add buffer encryption to "boxes"

1 files changed, 294 insertions, 0 deletions

diff --git a/src/box.c b/src/box.c
index 6d0f5d2..75d471d 100644
--- a/src/box.c
+++ b/src/box.c
@@ -8,6 +8,8 @@
 
 #include <aesni/all.h>
 
+#include <stdlib.h>
+
 static const AesNI_BoxAlgorithmInterface* aesni_box_algorithms[] =
 {
     &aesni_box_algorithm_aes128,
@@ -253,3 +255,295 @@ AesNI_StatusCode aesni_box_decrypt_block(
 {
     return aesni_box_decrypt_block_in_mode[box->mode](box, input, output, err_details);
 }
+
+static AesNI_StatusCode aesni_box_get_encrypted_buffer_size(
+    AesNI_Box* box,
+    size_t src_size,
+    size_t* dest_size,
+    size_t* padding_size,
+    AesNI_ErrorDetails* err_details)
+{
+    AesNI_StatusCode status = AESNI_SUCCESS;
+
+    switch (box->mode)
+    {
+        case AESNI_ECB:
+        case AESNI_CBC:
+        {
+            size_t block_size;
+
+            if (aesni_is_error(status = box->algorithm->get_block_size(
+                    &block_size, err_details)))
+                return status;
+
+            *padding_size = block_size - src_size % block_size;
+            *dest_size = src_size + *padding_size;
+            return status;
+        }
+
+        case AESNI_CFB:
+        case AESNI_OFB:
+        case AESNI_CTR:
+            *dest_size = src_size;
+            *padding_size = 0;
+            return status;
+
+        default:
+            return aesni_error_not_implemented(err_details, "unsupported mode of operation");
+    }
+}
+
+static AesNI_StatusCode aesni_box_encrypt_buffer_block(
+    AesNI_Box* box,
+    const void* src,
+    void* dest,
+    AesNI_ErrorDetails* err_details)
+{
+    AesNI_StatusCode status = AESNI_SUCCESS;
+
+    AesNI_BoxBlock plaintext;
+
+    if (aesni_is_error(status = box->algorithm->load_block(
+            &plaintext, src, err_details)))
+        return status;
+
+    AesNI_BoxBlock ciphertext;
+
+    if (aesni_is_error(status = aesni_box_encrypt_block(
+            box, &plaintext, &ciphertext, err_details)))
+        return status;
+
+    if (aesni_is_error(status = box->algorithm->store_block(
+            dest, &ciphertext, err_details)))
+        return status;
+
+    return status;
+}
+
+AesNI_StatusCode aesni_box_encrypt_buffer(
+    AesNI_Box* box,
+    const void* src,
+    size_t src_size,
+    void* dest,
+    size_t* dest_size,
+    AesNI_ErrorDetails* err_details)
+{
+    if (box == NULL)
+        return aesni_error_null_argument(err_details, "box");
+    if (dest_size == NULL)
+        return aesni_error_null_argument(err_details, "dest_size");
+
+    AesNI_StatusCode status = AESNI_SUCCESS;
+    size_t padding_size = 0;
+
+    if (aesni_is_error(status = aesni_box_get_encrypted_buffer_size(
+            box, src_size, dest_size, &padding_size, err_details)))
+        return status;
+
+    if (dest == NULL)
+        return AESNI_SUCCESS;
+    if (src == NULL)
+        return aesni_error_null_argument(err_details, "src");
+
+    size_t block_size;
+
+    if (aesni_is_error(status = box->algorithm->get_block_size(
+            &block_size, err_details)))
+        return status;
+
+    const size_t src_len = src_size / block_size;
+
+    for (size_t i = 0; i < src_len; ++i, (char*) src += block_size, (char*) dest += block_size)
+        if (aesni_is_error(status = aesni_box_encrypt_buffer_block(
+                box, src, dest, err_details)))
+            return status;
+
+    if (padding_size == 0)
+    {
+        const size_t partial_block_size = src_size % block_size;
+
+        if (partial_block_size != 0)
+        {
+            AesNI_BoxBlock plaintext;
+
+            if (aesni_is_error(status = box->algorithm->load_partial_block(
+                    &plaintext, src, partial_block_size, err_details)))
+                return status;
+
+            AesNI_BoxBlock ciphertext;
+
+            if (aesni_is_error(status = aesni_box_encrypt_block(
+                    box, &plaintext, &ciphertext, err_details)))
+                return status;
+
+            if (aesni_is_error(status = box->algorithm->store_partial_block(
+                    dest, &ciphertext, partial_block_size, err_details)))
+                return status;
+        }
+    }
+    else
+    {
+        AesNI_BoxBlock plaintext;
+
+        if (aesni_is_error(status = box->algorithm->load_block_with_padding(
+                &plaintext, src, src_size % block_size, err_details)))
+            return status;
+
+        AesNI_BoxBlock ciphertext;
+
+        if (aesni_is_error(status = aesni_box_encrypt_block(
