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mongoose/src/tls_aes128.c
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Sergey Lyubka d094e090ff Squash warnings
2024-03-27 08:58:48 +00:00

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/******************************************************************************
*
* THIS SOURCE CODE IS HEREBY PLACED INTO THE PUBLIC DOMAIN FOR THE GOOD OF ALL
*
* This is a simple and straightforward implementation of the AES Rijndael
* 128-bit block cipher designed by Vincent Rijmen and Joan Daemen. The focus
* of this work was correctness & accuracy. It is written in 'C' without any
* particular focus upon optimization or speed. It should be endian (memory
* byte order) neutral since the few places that care are handled explicitly.
*
* This implementation of Rijndael was created by Steven M. Gibson of GRC.com.
*
* It is intended for general purpose use, but was written in support of GRC's
* reference implementation of the SQRL (Secure Quick Reliable Login) client.
*
* See: http://csrc.nist.gov/archive/aes/rijndael/wsdindex.html
*
* NO COPYRIGHT IS CLAIMED IN THIS WORK, HOWEVER, NEITHER IS ANY WARRANTY MADE
* REGARDING ITS FITNESS FOR ANY PARTICULAR PURPOSE. USE IT AT YOUR OWN RISK.
*
*******************************************************************************/
/******************************************************************************/
#define AES_DECRYPTION 1 // whether AES decryption is supported
/******************************************************************************/
#define MG_ENCRYPT 1 // specify whether we're encrypting
#define MG_DECRYPT 0 // or decrypting
#include "arch.h"
#include "tls.h"
#include "tls_aes128.h"
#if MG_TLS == MG_TLS_BUILTIN
/******************************************************************************
* AES_INIT_KEYGEN_TABLES : MUST be called once before any AES use
******************************************************************************/
static void aes_init_keygen_tables(void);
/******************************************************************************
* AES_SETKEY : called to expand the key for encryption or decryption
******************************************************************************/
static int aes_setkey(aes_context *ctx, // pointer to context
int mode, // 1 or 0 for Encrypt/Decrypt
const uchar *key, // AES input key
uint keysize); // size in bytes (must be 16, 24, 32 for
// 128, 192 or 256-bit keys respectively)
// returns 0 for success
/******************************************************************************
* AES_CIPHER : called to encrypt or decrypt ONE 128-bit block of data
******************************************************************************/
static int aes_cipher(aes_context *ctx, // pointer to context
const uchar input[16], // 128-bit block to en/decipher
uchar output[16]); // 128-bit output result block
// returns 0 for success
/******************************************************************************
* GCM_CONTEXT : GCM context / holds keytables, instance data, and AES ctx
******************************************************************************/
typedef struct {
int mode; // cipher direction: encrypt/decrypt
uint64_t len; // cipher data length processed so far
uint64_t add_len; // total add data length
uint64_t HL[16]; // precalculated lo-half HTable
uint64_t HH[16]; // precalculated hi-half HTable
uchar base_ectr[16]; // first counter-mode cipher output for tag
uchar y[16]; // the current cipher-input IV|Counter value
uchar buf[16]; // buf working value
aes_context aes_ctx; // cipher context used
} gcm_context;
/******************************************************************************
* GCM_SETKEY : sets the GCM (and AES) keying material for use
******************************************************************************/
static int gcm_setkey(
gcm_context *ctx, // caller-provided context ptr
const uchar *key, // pointer to cipher key
const uint keysize // size in bytes (must be 16, 24, 32 for
// 128, 192 or 256-bit keys respectively)
); // returns 0 for success
/******************************************************************************
*
* GCM_CRYPT_AND_TAG
*
* This either encrypts or decrypts the user-provided data and, either
* way, generates an authentication tag of the requested length. It must be
* called with a GCM context whose key has already been set with GCM_SETKEY.
*
* The user would typically call this explicitly to ENCRYPT a buffer of data
* and optional associated data, and produce its an authentication tag.
*
* To reverse the process the user would typically call the companion
* GCM_AUTH_DECRYPT function to decrypt data and verify a user-provided
* authentication tag. The GCM_AUTH_DECRYPT function calls this function
* to perform its decryption and tag generation, which it then compares.
*
******************************************************************************/
static int gcm_crypt_and_tag(
gcm_context *ctx, // gcm context with key already setup
int mode, // cipher direction: MG_ENCRYPT (1) or MG_DECRYPT (0)
const uchar *iv, // pointer to the 12-byte initialization vector
size_t iv_len, // byte length if the IV. should always be 12
const uchar *add, // pointer to the non-ciphered additional data
size_t add_len, // byte length of the additional AEAD data
const uchar *input, // pointer to the cipher data source
uchar *output, // pointer to the cipher data destination
size_t length, // byte length of the cipher data
uchar *tag, // pointer to the tag to be generated
size_t tag_len); // byte length of the tag to be generated
/******************************************************************************
*
* GCM_START
*
* Given a user-provided GCM context, this initializes it, sets the encryption
* mode, and preprocesses the initialization vector and additional AEAD data.
*
******************************************************************************/
static int gcm_start(
gcm_context *ctx, // pointer to user-provided GCM context
int mode, // MG_ENCRYPT (1) or MG_DECRYPT (0)
const uchar *iv, // pointer to initialization vector
size_t iv_len, // IV length in bytes (should == 12)
const uchar *add, // pointer to additional AEAD data (NULL if none)
size_t add_len); // length of additional AEAD data (bytes)
/******************************************************************************
*
* GCM_UPDATE
*
* This is called once or more to process bulk plaintext or ciphertext data.
* We give this some number of bytes of input and it returns the same number
* of output bytes. If called multiple times (which is fine) all but the final
* invocation MUST be called with length mod 16 == 0. (Only the final call can
* have a partial block length of < 128 bits.)
