sign -in file -inkey key.pem -out sig
How to tell openssl rsautl to use key stored in TPM?
OpenSSL does not provide an ENGINE for TPMs. I believe you need to use TrouSerS.
Dr. Henson made some comments about it on the OpenSSL mailing list at TPM engine.
Can any one able to tell me how to encrypt and decrypt a xml file using openssl. I can able to create privatekey using the Linux command
openssl genrsa -out private.pem 1024
And got my private key as private.pem. Created public key using
openssl rsa -in private.pem -out public.pem -outform PEM -pubout
got my public key as public.pem
Now what I want is I want to encrypt the XML file using this public key and again want to decrypt using my private key.
Try:
$ openssl rsautl -encrypt -inkey public.pem -pubin -in file.xml -out file.xml.encrypted
Hint: I cheated and looked here:
http://www.devco.net/archives/2006/02/13/public_-_private_key_encryption_using_openssl.php