mirror of https://github.com/coder/coder.git
99 lines
2.5 KiB
Go
99 lines
2.5 KiB
Go
package dbcrypt
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import (
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"crypto/aes"
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"crypto/cipher"
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"crypto/rand"
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"crypto/sha256"
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"fmt"
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"io"
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"golang.org/x/xerrors"
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)
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// cipherAES256GCM is the name of the AES-256 cipher.
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// This is used to identify the cipher used to encrypt a value.
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// It is added to the digest to ensure that if, in the future,
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// we add a new cipher type, and a key is re-used, we don't
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// accidentally decrypt the wrong values.
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// When adding a new cipher type, add a new constant here
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// and ensure to add the cipher name to the digest of the new
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// cipher type.
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const (
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cipherAES256GCM = "aes256gcm"
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)
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type Cipher interface {
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Encrypt([]byte) ([]byte, error)
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Decrypt([]byte) ([]byte, error)
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HexDigest() string
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}
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// NewCiphers is a convenience function for creating multiple ciphers.
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// It currently only supports AES-256-GCM.
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func NewCiphers(keys ...[]byte) ([]Cipher, error) {
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var cs []Cipher
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for _, key := range keys {
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c, err := cipherAES256(key)
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if err != nil {
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return nil, err
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}
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cs = append(cs, c)
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}
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return cs, nil
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}
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// cipherAES256 returns a new AES-256 cipher.
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func cipherAES256(key []byte) (*aes256, error) {
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if len(key) != 32 {
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return nil, xerrors.Errorf("key must be 32 bytes")
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}
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block, err := aes.NewCipher(key)
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if err != nil {
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return nil, err
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}
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aead, err := cipher.NewGCM(block)
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if err != nil {
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return nil, err
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}
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// We add the cipher name to the digest to ensure that if, in the future,
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// we add a new cipher type, and a key is re-used, we don't accidentally
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// decrypt the wrong values.
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toDigest := []byte(cipherAES256GCM)
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toDigest = append(toDigest, key...)
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digest := fmt.Sprintf("%x", sha256.Sum256(toDigest))[:7]
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return &aes256{aead: aead, digest: digest}, nil
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}
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type aes256 struct {
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aead cipher.AEAD
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// digest is the first 7 bytes of the hex-encoded SHA-256 digest of aead.
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digest string
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}
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func (a *aes256) Encrypt(plaintext []byte) ([]byte, error) {
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nonce := make([]byte, a.aead.NonceSize())
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_, err := io.ReadFull(rand.Reader, nonce)
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if err != nil {
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return nil, err
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}
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dst := make([]byte, len(nonce))
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copy(dst, nonce)
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return a.aead.Seal(dst, nonce, plaintext, nil), nil
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}
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func (a *aes256) Decrypt(ciphertext []byte) ([]byte, error) {
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if len(ciphertext) < a.aead.NonceSize() {
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return nil, xerrors.Errorf("ciphertext too short")
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}
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decrypted, err := a.aead.Open(nil, ciphertext[:a.aead.NonceSize()], ciphertext[a.aead.NonceSize():], nil)
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if err != nil {
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return nil, &DecryptFailedError{Inner: err}
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}
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return decrypted, nil
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}
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func (a *aes256) HexDigest() string {
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return a.digest
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}
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