*
******************************************************************************/
static int gcm_update(gcm_context *ctx, // pointer to user-provided GCM context
size_t length, // length, in bytes, of data to process
const uchar *input, // pointer to source data
uchar *output); // pointer to destination data
/******************************************************************************
*
* GCM_FINISH
*
* This is called once after all calls to GCM_UPDATE to finalize the GCM.
* It performs the final GHASH to produce the resulting authentication TAG.
*
******************************************************************************/
static int gcm_finish(
gcm_context *ctx, // pointer to user-provided GCM context
uchar *tag, // ptr to tag buffer - NULL if tag_len = 0
size_t tag_len); // length, in bytes, of the tag-receiving buf
/******************************************************************************
*
* GCM_ZERO_CTX
*
* The GCM context contains both the GCM context and the AES context.
* This includes keying and key-related material which is security-
* sensitive, so it MUST be zeroed after use. This function does that.
*
******************************************************************************/
static void gcm_zero_ctx(gcm_context *ctx);
/******************************************************************************
*
* THIS SOURCE CODE IS HEREBY PLACED INTO THE PUBLIC DOMAIN FOR THE GOOD OF ALL
*
* This is a simple and straightforward implementation of the AES Rijndael
* 128-bit block cipher designed by Vincent Rijmen and Joan Daemen. The focus
* of this work was correctness & accuracy. It is written in 'C' without any
* particular focus upon optimization or speed. It should be endian (memory
* byte order) neutral since the few places that care are handled explicitly.
*
* This implementation of Rijndael was created by Steven M. Gibson of GRC.com.
*
* It is intended for general purpose use, but was written in support of GRC's
* reference implementation of the SQRL (Secure Quick Reliable Login) client.
*
* See: http://csrc.nist.gov/archive/aes/rijndael/wsdindex.html
*
* NO COPYRIGHT IS CLAIMED IN THIS WORK, HOWEVER, NEITHER IS ANY WARRANTY MADE
* REGARDING ITS FITNESS FOR ANY PARTICULAR PURPOSE. USE IT AT YOUR OWN RISK.
*
*******************************************************************************/
#include "tls.h"
#include "tls_aes128.h"
static int aes_tables_inited = 0; // run-once flag for performing key
// expasion table generation (see below)
/*
* The following static local tables must be filled-in before the first use of
* the GCM or AES ciphers. They are used for the AES key expansion/scheduling
* and once built are read-only and thread safe. The "gcm_initialize" function
* must be called once during system initialization to populate these arrays
* for subsequent use by the AES key scheduler. If they have not been built
* before attempted use, an error will be returned to the caller.
*
* NOTE: GCM Encryption/Decryption does NOT REQUIRE AES decryption. Since
* GCM uses AES in counter-mode, where the AES cipher output is XORed with
* the GCM input, we ONLY NEED AES encryption. Thus, to save space AES
* decryption is typically disabled by setting AES_DECRYPTION to 0 in aes.h.
*/
// We always need our forward tables
static uchar FSb[256]; // Forward substitution box (FSb)
static uint32_t FT0[256]; // Forward key schedule assembly tables
static uint32_t FT1[256];
static uint32_t FT2[256];
static uint32_t FT3[256];
#if AES_DECRYPTION // We ONLY need reverse for decryption
static uchar RSb[256]; // Reverse substitution box (RSb)
static uint32_t RT0[256]; // Reverse key schedule assembly tables
static uint32_t RT1[256];
static uint32_t RT2[256];
static uint32_t RT3[256];
#endif /* AES_DECRYPTION */
static uint32_t RCON[10]; // AES round constants
/*
* Platform Endianness Neutralizing Load and Store Macro definitions
* AES wants platform-neutral Little Endian (LE) byte ordering
*/
#define GET_UINT32_LE(n, b, i) \
{ \
(n) = ((uint32_t) (b)[(i)]) | ((uint32_t) (b)[(i) + 1] << 8) | \
((uint32_t) (b)[(i) + 2] << 16) | ((uint32_t) (b)[(i) + 3] << 24); \
}
#define PUT_UINT32_LE(n, b, i) \
{ \
(b)[(i)] = (uchar) ((n)); \
(b)[(i) + 1] = (uchar) ((n) >> 8); \
(b)[(i) + 2] = (uchar) ((n) >> 16); \
(b)[(i) + 3] = (uchar) ((n) >> 24); \
}
/*
* AES forward and reverse encryption round processing macros
*/
#define AES_FROUND(X0, X1, X2, X3, Y0, Y1, Y2, Y3) \
{ \
X0 = *RK++ ^ FT0[(Y0) & 0xFF] ^ FT1[(Y1 >> 8) & 0xFF] ^ \
FT2[(Y2 >> 16) & 0xFF] ^ FT3[(Y3 >> 24) & 0xFF]; \
\
X1 = *RK++ ^ FT0[(Y1) & 0xFF] ^ FT1[(Y2 >> 8) & 0xFF] ^ \
FT2[(Y3 >> 16) & 0xFF] ^ FT3[(Y0 >> 24) & 0xFF]; \
\
X2 = *RK++ ^ FT0[(Y2) & 0xFF] ^ FT1[(Y3 >> 8) & 0xFF] ^ \
FT2[(Y0 >> 16) & 0xFF] ^ FT3[(Y1 >> 24) & 0xFF]; \
\
X3 = *RK++ ^ FT0[(Y3) & 0xFF] ^ FT1[(Y0 >> 8) & 0xFF] ^ \
FT2[(Y1 >> 16) & 0xFF] ^ FT3[(Y2 >> 24) & 0xFF]; \
}
#define AES_RROUND(X0, X1, X2, X3, Y0, Y1, Y2, Y3) \
{ \
X0 = *RK++ ^ RT0[(Y0) & 0xFF] ^ RT1[(Y3 >> 8) & 0xFF] ^ \
RT2[(Y2 >> 16) & 0xFF] ^ RT3[(Y1 >> 24) & 0xFF]; \
\
X1 = *RK++ ^ RT0[(Y1) & 0xFF] ^ RT1[(Y0 >> 8) & 0xFF] ^ \
RT2[(Y3 >> 16) & 0xFF] ^ RT3[(Y2 >> 24) & 0xFF]; \
\
X2 = *RK++ ^ RT0[(Y2) & 0xFF] ^ RT1[(Y1 >> 8) & 0xFF] ^ \
RT2[(Y0 >> 16) & 0xFF] ^ RT3[(Y3 >> 24) & 0xFF]; \
\
X3 = *RK++ ^ RT0[(Y3) & 0xFF] ^ RT1[(Y2 >> 8) & 0xFF] ^ \
RT2[(Y1 >> 16) & 0xFF] ^ RT3[(Y0 >> 24) & 0xFF]; \
}
/*
* These macros improve the readability of the key
* generation initialization code by collapsing
* repetitive common operations into logical pieces.
