Added crypto.new_hmac() feature. (#1499)
Docs for crypto module refactored for easier maintenance.
This commit is contained in:
Johny Mattsson
Marcel Stör
parent
19f80abb32
commit
a112296850
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@ -156,31 +156,22 @@ int ICACHE_FLASH_ATTR crypto_fhash (const digest_mech_info_t *mi,
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}
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int ICACHE_FLASH_ATTR crypto_hmac (const digest_mech_info_t *mi,
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const char *data, size_t data_len,
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const char *key, size_t key_len,
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uint8_t *digest)
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void crypto_hmac_begin (void *ctx, const digest_mech_info_t *mi,
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const char *key, size_t key_len, uint8_t *k_opad)
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{
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if (!mi)
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return EINVAL;
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void *ctx = (void *)os_malloc (mi->ctx_size);
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if (!ctx)
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return ENOMEM;
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// If key too long, it needs to be hashed before use
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char tmp[mi->digest_size];
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if (key_len > mi->block_size)
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{
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mi->create (ctx);
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mi->update (ctx, key, key_len);
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mi->finalize (digest, ctx);
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key = digest;
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mi->finalize (tmp, ctx);
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key = tmp;
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key_len = mi->digest_size;
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mi->create (ctx); // refresh
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}
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const size_t bs = mi->block_size;
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uint8_t k_ipad[bs];
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uint8_t k_opad[bs];
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os_memset (k_ipad, 0x36, bs);
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os_memset (k_opad, 0x5c, bs);
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@ -191,16 +182,42 @@ int ICACHE_FLASH_ATTR crypto_hmac (const digest_mech_info_t *mi,
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k_opad[i] ^= key[i];
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}
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mi->create (ctx);
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mi->update (ctx, k_ipad, bs);
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mi->update (ctx, data, data_len);
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}
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void crypto_hmac_finalize (void *ctx, const digest_mech_info_t *mi,
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const uint8_t *k_opad, uint8_t *digest)
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{
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mi->finalize (digest, ctx);
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mi->create (ctx);
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mi->update (ctx, k_opad, bs);
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mi->update (ctx, k_opad, mi->block_size);
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mi->update (ctx, digest, mi->digest_size);
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mi->finalize (digest, ctx);
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}
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os_free (ctx);
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int crypto_hmac (const digest_mech_info_t *mi,
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const char *data, size_t data_len,
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const char *key, size_t key_len,
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uint8_t *digest)
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{
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if (!mi)
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return EINVAL;
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struct {
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uint8_t ctx[mi->ctx_size];
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uint8_t k_opad[mi->block_size];
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} *tmp = os_malloc (sizeof (*tmp));
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if (!tmp)
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return ENOMEM;
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mi->create (tmp->ctx);
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crypto_hmac_begin (tmp->ctx, mi, key, key_len, tmp->k_opad);
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mi->update (tmp->ctx, data, data_len);
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crypto_hmac_finalize (tmp->ctx, mi, tmp->k_opad, digest);
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os_free (tmp);
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return 0;
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}
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@ -66,7 +66,35 @@ int crypto_hash (const digest_mech_info_t *mi, const char *data, size_t data_len
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int crypto_fhash (const digest_mech_info_t *mi, read_fn read, int readarg, uint8_t *digest);
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/**
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* Generate a HMAC signature.
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* Commence calculating a HMAC signature.
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*
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* Once this fuction returns successfully, the @c ctx may be updated with
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* data in multiple passes uses @c mi->update(), before being finalized via
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* @c crypto_hmac_finalize().
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*
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* @param ctx A created context for the given mech @c mi.
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* @param mi A mech from @c crypto_digest_mech().
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* @param key The key bytes to use.
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* @param key_len Number of bytes the @c key comprises.
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* @param k_opad Buffer of size @c mi->block_size bytes to store the second
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* round of key material in.
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* Must be passed to @c crypto_hmac_finalize().
