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SIM cards are secure element (SE) which is tamper-resistant amd tamper-evident by design. The PIN code is stored in SE's isolated storage inaccessible from outside. SIM only responds if entered PIN is right or wrong. Three incorrect PIN attempts disable PIN verification. To reset PIN and PIN tries, 8-digit PIN Unlock Code(PUC) is required which also has 3 ...


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This is simply a number pad implementation of the plain old original scytale. Using the number 5 key on the pad instead of a rod. It's a basic substitution cipher. Was the TV show the first to use the number pad in this way? I cannot answer that. I doubt it.


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TL;DR: Secrets are reused, but encryption keys are not reused. With TLS 1.2 and lower the master secret was reused though and the encryption keys were derived from this. But this key derivation includes connection specific random data, so the keys are specific for the connection and not for all reuses of the same session. Knowledge of master secret (for ...


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Key splitting (best case scenario) The ideal cryptographic algorithm for this purpose is Shamir's Secret Sharing, as it provides Information theoretical security, meaning it's mathematically impossible to recover the actual key without having the k number of shares specified by the person splitting the key. We don't know how many shares are needed, and/or if ...


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WRT, "I am unable to generate and use an aes-256-gcm key in openssl": Understand that openssl genrsa is used to generate an asymmetric RSA key pair. openssl genrsa is not used to generate a symmetric AES key. The -aesxxx option that you are trying to use with the openssl genrsa command does not change the type of key that openssl genrsa generates. ...


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[Sorry in advance for the long explanation, but you've asked good questions about a complex topic.] Asymmetric encryption uses a keypair consisting of a public and private key; each pair of keys are generated together at the same time. Asymmetric means "not the same". In cryptography, we use it to mean "What the public key of a keypair ...


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Media attachments are shared and forwarded more frequently to multiple recepients than messages. If retention period is small, the attachment has to be reuploaded by the sender. Sender encrypts media elements with AES-CBC-256 key and uploads it to the server. The sender encrypts the key and the URL and sends it to the recepient. If the sender and recepients ...


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It explains what it means. It's not storing messages it is storing media. Since transmitting media can take a lot of bandwidth, it is better and easier for everyone if there can be a copy that is cached somewhere for lowered traffic needs and faster access. If a lot of people in the group and accessing, downloading, and playing that media over a long period ...


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