Credential files format

To use RPK or X509 certificate with Leshan demos your need to provide credentials files 🔒.
This page aims to share information about how generate such files.

RPK 🔑

Using OpenSSL

Create EC keys using default openssl pem encoding : (prime256v1 also know as secp256r1, is the default curve

openssl ecparam -out keys.pem -name prime256v1 -genkey 

Now we will convert those keys in formats which is used for Security(id 0) object in LWM2M specification and which is also well supported by the JVM.
Convert private Key to PKCS#8 format (DER encoding) :

openssl pkcs8 -topk8 -inform PEM -outform DER -in keys.pem -out cprik.der -nocrypt

Output public key portion in SubjectPublicKeyInfo format (DER encoding) :

openssl ec -in keys.pem -pubout -outform DER -out cpubk.der

For further information about Elliptic curves and OpenSSL, refer to openSSL wiki.
To find coordonates(x,y) of an elliptic curve public key, you can look at this post.

X509 📜

(Not yet available)

Get hexa string from file

On Linux

To get hexa string :

xxd -p -c 512 cpubk.der

Credential file formats

To try to find your way in the jungle of credentials file format your could have a look at :

• https://tls.mbed.org/kb/cryptography/asn1-key-structures-in-der-and-pem
• https://serverfault.com/questions/9708/what-is-a-pem-file-and-how-does-it-differ-from-other-openssl-generated-key-file
• https://support.ssl.com/Knowledgebase/Article/View/19/0/der-vs-crt-vs-cer-vs-pem-certificates-and-how-to-convert-them