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/*
* digest support for NTP, MD5 and with OpenSSL more
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include "ntp_fp.h"
#include "ntp_string.h"
#include "ntp_stdlib.h"
#include "ntp.h"
#include "ntp_md5.h" /* provides OpenSSL digest API */
#include "isc/string.h"
/*
* MD5authencrypt - generate message digest
*
* Returns length of MAC including key ID and digest.
*/
size_t
MD5authencrypt(
int type, /* hash algorithm */
const u_char * key, /* key pointer */
u_int32 * pkt, /* packet pointer */
size_t length /* packet length */
)
{
u_char digest[EVP_MAX_MD_SIZE];
u_int len;
EVP_MD_CTX *ctx;
/*
* Compute digest of key concatenated with packet. Note: the
* key type and digest type have been verified when the key
* was creaded.
*/
INIT_SSL();
ctx = EVP_MD_CTX_new();
if (!(ctx && EVP_DigestInit(ctx, EVP_get_digestbynid(type)))) {
msyslog(LOG_ERR,
"MAC encrypt: digest init failed");
EVP_MD_CTX_free(ctx);
return (0);
}
EVP_DigestUpdate(ctx, key, cache_secretsize);
EVP_DigestUpdate(ctx, (u_char *)pkt, length);
EVP_DigestFinal(ctx, digest, &len);
EVP_MD_CTX_free(ctx);
/* If the MAC is longer than the MAX then truncate it. */
if (len > MAX_MAC_LEN - 4)
len = MAX_MAC_LEN - 4;
memmove((u_char *)pkt + length + 4, digest, len);
return (len + 4);
}
/*
* MD5authdecrypt - verify MD5 message authenticator
*
* Returns one if digest valid, zero if invalid.
*/
int
MD5authdecrypt(
int type, /* hash algorithm */
const u_char * key, /* key pointer */
u_int32 * pkt, /* packet pointer */
size_t length, /* packet length */
size_t size /* MAC size */
)
{
u_char digest[EVP_MAX_MD_SIZE];
u_int len;
EVP_MD_CTX *ctx;
/*
* Compute digest of key concatenated with packet. Note: the
* key type and digest type have been verified when the key
* was created.
*/
INIT_SSL();
ctx = EVP_MD_CTX_new();
if (!(ctx && EVP_DigestInit(ctx, EVP_get_digestbynid(type)))) {
msyslog(LOG_ERR,
"MAC decrypt: digest init failed");
EVP_MD_CTX_free(ctx);
return (0);
}
EVP_DigestUpdate(ctx, key, cache_secretsize);
EVP_DigestUpdate(ctx, (u_char *)pkt, length);
EVP_DigestFinal(ctx, digest, &len);
EVP_MD_CTX_free(ctx);
/* If the MAC is longer than the MAX then truncate it. */
if (len > MAX_MAC_LEN - 4)
len = MAX_MAC_LEN - 4;
if (size != (size_t)len + 4) {
msyslog(LOG_ERR,
"MAC decrypt: MAC length error");
return (0);
}
return !isc_tsmemcmp(digest, (u_char *)pkt + length + 4, len);
}
/*
* Calculate the reference id from the address. If it is an IPv4
* address, use it as is. If it is an IPv6 address, do a md5 on
* it and use the bottom 4 bytes.
* The result is in network byte order.
*/
u_int32
addr2refid(sockaddr_u *addr)
{
u_char digest[20];
u_int32 addr_refid;
EVP_MD_CTX *ctx;
u_int len;
if (IS_IPV4(addr))
return (NSRCADR(addr));
INIT_SSL();
ctx = EVP_MD_CTX_new();
EVP_MD_CTX_init(ctx);
#ifdef EVP_MD_CTX_FLAG_NON_FIPS_ALLOW
/* MD5 is not used as a crypto hash here. */
EVP_MD_CTX_set_flags(ctx, EVP_MD_CTX_FLAG_NON_FIPS_ALLOW);
#endif
if (!EVP_DigestInit_ex(ctx, EVP_md5(), NULL)) {
msyslog(LOG_ERR,
"MD5 init failed");
EVP_MD_CTX_free(ctx); /* pedantic... but safe */
exit(1);
}
EVP_DigestUpdate(ctx, (u_char *)PSOCK_ADDR6(addr),
sizeof(struct in6_addr));
EVP_DigestFinal(ctx, digest, &len);
EVP_MD_CTX_free(ctx);
memcpy(&addr_refid, digest, sizeof(addr_refid));
return (addr_refid);
}
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