#OPENSSH GENERATE KEY SERIES#

The WikiPedia entry for Distinguished Encoding Rules.

The data in a PKCS#1 key is encoded using DER, which is a set of rules for serializing ASN.1 data. The x.509 format may be used to store keys generated using algorithms other than RSA. This is different from an x.509 public key, which looks like this: -BEGIN PUBLIC KEY. You can identify a PKCS#1 PEM-encoded public key by the markers used to delimit the base64 encoded data: -BEGIN RSA PUBLIC KEY. PKCS#1 is “the first of a family of standards called Public-Key Cryptography Standards (PKCS), published by RSA Laboratories.” ( Wikipedia). Our target format is a PEM-encoded PKCS#1 public key. The next step is to produce the appropriate output format. There may be better ways to do this, but this works: e_val = eval('0x' + ''.join( for x in We need to convert the character buffers currently holding e (the exponent) and n (the modulus) into numeric types. This leaves us with an array that, for an RSA key, will look like: # get the second field from the public key file.ĭlen = struct.unpack('>I', keydata)ĭata, keydata = keydata, keydata We can read this in with the following Python code: import sys

This duplicates the key type in the first field of the public key.įor more information on how RSA works and what the exponent and modulus are used for, read the Wikipedia article on RSA. algorithm name (one of (ssh-rsa, ssh-dsa)).The length is encoded as four octets (in big-endian order).

#OPENSSH GENERATE KEY SERIES#

What, you may ask, is PEM encoding? Privacy Enhanced Mail (PEM) is a specific type of Base64 encoding…which is to say it is a way of representing binary data using only printable ASCII characters.įor an ssh-rsa key, the PEM-encoded data is a series of (length, data) pairs. Briefly, an OpenSSH public key consists of three fields: The OpenSSH public key format is fully documented RFC 4253. If you have a recent version of OpenSSH (where recent means 5.6 or later), you can just do this: ssh-keygen -f key.pub -e -m pem QSYlFuShWrHPtiLmUdPoP6CV2mML1tk+l7DIIqXrQhLUKDACeM5roMx0kLhUWB8P

MwSXA9VNmhz+PiB+Dml4WWnKW/VHo2ujTXxq7+efMU4H2fn圓Se3KYOsFPFGZ1TN +xTBtWdEo7XGUujKDvC2/aZKukfjpOiUI8AhLAfjmlcD/UZ1QPh0mHsglRNCmpCw MIIBCgKCAQEA+xGZ/wcz9ugFpP07Nspo6U17l0YhFiFpxxU4pTk3Lifz9R3zsIsuĮRwta7+fWIfxOo208ett/jhskiVodSEt3QBGh4XBipyWopKwZ93HHaDVZAALi/2A JiUW5KFasc+2IuZR0+g/oJXaYwvW2T6XsMgipetCEtQoMAJ4zmugzHSQuFRYHw/7S6PUI2UĠ3glFmULvEV+qIxsVFT1ng3pj this: -BEGIN RSA PUBLIC KEY.

HFTilOTcuJ/P1HfOwiy4RHC1rv59Yh/E6jbT圆23+OGySJWh1IS3dAEaHhcGKnJaikrBn3cĬdoNVkAAuL/YD7FMG1Z0SjtcZS6MoO8Lb9pkq6R+Ok6JQjwCEsB+OaVwP9RnVA+HSYe圜VEĠKakLCbBJcD1U2aHP4+IH4OaXhZacpb9Ueja6NNfGrv558xTgfZ+fLdJ7cpg6wU8UZnVM1B That is, I wanted to go from this: ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQD7EZn/BzP26AWk/Ts2ymjpTXuXRiEWIWn I’ve posted a followup to this article that discusses ssh-agent.įor reasons best left to another post, I wanted to convert an SSH public key into a PKCS#1 PEM-encoded public key. $keyInfo = openssl_pkey_get_details($privKey) $pubKey = sshEncodePublicKey($rsaKey) //Public Keyįile_put_contents('/tmp/test.rsa', $pem) //save private key into fileįile_put_contents('/tmp/', $pubKey) //save public key into file Openssl_pkey_export($privKey, $pem) //Private Key $privKey = openssl_pkey_get_private($rsaKey)

'private_key_type' => OPENSSL_KEYTYPE_RSA)) This is based on Converting an OpenSSL generated RSA public key to OpenSSH format (PHP).

Openssh generate key