KRB5_GET_INIT_CREDS(3)

✨ KRB5_GET_INIT_CREDS — the group-chat edition ✨

okay so bestie, welcome to KRB5_GET_INIT_CREDS(3), fresh out of the Library Functions Manual. it's giving Kerberos, it's giving initial authentication, it's giving "let me get you a ticket so you can actually do stuff". let's go 💅

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🎀 NAME 🎀

krb5_get_init_creds, krb5_get_init_creds_keytab, krb5_get_init_creds_opt, krb5_get_init_creds_opt_alloc, krb5_get_init_creds_opt_free, krb5_get_init_creds_opt_init, krb5_get_init_creds_opt_set_address_list, krb5_get_init_creds_opt_set_addressless, krb5_get_init_creds_opt_set_anonymous, krb5_get_init_creds_opt_set_default_flags, krb5_get_init_creds_opt_set_etype_list, krb5_get_init_creds_opt_set_forwardable, krb5_get_init_creds_opt_set_pa_password, krb5_get_init_creds_opt_set_paq_request, krb5_get_init_creds_opt_set_preauth_list, krb5_get_init_creds_opt_set_proxiable, krb5_get_init_creds_opt_set_renew_life, krb5_get_init_creds_opt_set_salt, krb5_get_init_creds_opt_set_tkt_life, krb5_get_init_creds_opt_set_canonicalize, krb5_get_init_creds_opt_set_win2k, krb5_get_init_creds_password, krb5_prompt, krb5_prompter_posix — Kerberos 5 initial authentication functions

like. that's the whole roster. every single one of them is here, no cap.

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💖 LIBRARY 💖

Kerberos 5 Library (libkrb5, -lkrb5) — so you know where to link it, bestie 🫶

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🌸 SYNOPSIS 🌸

#include <krb5.h>

krb5_get_init_creds_opt;

krb5_error_code
krb5_get_init_creds_opt_alloc(krb5_context context,
    krb5_get_init_creds_opt **opt);

void
krb5_get_init_creds_opt_free(krb5_context context,
    krb5_get_init_creds_opt *opt);

void
krb5_get_init_creds_opt_init(krb5_get_init_creds_opt *opt);

void
krb5_get_init_creds_opt_set_address_list(krb5_get_init_creds_opt *opt,
    krb5_addresses *addresses);

void
krb5_get_init_creds_opt_set_addressless(krb5_get_init_creds_opt *opt,
    krb5_boolean addressless);

void
krb5_get_init_creds_opt_set_anonymous(krb5_get_init_creds_opt *opt,
    int anonymous);

void
krb5_get_init_creds_opt_set_change_password_prompt(krb5_get_init_creds_opt *opt,
    int change_password_prompt);

void
krb5_get_init_creds_opt_set_default_flags(krb5_context context,
    const char *appname, krb5_const_realm realm,
    krb5_get_init_creds_opt *opt);

void
krb5_get_init_creds_opt_set_etype_list(krb5_get_init_creds_opt *opt,
    krb5_enctype *etype_list, int etype_list_length);

void
krb5_get_init_creds_opt_set_forwardable(krb5_get_init_creds_opt *opt,
    int forwardable);

krb5_error_code
krb5_get_init_creds_opt_set_pa_password(krb5_context context,
    krb5_get_init_creds_opt *opt, const char *password,
    krb5_s2k_proc key_proc);

krb5_error_code
krb5_get_init_creds_opt_set_paq_request(krb5_context context,
    krb5_get_init_creds_opt *opt, krb5_boolean req_pac);

krb5_error_code
krb5_get_init_creds_opt_set_pkinit(krb5_context context,
    krb5_get_init_creds_opt *opt, const char *cert_file,
    const char *key_file, const char *x509_anchors, int flags,
    char *password);

void
krb5_get_init_creds_opt_set_preauth_list(krb5_get_init_creds_opt *opt,
    krb5_preauthtype *preauth_list, int preauth_list_length);

void
krb5_get_init_creds_opt_set_proxiable(krb5_get_init_creds_opt *opt,
    int proxiable);

void
krb5_get_init_creds_opt_set_renew_life(krb5_get_init_creds_opt *opt,
    krb5_deltat renew_life);

void
krb5_get_init_creds_opt_set_salt(krb5_get_init_creds_opt *opt,
    krb5_data *salt);

void
krb5_get_init_creds_opt_set_tkt_life(krb5_get_init_creds_opt *opt,
    krb5_deltat tkt_life);

krb5_error_code
krb5_get_init_creds_opt_set_canonicalize(krb5_context context,
    krb5_get_init_creds_opt *opt, krb5_boolean req);

krb5_error_code
krb5_get_init_creds_opt_set_win2k(krb5_context context,
    krb5_get_init_creds_opt *opt, krb5_boolean req);

krb5_error_code
krb5_get_init_creds(krb5_context context, krb5_creds *creds,
    krb5_principal client, krb5_prompter_fct prompter,
    void *prompter_data, krb5_deltat start_time,
    const char *in_tkt_service, krb5_get_init_creds_opt *options);

krb5_error_code
krb5_get_init_creds_password(krb5_context context, krb5_creds *creds,
    krb5_principal client, const char *password,
    krb5_prompter_fct prompter, void *prompter_data,
    krb5_deltat start_time, const char *in_tkt_service,
    krb5_get_init_creds_opt *in_options);

krb5_error_code
krb5_get_init_creds_keytab(krb5_context context, krb5_creds *creds,
    krb5_principal client, krb5_keytab keytab, krb5_deltat start_time,
    const char *in_tkt_service, krb5_get_init_creds_opt *options);

int
krb5_prompter_posix(krb5_context context, void *data, const char *name,
    const char *banner, int num_prompts, krb5_prompt prompts[]);

