aes: Move the AES-128-CBC encryption function to common code

Move the AES-128-CBC encryption function implemented in
tegra20-common/crypto.c into lib/aes.c . This is well re-usable common
code. Moreover, clean the code up a bit and fix the kerneldoc-style
annotations.

Signed-off-by: Marek Vasut <marex@denx.de>

3 files changed, 64 insertions, 70 deletions

diff --git a/arch/arm/cpu/tegra20-common/crypto.c b/arch/arm/cpu/tegra20-common/crypto.c
index 8209f76..b18e67c 100644
--- a/arch/arm/cpu/tegra20-common/crypto.c
+++ b/arch/arm/cpu/tegra20-common/crypto.c
@@ -19,74 +19,6 @@ enum security_op {
 	SECURITY_ENCRYPT	= 1 << 1,	/* Encrypt the data */
 };
 
-static void debug_print_vector(char *name, u32 num_bytes, u8 *data)
-{
-	u32 i;
-
-	debug("%s [%d] @0x%08x", name, num_bytes, (u32)data);
-	for (i = 0; i < num_bytes; i++) {
-		if (i % 16 == 0)
-			debug(" = ");
-		debug("%02x", data[i]);
-		if ((i+1) % 16 != 0)
-			debug(" ");
-	}
-	debug("\n");
-}
-
-/**
- * Apply chain data to the destination using EOR
- *
- * Each array is of length AES_AES_KEY_LENGTH.
- *
- * \param cbc_chain_data	Chain data
- * \param src			Source data
- * \param dst			Destination data, which is modified here
- */
-static void apply_cbc_chain_data(u8 *cbc_chain_data, u8 *src, u8 *dst)
-{
-	int i;
-
-	for (i = 0; i < 16; i++)
-		*dst++ = *src++ ^ *cbc_chain_data++;
-}
-
-/**
- * Encrypt some data with AES.
- *
- * \param key_schedule		Expanded key to use
- * \param src			Source data to encrypt
- * \param dst			Destination buffer
- * \param num_aes_blocks	Number of AES blocks to encrypt
- */
-static void encrypt_object(u8 *key_schedule, u8 *src, u8 *dst,
-			   u32 num_aes_blocks)
-{
-	u8 tmp_data[AES_KEY_LENGTH];
-	u8 *cbc_chain_data;
-	u32 i;
-
-	cbc_chain_data = zero_key;	/* Convenient array of 0's for IV */
-
-	for (i = 0; i < num_aes_blocks; i++) {
-		debug("encrypt_object: block %d of %d\n", i, num_aes_blocks);
-		debug_print_vector("AES Src", AES_KEY_LENGTH, src);
-
-		/* Apply the chain data */
-		apply_cbc_chain_data(cbc_chain_data, src, tmp_data);
-		debug_print_vector("AES Xor", AES_KEY_LENGTH, tmp_data);
-
-		/* encrypt the AES block */
-		aes_encrypt(tmp_data, key_schedule, dst);
-		debug_print_vector("AES Dst", AES_KEY_LENGTH, dst);
-
-		/* Update pointers for next loop. */
-		cbc_chain_data = dst;
-		src += AES_KEY_LENGTH;
-		dst += AES_KEY_LENGTH;
-	}
-}
-
 /**
  * Shift a vector left by one bit
  *
@@ -129,7 +61,7 @@ static void sign_object(u8 *key, u8 *key_schedule, u8 *src, u8 *dst,
 	for (i = 0; i < AES_KEY_LENGTH; i++)
 		tmp_data[i] = 0;
 
-	encrypt_object(key_schedule, tmp_data, left, 1);
+	aes_cbc_encrypt_blocks(key_schedule, tmp_data, left, 1);
 	debug_print_vector("AES(key, nonce)", AES_KEY_LENGTH, left);
 
 	left_shift_vector(left, k1, sizeof(left));
@@ -193,7 +125,7 @@ static int encrypt_and_sign(u8 *key, enum security_op oper, u8 *src,
 	if (oper & SECURITY_ENCRYPT) {
 		/* Perform this in place, resulting in src being encrypted. */
 		debug("encrypt_and_sign: begin encryption\n");
-		encrypt_object(key_schedule, src, src, num_aes_blocks);
+		aes_cbc_encrypt_blocks(key_schedule, src, src, num_aes_blocks);
 		debug("encrypt_and_sign: end encryption\n");
 	}
 
diff --git a/include/aes.h b/include/aes.h
index c70eda6..d9bb387 100644
--- a/include/aes.h
+++ b/include/aes.h
@@ -53,4 +53,14 @@ void aes_encrypt(u8 *in, u8 *expkey, u8 *out);
  */
 void aes_decrypt(u8 *in, u8 *expkey, u8 *out);
 
+/**
+ * aes_cbc_encrypt_blocks() - Encrypt multiple blocks of data with AES CBC.
+ *
+ * @key_exp		Expanded key to use
+ * @src			Source data to encrypt
+ * @dst			Destination buffer
+ * @num_aes_blocks	Number of AES blocks to encrypt
+ */
+void aes_cbc_encrypt_blocks(u8 *key_exp, u8 *src, u8 *dst, u32 num_aes_blocks);
+
 #endif /* _AES_REF_H_ */
diff --git a/lib/aes.c b/lib/aes.c
index e996b27..a6648f9 100644
--- a/lib/aes.c
+++ b/lib/aes.c
@@ -580,3 +580,55 @@ void aes_decrypt(u8 *in, u8 *expkey, u8 *out)
 
 	memcpy(out, state, sizeof(state));
 }
+
+static void debug_print_vector(char *name, u32 num_bytes, u8 *data)
+{
+#ifdef DEBUG
+	printf("%s [%d] @0x%08x", name, num_bytes, (u32)data);
+	print_buffer(0, data, 1, num_bytes, 16);
+#endif
+}
+
+/**
+ * Apply chain data to the destination using EOR
+ *
+ * Each array is of length AES_KEY_LENGTH.
+ *
+ * @cbc_chain_data	Chain data
+ * @src			Source data
+ * @dst			Destination data, which is modified here
+ */
+static void apply_cbc_chain_data(u8 *cbc_chain_data, u8 *src, u8 *dst)
+{
+	int i;
+
+	for (i = 0; i < AES_KEY_LENGTH; i++)
+		*dst++ = *src++ ^ *cbc_chain_data++;
+}
+
+void aes_cbc_encrypt_blocks(u8 *key_exp, u8 *src, u8 *dst, u32 num_aes_blocks)
+{
+	u8 zero_key[AES_KEY_LENGTH] = { 0 };
+	u8 tmp_data[AES_KEY_LENGTH];
+	/* Convenient array of 0's for IV */
+	u8 *cbc_chain_data = zero_key;
+	u32 i;
+
+	for (i = 0; i < num_aes_blocks; i++) {
+		debug("encrypt_object: block %d of %d\n", i, num_aes_blocks);
+		debug_print_vector("AES Src", AES_KEY_LENGTH, src);
+
+		/* Apply the chain data */
+		apply_cbc_chain_data(cbc_chain_data, src, tmp_data);
+		debug_print_vector("AES Xor", AES_KEY_LENGTH, tmp_data);
+
+		/* Encrypt the AES block */
+		aes_encrypt(tmp_data, key_exp, dst);
+		debug_print_vector("AES Dst", AES_KEY_LENGTH, dst);
+
+		/* Update pointers for next loop. */
+		cbc_chain_data = dst;
+		src += AES_KEY_LENGTH;
+		dst += AES_KEY_LENGTH;
+	}
+}