/* SPDX-License-Identifier: GPL-2.0-or-later */
/* Kerberos 5 crypto
 *
 * Copyright (C) 2025 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#ifndef _CRYPTO_KRB5_H
#define _CRYPTO_KRB5_H

#include <linux/crypto.h>
#include <crypto/aead.h>
#include <crypto/hash.h>

struct crypto_shash;
struct scatterlist;

/*
 * Per Kerberos v5 protocol spec crypto types from the wire.  These get mapped
 * to linux kernel crypto routines.
 */
#define KRB5_ENCTYPE_NULL                       0x0000
#define KRB5_ENCTYPE_DES_CBC_CRC                0x0001  /* DES cbc mode with CRC-32 */
#define KRB5_ENCTYPE_DES_CBC_MD4                0x0002  /* DES cbc mode with RSA-MD4 */
#define KRB5_ENCTYPE_DES_CBC_MD5                0x0003  /* DES cbc mode with RSA-MD5 */
#define KRB5_ENCTYPE_DES_CBC_RAW                0x0004  /* DES cbc mode raw */
/* XXX deprecated? */
#define KRB5_ENCTYPE_DES3_CBC_SHA               0x0005  /* DES-3 cbc mode with NIST-SHA */
#define KRB5_ENCTYPE_DES3_CBC_RAW               0x0006  /* DES-3 cbc mode raw */
#define KRB5_ENCTYPE_DES_HMAC_SHA1              0x0008
#define KRB5_ENCTYPE_DES3_CBC_SHA1              0x0010
#define KRB5_ENCTYPE_AES128_CTS_HMAC_SHA1_96    0x0011
#define KRB5_ENCTYPE_AES256_CTS_HMAC_SHA1_96    0x0012
#define KRB5_ENCTYPE_AES128_CTS_HMAC_SHA256_128 0x0013
#define KRB5_ENCTYPE_AES256_CTS_HMAC_SHA384_192 0x0014
#define KRB5_ENCTYPE_ARCFOUR_HMAC               0x0017
#define KRB5_ENCTYPE_ARCFOUR_HMAC_EXP           0x0018
#define KRB5_ENCTYPE_CAMELLIA128_CTS_CMAC       0x0019
#define KRB5_ENCTYPE_CAMELLIA256_CTS_CMAC       0x001a
#define KRB5_ENCTYPE_UNKNOWN                    0x01ff

#define KRB5_CKSUMTYPE_CRC32                    0x0001
#define KRB5_CKSUMTYPE_RSA_MD4                  0x0002
#define KRB5_CKSUMTYPE_RSA_MD4_DES              0x0003
#define KRB5_CKSUMTYPE_DESCBC                   0x0004
#define KRB5_CKSUMTYPE_RSA_MD5                  0x0007
#define KRB5_CKSUMTYPE_RSA_MD5_DES              0x0008
#define KRB5_CKSUMTYPE_NIST_SHA                 0x0009
#define KRB5_CKSUMTYPE_HMAC_SHA1_DES3           0x000c
#define KRB5_CKSUMTYPE_HMAC_SHA1_96_AES128      0x000f
#define KRB5_CKSUMTYPE_HMAC_SHA1_96_AES256      0x0010
#define KRB5_CKSUMTYPE_CMAC_CAMELLIA128         0x0011
#define KRB5_CKSUMTYPE_CMAC_CAMELLIA256         0x0012
#define KRB5_CKSUMTYPE_HMAC_SHA256_128_AES128   0x0013
#define KRB5_CKSUMTYPE_HMAC_SHA384_192_AES256   0x0014
#define KRB5_CKSUMTYPE_HMAC_MD5_ARCFOUR         -138 /* Microsoft md5 hmac cksumtype */

/*
 * Constants used for key derivation
 */
/* from rfc3961 */
#define KEY_USAGE_SEED_CHECKSUM         (0x99)
#define KEY_USAGE_SEED_ENCRYPTION       (0xAA)
#define KEY_USAGE_SEED_INTEGRITY        (0x55)

/*
 * Standard Kerberos error codes.
 */
#define KRB5_PROG_KEYTYPE_NOSUPP                -1765328233

