# MIT Kerberos Documentation

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# krb5_mk_ncred - Format a KRB-CRED message for an array of credentials.

krb5_error_code `krb5_mk_ncred`(krb5_context context, krb5_auth_context auth_context, krb5_creds ** creds, krb5_data ** der_out, krb5_replay_data * rdata_out)

param: | [in] context - Library context [in] auth_context - Authentication context [in] creds - Null-terminated array of credentials [out] der_out - Encoded credentials [out] rdata_out - Replay cache information (NULL if not needed)

retval: | 0 Success ENOMEM Insufficient memory KRB5_RC_REQUIRED Message replay detection requires rcache parameter
return: | Kerberos error codes

This function takes an array of credentials creds and formats a KRB-CRED message der_out to pass to `krb5_rd_cred()` .

The local and remote addresses in auth_context are optional; if either is specified, they are used to form the sender and receiver addresses in the KRB-CRED message.

If the `KRB5_AUTH_CONTEXT_DO_TIME` flag is set in auth_context , an entry for the message is entered in an in-memory replay cache to detect if the message is reflected by an attacker. If `KRB5_AUTH_CONTEXT_DO_TIME` is not set, no replay cache is used. If `KRB5_AUTH_CONTEXT_RET_TIME` is set in auth_context , the timestamp used for the KRB-CRED message is stored in rdata_out .

If either `KRB5_AUTH_CONTEXT_DO_SEQUENCE` or `KRB5_AUTH_CONTEXT_RET_SEQUENCE` is set, the auth_context local sequence number is included in the KRB-CRED message and then incremented. If `KRB5_AUTH_CONTEXT_RET_SEQUENCE` is set, the sequence number used is stored in rdata_out .

Use `krb5_free_data_contents()` to free der_out when it is no longer needed.

The message will be encrypted using the send subkey of auth_context if it is present, or the session key otherwise. If neither key is present, the credentials will not be encrypted, and the message should only be sent over a secure channel. No replay cache entry is used in this case.

Note

The rdata_out argument is required if the `KRB5_AUTH_CONTEXT_RET_TIME` or `KRB5_AUTH_CONTEXT_RET_SEQUENCE` flag is set in auth_context .