*/
#define ROTL8(x) ((x << 8) & 0xFFFFFFFF) | (x >> 24)
#define XTIME(x) ((x << 1) ^ ((x & 0x80) ? 0x1B : 0x00))
#define MUL(x, y) ((x && y) ? pow[(log[x] + log[y]) % 255] : 0)
#define MIX(x, y) \
{ \
y = ((y << 1) | (y >> 7)) & 0xFF; \
x ^= y; \
}
#define CPY128 \
{ \
*RK++ = *SK++; \
*RK++ = *SK++; \
*RK++ = *SK++; \
*RK++ = *SK++; \
}
/******************************************************************************
*
* AES_INIT_KEYGEN_TABLES
*
* Fills the AES key expansion tables allocated above with their static
* data. This is not "per key" data, but static system-wide read-only
* table data. THIS FUNCTION IS NOT THREAD SAFE. It must be called once
* at system initialization to setup the tables for all subsequent use.
*
******************************************************************************/
void aes_init_keygen_tables(void) {
int i, x, y, z; // general purpose iteration and computation locals
int pow[256];
int log[256];
if (aes_tables_inited) return;
// fill the 'pow' and 'log' tables over GF(2^8)
for (i = 0, x = 1; i < 256; i++) {
pow[i] = x;
log[x] = i;
x = (x ^ XTIME(x)) & 0xFF;
}
// compute the round constants
for (i = 0, x = 1; i < 10; i++) {
RCON[i] = (uint32_t) x;
x = XTIME(x) & 0xFF;
}
// fill the forward and reverse substitution boxes
FSb[0x00] = 0x63;
#if AES_DECRYPTION // whether AES decryption is supported
RSb[0x63] = 0x00;
#endif /* AES_DECRYPTION */
for (i = 1; i < 256; i++) {
x = y = pow[255 - log[i]];
MIX(x, y);
MIX(x, y);
MIX(x, y);
MIX(x, y);
FSb[i] = (uchar) (x ^= 0x63);
#if AES_DECRYPTION // whether AES decryption is supported
RSb[x] = (uchar) i;
#endif /* AES_DECRYPTION */
}
// generate the forward and reverse key expansion tables
for (i = 0; i < 256; i++) {
x = FSb[i];
y = XTIME(x) & 0xFF;
z = (y ^ x) & 0xFF;
FT0[i] = ((uint32_t) y) ^ ((uint32_t) x << 8) ^ ((uint32_t) x << 16) ^
((uint32_t) z << 24);
FT1[i] = ROTL8(FT0[i]);
FT2[i] = ROTL8(FT1[i]);
FT3[i] = ROTL8(FT2[i]);
#if AES_DECRYPTION // whether AES decryption is supported
x = RSb[i];
RT0[i] = ((uint32_t) MUL(0x0E, x)) ^ ((uint32_t) MUL(0x09, x) << 8) ^
((uint32_t) MUL(0x0D, x) << 16) ^ ((uint32_t) MUL(0x0B, x) << 24);
RT1[i] = ROTL8(RT0[i]);
RT2[i] = ROTL8(RT1[i]);
RT3[i] = ROTL8(RT2[i]);
#endif /* AES_DECRYPTION */
}
aes_tables_inited = 1; // flag that the tables have been generated
} // to permit subsequent use of the AES cipher
/******************************************************************************
*
* AES_SET_ENCRYPTION_KEY
*
* This is called by 'aes_setkey' when we're establishing a key for
* subsequent encryption. We give it a pointer to the encryption
* context, a pointer to the key, and the key's length in bytes.
* Valid lengths are: 16, 24 or 32 bytes (128, 192, 256 bits).
