Authenticated file encryption in the browser. The server receives neither the passphrase nor plaintext.
New files use BlindCrypt format v3. The public header, encrypted metadata, record order, record lengths, and every ciphertext record are authenticated.
Drop files here, or use the file picker. Up to 100 files and 64 MiB combined.
Maximum plaintext size: 64 MiB. The limit controls browser memory exposure.
Enter a passphrase or generate one.
Store the passphrase before encryption. BlindCrypt has no recovery mechanism.
Format v3 verifies the complete container before download. Legacy v1 and v2 files remain readable with explicit limitations.
Drop files here. Buffered decryption supports 64 MiB combined; verification supports individual v3 files up to 4 GiB.
Malformed sizes, excessive KDF settings, inconsistent records, truncation, and trailing data are rejected before costly processing where possible.
Format v3 applies NFC normalization. Legacy formats use the passphrase exactly as entered.
Messages use authenticated v3 encryption in a versioned text envelope. Limit: 64 KiB of UTF-8. Share the passphrase separately. Text is never rendered as HTML.
Strong settings. Generated passphrases are temporarily visible. Store one separately before confirming it. All secret fields clear after an operation.
Create a new v3 copy with a new passphrase or settings. No intermediate plaintext download. Limit: 64 MiB. This does not revoke old copies or establish missing legacy authenticity.
Legacy files otherwise restore as legacy-decrypted.bin. Keep your original encrypted copy until you have verified the replacement.
Up to 4 GiB, using 512 KiB records and a transactional save stream. Requires a browser with a local save-file picker. Other browsers retain the 64 MiB workflow above; the CLI is another option.
Choose a new output file. Decrypted bytes may be staged temporarily on disk; the destination is committed only after complete authentication. Cancellation cannot guarantee secure erasure of operating-system temporary files. Older BlindCrypt versions cannot open files beyond their 64 MiB limit.
Single-recipient JWE using RSA-OAEP-256 and AES-256-GCM. Limit: 16 MiB. This authenticates encrypted content, not the sender. New implementation: no independent cryptographic audit is claimed.
Keep the encrypted .bckey backup and its passphrase private. Only share the public .json file and independently confirm its fingerprint. Allow both downloads.
A fingerprint copied only from the same untrusted key file does not verify the recipient.
Review the repository threat model and format specification before using BlindCrypt for high-value data.
Cancellation takes effect between cryptographic operations. Batch downloads may require browser permission for multiple files.
Offline edition not enabled. No user files or secrets are cached.