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.svn/pristine/5d/5dca3ad5e01acc3892a93342d49523e7afb43b05.svn-base

@@ -0,0 +1,99 @@
+package securityUtil
+
+import (
+	"bytes"
+	"crypto/aes"
+	"crypto/cipher"
+	"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 b == nil || len(b) == 0 {
+		return nil, ErrInvalidPKCS7Data
+	}
+	if blocksize <= 0 {
+		return nil, ErrInvalidBlockSize
+	}
+	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 b == nil || len(b) == 0 {
+		return nil, ErrInvalidPKCS7Data
+	}
+	if blocksize <= 0 {
+		return nil, ErrInvalidBlockSize
+	}
+	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
+}
+
+func AESEncrypt_CBC_Pkcs7(src []byte, key []byte) ([]byte, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	src, err = pkcs7Pad(src, block.BlockSize())
+	if err != nil {
+		return nil, err
+	}
+
+	blockmode := cipher.NewCBCEncrypter(block, key)
+	blockmode.CryptBlocks(src, src)
+
+	return src, nil
+}
+
+func AESDecrypt_CBC_Pkcs7(src []byte, key []byte) ([]byte, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	blockmode := cipher.NewCBCDecrypter(block, key)
+	blockmode.CryptBlocks(src, src)
+	src, err = pkcs7Unpad(src, block.BlockSize())
+	if err != nil {
+		return nil, err
+	}
+
+	return src, nil
+}