/* Derive an encryption key from a usage key and (typically) checksum. */ static krb5_error_code enc_key(const struct krb5_enc_provider *enc, const struct krb5_hash_provider *hash, const krb5_keyblock *usage_keyblock, const krb5_data *checksum, krb5_keyblock *out) { krb5_keyblock *trunc_keyblock = NULL; krb5_data out_data = make_data(out->contents, out->length); krb5_crypto_iov iov; krb5_error_code ret; /* Copy usage_keyblock to trunc_keyblock and truncate if exportable. */ ret = krb5int_c_copy_keyblock(NULL, usage_keyblock, &trunc_keyblock); if (ret != 0) return ret; if (trunc_keyblock->enctype == ENCTYPE_ARCFOUR_HMAC_EXP) memset(trunc_keyblock->contents + 7, 0xab, 9); /* Compute HMAC(trunc_key, checksum) to produce the encryption key. */ iov.flags = KRB5_CRYPTO_TYPE_DATA; iov.data = *checksum; ret = krb5int_hmac_keyblock(hash, trunc_keyblock, &iov, 1, &out_data); krb5int_c_free_keyblock(NULL, trunc_keyblock); return ret; }
krb5_error_code krb5int_arcfour_gsscrypt(const krb5_keyblock *keyblock, krb5_keyusage usage, const krb5_data *kd_data, krb5_crypto_iov *data, size_t num_data) { const struct krb5_enc_provider *enc = &krb5int_enc_arcfour; const struct krb5_hash_provider *hash = &krb5int_hash_md5; krb5_keyblock *usage_keyblock = NULL, *enc_keyblock = NULL; krb5_error_code ret; ret = krb5int_c_init_keyblock(NULL, keyblock->enctype, enc->keybytes, &usage_keyblock); if (ret != 0) goto cleanup; ret = krb5int_c_init_keyblock(NULL, keyblock->enctype, enc->keybytes, &enc_keyblock); if (ret != 0) goto cleanup; /* Derive a usage key from the session key and usage. */ ret = usage_key(enc, hash, keyblock, usage, usage_keyblock); if (ret != 0) goto cleanup; /* Derive the encryption key from the usage key and kd_data. */ ret = enc_key(enc, hash, usage_keyblock, kd_data, enc_keyblock); if (ret != 0) goto cleanup; /* Encrypt or decrypt (encrypt_iov works for both) the input. */ ret = keyblock_crypt(enc, enc_keyblock, 0, data, num_data); cleanup: krb5int_c_free_keyblock(NULL, usage_keyblock); krb5int_c_free_keyblock(NULL, enc_keyblock); return ret; }
void KRB5_CALLCONV krb5_free_keyblock(krb5_context context, register krb5_keyblock *val) { krb5int_c_free_keyblock (context, val); }
krb5_error_code krb5int_arcfour_decrypt(const struct krb5_keytypes *ktp, krb5_key key, krb5_keyusage usage, const krb5_data *ivec, krb5_crypto_iov *data, size_t num_data) { const struct krb5_enc_provider *enc = ktp->enc; const struct krb5_hash_provider *hash = ktp->hash; krb5_error_code ret; krb5_crypto_iov *header, *trailer; krb5_keyblock *usage_keyblock = NULL, *enc_keyblock = NULL; krb5_data checksum, header_data, comp_checksum = empty_data(); header = krb5int_c_locate_iov(data, num_data, KRB5_CRYPTO_TYPE_HEADER); if (header == NULL || header->data.length != hash->hashsize + CONFOUNDERLENGTH) return KRB5_BAD_MSIZE; header_data = header->data; trailer = krb5int_c_locate_iov(data, num_data, KRB5_CRYPTO_TYPE_TRAILER); if (trailer != NULL && trailer->data.length != 0) return KRB5_BAD_MSIZE; /* Allocate buffers. */ ret = alloc_data(&comp_checksum, hash->hashsize); if (ret != 0) goto cleanup; ret = krb5int_c_init_keyblock(NULL, key->keyblock.enctype, enc->keybytes, &usage_keyblock); if (ret != 0) goto cleanup; ret = krb5int_c_init_keyblock(NULL, key->keyblock.enctype, enc->keybytes, &enc_keyblock); if (ret != 0) goto cleanup; checksum = make_data(header->data.data, hash->hashsize); /* Adjust pointers so confounder is at start of header. */ header->data.length -= hash->hashsize; header->data.data += hash->hashsize; /* We may have to try two usage values; see below. */ do { /* Derive a usage key from the session key and usage. */ ret = usage_key(enc, hash, &key->keyblock, usage, usage_keyblock); if (ret != 0) goto cleanup; /* Derive the encryption key