Cher Ami

Unicode compression, hybrid cryptography and steganography for your messages…


📥 Cher Ami for Windows (strictly regulated export)
📥 Cher Ami for Android (strictly regulated export)
also with UI in English.

The Cher Ami cipher is undergoing extended export-control procedures regarding (“dual-use” and) cryptography regulations in some foreign markets.

Copies of the app may be ordered only via email and are delivered only on the territory of Bulgaria.

Leaving the front door unlocked for you...

Encode as Stego

The newest edition of the app offers a convenient and secure way to compress and encrypt short texts and to exchange cryptographic keys. It fulfills the predominant role of a modern Enigma machine and complements the popular text-messaging systems with decentralized end-to-end content confidentiality. An empowering synergy of Unicode compression, hybrid cryptography, steganography, privacy…

No registration, no special permissions, no ads, no additional costs…

Purpose

Cher Ami is designed for privacy connoisseurs, travelers, celebrities and eloquent users of high social status at any age. If your statements are more important than the policies and glitches of the underlying communication system, this app is also for you. Mitigate the effects of data leaks and cyberstalking; autonomously shorten, protect and conceal your messages on Facebook/Metaverse platforms, Twitter, LinkedIn, Gmail and others; cover the holders of the decryption keys by publishing your ciphertexts… Even idle the Cher Ami cipher is a symbol of well-cultivated confidentiality.

Primary Features

  • Text compression.
  • Text encryption.
  • Local keystore.
  • Payload generation for secure key exchange via text messaging.
  • Diverse encodings.
  • Integrated text editor.

Encoding Capabilities

Cher Ami will sanitize and recode your Unicode texts from/to 5 other character sets:
• Steganography – zero-width glyphs;
• Emoji – subset of Emoji v.5.0 pictograms;
• SMS – chars in 3GPP TS 23.038;
• Base64URL – chars in RFC4648 §5;
• Binary – unpadded radix-2 number.
Max 1000 UTF-16 chars of text, 4280 bits of compressed payloads.

Unlike Other Compressors

Unicode compression with AI-based linguistic predictions; stateless; lossless; next-gen configurability.

On proper Bulgarian and less than 200 chars of English text it achieves up to twice better compression ratios than the popular Brotli compressor lev.9; even better ratios when compared to other industrial HTTP compressors. It doesn’t reuse and is incompatible with third-party compression software.

Compression Benchmarks

How much better is the short-text Unicode compression of Cher Ami when compared to the most popular compressors in this category?!

Key Management

The offered edition can manage an asymmetric key pair and up to 12 local keychains. Each keychain links two symmetric cryptographic secrets:
• 512-bit shared secret – from password-like text input, preshared among the communicating users;
• 512-bit optional exchanged secret – the shared secret ⊕ the result of Diffie-Hellman key exchange between two users.

Hybrid Cryptosystem

Symmetric crypto: combining synchronous stream ciphering and wide-range transposition, no explicit input integrity control; not proposed for other applications to ISO/IEC, NIST, or ENISA; employing fixed key lengths NOT greater than 56 bits (effective length per ciphertext) without parity bits.

Asymmetric crypto: statistically optimal key entropy, a custom MODP DH group, not publicly introduced in any RFC of the IETF; based on the computation of discrete logarithms in a multiplicative group of a finite field of fixed size NOT greater than 512 bits (Diffie-Hellman over Z/pZ).

Secure by design: forward secrecy and backward secrecy; cryptographic algorithms without CVE vulnerabilities, without hardware implementations and with added complexity through compression. Unlike other socially-oriented apps, Cher Ami upgrades the top OSI layer of preexisting security measures and doesn’t expose new attack surfaces against confidentiality. See the outstanding privacy policy as well!

Regulatory Highlights

Offered in compliance with the US Export Administration Regulation and the EU regulation on export.

Enforces your rights to privacy in the spirit of the GDPR, the ePrivacy Directive, the CCPA, and the COPPA.

• The Universal Windows Platform on PC or mobile, Android phones and tablets.
• 1280×720 or greater resolution, or resizable.
• 1GB or more total RAM.
• Quad-core 1.3GHz ARM or faster CPU.

Copyrights.

© 2021 Andrey Dimitrov Mitsov
Independent developer, digital artist, designer, technical writer, as the case may be for the various app contents: Andrey Mitsov. The creative activity determining the copyrights of the author is performed on the territory of the Republic of Bulgaria.
Date of first publishing: 22.01.2021.
FC of ver. 1.0: 2016.
First compression PoC: 2004.

Disclaimer.

This is neither advertising nor a commercial offering. The author may license the use of your copy of the app, but does not sell the app. Cher Ami is provided as a signed installation package, strictly on an ‘as is’ and ‘as available’ basis. This page does not create any obligations for the author.