independent of one another." The principle is practiced in the NSA's secure mobile phone called Fishbowl. The phones use two layers of encryption protocols, IPsec and Secure Real-time Transport Protocol (SRTP), to protect voice communications. The Samsung Galaxy S9 Tactical Edition is also an approved CSfC Component. Examples The figure shows from inside to outside the process of how the encrypted capsule is formed in the context of Echo Protocol, used by the Software Application GoldBug Messenger. GoldBug has implemented a hybrid system for authenticity and confidentiality. First layer of the encryption: The ciphertext of the original readable message is hashed, and subsequently the symmetric keys are encrypted via the asymmetric key - e.g. deploying the algorithm RSA. In an intermediate step the ciphertext, and the hash digest of the ciphertext are combined into a capsule, and packed together. It follows the approach: Encrypt-then-MAC. In order for the receiver to verify that the ciphertext has not been tampered with, the digest is computed before the ciphertext is decrypted. Second layer of encryption: Optionally it is still possible, therefore to encrypt the capsule of the first layer in addition with an AES-256, - comparable to a commonly shared, 32-character long symmetric password. Hybrid Encryption is then added to multiple encryption. Third layer of the encryption: Then, this capsule is transmitted via a secure SSL/TLS connection to the communication partner References Further reading "Multiple encryption" in "Ritter's Crypto Glossary and Dictionary of Technical Cryptography" Confidentiality through Multi-Encryption, in: Adams, David / Maier, Ann-Kathrin (2016): BIG SEVEN Study, open source crypto-messengers to be compared - or: Comprehensive Confidentiality Review & Audit of GoldBug, Encrypting E-Mail-Client & Secure Instant Messenger, Descriptions, tests and analysis reviews of 20 functions of the application GoldBug based on the essential fields and methods of evaluation of the 8 major international audit manuals for IT security investigations including 38 figures and 87 tables., URL: https://sf.net/projects/goldbug/files/bigseven-crypto-audit.pdf - English / German Language, Version 1.1, 305 pages, June 2016 (ISBN: DNB 110368003X - 2016B14779). A "way to combine multiple block algorithms" so that "a cryptanalyst must break both algorithms" in §15.8 of Applied Cryptography, Second Edition: Protocols, Algorithms, and Source Code in C by Bruce Schneier. Wiley Computer Publishing, John Wiley & Sons, Inc. S. Even and O. Goldreich, On the power of cascade ciphers, ACM Transactions on Computer Systems, vol. 3, pp. 108–116, 1985. M. Maurer and J. L. Massey, Cascade