*
******************************************************************************/
static int aes_set_encryption_key(aes_context *ctx, const uchar *key,
uint keysize) {
uint i; // general purpose iteration local
uint32_t *RK = ctx->rk; // initialize our RoundKey buffer pointer
for (i = 0; i < (keysize >> 2); i++) {
GET_UINT32_LE(RK[i], key, i << 2);
}
switch (ctx->rounds) {
case 10:
for (i = 0; i < 10; i++, RK += 4) {
RK[4] = RK[0] ^ RCON[i] ^ ((uint32_t) FSb[(RK[3] >> 8) & 0xFF]) ^
((uint32_t) FSb[(RK[3] >> 16) & 0xFF] << 8) ^
((uint32_t) FSb[(RK[3] >> 24) & 0xFF] << 16) ^
((uint32_t) FSb[(RK[3]) & 0xFF] << 24);
RK[5] = RK[1] ^ RK[4];
RK[6] = RK[2] ^ RK[5];
RK[7] = RK[3] ^ RK[6];
}
break;
case 12:
for (i = 0; i < 8; i++, RK += 6) {
RK[6] = RK[0] ^ RCON[i] ^ ((uint32_t) FSb[(RK[5] >> 8) & 0xFF]) ^
((uint32_t) FSb[(RK[5] >> 16) & 0xFF] << 8) ^
((uint32_t) FSb[(RK[5] >> 24) & 0xFF] << 16) ^
((uint32_t) FSb[(RK[5]) & 0xFF] << 24);
RK[7] = RK[1] ^ RK[6];
RK[8] = RK[2] ^ RK[7];
RK[9] = RK[3] ^ RK[8];
RK[10] = RK[4] ^ RK[9];
RK[11] = RK[5] ^ RK[10];
}
break;
case 14:
for (i = 0; i < 7; i++, RK += 8) {
RK[8] = RK[0] ^ RCON[i] ^ ((uint32_t) FSb[(RK[7] >> 8) & 0xFF]) ^
((uint32_t) FSb[(RK[7] >> 16) & 0xFF] << 8) ^
((uint32_t) FSb[(RK[7] >> 24) & 0xFF] << 16) ^
((uint32_t) FSb[(RK[7]) & 0xFF] << 24);
RK[9] = RK[1] ^ RK[8];
RK[10] = RK[2] ^ RK[9];
RK[11] = RK[3] ^ RK[10];
RK[12] = RK[4] ^ ((uint32_t) FSb[(RK[11]) & 0xFF]) ^
((uint32_t) FSb[(RK[11] >> 8) & 0xFF] << 8) ^
((uint32_t) FSb[(RK[11] >> 16) & 0xFF] << 16) ^
((uint32_t) FSb[(RK[11] >> 24) & 0xFF] << 24);
RK[13] = RK[5] ^ RK[12];
RK[14] = RK[6] ^ RK[13];
RK[15] = RK[7] ^ RK[14];
}
break;
default:
return -1;
}
return (0);
}
#if AES_DECRYPTION // whether AES decryption is supported
/******************************************************************************
*
* AES_SET_DECRYPTION_KEY
*
* This is called by 'aes_setkey' when we're establishing a
* key for subsequent decryption. We give it a pointer to
* the encryption context, a pointer to the key, and the key's
* length in bits. Valid lengths are: 128, 192, or 256 bits.
*
******************************************************************************/
static int aes_set_decryption_key(aes_context *ctx, const uchar *key,
uint keysize) {
int i, j;
aes_context cty; // a calling aes context for set_encryption_key
uint32_t *RK = ctx->rk; // initialize our RoundKey buffer pointer
uint32_t *SK;
int ret;
cty.rounds = ctx->rounds; // initialize our local aes context
cty.rk = cty.buf; // round count and key buf pointer
if ((ret = aes_set_encryption_key(&cty, key, keysize)) != 0) return (ret);
SK = cty.rk + cty.rounds * 4;
CPY128 // copy a 128-bit block from *SK to *RK
for (i = ctx->rounds - 1, SK -= 8; i > 0; i--, SK -= 8) {
for (j = 0; j < 4; j++, SK++) {
*RK++ = RT0[FSb[(*SK) & 0xFF]] ^ RT1[FSb[(*SK >> 8) & 0xFF]] ^
RT2[FSb[(*SK >> 16) & 0xFF]] ^ RT3[FSb[(*SK >> 24) & 0xFF]];
}
}
CPY128 // copy a 128-bit block from *SK to *RK
memset(&cty, 0, sizeof(aes_context)); // clear local aes context
return (0);
}
#endif /* AES_DECRYPTION */
/******************************************************************************
*
* AES_SETKEY
*
* Invoked to establish the key schedule for subsequent encryption/decryption
*
******************************************************************************/
static int aes_setkey(aes_context *ctx, // AES context provided by our caller
int mode, // ENCRYPT or DECRYPT flag
const uchar *key, // pointer to the key
uint keysize) // key length in bytes
{
// since table initialization is not thread safe, we could either add
// system-specific mutexes and init the AES key generation tables on
// demand, or ask the developer to simply call "gcm_initialize" once during
// application startup before threading begins. That's what we choose.
if (!aes_tables_inited) return (-1); // fail the call when not inited.
ctx->mode = mode; // capture the key type we're creating
ctx->rk = ctx->buf; // initialize our round key pointer
switch (keysize) // set the rounds count based upon the keysize
{
case 16:
ctx->rounds = 10;
break; // 16-byte, 128-bit key
case 24:
ctx->rounds = 12;
break; // 24-byte, 192-bit key
case 32:
ctx->rounds = 14;
break; // 32-byte, 256-bit key
default:
return (-1);
}
#if AES_DECRYPTION
if (mode == MG_DECRYPT) // expand our key for encryption or decryption
return (aes_set_decryption_key(ctx, key, keysize));
else /* MG_ENCRYPT */
#endif /* AES_DECRYPTION */
return (aes_set_encryption_key(ctx, key, keysize));
}
/******************************************************************************
*
* AES_CIPHER
*
* Perform AES encryption and decryption.
* The AES context will have been setup with the encryption mode
* and all keying information appropriate for the task.