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*/
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void crypto_hmac_begin (void *ctx, const digest_mech_info_t *mi, const char *key, size_t key_len, uint8_t *k_opad);
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/**
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* Finalizes calculating a HMAC signature.
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* @param ctx The created context used with @c crypto_hmac_begin().
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* @param mi The mech used with @c crypto_hmac_begin().
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* @param k_opad Second round of keying material, obtained
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* from @c crypto_hmac_begin().
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* @param digest Output buffer, must be at least @c mi->digest_size in size.
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*/
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void crypto_hmac_finalize (void *ctx, const digest_mech_info_t *mi, const uint8_t *k_opad, uint8_t *digest);
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/**
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* Generate a HMAC signature in one pass.
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* Implemented in terms of @c crypto_hmac_begin() / @c crypto_hmac_end().
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* @param mi A mech from @c crypto_digest_mech(). A null pointer @c mi
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* is harmless, but will of course result in an error return.
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* @param data The data to generate a signature for.
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@ -9,11 +9,18 @@
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#include "vfs.h"
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#include "../crypto/digests.h"
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#include "../crypto/mech.h"
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#include "lmem.h"
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#include "user_interface.h"
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#include "rom.h"
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typedef struct {
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const digest_mech_info_t *mech_info;
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void *ctx;
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uint8_t *k_opad;
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} digest_user_datum_t;
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/**
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* hash = crypto.sha1(input)
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*
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@ -150,11 +157,6 @@ static int crypto_lhash (lua_State *L)
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return 1;
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}
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typedef struct digest_user_datum_t {
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const digest_mech_info_t *mech_info;
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void *ctx;
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} digest_user_datum_t;
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/* General Usage for extensible hash functions:
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* sha = crypto.new_hash("MD5")
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* sha.update("Data")
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@ -162,19 +164,30 @@ typedef struct digest_user_datum_t {
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* strdigest = crypto.toHex(sha.finalize())
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*/
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/* crypto.new_hash("MECHTYPE") */
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static int crypto_new_hash (lua_State *L)
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#define WANT_HASH 0
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#define WANT_HMAC 1
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static int crypto_new_hash_hmac (lua_State *L, int what)
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{
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const digest_mech_info_t *mi = crypto_digest_mech (luaL_checkstring (L, 1));
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if (!mi)
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return bad_mech (L);
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void *ctx = os_malloc (mi->ctx_size);
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if (ctx==NULL)
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return bad_mem (L);
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size_t len = 0;
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const char *key = 0;
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uint8_t *k_opad = 0;
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if (what == WANT_HMAC)
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{
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key = luaL_checklstring (L, 2, &len);
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k_opad = luaM_malloc (L, mi->block_size);
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}
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void *ctx = luaM_malloc (L, mi->ctx_size);
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mi->create (ctx);
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if (what == WANT_HMAC)
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crypto_hmac_begin (ctx, mi, key, len, k_opad);
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// create a userdataum with specific metatable
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digest_user_datum_t *dudat = (digest_user_datum_t *)lua_newuserdata(L, sizeof(digest_user_datum_t));
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luaL_getmetatable(L, "crypto.hash");
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@ -183,10 +196,24 @@ static int crypto_new_hash (lua_State *L)
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// Set pointers to the mechanics and CTX
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dudat->mech_info = mi;
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dudat->ctx = ctx;
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dudat->k_opad = k_opad;
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return 1; // Pass userdata object back
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}
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/* crypto.new_hash("MECHTYPE") */