/*
 * Mode of operation.
 */
enum krb5_crypto_mode {
        KRB5_CHECKSUM_MODE,     /* Checksum only */
        KRB5_ENCRYPT_MODE,      /* Fully encrypted, possibly with integrity checksum */
};

struct krb5_buffer {
        unsigned int    len;
        void            *data;
};

/*
 * Kerberos encoding type definition.
 */
struct krb5_enctype {
        int             etype;          /* Encryption (key) type */
        int             ctype;          /* Checksum type */
        const char      *name;          /* "Friendly" name */
        const char      *encrypt_name;  /* Crypto encrypt+checksum name */
        const char      *cksum_name;    /* Crypto checksum name */
        const char      *hash_name;     /* Crypto hash name */
        const char      *derivation_enc; /* Cipher used in key derivation */
        u16             block_len;      /* Length of encryption block */
        u16             conf_len;       /* Length of confounder (normally == block_len) */
        u16             cksum_len;      /* Length of checksum */
        u16             key_bytes;      /* Length of raw key, in bytes */
        u16             key_len;        /* Length of final key, in bytes */
        u16             hash_len;       /* Length of hash in bytes */
        u16             prf_len;        /* Length of PRF() result in bytes */
        u16             Kc_len;         /* Length of Kc in bytes */
        u16             Ke_len;         /* Length of Ke in bytes */
        u16             Ki_len;         /* Length of Ki in bytes */
        bool            keyed_cksum;    /* T if a keyed cksum */

        const struct krb5_crypto_profile *profile;

        int (*random_to_key)(const struct krb5_enctype *krb5,
                             const struct krb5_buffer *in,
                             struct krb5_buffer *out);  /* complete key generation */
};

/*
 * krb5_api.c
 */
const struct krb5_enctype *crypto_krb5_find_enctype(u32 enctype);
size_t crypto_krb5_how_much_buffer(const struct krb5_enctype *krb5,
                                   enum krb5_crypto_mode mode,
                                   size_t data_size, size_t *_offset);
size_t crypto_krb5_how_much_data(const struct krb5_enctype *krb5,
                                 enum krb5_crypto_mode mode,
                                 size_t *_buffer_size, size_t *_offset);
void crypto_krb5_where_is_the_data(const struct krb5_enctype *krb5,
                                   enum krb5_crypto_mode mode,
                                   size_t *_offset, size_t *_len);
struct crypto_aead *crypto_krb5_prepare_encryption(const struct krb5_enctype *krb5,
                                                   const struct krb5_buffer *TK,
                                                   u32 usage, gfp_t gfp);
struct crypto_shash *crypto_krb5_prepare_checksum(const struct krb5_enctype *krb5,
                                                  const struct krb5_buffer *TK,
                                                  u32 usage, gfp_t gfp);
ssize_t crypto_krb5_encrypt(const struct krb5_enctype *krb5,
                            struct crypto_aead *aead,
                            struct scatterlist *sg, unsigned int nr_sg,
                            size_t sg_len,
                            size_t data_offset, size_t data_len,
                            bool preconfounded);
int crypto_krb5_decrypt(const struct krb5_enctype *krb5,
                        struct crypto_aead *aead,
                        struct scatterlist *sg, unsigned int nr_sg,
                        size_t *_offset, size_t *_len);
ssize_t crypto_krb5_get_mic(const struct krb5_enctype *krb5,
                            struct crypto_shash *shash,
                            const struct krb5_buffer *metadata,
                            struct scatterlist *sg, unsigned int nr_sg,
                            size_t sg_len,
                            size_t data_offset, size_t data_len);
int crypto_krb5_verify_mic(const struct krb5_enctype *krb5,
                           struct crypto_shash *shash,
                           const struct krb5_buffer *metadata,
                           struct scatterlist *sg, unsigned int nr_sg,
                           size_t *_offset, size_t *_len);

/*
 * krb5_kdf.c
 */
int crypto_krb5_calc_PRFplus(const struct krb5_enctype *krb5,
                             const struct krb5_buffer *K,
                             unsigned int L,
                             const struct krb5_buffer *S,
                             struct krb5_buffer *result,
                             gfp_t gfp);

#endif /* _CRYPTO_KRB5_H */