*
******************************************************************************/
static int aes_cipher(aes_context *ctx, const uchar input[16],
uchar output[16]) {
int i;
uint32_t *RK, X0, X1, X2, X3, Y0, Y1, Y2, Y3; // general purpose locals
RK = ctx->rk;
GET_UINT32_LE(X0, input, 0);
X0 ^= *RK++; // load our 128-bit
GET_UINT32_LE(X1, input, 4);
X1 ^= *RK++; // input buffer in a storage
GET_UINT32_LE(X2, input, 8);
X2 ^= *RK++; // memory endian-neutral way
GET_UINT32_LE(X3, input, 12);
X3 ^= *RK++;
#if AES_DECRYPTION // whether AES decryption is supported
if (ctx->mode == MG_DECRYPT) {
for (i = (ctx->rounds >> 1) - 1; i > 0; i--) {
AES_RROUND(Y0, Y1, Y2, Y3, X0, X1, X2, X3);
AES_RROUND(X0, X1, X2, X3, Y0, Y1, Y2, Y3);
}
AES_RROUND(Y0, Y1, Y2, Y3, X0, X1, X2, X3);
X0 = *RK++ ^ ((uint32_t) RSb[(Y0) & 0xFF]) ^
((uint32_t) RSb[(Y3 >> 8) & 0xFF] << 8) ^
((uint32_t) RSb[(Y2 >> 16) & 0xFF] << 16) ^
((uint32_t) RSb[(Y1 >> 24) & 0xFF] << 24);
X1 = *RK++ ^ ((uint32_t) RSb[(Y1) & 0xFF]) ^
((uint32_t) RSb[(Y0 >> 8) & 0xFF] << 8) ^
((uint32_t) RSb[(Y3 >> 16) & 0xFF] << 16) ^
((uint32_t) RSb[(Y2 >> 24) & 0xFF] << 24);
X2 = *RK++ ^ ((uint32_t) RSb[(Y2) & 0xFF]) ^
((uint32_t) RSb[(Y1 >> 8) & 0xFF] << 8) ^
((uint32_t) RSb[(Y0 >> 16) & 0xFF] << 16) ^
((uint32_t) RSb[(Y3 >> 24) & 0xFF] << 24);
X3 = *RK++ ^ ((uint32_t) RSb[(Y3) & 0xFF]) ^
((uint32_t) RSb[(Y2 >> 8) & 0xFF] << 8) ^
((uint32_t) RSb[(Y1 >> 16) & 0xFF] << 16) ^
((uint32_t) RSb[(Y0 >> 24) & 0xFF] << 24);
} else /* MG_ENCRYPT */
{
#endif /* AES_DECRYPTION */
for (i = (ctx->rounds >> 1) - 1; i > 0; i--) {
AES_FROUND(Y0, Y1, Y2, Y3, X0, X1, X2, X3);
AES_FROUND(X0, X1, X2, X3, Y0, Y1, Y2, Y3);
}
AES_FROUND(Y0, Y1, Y2, Y3, X0, X1, X2, X3);
X0 = *RK++ ^ ((uint32_t) FSb[(Y0) & 0xFF]) ^
((uint32_t) FSb[(Y1 >> 8) & 0xFF] << 8) ^
((uint32_t) FSb[(Y2 >> 16) & 0xFF] << 16) ^
((uint32_t) FSb[(Y3 >> 24) & 0xFF] << 24);
X1 = *RK++ ^ ((uint32_t) FSb[(Y1) & 0xFF]) ^
((uint32_t) FSb[(Y2 >> 8) & 0xFF] << 8) ^
((uint32_t) FSb[(Y3 >> 16) & 0xFF] << 16) ^
((uint32_t) FSb[(Y0 >> 24) & 0xFF] << 24);
X2 = *RK++ ^ ((uint32_t) FSb[(Y2) & 0xFF]) ^
((uint32_t) FSb[(Y3 >> 8) & 0xFF] << 8) ^
((uint32_t) FSb[(Y0 >> 16) & 0xFF] << 16) ^
((uint32_t) FSb[(Y1 >> 24) & 0xFF] << 24);
X3 = *RK++ ^ ((uint32_t) FSb[(Y3) & 0xFF]) ^
((uint32_t) FSb[(Y0 >> 8) & 0xFF] << 8) ^
((uint32_t) FSb[(Y1 >> 16) & 0xFF] << 16) ^
((uint32_t) FSb[(Y2 >> 24) & 0xFF] << 24);
#if AES_DECRYPTION // whether AES decryption is supported
}
#endif /* AES_DECRYPTION */
PUT_UINT32_LE(X0, output, 0);
PUT_UINT32_LE(X1, output, 4);
PUT_UINT32_LE(X2, output, 8);
PUT_UINT32_LE(X3, output, 12);
return (0);
}
/* end of aes.c */
/******************************************************************************
*
* THIS SOURCE CODE IS HEREBY PLACED INTO THE PUBLIC DOMAIN FOR THE GOOD OF ALL
*
* This is a simple and straightforward implementation of AES-GCM authenticated
* encryption. The focus of this work was correctness & accuracy. It is written
* in straight 'C' without any particular focus upon optimization or speed. It
* should be endian (memory byte order) neutral since the few places that care
* are handled explicitly.
*
* This implementation of AES-GCM was created by Steven M. Gibson of GRC.com.
*
* It is intended for general purpose use, but was written in support of GRC's
* reference implementation of the SQRL (Secure Quick Reliable Login) client.
*
* See: http://csrc.nist.gov/publications/nistpubs/800-38D/SP-800-38D.pdf
* http://csrc.nist.gov/groups/ST/toolkit/BCM/documents/proposedmodes/
* gcm/gcm-revised-spec.pdf
*
* NO COPYRIGHT IS CLAIMED IN THIS WORK, HOWEVER, NEITHER IS ANY WARRANTY MADE
* REGARDING ITS FITNESS FOR ANY PARTICULAR PURPOSE. USE IT AT YOUR OWN RISK.
*
*******************************************************************************/
/******************************************************************************
* ==== IMPLEMENTATION WARNING ====
*
* This code was developed for use within SQRL's fixed environmnent. Thus, it
* is somewhat less "general purpose" than it would be if it were designed as
* a general purpose AES-GCM library. Specifically, it bothers with almost NO
* error checking on parameter limits, buffer bounds, etc. It assumes that it
* is being invoked by its author or by someone who understands the values it
* expects to receive. Its behavior will be undefined otherwise.
*
* All functions that might fail are defined to return 'ints' to indicate a
* problem. Most do not do so now. But this allows for error propagation out
* of internal functions if robust error checking should ever be desired.
