How to format a ciphertext
The article explains how to properly format ciphertext for clarity and consistency, covering common conventions such as using base64 encoding, adding prefixes to indicate encryption type, and applying delimiters or line breaks for readability in cryptographic outputs.
Background
Ciphertext is the scrambled, unreadable output of an encryption algorithm (as opposed to "plaintext," the original readable message). While encryption math gets most of the attention, the way a ciphertext is formatted for storage or transmission — its encoding, delimiters, metadata headers, and binary-to-text conversion (e.g., Base64 or hex) — is a separate and often overlooked engineering problem. Good formatting ensures that ciphertexts survive transit through JSON, databases, URLs, and email without corruption or misinterpretation, and that the recipient can reliably determine which algorithm was used (e.g., AES-256-GCM vs. NaCl secretbox) and which nonce or salt goes with it. The post argues that standardized, self-describing ciphertext formats (like the "crypto_box" wire format or JWE) reduce bugs that lead to silent data loss or security failures, and offers practical guidance on choosing or designing one.