The key expansion routine could be get little more generic, become
a kernel doc entry and then get exported.
Signed-off-by: Sebastian Siewior <sebastian@xxxxxxxxxxxxx>
---
crypto/aes_generic.c | 56 +++++++++++++++++++++++++++++++++++++++++--------
include/crypto/aes.h | 8 +++++-
2 files changed, 53 insertions(+), 11 deletions(-)
diff --git a/crypto/aes_generic.c b/crypto/aes_generic.c
index f33a99c..9322531 100644
--- a/crypto/aes_generic.c
+++ b/crypto/aes_generic.c
@@ -229,18 +229,29 @@ static void __init gen_tabs(void)
ctx->key_enc[8 * i + 15] = t; \
} while (0)
-int crypto_aes_set_key(struct crypto_tfm *tfm, const u8 *in_key,
+/**
+ * crypto_aes_expand_key - Expands the AES key as described in FIPS-197
+ * @ctx: The location where the computed key will be stored.
+ * @in_key: The supplied key.
+ * @key_len: The length of the supplied key.
+ *
+ * Returns 0 on success. The function fails only if an invalid key size (or
+ * pointer) is supplied.
+ * The expanded key size is 240 bytes (max of 14 rounds with a unique 16 bytes
+ * key schedule plus a 16 bytes key which is used before the first round).
+ * The decryption key is prepared for the "Equivalent Inverse Cipher" as
+ * described in FIPS-197. The first slot (16 bytes) of each key (enc or dec) is
+ * for the initial combination, the second slot for the first round and so on.
+ */
+int crypto_aes_expand_key(struct crypto_aes_ctx *ctx, const u8 *in_key,
unsigned int key_len)
{
- struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
const __le32 *key = (const __le32 *)in_key;
- u32 *flags = &tfm->crt_flags;
u32 i, t, u, v, w, j;
- if (key_len % 8) {
- *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
+ if (key_len != AES_KEYSIZE_128 && key_len != AES_KEYSIZE_192 &&
+ key_len != AES_KEYSIZE_256)
return -EINVAL;
- }
ctx->key_length = key_len;
@@ -250,20 +261,20 @@ int crypto_aes_set_key(struct crypto_tfm *tfm, const u8 *in_key,
ctx->key_dec[key_len + 27] = ctx->key_enc[3] = le32_to_cpu(key[3]);
switch (key_len) {
- case 16:
+ case AES_KEYSIZE_128:
t = ctx->key_enc[3];
for (i = 0; i < 10; ++i)
loop4(i);
break;
- case 24:
+ case AES_KEYSIZE_192:
ctx->key_enc[4] = le32_to_cpu(key[4]);
t = ctx->key_enc[5] = le32_to_cpu(key[5]);
for (i = 0; i < 8; ++i)
loop6(i);
break;
- case 32:
+ case AES_KEYSIZE_256:
ctx->key_enc[4] = le32_to_cpu(key[4]);
ctx->key_enc[5] = le32_to_cpu(key[5]);
ctx->key_enc[6] = le32_to_cpu(key[6]);
@@ -284,6 +295,33 @@ int crypto_aes_set_key(struct crypto_tfm *tfm, const u8 *in_key,
}
return 0;
}
+EXPORT_SYMBOL_GPL(crypto_aes_expand_key);
+
+/**
+ * crypto_aes_set_key - Set the AES key.
+ * @tfm: The %crypto_tfm that is used in the context.
+ * @in_key: The input key.
+ * @key_len: The size of the key.
+ *
+ * Returns 0 on success, on failure the %CRYPTO_TFM_RES_BAD_KEY_LEN flag in tfm
+ * is set. The function uses crypto_aes_expand_key() to expand the key.
+ * &crypto_aes_ctx _must_ be the private data embedded in @tfm which is
+ * retrieved with crypto_tfm_ctx().
+ */
+int crypto_aes_set_key(struct crypto_tfm *tfm, const u8 *in_key,
+ unsigned int key_len)
+{
+ struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
+ u32 *flags = &tfm->crt_flags;
+ int ret;
+
+ ret = crypto_aes_expand_key(ctx, in_key, key_len);
+ if (!ret)
+ return 0;
+
+ *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
+ return -EINVAL;
+}
EXPORT_SYMBOL_GPL(crypto_aes_set_key);
/* encrypt a block of text */
diff --git a/include/crypto/aes.h b/include/crypto/aes.h
index d480b76..40008d6 100644
--- a/include/crypto/aes.h
+++ b/include/crypto/aes.h
@@ -14,11 +14,13 @@
#define AES_KEYSIZE_192 24
#define AES_KEYSIZE_256 32
#define AES_BLOCK_SIZE 16
+#define AES_MAX_KEYLENGTH (15 * 16)
+#define AES_MAX_KEYLENGTH_U32 (AES_MAX_KEYLENGTH / sizeof(u32))
struct crypto_aes_ctx {
u32 key_length;
- u32 key_enc[60];
- u32 key_dec[60];
+ u32 key_enc[AES_MAX_KEYLENGTH_U32];
+ u32 key_dec[AES_MAX_KEYLENGTH_U32];
};
extern u32 crypto_ft_tab[4][256];
@@ -28,4 +30,6 @@ extern u32 crypto_il_tab[4][256];
int crypto_aes_set_key(struct crypto_tfm *tfm, const u8 *in_key,
unsigned int key_len);
+int crypto_aes_expand_key(struct crypto_aes_ctx *ctx, const u8 *in_key,
+ unsigned int key_len);
#endif
--
1.5.3.7
-
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