From f5c4671bfbad96bf346bd7e9a21fc4317b4959df Mon Sep 17 00:00:00 2001
From: Indrajith K L
Date: Sat, 3 Dec 2022 17:00:20 +0530
Subject: Adds most of the tools

---
 v_windows/v/old/vlib/crypto/aes/aes_cbc.v | 126 ++++++++++++++++++++++++++++++
 1 file changed, 126 insertions(+)
 create mode 100644 v_windows/v/old/vlib/crypto/aes/aes_cbc.v

(limited to 'v_windows/v/old/vlib/crypto/aes/aes_cbc.v')

diff --git a/v_windows/v/old/vlib/crypto/aes/aes_cbc.v b/v_windows/v/old/vlib/crypto/aes/aes_cbc.v
new file mode 100644
index 0000000..253f79c
--- /dev/null
+++ b/v_windows/v/old/vlib/crypto/aes/aes_cbc.v
@@ -0,0 +1,126 @@
+// Copyright (c) 2019-2021 Alexander Medvednikov. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
+// Cipher block chaining (CBC) mode.
+// CBC provides confidentiality by xoring (chaining) each plaintext block
+// with the previous ciphertext block before applying the block cipher.
+// See NIST SP 800-38A, pp 10-11
+// NOTE this will be moved to crypto.cipher interface (joe-c)
+module aes
+
+import crypto.cipher
+import crypto.internal.subtle
+
+struct AesCbc {
+mut:
+	b          AesCipher
+	block_size int
+	iv         []byte
+	tmp        []byte
+}
+
+// internal
+fn new_aes_cbc(b AesCipher, iv []byte) AesCbc {
+	return AesCbc{
+		b: b
+		block_size: b.block_size()
+		iv: iv.clone()
+		tmp: []byte{len: (b.block_size())}
+	}
+}
+
+// new_cbc returns a `AesCbc` which encrypts in cipher block chaining
+// mode, using the given Block. The length of iv must be the same as the
+// Block's block size.
+pub fn new_cbc(b AesCipher, iv []byte) AesCbc {
+	if iv.len != b.block_size() {
+		panic('crypto.cipher.new_cbc_encrypter: IV length must equal block size')
+	}
+	return new_aes_cbc(b, iv)
+}
+
+// block_size returns the block size of the checksum in bytes.
+pub fn (x &AesCbc) block_size() int {
+	return x.block_size
+}
+
+// encrypt_blocks encrypts the blocks in `src_` to `dst_`.
+// Please note: `dst_` is mutable for performance reasons.
+pub fn (x &AesCbc) encrypt_blocks(mut dst_ []byte, src_ []byte) {
+	unsafe {
+		mut dst := *dst_
+		mut src := src_
+		if src.len % x.block_size != 0 {
+			panic('crypto.cipher: input not full blocks')
+		}
+		if dst.len < src.len {
+			panic('crypto.cipher: output smaller than input')
+		}
+		if subtle.inexact_overlap(dst[..src.len], src_) {
+			panic('crypto.cipher: invalid buffer overlap')
+		}
+		mut iv := x.iv
+		for src.len > 0 {
+			// Write the xor to dst, then encrypt in place.
+			cipher.xor_bytes(mut dst[..x.block_size], src[..x.block_size], iv)
+			x.b.encrypt(mut dst[..x.block_size], mut dst[..x.block_size])
+			// Move to the next block with this block as the next iv.
+			iv = dst[..x.block_size]
+			if x.block_size >= src.len {
+				src = []
+			} else {
+				src = src[x.block_size..]
+			}
+			dst = dst[x.block_size..]
+		}
+		// Save the iv for the next crypt_blocks call.
+		copy(x.iv, iv)
+	}
+}
+
+// decrypt_blocks decrypts the blocks in `src` to `dst`.
+// Please note: `dst` is mutable for performance reasons.
+pub fn (mut x AesCbc) decrypt_blocks(mut dst []byte, src []byte) {
+	if src.len % x.block_size != 0 {
+		panic('crypto.cipher: input not full blocks')
+	}
+	if dst.len < src.len {
+		panic('crypto.cipher: output smaller than input')
+	}
+	if subtle.inexact_overlap((*dst)[..src.len], src) {
+		panic('crypto.cipher: invalid buffer overlap')
+	}
+	if src.len == 0 {
+		return
+	}
+	// For each block, we need to xor the decrypted data with the previous block's ciphertext (the iv).
+	// To avoid making a copy each time, we loop over the blocks BACKWARDS.
+	mut end := src.len
+	mut start := end - x.block_size
+	mut prev := start - x.block_size
+	// Copy the last block of ciphertext in preparation as the new iv.
+	copy(x.tmp, src[start..end])
+	// Loop over all but the first block.
+	for start > 0 {
+		mut src_chunk := src[start..end]
+		x.b.decrypt(mut (*dst)[start..end], mut src_chunk)
+		cipher.xor_bytes(mut (*dst)[start..end], (*dst)[start..end], src[prev..start])
+		end = start
+		start = prev
+		prev -= x.block_size
+	}
+	// The first block is special because it uses the saved iv.
+	mut src_chunk := src[start..end]
+	x.b.decrypt(mut (*dst)[start..end], mut src_chunk)
+	cipher.xor_bytes(mut (*dst)[start..end], (*dst)[start..end], x.iv)
+	// Set the new iv to the first block we copied earlier.
+	x.iv = x.tmp
+	x.tmp = x.iv
+}
+
+fn (x &AesCbc) set_iv(iv []byte) {
+	if iv.len != x.iv.len {
+		panic('cipher: incorrect length IV')
+	}
+	copy(x.iv, iv)
+}
-- 
cgit v1.2.3