refactor: naming cleanup and crypto package improvements (#551)

* refactor: naming cleanup across all packages

crypto/errors.go

@@ -0,0 +1,15 @@
+package crypto
+
+import "errors"
+
+// Sentinel errors for crypto operations.
+var (
+	errShortCiphertext   = errors.New("ciphertext too short")
+	errInvalidBlockSize  = errors.New("ciphertext is not a multiple of the block size")
+	errInvalidIVLength   = errors.New("IV length must equal block size")
+	errInvalidPadding    = errors.New("invalid PKCS5 padding")
+	errInvalidNonceLen   = errors.New("nonce length must equal GCM nonce size")
+	errUnsupportedIVLen  = errors.New("unsupported IV length")
+	errDecodeASN1        = errors.New("failed to decode ASN1 data")
+	errDPAPINotSupported = errors.New("DPAPI not supported on this platform") //nolint:unused // used on darwin/linux only
+)