What cellular encryption algorithms are currently in use globally

Question

I want to understand how cellular networks protect communication. What encryption algorithms are used in mobile networks worldwide, and how do they differ between regions or network generations (like 4G, 5G)?

Answer 1

Overview of Cellular Network Encryption

Cellular networks employ encryption to protect both the confidentiality and integrity of user data. The encryption process involves two primary components:

1. Air Interface Encryption: Protects data transmitted between the User Equipment (UE, e.g., your smartphone) and the Base Station (BS).
2. Network Domain Security: Secures data within the core network.

Encryption Algorithms by Network Generation:

2G (GSM)

• A5/1, A5/2, A5/3, A5/4: Stream ciphers used for air interface encryption. A5/1 is widely used but considered insecure due to vulnerabilities.
• Network Domain: Typically, no end-to-end encryption; security relies on the air interface encryption.

3G (UMTS)

• KASUMI (A5/3, A5/4): A block cipher used for air interface encryption, providing better security than A5/1.
• Network Domain: Introduces IPsec for securing the core network.

4G (LTE)

• SNOW 3G, AES (in some implementations for EPS Encryption): Used for air interface encryption.
  • SNOW 3G: A stream cipher, standard for LTE.
  • AES (Advanced Encryption Standard): A block cipher, used in EPS (Evolved Packet System) for core network security and in some cases for air interface.
• Network Domain: IPsec and AES are commonly used for core network security.

5G (NR)

• NEA (Network Encryption Algorithm) 1, 2, and 3, which include:
  • 128-EEA1 and 128-EIA1 (AES-128 in CTR mode for encryption and AES-128 in CMAC mode for integrity): Mandatory for 5G.
  • 256-EEA2 and 256-EIA2 (AES-256 in CTR mode for encryption and AES-256 in CMAC mode for integrity): Optional but recommended for higher security.
• Network Domain: TLS 1.3, IPsec, and AES-256 are used for enhanced core network security.

Regional Variations and Considerations:

• China: Often employs custom or region-specific variants, such as ZUC (a stream cipher) for air interface encryption in some 4G and potentially 5G implementations.
• Europe and Americas: Tend to adhere strictly to global standards like AES for 4G and the NEA algorithms for 5G.
• India: Has mandated the use of A5/4 for 2G, moving towards global standards for newer network generations.