1 /* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
2 /* lib/crypto/krb/prf_dk.c - RFC 3961 simplified profile PRF */
4 * Copyright (C) 2004 by the Massachusetts Institute of Technology.
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18 * to distribution of the software without specific, written prior
19 * permission. Furthermore if you modify this software you must label
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27 #include "crypto_int.h"
30 krb5int_dk_prf(const struct krb5_keytypes *ktp, krb5_key key,
31 const krb5_data *in, krb5_data *out)
33 const struct krb5_enc_provider *enc = ktp->enc;
34 const struct krb5_hash_provider *hash = ktp->hash;
36 krb5_data cksum = empty_data(), prfconst = make_data("prf", 3);
40 /* Hash the input data into an allocated buffer. */
41 ret = alloc_data(&cksum, hash->hashsize);
44 iov.flags = KRB5_CRYPTO_TYPE_DATA;
46 ret = hash->hash(&iov, 1, &cksum);
50 /* Derive a key using the PRF constant. */
51 ret = krb5int_derive_key(ktp->enc, key, &kp, &prfconst, DERIVE_RFC3961);
55 /* Truncate the hash to the closest multiple of the block size. */
56 iov.data.data = cksum.data;
57 iov.data.length = (hash->hashsize / enc->block_size) * enc->block_size;
59 /* Encrypt the truncated hash in the derived key to get the output. */
60 ret = ktp->enc->encrypt(kp, NULL, &iov, 1);
63 memcpy(out->data, iov.data.data, out->length);
66 zapfree(cksum.data, hash->hashsize);
67 krb5_k_free_key(NULL, kp);