Module crypto 

Re-exports

pub use chachapoly::wipe;

pub use chachapoly::wipe_vec;

pub use guarded_key::GuardedKey;

pub use crate::simd::image::nearest_neighbor_downsample_rgba;

Modules

chachapoly

ChaCha20-Poly1305 (RFC 8439), tuned for many short messages.

gcm

AES-256-GCM with a 16-byte nonce and no associated data: the attachment cipher (0xChat-compatible). A stitched AES-NI/PCLMULQDQ engine where it has been measured to win, RustCrypto’s ctr + ghash everywhere else; both produce the same bytes.

guarded_key

Memory-hardened key storage: 128 indistinguishable arrays with decoy writes.

sha256

SHA-256 for bulk data: attachments, files and blobs.

stream

Attachment AES-256-GCM over a file, a chunk at a time: the cipher of super::decrypt_data (16-byte nonce, 16-byte tag appended) without the file ever sitting whole in memory.

Structs

AtRestOpener

The per-string half of open_batch; the vault is read at the first ciphertext, so a batch of plaintext rows never touches it.

EncryptionParams

Parameters for AES-256-GCM file encryption (hex-encoded key + nonce).

GuardedSigner

A signer backed by the MY_SECRET_KEY vault.

Constants

RECOGNISED_MIMES

Detect MIME type from file magic bytes. Supports PNG, JPEG, GIF, WebP, TIFF, ICO, and SVG. Returns “application/octet-stream” for unrecognized formats. Every type mime_from_magic_bytes can name.

Functions

attachment_identity_basis

Identity basis for a RECEIVED attachment: the sender’s ox (plaintext hash) when provided — it’s what enables honest cross-message dedup — else a digest of nonce+url. Never the raw nonce: senders can and do reuse nonces, which cross-bound DIFFERENT files to one identity (the “new image renders as an old one” class). The upload URL is unique per ciphertext, so the digest is collision-resistant even against nonce reuse. Nothing honest ever writes a file under the digest name, so existence of one is never proof of download — reuse decisions stay with the content-verified download path.

bounded_image_limits

Shared decode limits for decode_image_bounded and call sites that need their own ImageReader (fixed-format decodes).

decode_image_bounded

Decode an image with allocation limits. A tiny file declaring 60000×60000 would otherwise allocate ~14 GB before a single pixel decodes — every decode of bytes we didn’t author must go through this.

decrypt_and_save_attachment

Decrypt a DM file attachment and save to the download directory.

decrypt_and_save_attachment_owned

decrypt_and_save_attachment for a caller that owns the download: it is decrypted in place rather than copied first.

decrypt_blob_with_key

ChaCha20-Poly1305 decrypt nonce(12) || ct || tag(16) with an explicit key.

decrypt_data

Decrypt data with AES-256-GCM using a 16-byte nonce (0xChat-compatible). Input format: ciphertext || 16-byte auth tag.

decrypt_data_owned

decrypt_data in place, for a caller that owns the ciphertext: the plaintext comes back in the same allocation, so nothing the size of the file is copied.

decrypt_with_key

Decrypt a hex-encoded ChaCha20-Poly1305 ciphertext with an explicit key.

encrypt_blob_with_key

ChaCha20-Poly1305 encrypt raw bytes with an explicit key → nonce(12) || ct || tag(16).

encrypt_data

Encrypt data with AES-256-GCM using a 16-byte nonce (0xChat-compatible).

encrypt_with_key

Encrypt a string with an explicit key (ChaCha20-Poly1305), hex nonce || ct || tag.

extension_from_mime

Convert a MIME type to a file extension. Falls back to using the MIME subtype when unknown.

format_bytes

Format bytes into human-readable format (KB, MB, GB).

generate_encryption_params

Generate random AES-256-GCM encryption parameters.

generate_image_metadata

Generate image metadata (thumbhash + dimensions) from raw file bytes.

generate_thumbhash_from_rgba

Generate a thumbhash from RGBA8 pixel data.

hash_pass

Derive a 32-byte key from a password using Argon2id. Parameters: 150MB memory, 10 iterations (matches src-tauri).

is_encryption_enabled

Check if encryption is enabled in the database.

is_image_mime

Returns true if the provided MIME type is an image/*.

looks_encrypted

Check if a string looks like encrypted content (hex-encoded ChaCha20 output). Minimum (empty message): 12 + 0 + 16 = 28 bytes = 56 hex chars.

maybe_decrypt

Conditionally decrypt content. Handles crash recovery — if decryption fails on non-encrypted-looking content, returns it as-is.

maybe_decrypt_blob

Decrypt a secret key BLOB. Tolerant of the half-migrated DB: a 32-byte value is a raw (not-yet-wrapped / encryption-off) key, and anything that fails to authenticate is returned as-is, so a mixed store always reads back correctly.

maybe_decrypt_inner

Decrypt a hex-encoded ChaCha20-Poly1305 ciphertext using ENCRYPTION_KEY vault. If password is Some, derives a key from it instead.

maybe_decrypt_text

Decrypt a text field. A value that doesn’t look encrypted (or can’t be decrypted) is returned as-is — pre-migration rows and encryption-off rows.

maybe_encrypt

Conditionally encrypt content based on encryption_enabled setting.

maybe_encrypt_blob

Encrypt a secret key BLOB for at-rest storage. Off → unchanged. Enabled but the vault is empty → Err (never silently persists a secret in plaintext).

maybe_encrypt_inner

Encrypt a string using ENCRYPTION_KEY vault (ChaCha20-Poly1305). If password is Some, derives a key from it instead.

maybe_encrypt_text

Encrypt a text field for at-rest storage. Off → unchanged. Enabled but the vault is empty → Err.

mime_from_extension

Get MIME type from file extension.

mime_from_extension_safe

Convert a file extension to a MIME type, with an optional restriction to image/* types.

mime_from_magic_bytes

open_batch

Opens many at-rest strings for one vault read and one key schedule, where maybe_decrypt pays both per string (the vault read is nearly all of it). Sync, and the opener cannot leave the closure, so the key never crosses an await.

resolve_unique_filename

Resolve a unique filename in dir, appending -1, -2, etc. on collision.

sanitize_filename

Sanitize a filename for safe filesystem use. Strips path traversal, dangerous characters, and truncates to 64-char stem.

sha256_hex

Calculate SHA-256 hash of data, returned as hex string.