A5.3 Decryptor

The confidentiality and security of GSM cellular telephony is safeguarded by the A5 Group of cryptosystems. The 1st two affiliates of this family, A5.1 and A5.2 were proposed in the late 1980’s in an opaque procedure and were saved as a secret until they were reverse engineered in 1999 from original handsets. Subsequently in 2002, the A5.3 algorithm was established for Third Generation GSM telephony, and its requirements were circulated in 2003.

Moreover, it is important to note that the usage of various encryption algorithms, A5.1, A5.2 and A5.3 by GSM, makes the task for the LEAs more difficult. Thus, if any LEA must intercept the GSM communications and ideally A5.3 Decryptors would be required to decrypt the communications.

What is an A5.3 Decryptor and how does it work?


Generating two 114-bit keystream series, The GSM A5.3 algorithm utilizes one for uplink encryption/decryption and the other for downlink. A5.3 encryption is also referred to as Kasumi, is a block cipher utilized to encode communications on 3G wireless networks.

Ideally, to decode GSM communications by utilizing A5.3 encryption algorithm, an A5.3 Decryptor is required. However, the use of 128 bit encryption makes it impossible to decode it in real time with standard computational devices. Hence a different technique is used to break the GSM cell phone communication which uses Kasumi encryption algorithm.
The interception solutions in such cases uses active techniques wherein the phones using A5.3 encryption algorithms are pushed to lower levels of encryption such as A5.1 or A5.2 and then are decrypted using their respective decrypting solutions. Thus, the need for having a A5.3 Decryptor is obviated. Stratign has multiple solutions to intercept cell phone communications.

The GSM Monitoring Solutions from Stratign: Cell Phone Interceptors

The Mobile-phone Interceptor equipment from Stratign is employed for GSM interception to gather intelligence on criminals and terrorists. It is not obligatory to possess a hard-wired link to the cellular supplier. This is because the GSM Interceptor can oversee GSM signals, off-the-air.

These Mobile Phone Interceptors from Stratign can detect the GSM communications using A5.1/A5.2 or A5.3 encryption keys used for communications almost instantly, permitting the user to track and evaluate the actions of suspected terrorists & criminals.

1. Semi-Active Cell Phone Interceptor System


To capture Voice and SMS from mobile phone network without obtaining any help from service provider, Stratign advocates their off-the-air GSM monitoring system which is built to monitor voice and SMS along with call-oriented data from any GSM network operating in bands – 2G/3G/4G(LTE)/5G bands. Additionally, it is primarily useful to prevent & offset criminal actions of the targets, to disorder criminal group activity and to employ several tasks in fighting against terrorism. The system will permit you to monitor 4/6/12/16/32 mobile phones, all at once from any multiple service providers (configurable).

2. Passive Cell Phone Interceptor System


The mobile phone Monitoring System is a multi-channel Interception system which can be tuned and used to intercept communications, all over the world from any service provider. The system can ensure monitoring and decoding of voice conversation from the universal 2G/3G/4G/5G Cellular networks in a static or mobile environment. The intercepted voice calls, SMS’s & protocol information on the control PC hard drive are compressed & collected by the system. It has user-friendly interfaces, which permits the user to operate numerous kinds of tasks, to offer the system control while its being operated. The system can be configured to monitor 4/6/12/16/32 duplex transmissions.

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