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crypto: Move CBC handling into enc_xform_aes_cbc.

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Add an IV to the context that is initialized by the reinit hook.
Encrypt and decrypt operations handle cipher block chaining along with
updating the IV saved in the context.

Reviewed by:	markj
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D33487
This commit is contained in:
John Baldwin 2021-12-16 13:47:44 -08:00
parent 246982c196
commit d55df8dcf7
1 changed files with 37 additions and 7 deletions
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44
sys/opencrypto/xform_aes_cbc.c
View file

@ -53,15 +53,21 @@ __FBSDID("$FreeBSD$");
#include <crypto/rijndael/rijndael.h>
#include <opencrypto/xform_enc.h>
struct aes_cbc_ctx {
rijndael_ctx key;
char iv[AES_BLOCK_LEN];
};
static int aes_cbc_setkey(void *, const uint8_t *, int);
static void aes_cbc_encrypt(void *, const uint8_t *, uint8_t *);
static void aes_cbc_decrypt(void *, const uint8_t *, uint8_t *);
static void aes_cbc_reinit(void *, const uint8_t *, size_t);
/* Encryption instances */
const struct enc_xform enc_xform_aes_cbc = {
.type = CRYPTO_AES_CBC,
.name = "AES-CBC",
.ctxsize = sizeof(rijndael_ctx),
.ctxsize = sizeof(struct aes_cbc_ctx),
.blocksize = AES_BLOCK_LEN,
.ivsize = AES_BLOCK_LEN,
.minkey = AES_MIN_KEY,
@ -69,30 +75,54 @@ const struct enc_xform enc_xform_aes_cbc = {
.encrypt = aes_cbc_encrypt,
.decrypt = aes_cbc_decrypt,
.setkey = aes_cbc_setkey,
.reinit = aes_cbc_reinit,
};
/*
* Encryption wrapper routines.
*/
static void
aes_cbc_encrypt(void *key, const uint8_t *in, uint8_t *out)
aes_cbc_encrypt(void *vctx, const uint8_t *in, uint8_t *out)
{
rijndael_encrypt(key, in, out);
struct aes_cbc_ctx *ctx = vctx;
for (u_int i = 0; i < AES_BLOCK_LEN; i++)
out[i] = in[i] ^ ctx->iv[i];
rijndael_encrypt(&ctx->key, out, out);
memcpy(ctx->iv, out, AES_BLOCK_LEN);
}
static void
aes_cbc_decrypt(void *key, const uint8_t *in, uint8_t *out)
aes_cbc_decrypt(void *vctx, const uint8_t *in, uint8_t *out)
{
rijndael_decrypt(key, in, out);
struct aes_cbc_ctx *ctx = vctx;
char block[AES_BLOCK_LEN];
memcpy(block, in, AES_BLOCK_LEN);
rijndael_decrypt(&ctx->key, in, out);
for (u_int i = 0; i < AES_BLOCK_LEN; i++)
out[i] ^= ctx->iv[i];
memcpy(ctx->iv, block, AES_BLOCK_LEN);
explicit_bzero(block, sizeof(block));
}
static int
aes_cbc_setkey(void *sched, const uint8_t *key, int len)
aes_cbc_setkey(void *vctx, const uint8_t *key, int len)
{
struct aes_cbc_ctx *ctx = vctx;
if (len != 16 && len != 24 && len != 32)
return (EINVAL);
rijndael_set_key(sched, key, len * 8);
rijndael_set_key(&ctx->key, key, len * 8);
return (0);
}
static void
aes_cbc_reinit(void *vctx, const uint8_t *iv, size_t iv_len)
{
struct aes_cbc_ctx *ctx = vctx;
KASSERT(iv_len == sizeof(ctx->iv), ("%s: bad IV length", __func__));
memcpy(ctx->iv, iv, sizeof(ctx->iv));
}