from the usage key and checksum. */ ret = enc_key(enc, hash, usage_keyblock, &checksum, enc_keyblock); if (ret) goto cleanup; /* Decrypt the ciphertext. */ ret = keyblock_crypt(enc, enc_keyblock, ivec, data, num_data); if (ret != 0) goto cleanup; /* Compute HMAC(usage key, plaintext) to get the checksum. */ ret = krb5int_hmac_keyblock(hash, usage_keyblock, data, num_data, &comp_checksum); if (ret != 0) goto cleanup; if (k5_bcmp(checksum.data, comp_checksum.data, hash->hashsize) != 0) { if (usage == 9) { /* * RFC 4757 specifies usage 8 for TGS-REP encrypted parts * encrypted in a subkey, but the value used by MS is actually * 9. We now use 9 to start with, but fall back to 8 on * failure in case we are communicating with a KDC using the * value from the RFC. ivec is always NULL in this case. * We need to re-encrypt the data in the wrong key first. */ ret = keyblock_crypt(enc, enc_keyblock, NULL, data, num_data); if (ret != 0) goto cleanup; usage = 8; continue; } ret = KRB5KRB_AP_ERR_BAD_INTEGRITY; goto cleanup; } break; } while (1); cleanup: header->data = header_data; /* Restore header pointers. */ krb5int_c_free_keyblock(NULL, usage_keyblock); krb5int_c_free_keyblock(NULL, enc_keyblock); zapfree(comp_checksum.data, comp_checksum.length); return ret; }
krb5_error_code krb5int_arcfour_encrypt(const struct krb5_keytypes *ktp, krb5_key key, krb5_keyusage usage, const krb5_data *ivec, krb5_crypto_iov *data, size_t num_data) { const struct krb5_enc_provider *enc = ktp->enc; const struct krb5_hash_provider *hash = ktp->hash; krb5_error_code ret; krb5_crypto_iov *header, *trailer; krb5_keyblock *usage_keyblock = NULL, *enc_keyblock = NULL; krb5_data checksum, confounder, header_data; size_t i; /* * Caller must have provided space for the header, padding * and trailer; per RFC 4757 we will arrange it as: * * Checksum | E(Confounder | Plaintext) */ header = krb5int_c_locate_iov(data, num_data, KRB5_CRYPTO_TYPE_HEADER); if (header == NULL || header->data.length < hash->hashsize + CONFOUNDERLENGTH) return KRB5_BAD_MSIZE; header_data = header->data; /* Trailer may be absent. */ trailer = krb5int_c_locate_iov(data, num_data, KRB5_CRYPTO_TYPE_TRAILER); if (trailer != NULL) trailer->data.length = 0; /* Ensure that there is no padding. */ for (i = 0; i < num_data; i++) { if (data[i].flags == KRB5_CRYPTO_TYPE_PADDING) data[i].data.length = 0; } ret = krb5int_c_init_keyblock(NULL, key->keyblock.enctype, enc->keybytes, &usage_keyblock); if (ret != 0) goto cleanup; ret = krb5int_c_init_keyblock(NULL, key->keyblock.enctype, enc->keybytes, &enc_keyblock); if (ret != 0) goto cleanup; /* Derive a usage key from the session key and usage. */ ret = usage_key(enc, hash, &key->keyblock, usage, usage_keyblock); if (ret != 0) goto cleanup; /* Generate a confounder in the header block, after the checksum. */ header->data.length = hash->hashsize + CONFOUNDERLENGTH; confounder = make_data(header->data.data + hash->hashsize, CONFOUNDERLENGTH); ret = krb5_c_random_make_octets(0, &confounder); if (ret != 0) goto cleanup; checksum = make_data(header->data.data, hash->hashsize); /* Adjust pointers so confounder is at start of header. */ header->data.length -= hash->hashsize; header->data.data += hash->hashsize; /* Compute the checksum using the usage key. */ ret = krb5int_hmac_keyblock(hash, usage_keyblock, data, num_data, &checksum); if (ret != 0) goto cleanup; /* Derive the encryption key from the usage key and checksum. */ ret = enc_key(enc, hash, usage_keyblock, &checksum, enc_keyblock); if (ret) goto cleanup; ret = keyblock_crypt(enc, enc_keyblock, ivec, data, num_data); cleanup: header->data = header_data; /* Restore header pointers. */ krb5int_c_free_keyblock(NULL, usage_keyblock); krb5int_c_free_keyblock(NULL, enc_keyblock); return ret; }