*
******************************************************************************/
/* Calculating the "GHASH"
*
* There are many ways of calculating the so-called GHASH in software, each with
* a traditional size vs performance tradeoff. The GHASH (Galois field hash) is
* an intriguing construction which takes two 128-bit strings (also the cipher's
* block size and the fundamental operation size for the system) and hashes them
* into a third 128-bit result.
*
* Many implementation solutions have been worked out that use large precomputed
* table lookups in place of more time consuming bit fiddling, and this approach
* can be scaled easily upward or downward as needed to change the time/space
* tradeoff. It's been studied extensively and there's a solid body of theory
* and practice. For example, without using any lookup tables an implementation
* might obtain 119 cycles per byte throughput, whereas using a simple, though
* large, key-specific 64 kbyte 8-bit lookup table the performance jumps to 13
* cycles per byte.
*
* And Intel's processors have, since 2010, included an instruction which does
* the entire 128x128->128 bit job in just several 64x64->128 bit pieces.
*
* Since SQRL is interactive, and only processing a few 128-bit blocks, I've
* settled upon a relatively slower but appealing small-table compromise which
* folds a bunch of not only time consuming but also bit twiddling into a simple
* 16-entry table which is attributed to Victor Shoup's 1996 work while at
* Bellcore: "On Fast and Provably Secure MessageAuthentication Based on
* Universal Hashing." See: http://www.shoup.net/papers/macs.pdf
* See, also section 4.1 of the "gcm-revised-spec" cited above.
*/
/*
* This 16-entry table of pre-computed constants is used by the
* GHASH multiplier to improve over a strictly table-free but
* significantly slower 128x128 bit multiple within GF(2^128).
*/
static const uint64_t last4[16] = {
0x0000, 0x1c20, 0x3840, 0x2460, 0x7080, 0x6ca0, 0x48c0, 0x54e0,
0xe100, 0xfd20, 0xd940, 0xc560, 0x9180, 0x8da0, 0xa9c0, 0xb5e0};
/*
* Platform Endianness Neutralizing Load and Store Macro definitions
* GCM wants platform-neutral Big Endian (BE) byte ordering
*/
#define GET_UINT32_BE(n, b, i) \
{ \
(n) = ((uint32_t) (b)[(i)] << 24) | ((uint32_t) (b)[(i) + 1] << 16) | \
((uint32_t) (b)[(i) + 2] << 8) | ((uint32_t) (b)[(i) + 3]); \
}
#define PUT_UINT32_BE(n, b, i) \
{ \
(b)[(i)] = (uchar) ((n) >> 24); \
(b)[(i) + 1] = (uchar) ((n) >> 16); \
(b)[(i) + 2] = (uchar) ((n) >> 8); \
(b)[(i) + 3] = (uchar) ((n)); \
}
/******************************************************************************
*
* GCM_INITIALIZE
*
* Must be called once to initialize the GCM library.
*
* At present, this only calls the AES keygen table generator, which expands
* the AES keying tables for use. This is NOT A THREAD-SAFE function, so it
* MUST be called during system initialization before a multi-threading
* environment is running.
*
******************************************************************************/
int mg_gcm_initialize(void) {
aes_init_keygen_tables();
return (0);
}
/******************************************************************************
*
* GCM_MULT
*
* Performs a GHASH operation on the 128-bit input vector 'x', setting
* the 128-bit output vector to 'x' times H using our precomputed tables.
* 'x' and 'output' are seen as elements of GCM's GF(2^128) Galois field.
*
******************************************************************************/
static void gcm_mult(gcm_context *ctx, // pointer to established context
const uchar x[16], // pointer to 128-bit input vector
uchar output[16]) // pointer to 128-bit output vector
{
int i;
uchar lo, hi, rem;
uint64_t zh, zl;
lo = (uchar) (x[15] & 0x0f);
hi = (uchar) (x[15] >> 4);
zh = ctx->HH[lo];
zl = ctx->HL[lo];
for (i = 15; i >= 0; i--) {
lo = (uchar) (x[i] & 0x0f);
hi = (uchar) (x[i] >> 4);
if (i != 15) {
rem = (uchar) (zl & 0x0f);
zl = (zh << 60) | (zl >> 4);
zh = (zh >> 4);
zh ^= (uint64_t) last4[rem] << 48;
zh ^= ctx->HH[lo];
zl ^= ctx->HL[lo];
}
rem = (uchar) (zl & 0x0f);
zl = (zh << 60) | (zl >> 4);
zh = (zh >> 4);
zh ^= (uint64_t) last4[rem] << 48;
zh ^= ctx->HH[hi];
zl ^= ctx->HL[hi];
}
PUT_UINT32_BE(zh >> 32, output, 0);
PUT_UINT32_BE(zh, output, 4);
PUT_UINT32_BE(zl >> 32, output, 8);
PUT_UINT32_BE(zl, output, 12);
}
/******************************************************************************
*
* GCM_SETKEY
*
* This is called to set the AES-GCM key. It initializes the AES key
* and populates the gcm context's pre-calculated HTables.