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static int crypto_new_hash (lua_State *L)
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{
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return crypto_new_hash_hmac (L, WANT_HASH);
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}
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/* crypto.new_hmac("MECHTYPE", "KEY") */
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static int crypto_new_hmac (lua_State *L)
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{
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return crypto_new_hash_hmac (L, WANT_HMAC);
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}
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/* Called as object, params:
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1 - userdata "this"
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2 - new string to add to the hash state */
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@ -197,7 +224,6 @@ static int crypto_hash_update (lua_State *L)
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size_t sl;
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dudat = (digest_user_datum_t *)luaL_checkudata(L, 1, "crypto.hash");
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luaL_argcheck(L, dudat, 1, "crypto.hash expected");
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const digest_mech_info_t *mi = dudat->mech_info;
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@ -217,11 +243,13 @@ static int crypto_hash_finalize (lua_State *L)
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size_t sl;
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dudat = (digest_user_datum_t *)luaL_checkudata(L, 1, "crypto.hash");
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luaL_argcheck(L, dudat, 1, "crypto.hash expected");
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const digest_mech_info_t *mi = dudat->mech_info;
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uint8_t digest[mi->digest_size]; // Allocate as local
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if (dudat->k_opad)
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crypto_hmac_finalize (dudat->ctx, mi, dudat->k_opad, digest);
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else
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mi->finalize (digest, dudat->ctx);
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lua_pushlstring (L, digest, sizeof (digest));
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@ -235,9 +263,11 @@ static int crypto_hash_gcdelete (lua_State *L)
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digest_user_datum_t *dudat;
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dudat = (digest_user_datum_t *)luaL_checkudata(L, 1, "crypto.hash");
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luaL_argcheck(L, dudat, 1, "crypto.hash expected");
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os_free(dudat->ctx);
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// luaM_free() uses type info to obtain original size, so have to delve
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// one level deeper and explicitly pass the size due to void*
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luaM_realloc_ (L, dudat->ctx, dudat->mech_info->ctx_size, 0);
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luaM_free (L, dudat->k_opad);
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return 0;
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}
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@ -386,6 +416,7 @@ static const LUA_REG_TYPE crypto_map[] = {
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{ LSTRKEY( "fhash" ), LFUNCVAL( crypto_flhash ) },
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{ LSTRKEY( "new_hash" ), LFUNCVAL( crypto_new_hash ) },
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{ LSTRKEY( "hmac" ), LFUNCVAL( crypto_lhmac ) },
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{ LSTRKEY( "new_hmac" ), LFUNCVAL( crypto_new_hmac ) },
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{ LSTRKEY( "encrypt" ), LFUNCVAL( lcrypto_encrypt ) },
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{ LSTRKEY( "decrypt" ), LFUNCVAL( lcrypto_decrypt ) },
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{ LNILKEY, LNILVAL }
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@ -5,6 +5,16 @@
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The crypto modules provides various functions for working with cryptographic algorithms.
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The following encryption/decryption algorithms/modes are supported:
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- `"AES-ECB"` for 128-bit AES in ECB mode (NOT recommended)
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- `"AES-CBC"` for 128-bit AES in CBC mode
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The following hash algorithms are supported:
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- MD2 (not available by default, has to be explicitly enabled in `app/include/user_config.h`)
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- MD5
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- SHA1
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- SHA256, SHA384, SHA512 (unless disabled in `app/include/user_config.h`)
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## crypto.encrypt()
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Encrypts Lua strings.
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@ -13,9 +23,7 @@ Encrypts Lua strings.
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`crypto.encrypt(algo, key, plain [, iv])`
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#### Parameters
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- `algo` the name of the encryption algorithm to use, one of
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- `"AES-ECB"` for 128-bit AES in ECB mode
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- `"AES-CBC"` for 128-bit AES in CBC mode
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- `algo` the name of a supported encryption algorithm to use
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- `key` the encryption key as a string; for AES encryption this *MUST* be 16 bytes long
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- `plain` the string to encrypt; it will be automatically zero-padded to a 16-byte boundary if necessary
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- `iv` the initilization vector, if using AES-CBC; defaults to all-zero if not given
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@ -40,9 +48,7 @@ Decrypts previously encrypted data.
