Implemented encryption functionality of spc and password generation; refactors on spc and server

crypto/cbc.go

@@ -0,0 +1,99 @@
+package crypto
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"fmt"
+	"io"
+
+	"github.com/cloudflare/redoctober/padding"
+)
+
+func GenerateKeyFromPassword(pass []byte) ([]byte, error) {
+	if len(pass) < 8 {
+		return nil, fmt.Errorf("master password must be at least 8 characters")
+	}
+
+	for idx := 0; len(pass) < 32; idx++ {
+		pass = append(pass, pass[idx])
+
+		if idx == len(pass) {
+			idx = 0
+		}
+	}
+
+	return pass, nil
+}
+
+func CombinePasswordAndKey(pass, key []byte) ([]byte, error) {
+	if len(pass) < 8 {
+		return nil, fmt.Errorf("master password must be at least 8 characters")
+	}
+	if len(key) != 16 {
+		return nil, fmt.Errorf("key was not of length 16")
+	}
+
+	for idx := 0; len(pass) < 16; idx++ {
+		pass = append(pass, pass[idx])
+	}
+
+	return append(pass[:16], key...), nil
+}
+
+func CBCEncrypt(key []byte, plaintext []byte) ([]byte, error) {
+	if len(key) != 32 {
+		return nil, fmt.Errorf("key is not 32 bytes")
+	}
+
+	plaintext = padding.AddPadding(plaintext)
+
+	if len(plaintext)%aes.BlockSize != 0 {
+		return nil, fmt.Errorf("plaintext is not a multiple of the block size")
+	}
+
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	ciphertext := make([]byte, aes.BlockSize+len(plaintext))
+	iv := ciphertext[:aes.BlockSize]
+
+	if _, err := io.ReadFull(rand.Reader, iv); err != nil {
+		return nil, err
+	}
+
+	mode := cipher.NewCBCEncrypter(block, iv)
+	mode.CryptBlocks(ciphertext[aes.BlockSize:], plaintext)
+
+	return ciphertext, nil
+}
+
+func CBCDecrypt(key []byte, ciphertext []byte) ([]byte, error) {
+	if len(key) != 32 {
+		return nil, fmt.Errorf("key is not 32 bytes")
+	}
+
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(ciphertext) < aes.BlockSize {
+		return nil, err
+	}
+
+	iv := ciphertext[:aes.BlockSize]
+
+	ciphertext = ciphertext[aes.BlockSize:]
+
+	if len(ciphertext)%aes.BlockSize != 0 {
+		return nil, fmt.Errorf("ciphertext is not a multiple of the block size")
+	}
+
+	mode := cipher.NewCBCDecrypter(block, iv)
+	mode.CryptBlocks(ciphertext, ciphertext)
+
+	return padding.RemovePadding(ciphertext)
+}