*
******************************************************************************/
static int gcm_setkey(
gcm_context *ctx, // pointer to caller-provided gcm context
const uchar *key, // pointer to the AES encryption key
const uint keysize) // size in bytes (must be 16, 24, 32 for
// 128, 192 or 256-bit keys respectively)
{
int ret, i, j;
uint64_t hi, lo;
uint64_t vl, vh;
unsigned char h[16];
memset(ctx, 0, sizeof(gcm_context)); // zero caller-provided GCM context
memset(h, 0, 16); // initialize the block to encrypt
// encrypt the null 128-bit block to generate a key-based value
// which is then used to initialize our GHASH lookup tables
if ((ret = aes_setkey(&ctx->aes_ctx, MG_ENCRYPT, key, keysize)) != 0)
return (ret);
if ((ret = aes_cipher(&ctx->aes_ctx, h, h)) != 0) return (ret);
GET_UINT32_BE(hi, h, 0); // pack h as two 64-bit ints, big-endian
GET_UINT32_BE(lo, h, 4);
vh = (uint64_t) hi << 32 | lo;
GET_UINT32_BE(hi, h, 8);
GET_UINT32_BE(lo, h, 12);
vl = (uint64_t) hi << 32 | lo;
ctx->HL[8] = vl; // 8 = 1000 corresponds to 1 in GF(2^128)
ctx->HH[8] = vh;
ctx->HH[0] = 0; // 0 corresponds to 0 in GF(2^128)
ctx->HL[0] = 0;
for (i = 4; i > 0; i >>= 1) {
uint32_t T = (uint32_t) (vl & 1) * 0xe1000000U;
vl = (vh << 63) | (vl >> 1);
vh = (vh >> 1) ^ ((uint64_t) T << 32);
ctx->HL[i] = vl;
ctx->HH[i] = vh;
}
for (i = 2; i < 16; i <<= 1) {
uint64_t *HiL = ctx->HL + i, *HiH = ctx->HH + i;
vh = *HiH;
vl = *HiL;
for (j = 1; j < i; j++) {
HiH[j] = vh ^ ctx->HH[j];
HiL[j] = vl ^ ctx->HL[j];
}
}
return (0);
}
/******************************************************************************
*
* GCM processing occurs four phases: SETKEY, START, UPDATE and FINISH.
*
* SETKEY:
*
* START: Sets the Encryption/Decryption mode.
* Accepts the initialization vector and additional data.
*
* UPDATE: Encrypts or decrypts the plaintext or ciphertext.
*
* FINISH: Performs a final GHASH to generate the authentication tag.
*
******************************************************************************
*
* GCM_START
*
* Given a user-provided GCM context, this initializes it, sets the encryption
* mode, and preprocesses the initialization vector and additional AEAD data.
*
******************************************************************************/
int gcm_start(gcm_context *ctx, // pointer to user-provided GCM context
int mode, // GCM_ENCRYPT or GCM_DECRYPT
const uchar *iv, // pointer to initialization vector
size_t iv_len, // IV length in bytes (should == 12)
const uchar *add, // ptr to additional AEAD data (NULL if none)
size_t add_len) // length of additional AEAD data (bytes)
{
int ret; // our error return if the AES encrypt fails
uchar work_buf[16]; // XOR source built from provided IV if len != 16
const uchar *p; // general purpose array pointer
size_t use_len; // byte count to process, up to 16 bytes
size_t i; // local loop iterator
// since the context might be reused under the same key
// we zero the working buffers for this next new process
memset(ctx->y, 0x00, sizeof(ctx->y));
memset(ctx->buf, 0x00, sizeof(ctx->buf));
ctx->len = 0;
ctx->add_len = 0;
ctx->mode = mode; // set the GCM encryption/decryption mode
ctx->aes_ctx.mode = MG_ENCRYPT; // GCM *always* runs AES in ENCRYPTION mode
if (iv_len == 12) { // GCM natively uses a 12-byte, 96-bit IV
memcpy(ctx->y, iv, iv_len); // copy the IV to the top of the 'y' buff
ctx->y[15] = 1; // start "counting" from 1 (not 0)
} else // if we don't have a 12-byte IV, we GHASH whatever we've been given
{
memset(work_buf, 0x00, 16); // clear the working buffer
PUT_UINT32_BE(iv_len * 8, work_buf, 12); // place the IV into buffer
p = iv;
while (iv_len > 0) {
use_len = (iv_len < 16) ? iv_len : 16;
for (i = 0; i < use_len; i++) ctx->y[i] ^= p[i];
gcm_mult(ctx, ctx->y, ctx->y);
iv_len -= use_len;
p += use_len;
}
for (i = 0; i < 16; i++) ctx->y[i] ^= work_buf[i];
gcm_mult(ctx, ctx->y, ctx->y);
}
if ((ret = aes_cipher(&ctx->aes_ctx, ctx->y, ctx->base_ectr)) != 0)
return (ret);
ctx->add_len = add_len;
p = add;
while (add_len > 0) {
use_len = (add_len < 16) ? add_len : 16;
for (i = 0; i < use_len; i++) ctx->buf[i] ^= p[i];
gcm_mult(ctx, ctx->buf, ctx->buf);
add_len -= use_len;
p += use_len;
}
return (0);
}
/******************************************************************************
*
* GCM_UPDATE
*
* This is called once or more to process bulk plaintext or ciphertext data.
* We give this some number of bytes of input and it returns the same number
* of output bytes. If called multiple times (which is fine) all but the final
* invocation MUST be called with length mod 16 == 0. (Only the final call can
* have a partial block length of < 128 bits.)
*
******************************************************************************/
int gcm_update(gcm_context *ctx, // pointer to user-provided GCM context
size_t length, // length, in bytes, of data to process
const uchar *input, // pointer to source data
uchar *output) // pointer to destination data
{
int ret; // our error return if the AES encrypt fails
uchar ectr[16]; // counter-mode cipher output for XORing
size_t use_len; // byte count to process, up to 16 bytes
size_t i; // local loop iterator
ctx->len += length; // bump the GCM context's running length count
while (length > 0) {
// clamp the length to process at 16 bytes
use_len = (length < 16) ? length : 16;
// increment the context's 128-bit IV||Counter 'y' vector
for (i = 16; i > 12; i--)
if (++ctx->y[i - 1] != 0) break;
// encrypt the context's 'y' vector under the established key
if ((ret = aes_cipher(&ctx->aes_ctx, ctx->y, ectr)) != 0) return (ret);
// encrypt or decrypt the input to the output
if (ctx->mode == MG_ENCRYPT) {
for (i = 0; i < use_len; i++) {
// XOR the cipher's ouptut vector (ectr) with our input
output[i] = (uchar) (ectr[i] ^ input[i]);
// now we mix in our data into the authentication hash.
