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authorWim <wim@42.be>2022-01-31 00:27:37 +0100
committerWim <wim@42.be>2022-03-20 14:57:48 +0100
commite3cafeaf9292f67459ff1d186f68283bfaedf2ae (patch)
treeb69c39620aa91dba695b3b935c6651c0fb37ce75 /vendor/go.mau.fi/whatsmeow/util/cbcutil/cbc.go
parente7b193788a56ee7cdb02a87a9db0ad6724ef66d5 (diff)
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Add dependencies/vendor (whatsapp)
Diffstat (limited to 'vendor/go.mau.fi/whatsmeow/util/cbcutil/cbc.go')
-rw-r--r--vendor/go.mau.fi/whatsmeow/util/cbcutil/cbc.go101
1 files changed, 101 insertions, 0 deletions
diff --git a/vendor/go.mau.fi/whatsmeow/util/cbcutil/cbc.go b/vendor/go.mau.fi/whatsmeow/util/cbcutil/cbc.go
new file mode 100644
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--- /dev/null
+++ b/vendor/go.mau.fi/whatsmeow/util/cbcutil/cbc.go
@@ -0,0 +1,101 @@
+/*
+CBC describes a block cipher mode. In cryptography, a block cipher mode of operation is an algorithm that uses a
+block cipher to provide an information service such as confidentiality or authenticity. A block cipher by itself
+is only suitable for the secure cryptographic transformation (encryption or decryption) of one fixed-length group of
+bits called a block. A mode of operation describes how to repeatedly apply a cipher's single-block operation to
+securely transform amounts of data larger than a block.
+
+This package simplifies the usage of AES-256-CBC.
+*/
+package cbcutil
+
+/*
+Some code is provided by the GitHub user locked (github.com/locked):
+https://gist.github.com/locked/b066aa1ddeb2b28e855e
+Thanks!
+*/
+import (
+ "bytes"
+ "crypto/aes"
+ "crypto/cipher"
+ "crypto/rand"
+ "fmt"
+ "io"
+)
+
+/*
+Decrypt is a function that decrypts a given cipher text with a provided key and initialization vector(iv).
+*/
+func Decrypt(key, iv, ciphertext []byte) ([]byte, error) {
+ block, err := aes.NewCipher(key)
+
+ if err != nil {
+ return nil, err
+ }
+
+ if len(ciphertext) < aes.BlockSize {
+ return nil, fmt.Errorf("ciphertext is shorter then block size: %d / %d", len(ciphertext), aes.BlockSize)
+ }
+
+ if iv == nil {
+ iv = ciphertext[:aes.BlockSize]
+ ciphertext = ciphertext[aes.BlockSize:]
+ }
+
+ cbc := cipher.NewCBCDecrypter(block, iv)
+ cbc.CryptBlocks(ciphertext, ciphertext)
+
+ return unpad(ciphertext)
+}
+
+/*
+Encrypt is a function that encrypts plaintext with a given key and an optional initialization vector(iv).
+*/
+func Encrypt(key, iv, plaintext []byte) ([]byte, error) {
+ plaintext = pad(plaintext, aes.BlockSize)
+
+ if len(plaintext)%aes.BlockSize != 0 {
+ return nil, fmt.Errorf("plaintext is not a multiple of the block size: %d / %d", len(plaintext), aes.BlockSize)
+ }
+
+ block, err := aes.NewCipher(key)
+ if err != nil {
+ return nil, err
+ }
+
+ var ciphertext []byte
+ if iv == nil {
+ ciphertext = make([]byte, aes.BlockSize+len(plaintext))
+ iv := ciphertext[:aes.BlockSize]
+ if _, err := io.ReadFull(rand.Reader, iv); err != nil {
+ return nil, err
+ }
+
+ cbc := cipher.NewCBCEncrypter(block, iv)
+ cbc.CryptBlocks(ciphertext[aes.BlockSize:], plaintext)
+ } else {
+ ciphertext = make([]byte, len(plaintext))
+
+ cbc := cipher.NewCBCEncrypter(block, iv)
+ cbc.CryptBlocks(ciphertext, plaintext)
+ }
+
+ return ciphertext, nil
+}
+
+func pad(ciphertext []byte, blockSize int) []byte {
+ padding := blockSize - len(ciphertext)%blockSize
+ padtext := bytes.Repeat([]byte{byte(padding)}, padding)
+ return append(ciphertext, padtext...)
+}
+
+func unpad(src []byte) ([]byte, error) {
+ length := len(src)
+ padLen := int(src[length-1])
+
+ if padLen > length {
+ return nil, fmt.Errorf("padding is greater then the length: %d / %d", padLen, length)
+ }
+
+ return src[:(length - padLen)], nil
+}