+                box, &plaintext, &ciphertext, err_details)))
+            return status;
+
+        if (aesni_is_error(status = box->algorithm->store_block(
+                dest, &ciphertext, err_details)))
+            return status;
+    }
+
+    return status;
+}
+
+static AesNI_StatusCode aesni_box_get_decrypted_buffer_size(
+    AesNI_Box* box,
+    size_t src_size,
+    size_t* dest_size,
+    size_t* max_padding_size,
+    AesNI_ErrorDetails* err_details)
+{
+    AesNI_StatusCode status = AESNI_SUCCESS;
+
+    switch (box->mode)
+    {
+        case AESNI_ECB:
+        case AESNI_CBC:
+        {
+            size_t block_size;
+
+            if (aesni_is_error(status = box->algorithm->get_block_size(
+                    &block_size, err_details)))
+                return status;
+
+            if (src_size % block_size != 0)
+                return aesni_error_invalid_plaintext_length(err_details);
+
+            *dest_size = src_size;
+            *max_padding_size = block_size;
+            return status;
+        }
+
+        case AESNI_CFB:
+        case AESNI_OFB:
+        case AESNI_CTR:
+            *dest_size = src_size;
+            *max_padding_size = 0;
+            return status;
+
+        default:
+            return aesni_error_not_implemented(err_details, "unsupported mode of operation");
+    }
+}
+
+static AesNI_StatusCode aesni_box_decrypt_buffer_block(
+    AesNI_Box* box,
+    const void* src,
+    void* dest,
+    AesNI_ErrorDetails* err_details)
+{
+    AesNI_StatusCode status = AESNI_SUCCESS;
+
+    AesNI_BoxBlock ciphertext;
+
+    if (aesni_is_error(status = box->algorithm->load_block(
+            &ciphertext, src, err_details)))
+        return status;
+
+    AesNI_BoxBlock plaintext;
+
+    if (aesni_is_error(status = aesni_box_decrypt_block(
+            box, &ciphertext, &plaintext, err_details)))
+        return status;
+
+    if (aesni_is_error(status = box->algorithm->store_block(
+            dest, &plaintext, err_details)))
+        return status;
+
+    return status;
+}
+
+AesNI_StatusCode aesni_box_decrypt_buffer(
+    AesNI_Box* box,
+    const void* src,
+    size_t src_size,
+    void* dest,
+    size_t* dest_size,
+    AesNI_ErrorDetails* err_details)
+{
+    if (box == NULL)
+        return aesni_error_null_argument(err_details, "box");
+    if (dest_size == NULL)
+        return aesni_error_null_argument(err_details, "dest_size");
+
+    AesNI_StatusCode status = AESNI_SUCCESS;
+    size_t padding_size = 0;
+
+    if (aesni_is_error(status = aesni_box_get_decrypted_buffer_size(
+            box, src_size, dest_size, &padding_size, err_details)))
+        return status;
+
+    if (dest == NULL)
+        return AESNI_SUCCESS;
+    if (src == NULL)
+        return aesni_error_null_argument(err_details, "src");
+
+    size_t block_size;
+
+    if (aesni_is_error(status = box->algorithm->get_block_size(
+            &block_size, err_details)))
+        return status;
+
+    const size_t src_len = src_size / block_size;
+
+    for (size_t i = 0; i < src_len; ++i, (char*) src += block_size, (char*) dest += block_size)
+        if (aesni_is_error(status = aesni_box_decrypt_buffer_block(
+                box, src, dest, err_details)))
+            return status;
+
+    if (padding_size == 0)
+    {
+        const size_t partial_block_size = src_size % block_size;
+
+        if (partial_block_size != 0)
+        {
+            AesNI_BoxBlock ciphertext;
+
+            if (aesni_is_error(status = box->algorithm->load_partial_block(
+                    &ciphertext, src, partial_block_size, err_details)))
+                return status;
+
+            AesNI_BoxBlock plaintext;
+
+            if (aesni_is_error(status = aesni_box_decrypt_block(
+                    box, &ciphertext, &plaintext, err_details)))
+                return status;
+
+            if (aesni_is_error(status = box->algorithm->store_partial_block(
+                    dest, &plaintext, partial_block_size, err_details)))
+                return status;
+        }
+    }
+    else
+    {
+        padding_size = ((unsigned char*) dest)[-1];
+
+        if (padding_size > block_size)
+            return aesni_error_invalid_pkcs7_padding(err_details);
+
+        for (size_t i = 1; i < padding_size; ++i)
+            if (((unsigned char*) dest)[0 - i] != padding_size)
+                return aesni_error_invalid_pkcs7_padding(err_details);
+
+        *dest_size -= padding_size;
+    }
+
+    return status;
+}