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🦋 DESCRIPTION 🦋

So the whole point, the moment, the main character energy: getting an initial credential ticket for a principal. ✨

And honestly? that may include changing an expired password, and doing preauthentication. it's a whole journey. This is the interface that replaces the deprecated krb5_in_tkt and krb5_in_cred functions — those are old news, we don't talk about them 💀

If you only want to verify a username and password, bestie, consider using krb5_verify_user(3) instead, since it also verifies that initial credentials with using a keytab to make sure the response was from the KDC. like, extra safety, extra slay.

okay so the flow:

1. First a krb5_get_init_creds_opt structure is initialized with krb5_get_init_creds_opt_alloc() or krb5_get_init_creds_opt_init().
2. krb5_get_init_creds_opt_alloc() allocates a extendible structures that needs to be freed with krb5_get_init_creds_opt_free(). you HAVE to free it. no leaks in this household 🚫
3. The structure may be modified by any of the krb5_get_init_creds_opt_set() functions to change request parameters and authentication information.

If the caller want to use the default options, NULL can be passed instead. easy. lazy-girl-approved 🙈

The the actual request to the KDC is done by any of the krb5_get_init_creds(), krb5_get_init_creds_password(), or krb5_get_init_creds_keytab() functions.

• krb5_get_init_creds() is the least specialized function and can, with the right in data, behave like the latter two.
• The latter two are there for compatibility with older releases and they are slightly easier to use.

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🍓 the krb5_prompt struct, look at her 🍓

krb5_prompt is a structure containing the following elements:

typedef struct {
    const char *prompt;
    int hidden;
    krb5_data *reply;
    krb5_prompt_type type
} krb5_prompt;

okay breaking it down:

• prompt is the prompt that should shown to the user.
• If hidden is set, the prompter function shouldn't echo the output to the display device. (secret girl era 🤫)
• reply must be preallocated; it will not be allocated by the prompter function. so like, do it yourself bestie.

Possible values for the type element are:

• KRB5_PROMPT_TYPE_PASSWORD
• KRB5_PROMPT_TYPE_NEW_PASSWORD
• KRB5_PROMPT_TYPE_NEW_PASSWORD_AGAIN
• KRB5_PROMPT_TYPE_PREAUTH
• KRB5_PROMPT_TYPE_INFO

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🧚 prompter things

krb5_prompter_posix() is the default prompter function in a POSIX environment. It matches the krb5_prompter_fct and can be used in the krb5_get_init_creds functions. krb5_prompter_posix() doesn't require prompter_data. iconic behavior, honestly 👑

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⭐ the args, one by one

• If the start_time is zero, then the requested ticket will be valid beginning immediately. Otherwise, the start_time indicates how far in the future the ticket should be postdated.
• If the in_tkt_service name is non-NULL, that principal name will be used as the server name for the initial ticket request. The realm of the name specified will be ignored and will be set to the realm of the client name. If no in_tkt_service name is specified, krbtgt/CLIENT-REALM@CLIENT-REALM will be used.
• For the rest of arguments, a configuration or library default will be used if no value is specified in the options structure.

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💜 the krb5_get_init_creds_opt_set* girlies

• krb5_get_init_creds_opt_set_address_list() sets the list of addresses that is should be stored in the ticket.
• krb5_get_init_creds_opt_set_addressless() controls if the ticket is requested with addresses or not, krb5_get_init_creds_opt_set_address_list() overrides this option. (so the list one wins the argument, periodt)
• krb5_get_init_creds_opt_set_anonymous() make the request anonymous if the anonymous parameter is non-zero.
• krb5_get_init_creds_opt_set_default_flags() sets the default flags using the configuration file.
• krb5_get_init_creds_opt_set_etype_list() set a list of enctypes that the client is willing to support in the request.
• krb5_get_init_creds_opt_set_forwardable() request a forwardable ticket.
• krb5_get_init_creds_opt_set_pa_password() set the password and key_proc that is going to be used to get a new ticket. password or key_proc can be NULL if the caller wants to use the default values. If the password is unset and needed, the user will be prompted for it.
• krb5_get_init_creds_opt_set_paq_request() sets the password that is going to be used to get a new ticket. (yes bestie, that's literally what it says. we report, we don't editorialize 💀)
• krb5_get_init_creds_opt_set_preauth_list() sets the list of client-supported preauth types.
• krb5_get_init_creds_opt_set_proxiable() makes the request proxiable.
• krb5_get_init_creds_opt_set_renew_life() sets the requested renewable lifetime.
• krb5_get_init_creds_opt_set_salt() sets the salt that is going to be used in the request.
• krb5_get_init_creds_opt_set_tkt_life() sets requested ticket lifetime.
• krb5_get_init_creds_opt_set_canonicalize() requests that the KDC canonicalize the client principal if possible.
• krb5_get_init_creds_opt_set_win2k() turns on compatibility with Windows 2000. (a retro moment 🎀)

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👑 SEE ALSO 👑

• krb5(3)
• krb5_creds(3)
• krb5_verify_user(3)
• krb5.conf(5)
• kerberos(8)

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and that's the whole page, bestie!! this one's from HEIMDAL, dated Sep 16, 2006 — yeah she's vintage but she ATE and she's still serving. go get those credentials, ily 🫶💖✨