2 files changed, 206 insertions, 0 deletions
diff --git a/vendor/go.mau.fi/libsignal/cipher/Cbc.go b/vendor/go.mau.fi/libsignal/cipher/Cbc.go
new file mode 100644
index 00000000..6a6db5df
--- /dev/null
+++ b/vendor/go.mau.fi/libsignal/cipher/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 cipher
+
+/*
+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 DecryptCbc(iv, key, 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 EncryptCbc(iv, key, 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
+}
diff --git a/vendor/go.mau.fi/libsignal/cipher/Cipher.go b/vendor/go.mau.fi/libsignal/cipher/Cipher.go
new file mode 100644
index 00000000..edfb428f
--- /dev/null
+++ b/vendor/go.mau.fi/libsignal/cipher/Cipher.go
@@ -0,0 +1,105 @@
+// Package cipher is a package for common encrypt/decrypt of symmetric key messages.
+package cipher
+
+import (
+	"bytes"
+	"crypto/aes"
+	"crypto/cipher"
+	"errors"
+)
+
+// Decrypt will use the given key, iv, and ciphertext and return
+// the plaintext bytes.
+func Decrypt(iv, key, ciphertext []byte) ([]byte, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+	if len(ciphertext) < aes.BlockSize {
+		return nil, errors.New("ciphertext too short")
+	}
+	cbc := cipher.NewCBCDecrypter(block, iv)
+	cbc.CryptBlocks(ciphertext, ciphertext)
+
+	unpaddedText, err := pkcs7Unpad(ciphertext, aes.BlockSize)
+	if err != nil {
+		return nil, err
+	}
+
+	return unpaddedText, nil
+}
+
+// Encrypt will use the given iv, key, and plaintext bytes
+// and return ciphertext bytes.
+func Encrypt(iv, key, plaintext []byte) ([]byte, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+	paddedText, err := pkcs7Pad(plaintext, block.BlockSize())
+	if err != nil {
+		return nil, err
+	}
+	ciphertext := make([]byte, len(paddedText))
+	mode := cipher.NewCBCEncrypter(block, iv)
+	mode.CryptBlocks(ciphertext, paddedText)
+
+	return ciphertext, nil
+}
+
+// PKCS7 padding.
+
+// PKCS7 errors.
+var (
+	// ErrInvalidBlockSize indicates hash blocksize <= 0.
+	ErrInvalidBlockSize = errors.New("invalid blocksize")
+
+	// ErrInvalidPKCS7Data indicates bad input to PKCS7 pad or unpad.
+	ErrInvalidPKCS7Data = errors.New("invalid PKCS7 data (empty or not padded)")
+
+	// ErrInvalidPKCS7Padding indicates PKCS7 unpad fails to bad input.
+	ErrInvalidPKCS7Padding = errors.New("invalid padding on input")
+)
+
+// pkcs7Pad right-pads the given byte slice with 1 to n bytes, where
+// n is the block size. The size of the result is x times n, where x
+// is at least 1.
+func pkcs7Pad(b []byte, blocksize int) ([]byte, error) {
+	if blocksize <= 0 {
+		return nil, ErrInvalidBlockSize
+	}
+	if b == nil || len(b) == 0 {
+		return nil, ErrInvalidPKCS7Data
+	}
+	n := blocksize - (len(b) % blocksize)
+	pb := make([]byte, len(b)+n)
+	copy(pb, b)
+	copy(pb[len(b):], bytes.Repeat([]byte{byte(n)}, n))
+	return pb, nil
+}
+
+// pkcs7Unpad validates and unpads data from the given bytes slice.
+// The returned value will be 1 to n bytes smaller depending on the
+// amount of padding, where n is the block size.
+func pkcs7Unpad(b []byte, blocksize int) ([]byte, error) {
+	if blocksize <= 0 {
+		return nil, ErrInvalidBlockSize
+	}
+	if b == nil || len(b) == 0 {
+		return nil, ErrInvalidPKCS7Data
+	}
+	if len(b)%blocksize != 0 {
+		return nil, ErrInvalidPKCS7Padding
+	}
+	c := b[len(b)-1]
+	n := int(c)
+	if n == 0 || n > len(b) {
+		return nil, ErrInvalidPKCS7Padding
+	}
+	for i := 0; i < n; i++ {
+		if b[len(b)-n+i] != c {
+			return nil, ErrInvalidPKCS7Padding
+		}
+	}
+	return b[:len(b)-n], nil
+}