void tmd_aes_ctx_init(const aes_gcm *gcm, aes_ctx *ctx
, const aes_key *key, const uint8_t *iv, uint32_t len)
{
ctx->length_aad = 0;
ctx->length_input = 0;
block128_zero(&ctx->tag);
block128_zero(&ctx->iv);
if (len == 12) {
block128_copy_bytes(&ctx->iv, iv, 12);
ctx->iv.b[15] = 0x01;
} else {
uint32_t origlen = len << 3;
int i;
for (; len >= 16; len -= 16, iv += 16) {
block128_xor(&ctx->iv, (block128 *) iv);
tmd_gf_mul(&ctx->iv, &gcm->h);
}
if (len > 0) {
block128_xor_bytes(&ctx->iv, iv, len);
tmd_gf_mul(&ctx->iv, &gcm->h);
}
for (i = 15; origlen; --i, origlen >>= 8)
ctx->iv.b[i] ^= (uint8_t) origlen;
tmd_gf_mul(&ctx->iv, &gcm->h);
}
block128_copy(&ctx->civ, &ctx->iv);
}
void aes_gcm_init(aes_gcm *gcm, aes_key *key, uint8_t *iv, uint32_t len)
{
gcm->length_aad = 0;
gcm->length_input = 0;
block128_zero(&gcm->h);
block128_zero(&gcm->tag);
block128_zero(&gcm->iv);
memcpy(&gcm->key, key, sizeof(aes_key));
/* prepare H : encrypt_K(0^128) */
aes_encrypt_block(&gcm->h, key, &gcm->h);
if (len == 12) {
block128_copy_bytes(&gcm->iv, iv, 12);
gcm->iv.b[15] = 0x01;
} else {
uint32_t origlen = len << 3;
int i;
for (; len >= 16; len -= 16, iv += 16) {
block128_xor(&gcm->iv, (block128 *) iv);
gf_mul(&gcm->iv, &gcm->h);
}
if (len > 0) {
block128_xor_bytes(&gcm->iv, iv, len);
gf_mul(&gcm->iv, &gcm->h);
}
for (i = 15; origlen; --i, origlen >>= 8)
gcm->iv.b[i] ^= (uint8_t) origlen;
gf_mul(&gcm->iv, &gcm->h);
}
block128_copy(&gcm->civ, &gcm->iv);
}
void tmd_aes_generic_gcm_decrypt(uint8_t *output, const aes_gcm *gcm, const aes_ctx *ctx, const aes_key *key, const uint8_t *input, uint32_t length, aes_ctx *newCTX)
{
aes_block out;
memcpy(newCTX, ctx, sizeof(aes_ctx));
newCTX->length_input += length;
for (; length >= 16; input += 16, output += 16, length -= 16) {
block128_inc_be(&newCTX->civ);
aes_encrypt_block(&out, key, &newCTX->civ);
gcm_ghash_add(gcm, newCTX, (block128 *) input);
block128_xor(&out, (block128 *) input);
block128_copy((block128 *) output, &out);
}
if (length > 0) {
aes_block tmp;
int i;
block128_inc_be(&newCTX->civ);
block128_zero(&tmp);
block128_copy_bytes(&tmp, input, length);
gcm_ghash_add(gcm, newCTX, &tmp);
aes_encrypt_block(&out, key, &newCTX->civ);
block128_xor_bytes(&tmp, out.b, length);
for (i = 0; i < length; i++) {
output[i] = tmp.b[i];
}
}
}
void aes_gcm_decrypt(uint8_t *output, aes_gcm *gcm, uint8_t *input, uint32_t length)
{
aes_block out;
gcm->length_input += length;
for (; length >= 16; input += 16, output += 16, length -= 16) {
block128_inc_be(&gcm->civ);
aes_encrypt_block(&out, &gcm->key, &gcm->civ);
gcm_ghash_add(gcm, (block128 *) input);
block128_xor(&out, (block128 *) input);
block128_copy((block128 *) output, &out);
}
if (length > 0) {
aes_block tmp;
int i;
block128_inc_be(&gcm->civ);
block128_zero(&tmp);
block128_copy_bytes(&tmp, input, length);
gcm_ghash_add(gcm, &tmp);
aes_encrypt_block(&out, &gcm->key, &gcm->civ);
block128_xor_bytes(&tmp, out.b, length);
for (i = 0; i < length; i++) {
output[i] = tmp.b[i];
}
}
}
void tmd_aes_gcm_aad(const aes_gcm *gcm, aes_ctx *ctx, const uint8_t *input, uint32_t length)
{
ctx->length_aad += length;
for (; length >= 16; input += 16, length -= 16) {
gcm_ghash_add(gcm, ctx, (block128 *) input);
}
if (length > 0) {
aes_block tmp;
block128_zero(&tmp);
block128_copy_bytes(&tmp, input, length);
gcm_ghash_add(gcm, ctx, &tmp);
}
}
void aes_gcm_aad(aes_gcm *gcm, uint8_t *input, uint32_t length)
{
gcm->length_aad += length;
for (; length >= 16; input += 16, length -= 16) {
gcm_ghash_add(gcm, (block128 *) input);
}
if (length > 0) {
aes_block tmp;
block128_zero(&tmp);
block128_copy_bytes(&tmp, input, length);
gcm_ghash_add(gcm, &tmp);
}
}
void tmd_aes_gcm_init(aes_gcm *gcm, const aes_key *key)
{
block128_zero(&gcm->h);
/* prepare H : encrypt_K(0^128) */
aes_encrypt_block(&gcm->h, key, &gcm->h);
}
