COAP-OSCORE-CONF(5)

NAME
coap-oscore-conf - CoAP OSCORE configuration file format

DESCRIPTION

The OSCORE configuration file is read in when using the *-E* oscore_conf_file option for the coap-client(5) or coap-server(5) executables. This then allows a client or server to use OSCORE to protect the CoAP information between endpoints (RFC8613).

It is also read in and parsed by coap_new_oscore_conf(3).

This configuration file can be a configuration held in memory, the formatting of the memory region is same as that for a file as if the file was mapped into memory. The coap_new_oscore_conf(3) function uses the memory version of the file.

The configuration file comprises of a set of keywords, the value of the keyword encoding type and the keyword value, one per line, comma separated.

keyword,encoding,value

The keywords are case sensitive. If a line starts with a #, then it is treated as a comment line and so is ignored. Empty lines are also valid and ignored.

The possible encodings are:

ascii
    The value is encoded as a binary representation of the ascii string. This string can optionally be enclosed in ".

bool
    The textual string is either true or false and is subsequently encoded as an integer number.

hex
    The value is encoded as a binary representation of the hex string. This string can optionally be enclosed in ".

integer
    The value is encoded as an integer number.

text
    The string value is mapped and then encoded as an integer number. This string can optionally be enclosed in ". A subset of the Names from https://www.iana.org/assignments/cose/cose.xhtml#algorithms or https://www.iana.org/assignments/cose/cose.xhtml#elliptic-curves are supported.

The valid keywords are:

master_secret
    (hex or ascii) (Required) (No default) "RFC8613 Section 3.1. Security Context Definition". Master Secret. Variable length. Must be the same for both client and server.

master_salt
    (hex or ascii) (Optional) (No default) "RFC8613 Section 3.1. Security Context Definition". Master Salt. Variable length. Must be the same for both client and server.

id_context
    (hex or ascii) (Optional) (No default) "RFC8613 Section 3.1. Security Context Definition". ID Context. Variable length. Must be the same for both client and server.

sender_id
    (hex or ascii) (Required) (No default) "RFC8613 Section 3.1. Security Context Definition". Sender ID. This is the local application ID. Maximum length is determined by the AEAD Algorithm (typically 7 bytes).

recipient_id
    (hex or ascii) (Required for client, else Optional) (No default) "RFC8613 Section 3.1. Security Context Definition". Recipient ID. This is the remote peer application ID. Maximum length is determined by the AEAD Algorithm (typically 7 bytes). For servers, there can be zero or more (unique) recipient_ids. Additional recipient_ids can be added programmatically to the OSCORE configuration - see coap_new_oscore_recipient(3). For clients, there should only be one recipient_id (only the first is used).

replay_window
    (integer) (Optional) (Default is 32) "RFC8613 Section 3.1. Security Context Definition". Recipient Replay Window (Server Only). Supported values are 1 - 63.

aead_alg
    (integer or text) (Optional) (Default is 10 or "AES-CCM-16-64-128") "RFC8613 Section 3.1. Security Context Definition". AEAD Algorithm. Only the mandatory and a small subset of the algorithms are supported depending on the TLS library.

hkdf_alg
    (integer or text) (Optional) (Default is -10 or "direct+HKDF-SHA-256") "RFC8613 Section 3.1. Security Context Definition". HDKF Algorithm. Only the mandatory and a small subset of the algorithms are supported depending on the TLS library.

rfc8613_b_1_2
    (bool) (Optional) (Default is true) "RFC8613 Appendix B.1.2. Replay Window". Enable server rebooting Replay Window.

rfc8613_b_2
    (bool) (Optional) (Default is false) "RFC8613 Appendix B.2. Security Context Derived Multiple Times". Enable Security Context protocol.

ssn_freq
    (integer) (Optional) (Default is 1) "RFC8613 Appendix B.1.1. Sender Sequence Number". Sender Sequence Number frequency non-volatile storage update rate. Has to be a positive number.

Diagnostic testing options

break_sender_key
    (bool) (Optional) (Default is false) Enable random breaking of the derived sender key.

break_recipient_key
    (bool) (Optional) (Default is false) Enable random breaking of the derived recipient key.

EXAMPLE SERVER OSCORE CONFIGURATION FILE

    # Master Secret (same for both client and server)
    master_secret,hex,"0102030405060708090a0b0c0d0e0f10"
    # Master Salt (same for both client and server)
    master_salt,hex,"9e7ca92223786340"
    # Sender ID
    sender_id,ascii,"server"
    # Recipient ID
    recipient_id,ascii,"client"
    # Replay Window (usually 32)
    replay_window,integer,32
    # AEAD COSE Cipher Algorithm (usually 10)
    aead_alg,integer,10
    # HKDF COSE Algorithm (usually -10)
    hkdf_alg,integer,-10

EXAMPLE CLIENT OSCORE CONFIGURATION FILE

    # Master Secret (same for both client and server)
    master_secret,hex,"0102030405060708090a0b0c0d0e0f10"
    # Master Salt (same for both client and server)
    master_salt,hex,"9e7ca92223786340"
    # Sender ID (This is the client who is the Sender)
    sender_id,ascii,"client"
    # Recipient ID (It is the server that is remote)
    recipient_id,ascii,"server"
    # Replay Window (usually 32)
    replay_window,integer,32
    # AEAD COSE Cipher Algorithm (usually 10)
    aead_alg,integer,10
    # HKDF COSE Algorithm (usually -10)
    hkdf_alg,integer,-10

SEE ALSO

coap-client(5), coap-server(5) and coap_new_oscore_conf(3)

FURTHER INFORMATION

See

"RFC8613: Object Security for Constrained RESTful Environments (OSCORE)"

for further information.

BUGS

Please raise an issue on GitHub at https://github.com/obgm/libcoap/issues to report any bugs.

Please raise a Pull Request at https://github.com/obgm/libcoap/pulls for any fixes.

AUTHORS

The libcoap project <libcoap-developers@lists.sourceforge.net>