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author | Wim <wim@42.be> | 2022-01-31 00:27:37 +0100 |
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committer | Wim <wim@42.be> | 2022-03-20 14:57:48 +0100 |
commit | e3cafeaf9292f67459ff1d186f68283bfaedf2ae (patch) | |
tree | b69c39620aa91dba695b3b935c6651c0fb37ce75 /vendor/go.mau.fi/whatsmeow/util/cbcutil/cbc.go | |
parent | e7b193788a56ee7cdb02a87a9db0ad6724ef66d5 (diff) | |
download | matterbridge-msglm-e3cafeaf9292f67459ff1d186f68283bfaedf2ae.tar.gz matterbridge-msglm-e3cafeaf9292f67459ff1d186f68283bfaedf2ae.tar.bz2 matterbridge-msglm-e3cafeaf9292f67459ff1d186f68283bfaedf2ae.zip |
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.go | 101 |
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 index 00000000..05fa8577 --- /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 +} |