// if we're ENcrypting we XOR in the post-XOR (output)
// results, but if we're DEcrypting we XOR in the input
// data
ctx->buf[i] ^= output[i];
}
} else {
for (i = 0; i < use_len; i++) {
// but if we're DEcrypting we XOR in the input data first,
// i.e. before saving to ouput data, otherwise if the input
// and output buffer are the same (inplace decryption) we
// would not get the correct auth tag
ctx->buf[i] ^= input[i];
// XOR the cipher's ouptut vector (ectr) with our input
output[i] = (uchar) (ectr[i] ^ input[i]);
}
}
gcm_mult(ctx, ctx->buf, ctx->buf); // perform a GHASH operation
length -= use_len; // drop the remaining byte count to process
input += use_len; // bump our input pointer forward
output += use_len; // bump our output pointer forward
}
return (0);
}
/******************************************************************************
*
* GCM_FINISH
*
* This is called once after all calls to GCM_UPDATE to finalize the GCM.
* It performs the final GHASH to produce the resulting authentication TAG.
*
******************************************************************************/
int gcm_finish(gcm_context *ctx, // pointer to user-provided GCM context
uchar *tag, // pointer to buffer which receives the tag
size_t tag_len) // length, in bytes, of the tag-receiving buf
{
uchar work_buf[16];
uint64_t orig_len = ctx->len * 8;
uint64_t orig_add_len = ctx->add_len * 8;
size_t i;
if (tag_len != 0) memcpy(tag, ctx->base_ectr, tag_len);
if (orig_len || orig_add_len) {
memset(work_buf, 0x00, 16);
PUT_UINT32_BE((orig_add_len >> 32), work_buf, 0);
PUT_UINT32_BE((orig_add_len), work_buf, 4);
PUT_UINT32_BE((orig_len >> 32), work_buf, 8);
PUT_UINT32_BE((orig_len), work_buf, 12);
for (i = 0; i < 16; i++) ctx->buf[i] ^= work_buf[i];
gcm_mult(ctx, ctx->buf, ctx->buf);
for (i = 0; i < tag_len; i++) tag[i] ^= ctx->buf[i];
}
return (0);
}
/******************************************************************************
*
* GCM_CRYPT_AND_TAG
*
* This either encrypts or decrypts the user-provided data and, either
* way, generates an authentication tag of the requested length. It must be
* called with a GCM context whose key has already been set with GCM_SETKEY.
*
* The user would typically call this explicitly to ENCRYPT a buffer of data
* and optional associated data, and produce its an authentication tag.
*
* To reverse the process the user would typically call the companion
* GCM_AUTH_DECRYPT function to decrypt data and verify a user-provided
* authentication tag. The GCM_AUTH_DECRYPT function calls this function
* to perform its decryption and tag generation, which it then compares.
*
******************************************************************************/
int gcm_crypt_and_tag(
gcm_context *ctx, // gcm context with key already setup
int mode, // cipher direction: GCM_ENCRYPT or GCM_DECRYPT
const uchar *iv, // pointer to the 12-byte initialization vector
size_t iv_len, // byte length if the IV. should always be 12
const uchar *add, // pointer to the non-ciphered additional data
size_t add_len, // byte length of the additional AEAD data
const uchar *input, // pointer to the cipher data source
uchar *output, // pointer to the cipher data destination
size_t length, // byte length of the cipher data
uchar *tag, // pointer to the tag to be generated
size_t tag_len) // byte length of the tag to be generated
{ /*
assuming that the caller has already invoked gcm_setkey to
prepare the gcm context with the keying material, we simply
invoke each of the three GCM sub-functions in turn...
*/
gcm_start(ctx, mode, iv, iv_len, add, add_len);
gcm_update(ctx, length, input, output);
gcm_finish(ctx, tag, tag_len);
return (0);
}
/******************************************************************************
*
* GCM_ZERO_CTX
*
* The GCM context contains both the GCM context and the AES context.
* This includes keying and key-related material which is security-
* sensitive, so it MUST be zeroed after use. This function does that.
*
******************************************************************************/
void gcm_zero_ctx(gcm_context *ctx) {
// zero the context originally provided to us
memset(ctx, 0, sizeof(gcm_context));
}
//
// aes-gcm.c
// Pods
//
// Created by Markus Kosmal on 20/11/14.
//
//
int mg_aes_gcm_encrypt(unsigned char *output, //
const unsigned char *input, size_t input_length,
const unsigned char *key, const size_t key_len,
const unsigned char *iv, const size_t iv_len,
unsigned char *aead, size_t aead_len, unsigned char *tag,
const size_t tag_len) {
int ret = 0; // our return value
gcm_context ctx; // includes the AES context structure
gcm_setkey(&ctx, key, (uint) key_len);
ret = gcm_crypt_and_tag(&ctx, MG_ENCRYPT, iv, iv_len, aead, aead_len, input,
output, input_length, tag, tag_len);
gcm_zero_ctx(&ctx);
return (ret);
}
int mg_aes_gcm_decrypt(unsigned char *output, const unsigned char *input,
size_t input_length, const unsigned char *key,
const size_t key_len, const unsigned char *iv,
const size_t iv_len) {
int ret = 0; // our return value
gcm_context ctx; // includes the AES context structure
size_t tag_len = 0;
unsigned char *tag_buf = NULL;
gcm_setkey(&ctx, key, (uint) key_len);
ret = gcm_crypt_and_tag(&ctx, MG_DECRYPT, iv, iv_len, NULL, 0, input, output,
input_length, tag_buf, tag_len);
gcm_zero_ctx(&ctx);
return (ret);
}
#endif
// End of aes128 PD
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