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author | Indrajith K L | 2022-12-03 17:00:20 +0530 |
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committer | Indrajith K L | 2022-12-03 17:00:20 +0530 |
commit | f5c4671bfbad96bf346bd7e9a21fc4317b4959df (patch) | |
tree | 2764fc62da58f2ba8da7ed341643fc359873142f /v_windows/v/old/vlib/crypto/aes/aes_cbc.v | |
download | cli-tools-windows-master.tar.gz cli-tools-windows-master.tar.bz2 cli-tools-windows-master.zip |
Diffstat (limited to 'v_windows/v/old/vlib/crypto/aes/aes_cbc.v')
-rw-r--r-- | v_windows/v/old/vlib/crypto/aes/aes_cbc.v | 126 |
1 files changed, 126 insertions, 0 deletions
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) +} |