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`crypto.decrypt(algo, key, cipher [, iv])`
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#### Parameters
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- `algo` the name of the encryption algorithm to use, one of
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- `"AES-ECB"` for 128-bit AES in ECB mode
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- `"AES-CBC"` for 128-bit AES in CBC mode
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- `algo` the name of a supported encryption algorithm to use
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- `key` the encryption key as a string; for AES encryption this *MUST* be 16 bytes long
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- `cipher` the cipher text to decrypt (as obtained from `crypto.encrypt()`)
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- `iv` the initilization vector, if using AES-CBC; defaults to all-zero if not given
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@ -75,13 +81,6 @@ Compute a cryptographic hash of a a file.
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- `algo` the hash algorithm to use, case insensitive string
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- `filename` the path to the file to hash
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Supported hash algorithms are:
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- MD2 (not available by default, has to be explicitly enabled in `app/include/user_config.h`)
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- MD5
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- SHA1
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- SHA256, SHA384, SHA512 (unless disabled in `app/include/user_config.h`)
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#### Returns
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A binary string containing the message digest. To obtain the textual version (ASCII hex characters), please use [`crypto.toHex()`](#cryptotohex ).
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@ -101,13 +100,6 @@ Compute a cryptographic hash of a Lua string.
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`algo` the hash algorithm to use, case insensitive string
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`str` string to hash contents of
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Supported hash algorithms are:
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- MD2 (not available by default, has to be explicitly enabled in `app/include/user_config.h`)
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- MD5
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- SHA1
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- SHA256, SHA384, SHA512 (unless disabled in `app/include/user_config.h`)
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#### Returns
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A binary string containing the message digest. To obtain the textual version (ASCII hex characters), please use [`crypto.toHex()`](#cryptotohex ).
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@ -126,13 +118,6 @@ Create a digest/hash object that can have any number of strings added to it. Obj
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#### Parameters
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`algo` the hash algorithm to use, case insensitive string
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Supported hash algorithms are:
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- MD2 (not available by default, has to be explicitly enabled in `app/include/user_config.h`)
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- MD5
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- SHA1
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- SHA256, SHA384, SHA512 (unless disabled in `app/include/user_config.h`)
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#### Returns
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Userdata object with `update` and `finalize` functions available.
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@ -157,13 +142,6 @@ Compute a [HMAC](https://en.wikipedia.org/wiki/Hash-based_message_authentication
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- `str` data to calculate the hash for
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- `key` key to use for signing, may be a binary string
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Supported hash algorithms are:
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- MD2 (not available by default, has to be explicitly enabled in `app/include/user_config.h`)
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- MD5
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- SHA1
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- SHA256, SHA384, SHA512 (unless disabled in `app/include/user_config.h`)
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#### Returns
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A binary string containing the HMAC signature. Use [`crypto.toHex()`](#cryptotohex ) to obtain the textual version.
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@ -172,6 +150,30 @@ A binary string containing the HMAC signature. Use [`crypto.toHex()`](#cryptotoh
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print(crypto.toHex(crypto.hmac("sha1","abc","mysecret")))
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```
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## crypto.new_hmac()
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Create a hmac object that can have any number of strings added to it. Object has `update` and `finalize` functions.
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#### Syntax
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`hmacobj = crypto.new_hmac(algo, key)`
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#### Parameters
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- `algo` the hash algorithm to use, case insensitive string
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- `key` the key to use (may be a binary string)
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#### Returns
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Userdata object with `update` and `finalize` functions available.
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#### Example
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```lua
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hmacobj = crypto.new_hmac("SHA1", "s3kr3t")
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hmacobj:update("FirstString"))
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hmacobj:update("SecondString"))
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digest = hmacobj:finalize()
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print(crypto.toHex(digest))
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```
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## crypto.mask()
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Applies an XOR mask to a Lua string. Note that this is not a proper cryptographic mechanism, but some protocols may use it nevertheless.
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